[Federal Register Volume 86, Number 187 (Thursday, September 30, 2021)]
[Proposed Rules]
[Pages 54298-54338]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2021-21219]
[[Page 54297]]
Vol. 86
Thursday,
No. 187
September 30, 2021
Part II
Department of the Interior
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Fish and Wildlife Service
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50 CFR Part 17
Endangered and Threatened Wildlife and Plants; Removal of 23 Extinct
Species From the Lists of Endangered and Threatened Wildlife and
Plants; Proposed Rule
Federal Register / Vol. 86, No. 187 / Thursday, September 30, 2021 /
Proposed Rules
[[Page 54298]]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FF09E22000 FXES11130900000 201]
RIN 1018-BC98
Endangered and Threatened Wildlife and Plants; Removal of 23
Extinct Species From the Lists of Endangered and Threatened Wildlife
and Plants
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Proposed rule.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to
remove 23 species from the Federal Lists of Endangered and Threatened
Wildlife and Plants due to extinction. This proposal is based on a
review of the best available scientific and commercial information,
which indicates that these species are no longer extant and, as such,
no longer meet the definition of an endangered species or a threatened
species under the Endangered Species Act of 1973, as amended (Act). We
are seeking information and comments from the public regarding this
proposed rule.
DATES: We will accept comments received or postmarked on or before
November 29, 2021. Comments submitted electronically using the Federal
eRulemaking Portal (see ADDRESSES, below) must be received by 11:59
p.m. Eastern Time on the closing date. We must receive requests for a
public hearing, in writing, at the address shown in FOR FURTHER
INFORMATION CONTACT by November 15, 2021.
ADDRESSES: You may submit comments by one of the following methods:
(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter the appropriate docket
number (see table under Public Comments in SUPPLEMENTARY INFORMATION).
Then, click on the Search button. On the resulting page, in the Search
panel on the left side of the screen, under the Document Type heading,
check the Proposed Rule box to locate this document. You may submit a
comment by clicking on ``Comment Now!''
(2) By hard copy: Submit by U.S. mail to: Public Comments
Processing, Attn: [Insert appropriate docket number; see table under
Public Comments in SUPPLEMENTARY INFORMATION], U.S. Fish and Wildlife
Service, MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.
We request that you send comments only by the methods described
above. We will post all comments on http://www.regulations.gov. This
generally means that we will post any personal information you provide
us (see Public Comments, below, for more information).
FOR FURTHER INFORMATION CONTACT:
------------------------------------------------------------------------
Species Contact information
------------------------------------------------------------------------
Bridled white-eye, Kauai akialoa, Kauai Earl Campbell, Field
nukupuu, Kauai `o`o (honeyeater), Supervisor, Pacific Islands
large Kauai thrush (kama), little Fish and Wildlife Office, 808-
Mariana fruit bat, Maui akepa, Maui 792-9400, 300 Ala Moana
nukupuu, Molokai creeper (kakawahie), Boulevard, Suite 3-122,
Phyllostegia glabra var. lanaiensis Honolulu, HI 96850.
(no common name), and po`ouli
(honeycreeper).
Bachman's warbler...................... Thomas McCoy, Field Supervisor,
South Carolina Field Office,
843-300-0431, 176 Croghan
Spur, Charleston, SC 29407.
Flat pigtoe, southern acornshell, Stephen Ricks, Field
stirrupshell, and upland combshell. Supervisor, Mississippi Field
Office, 601-321-1122, 6578
Dogwood View Parkway, Suite A,
Jackson, MS 39213.
Green blossom (pearly mussel), Daniel Elbert, Field
tubercled blossom (pearly mussel), Supervisor, Tennessee Field
turgid blossom (pearly mussel), and Office, 931-528-6481, Interior
yellow blossom (pearly mussel). Region 2--South Atlantic-Gulf
(Tennessee), 446 Neal Street,
Cookeville, TN 38506.
Ivory-billed woodpecker................ Joe Ranson, Field Supervisor,
Louisiana Field Office, 337-
291-3113, 200 Dulles Dr.,
Lafayette, LA 70506.
San Marcos gambusia.................... Adam Zerrenner, Field
Supervisor, Austin Ecological
Services Field Office, 512-490-
0057 (ext. 248), 10711 Burnet
Rd., Suite 200, Austin, Texas
78758.
Scioto madtom.......................... Patrice Ashfield, Field
Supervisor, Ohio Ecological
Services Field Office, 614-416-
8993, 4625 Morse Road, Suite
104, Columbus, OH 43230.
------------------------------------------------------------------------
Persons who use a telecommunications device for the deaf (TDD) may
call the Federal Relay Service at 800-877-8339.
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Section 4 of the Act (16 U.S.C.
1533) and its implementing regulations in title 50 of the Code of
Federal Regulations (50 CFR part 424) set forth the procedures for
adding species to, removing species from, or reclassifying species on
the Federal Lists of Endangered and Threatened Wildlife and Plants
(List or Lists) in 50 CFR part 17. Under our regulations at 50 CFR
424.11(e)(1), a species shall be delisted if, after conducting a status
review based on the best scientific and commercial data available, we
determine that the species is extinct. The 23 species within this
proposed rule are currently listed as endangered or threatened; we are
proposing to delist them due to extinction. We can only delist a
species by issuing a rule to do so.
What this document does. We propose to remove 23 species from the
Lists due to extinction.
The basis for our action. We may determine that a species should be
removed from the List because it no longer meets the definition of an
endangered species or a threatened species, including whether the best
available information indicates that a species is extinct.
Information Requested
Public Comments
We intend that any final rule resulting from this proposal will be
based on the best available scientific and commercial data and will be
as accurate and effective as possible. Therefore, we request comments
or information from other concerned governmental agencies, Native
American Tribes, the scientific community, industry, or any other
interested parties concerning this proposed rule. Comments should be as
specific as possible. We are specifically requesting comments on any
additional information on whether these species
[[Page 54299]]
are extant or extinct. This information can include:
(1) Any information that indicates whether the best available
information supports a determination that one of the species is or is
not extinct, including:
(a) Biological or ecological requirements as it relates to the
detectability of the species, including but not limited to: Lifespan,
life stage, maturation period, physical description and ease of
identification, vocalization, and habitat requirements for feeding,
breeding, and sheltering;
(b) Survey efforts past and current including information on how
extensive the surveys were, the methodology used in the survey, and how
effective were the methods used to detect the species (i.e., were the
surveys designed to effectively detect the species if it is present in
the area?); or
(c) Last sighting of the species including a description of
location of the sighting, the type of sighting (e.g., visual or
auditory), length of time since last detection, and the frequency of
last sightings.
(2) Factors that may have resulted in the extinction of the
species, which may include habitat modification or destruction,
overutilization, disease, predation, the inadequacy of existing
regulatory mechanisms, or other natural or manmade factors.
Please include sufficient information with your submission (such as
scientific journal articles or other publications) to allow us to
verify any scientific or commercial information you include.
Please note that submissions merely stating support for, or
opposition to, the action under consideration without providing
supporting information, although noted, will not be considered in
making a determination, as section 4(b)(1)(A) of the Act directs that
determinations as to whether any species is an endangered or a
threatened species must be made ``solely on the basis of the best
scientific and commercial data available.''
You may submit your comments and materials concerning this proposed
rule by one of the methods listed in ADDRESSES. We request that you
send comments only by the methods described in ADDRESSES.
You may submit your comments or materials electronically, or view a
detailed description of the basis for a species determination, on the
internet at http://www.regulations.gov under the following docket
numbers:
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Species Docket No.
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Kauai akialoa............................. FWS-R1-ES-2020-0104
Kauai nukupuu............................. FWS-R1-ES-2020-0104
Kauai `o`o (honeyeater)................... FWS-R1-ES-2020-0104
Large Kauai thrush (kam'a)................ FWS-R1-ES-2020-0104
Maui akepa................................ FWS-R1-ES-2020-0104
Maui nukupuu.............................. FWS-R1-ES-2020-0104
Molokai creeper (kakawahie)............... FWS-R1-ES-2020-0104
Po`ouli (honeycreeper).................... FWS-R1-ES-2020-0104
Bridled white-eye......................... FWS-R1-ES-2020-0104
Little Mariana fruit bat.................. FWS-R1-ES-2020-0104
Phyllostegia glabra var. lanaiensis (no FWS-R1-ES-2020-0104
common name).............................
San Marcos gambusia....................... FWS-R2-ES-2020-0105
Scioto madtom............................. FWS-R3-ES-2020-0106
Flat pigtoe............................... FWS-R4-ES-2020-0107
Southern acornshell....................... FWS-R4-ES-2020-0107
Stirrupshell.............................. FWS-R4-ES-2020-0107
Upland combshell.......................... FWS-R4-ES-2020-0107
Green blossom (pearly mussel)............. FWS-R4-ES-2020-0108
Tubercled blossom (pearly mussel)......... FWS-R4-ES-2020-0108
Turgid blossom (pearly mussel)............ FWS-R4-ES-2020-0108
Yellow blossom (pearly mussel)............ FWS-R4-ES-2020-0108
Ivory-billed woodpecker................... FWS-R4-ES-2020-0109
Bachman's warbler......................... FWS-R4-ES-2020-0110
------------------------------------------------------------------------
Supporting information used to prepare the determinations, as well
as comments and materials we receive, will be available for public
inspection on http://www.regulations.gov, or by contacting the
appropriate person, as specified under FOR FURTHER INFORMATION CONTACT.
If you submit information via http://www.regulations.gov, your
entire submission--including any personal identifying information--will
be posted on the website. If your submission is made via a hardcopy
that includes personal identifying information, you may request at the
top of your document that we withhold this information from public
review. However, we cannot guarantee that we will be able to do so. We
will post all hardcopy submissions on http://www.regulations.gov.
Because we will consider all comments and information we receive
during the comment period, our final determinations may differ from
this proposal. Based on the new information we receive (and any
comments on that new information), we may conclude that the species
should remain listed as endangered or threatened, or reclassify from
threatened to endangered, instead of being delisted because new
evidence indicates that it is not extinct.
Public Hearing
Section 4(b)(5) of the Act provides for a public hearing on this
proposal, if requested. Requests must be received by the applicable
date specified in DATES. Such requests must be sent to the address
shown in FOR FURTHER INFORMATION CONTACT. We will schedule a public
hearing on this proposal, if requested, and announce the date, time,
and place of the hearing, as well as how to obtain reasonable
accommodations, in the Federal Register and local newspapers at least
15 days before the hearing. For the immediate future, we will provide
these public hearings using webinars that will be announced on the
Service's website, in addition to the Federal Register. The use of
these virtual public hearings is consistent with our regulations at 50
CFR 424.16(c)(3).
Peer Review
In accordance with our policy, ``Notice of Interagency Cooperative
Policy for Peer Review in Endangered Species Act Activities,'' which
was published on July 1, 1994 (59 FR 34270)
[[Page 54300]]
and our August 22, 2016, Director's Memorandum ``Peer Review Process,''
we will seek, or have sought, the expert opinion of at least three
appropriate and independent specialists regarding scientific data and
interpretations contained in this proposed rule for each species or
group of species. In certain cases, species will be grouped together
for peer review based on similarities in biology or geographic
occurrences. We will send copies of the five-year species status
reviews to the peer reviewers immediately following publication in the
Federal Register. We will ensure that the opinions of peer reviewers
are objective and unbiased by following the guidelines set forth in the
Director's Memo, which updates and clarifies Service policy on peer
review (U.S. Fish and Wildlife Service 2016). The purpose of such
review is to ensure that our decisions are based on scientifically
sound data, assumptions, and analysis. Accordingly, our final decisions
may differ from this proposal.
Background
Section 4(c) of the Act requires the Service to maintain and
publish Lists of Endangered and Threatened Species. This includes
delisting species that are extinct or presumed extinct based on the
best scientific and commercial data available. The Service can decide
to delist a species presumed extinct on its own initiative, as a result
of a 5-year review under section 4(c)(2) of the Act, or because we are
petitioned to delist due to extinction. Congress made clear that an
integral part of the statutory framework is for the Service to make
delisting decisions when appropriate and revise the Lists accordingly.
For example, section 4(c)(1) of the Act requires the Service to revise
the Lists to reflect recent determinations, designations, and
revisions. Similarly, section 4(c)(2) requires the Service to review
the lists at least every 5 years; determine, based on those reviews,
whether any species should be delisted or reclassified; and, if so,
apply the same standards and procedures as for listings under sections
4(a) and 4(b). Finally, to make a finding that a particular action is
warranted but precluded, the Service must make two determinations: (1)
That the immediate proposal and timely promulgation of a final
regulation is precluded by pending proposals to determine whether any
species is endangered or threatened; and (2) that expeditious progress
is being made to add qualified species to either of the Lists and to
remove species from the Lists (16 U.S.C. 1533(b)(3)(B)(iii)). Delisting
species that will not benefit from the Act's protections because they
are extinct allows us to allocate resources responsibly for on-the-
ground conservation efforts, recovery planning, 5-year reviews, and
other protections for species that are extant and will therefore
benefit from those actions.
Regulatory and Analytical Framework
Section 4 of the Act (16 U.S.C. 1533) and its implementing
regulations (50 CFR part 424) set forth the procedures for adding
species to, removing species from, or reclassifying species on the
Lists. Our regulations (50 CFR 424.11(e)) state that the Secretary
shall delist a species if the Secretary finds that, after conducting a
status review based on the best scientific and commercial data
available:
(1) The species is extinct;
(2) The species does not meet the definition of an endangered
species or a threatened species. In making such a determination, we
consider the same five factors and apply the same standards set
forth as for listing and reclassification; or
(3) The listed entity does not meet the statutory definition of
a species.
In this proposed rule, we use the commonly understood biological
definition of ``extinction'' as meaning that no living individuals of
the species remain in existence. A determination of extinction will be
informed by the best available information to indicate that no
individuals of the species remain alive, either in the wild or
captivity. This is in contrast to ``functional extinction,'' where
individuals of the species remain alive but the species is no longer
viable and/or no reproduction will occur (e.g., any remaining females
cannot reproduce, only males remain, etc.).
In our analyses, we attempted to minimize the possibility of either
(1) prematurely determining that a species is extinct where individuals
exist but remain undetected, or (2) assuming the species is extant when
extinction has already occurred. Our determinations of whether the best
available information indicates that a species is extinct included an
analysis of the following criteria: Detectability of the species,
adequacy of survey efforts, and time since last detection. All three
criteria require taking into account applicable aspects of species'
life history. Other lines of evidence may also support the
determination and be included in our analysis.
In conducting our analyses of whether these species are extinct, we
considered and thoroughly evaluated the best scientific and commercial
data available. We reviewed the information available in our files, and
other available published and unpublished information. These
evaluations may include information from recognized experts; Federal,
State, and Tribal governments; academic institutions; foreign
governments; private entities; and other members of the public.
The 5-year reviews of these species contain more detailed
biological information on each species. This supporting information can
be found on the internet at http://www.regulations.gov under the
appropriate docket number (see table under Public Comments, above). The
following information summarizes the analyses for each of the species
proposed for delisting by this rule.
Summary of Biological Status and Threats
Mammals
Little Mariana Fruit Bat (Pteropus tokudae)
I. Background
The little Mariana fruit bat (Pteropus tokudae) was listed as
endangered on August 27, 1984 (49 FR 33881), and was included in the
Recovery Plan for Mariana Fruit Bat (Pteropus mariannus, or fanihi in
the Chamorro language) and the Little Mariana Fruit Bat (USFWS 1990).
Last observed in 1968, the little Mariana fruit bat was ``among the
most critically endangered species of wildlife under U.S.
jurisdiction,'' as noted in the 1984 final listing rule (49 FR 33881,
August 27, 1984, p. 49 FR 33882), which cited hunting and loss of
habitat as the primary factors contributing to its rarity. Three 5-year
status reviews have been completed; the 2009 (initiated on March 8,
2007; see 72 FR 10547) and 2015 (initiated on February 5, 2013; see 78
FR 8185) reviews did not recommend a change in status (USFWS 2009b,
2015). The 5-year status review completed in 2019 (initiated on May 7,
2018; see 83 FR 20088) recommended delisting due to extinction likely
resulting from habitat loss, poaching, and predation by the brown tree
snake (Boiga irregularis). This recommendation was based on a
reassessment of all available information for the species, coupled with
an evaluation of population trends and threats affecting the larger,
extant Mariana fruit bat, which likely shares similar behavioral and
biological traits and provides important context for the historical
decline of the little Mariana fruit bat. (USFWS 2019).
The little Mariana fruit bat was first described from a male type
specimen collected in August 1931 (Tate 1934, p. 1). Its original
scientific name, Pteropus tokudae, remains current. Only three
confirmed observations of the little Mariana fruit bat existed in the
[[Page 54301]]
literature based on collections of three specimens: Two males in 1931
(Tate 1934, p. 3), and a female in 1968 (Perez 1972, p. 146), all on
the island of Guam where it was presumably endemic. Despite the dearth
of confirmed collections and observations, two relatively recent
studies have confirmed the taxonomic validity of the little Mariana
fruit bat, via morphology (Buden et al. 2013, entire) and genetics
(Almeida et al. 2014, entire). A study of the physical morphology of
several Micronesia Pteropus spp., including all three known little
Mariana fruit bat specimens, concluded that the species was a distinct
taxon (Buden et al. 2013, entire). Subsequently, genetic analysis of
skin samples from 50 of the 63 described Pteropus species supported the
Mariana little fruit bat's taxonomic distinctness (Almeida et al. 2014,
entire).
The little Mariana fruit bat belonged to a primarily tropical group
of bats in the Megachiroptera suborder characterized by relatively
large size, frugivorous diet (fruit-eating), and lack of echolocation.
Its genus, Pteropus, comprises 63 species, including many coastal
species endemic to Pacific islands (Almeida et al. 2014, pp. 83-84).
Given the homogeneity of life-history traits within the Pteropus genus,
we expect that the little Mariana fruit bat exhibited similar behavior
and life history to other members of the genus, including group
roosting and foraging within forest habitat, lengthy care of few
offspring, and slow population growth (USFWS 1990, p. 7; Wiles 1987, p.
154). Lifespan for the little Mariana fruit bat is unknown, but the
Mariana fruit bat may survive for 30 years in captivity (USFWS 2020,
unpaginated) and other bats within the genus live between 14 and 40
years. In the most recent 5-year review completed in 2019, we drew upon
our knowledge of the larger and still extant Mariana fruit bat's
biology to extrapolate a likely timeline and explanation for the little
Mariana fruit bat's rarity, decline, and eventual extinction.
The earliest available scientific literature indicates that the
little Mariana fruit bat was always likely rare, as suggested by
written accounts of the species first recorded in the early 1900s
(Baker 1948, p. 54; Perez 1972, pp. 145-146; Wiles 1987, p 154). In
addition to possibly having been inherently rare, as suggested by the
literature, a concurrent decline in the little Mariana fruit bat
population likely occurred during the well-documented decrease in
Mariana fruit bat abundance on Guam in the 1900s. In 1920, it was ``not
an uncommon sight'' to see fruit bats flying over the forest during the
daytime in Guam (Wiles 1987, p. 150). Just 10 years later (when the
first two little Mariana fruit bat specimens were collected), fruit
bats were uncommon on the island (Wiles 1987, p. 150), and were found
mostly in northern Guam; introduced firearms may have been a
contributing factor in their decline because they increased the
efficiency of hunting (Wiles 1987, p. 150).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The little Mariana fruit bat was much smaller than the related
Mariana fruit bat (Tate 1934, p. 2; Perez 1972, p. 146; Buden et al.
2013, pp. 109-110). Adult bats measured approximately 5.5 to 5.9 inches
(in) (14 to 15.1 centimeters (cm)) in head-body length, with a wingspan
of approximately 25.6 to 27.9 in (650 to 709 mm). The adults weighed
approximately 5.36 ounces (152 grams). Although primarily dark brown in
color, the little Mariana fruit bat showed some variation on the neck
and head which could appear pale gold and grayish or yellowish-brown in
color. Because of their small size (O'Shea and Bogan 2003, pp. 49, 254;
USFWS 2009, p. 55), it is possible that adult little Mariana fruit bats
were historically confused with juvenile fruit bats. Therefore,
historical accounts of the species may have been underrepresented
(Perez 1972, p. 143; Wiles 1987, p. 15).
The challenges of surveying for the Mariana fruit bat and most
Pteropus spp. (including in theory, the little Mariana fruit bat) are
numerous. Mariana fruit bats sleep during the day in canopy emergent
trees, either solitarily or within colonial aggregations that may occur
across several acres (O'Shea and Bogan 2003, p. 254; Utzurrum et al.
2003, p. 49; USFWS 2009, p. 269). The tropical islands where many
tropical fruit bats (Pteropus spp.) are located have widely diverse and
steeply topographical habitat, making surveys difficult. Additionally,
most Pteropus spp. choose roost sites (both colonial and individual)
that occur in locations difficult for people to reach, such as adjacent
to steep cliffsides in remote forest areas (Wilson and Graham 1992, p.
65). The selection of roost sites in these areas is likely both a
result of their evolved biology (for example to take advantage of
updrafts for flight (Wilson and Graham 1992, p. 4)) and learned
behavior to avoid poachers (USFWS 2009, pp. 24-25; Mildenstein and
Johnson 2017, p. 36). To avoid triggering this avoidance behavior,
surveyors must generally keep a distance of 164 feet (50 meters) and
survey only downwind of roost sites (Mildenstein and Boland 2010, pp.
12-13; Mildenstein and Johnson 2017, pp. 55, 86). Additionally,
Pteropus spp. typically sleep during the day and do not vocalize, and
flying individuals may be easily counted twice due to their foraging
patterns (Utuzurrum et al. 2003, p. 54).
Survey Effort
Historically, surveys to estimate colonial fruit bat numbers have
generally involved two relatively simple and inexpensive methods,
direct counts and station counts (or departure, or exit counts)
(Utuzurrum et al. 2003, pp. 53-54). With direct counts, surveyors
attempt to determine the number of bats in a roosting colony (or
individual bats) at a single site during the day. Direct counts usually
involve use of binoculars or a spotting scope, depending on the
observation distance from the colony or individuals (Kunz et al. 1996;
Eby et al. 1999; Garnett et al. 1999; Worthington et al. 2001 as cited
in Mildenstein and Boland 2010, pp. 2-3). Conversely, surveyors conduct
exit counts in the late afternoon to early evening when bats begin to
depart from the roost site for evening foraging. Exit counts are
typically conducted at locations with wide and unimpeded views of
either areas known to contain colonies, or forested areas that would
likely serve as roost sites for bats. Occasionally, surveyors may
conduct both exit and direct counts by boat or by air with a
helicopter. More recently, direct and exit count surveys involve use of
computers and digital photography to aid the process (Mildenstein and
Boland 2010, pp. 2-3).
By 1945, fruit bats were difficult to locate even in the northern
half of Guam, where they were largely confined to forested cliff lines
along the coasts (Baker 1948, p. 54). During surveys conducted between
1963 and 1968, the Guam Division of Aquatic and Wildlife Resources
(DAWR) confirmed that bats were declining across much of Guam and were
absent in the south. It was also during these same field studies that
the third and last little Mariana fruit bat was collected in northern
Guam in 1968 (Baker 1948, p. 146).
Increased survey efforts during the late 1970s and early 1980s
reported no confirmed sightings of the little Mariana fruit bat
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987,
entire; Wiles 1987, pp. 153-154). When the little Mariana fruit bat was
listed as endangered (49 FR 33881; August 27, 1984), we noted that the
species was on the verge of extinction
[[Page 54302]]
and had not been verifiably observed after 1968. When we published a
joint recovery plan for the little Mariana fruit bat and the Mariana
fruit bat in 1990, we considered the little Mariana fruit bat already
extinct based upon the available literature (USFWS 1990, p. 7).
During the 1990s, researchers recorded decreasing Mariana fruit bat
numbers on Guam and increasing fatalities of immature bats. They
hypothesized the decline was due to predation by the brown tree snake
(Wiles et al. 1995, pp. 33-34, 39-42). With bat abundance continuing to
decline in the 2000s, researchers now estimate the island's Mariana
fruit bat population currently fluctuates between 15 and 45 individuals
(Mildenstein and Johnson 2017, p. 24; USFWS 2017, p. 54). Even if the
little Mariana fruit bat persisted at undetectable numbers for some
time after its last confirmed collection in 1968, it is highly likely
the little Mariana fruit bat experienced the same pattern of decline
that we are now seeing in the Mariana fruit bat.
Time Since Last Detection
As stated above, the little Mariana fruit bat was last collected in
northern Guam in 1968 (Baker 1948, p. 146). Intensive survey efforts
conducted by Guam DAWR and other researchers in subsequent decades have
failed to locate the species. Decades of monthly (and, later, annual)
surveys for the related Mariana fruit bat by qualified personnel in
northern Guam have failed to detect the little Mariana fruit bat
(Wheeler and Aguon 1978, entire; Wheeler 1979, entire; Wiles 1987,
entire; Wiles 1987, pp. 153-154; USFWS 1990, p. 7).
III. Analysis
Like the majority of bat species in the genus Pteropus, specific
biological traits likely exacerbated the little Mariana fruit bat's
susceptibility to human activities and natural events (Wilson and
Graham 1992, pp. 1-8). For example, low fecundity in the genus due to
late reproductive age and small broods (1 to 2 young annually) inhibits
population rebound from catastrophic events such as typhoons, and from
slow progression of habitat loss and hunting pressure that we know
occurred over time. The tendency of Pteropus bats to roost together in
sizeable groups or colonies in large trees rising above the surrounding
canopy makes them easily detected by hunters (Wilson and Graham 1992,
p. 4). Additionally, Pteropus bats show a strong tendency for roost
site fidelity, often returning to the same roost tree year after year
to raise their young (Wilson and Graham 1992, p. 4; Mildenstein and
Johnson 2017, pp. 54, 68). This behavior likely allowed hunters and
(later) poachers to easily locate and kill the little Mariana fruit bat
and, with the introduction of firearms, kill them more efficiently
(Wiles 1987, pp. 151, 154; USFWS 2009, pp. 24-25; Mildenstein and
Johnston 2017, pp. 41-42). The vulnerability of the entire genus
Pteropus is evidenced by the fact that 6 of the 62 species in this
genus have become extinct in the last 150 years (including the little
Mariana fruit bat). The International Union for Conservation of Nature
(IUCN) categorizes an additional 37 species in this genus at risk of
extinction (Almeida et al. 2014, p. 84).
In discussing survey results for the Mariana fruit bat in the late
1980s, experts wrote that the level of illegal poaching of bats on Guam
remained extremely high, despite the establishment of several legal
measures to protect the species beginning in 1966 (Wiles 1987, p. 154).
They also wrote about the effects of brown tree snake predation on
various fruit bats species (Savidge, 1987, entire; Wiles 1987, pp. 155-
156). To date, there is only one documented instance of brown tree
snake actually preying on the Mariana fruit bat; in that case, three
young bats were found within the stomach of a snake (Wiles 1987, p.
155). However, immature Pteropus pups are particularly vulnerable to
predators between approximately 3 weeks and 3 months of age. During
this timeframe, the mother bats stop taking their young with them while
they forage in the evenings, leaving them alone to wait at their roost
tree (Wiles 1987, p. 155).
Only three specimens of little Mariana fruit bat have ever been
collected, all on the island of Guam, and no other confirmed captures
or observations of this species exist. Based on the earliest records,
the species was already rare in the early 1900s. Therefore, since its
discovery, the little Mariana fruit bat likely experienced greater
susceptibility to a variety of factors because of its small population
size. Predation by the brown tree snake, alteration and loss of
habitat, increased hunting pressure, and possibly competition with the
related Mariana fruit bat for the same resources under the increasingly
challenging conditions contributed to the species' decreased ability to
persist.
It is highly likely the brown tree snake, the primary threat
thought to be the driver of multiple bird and reptile species
extirpations and extinctions on Guam, has been present throughout the
little Mariana fruit bat's range for at least the last half-century,
and within the last northern refuge in northern Guam since at least the
1980s. Because of its life history and the challenges presented by its
small population size, we conclude that the little Mariana fruit bat
was extremely susceptible to predation by the brown tree snake.
IV. Conclusion
At the time of listing in 1984, hunting and loss of habitat were
considered the primary threats to the little Mariana fruit bat. The
best available information now indicates that the little Mariana fruit
bat is extinct. The species appears to have been vulnerable to
pervasive, rangewide threats including habitat loss, poaching, and
predation by the brown tree snake. Since its last detection in 1968,
qualified observers have conducted surveys and searches throughout the
range of the little Mariana fruit bat but have not detected the
species. Available information indicates that the species was not able
to persist in the face of anthropogenic and environmental stressors,
and we conclude that the best available scientific and commercial
information indicates that the species is extinct.
Birds
Bachman's Warbler (Vermivora bachmanii)
I. Background
The Bachman's warbler (Vermivora bachmanii) was listed on March 11,
1967 (32 FR 4001), as endangered under the Endangered Species
Preservation Act of 1966, as a result of the loss of breeding and
wintering habitat. Two 5-year reviews were completed for the species on
February 9, 2007 (initiated on July 26, 2005; see 70 FR 43171), and May
6, 2015 (initiated on September 23, 2014; see 79 FR 56821). Both 5-year
reviews recommended that if the species was not detected within the
following 5 years, it would be appropriate to delist due to extinction.
The Bachman's warbler was first named in 1833 as Sylvia bachmanii
based on a bird observed in a swamp near Charleston, South Carolina
(AOU 1983, pp. 601-602). The Bachman's warbler was among the smallest
warblers with a total length of 11.0 to 11.5 centimeters (cm) (4.3 to
4.5 inches (in)). The species was found in the southeastern portions of
the United States from the south Atlantic and Gulf Coastal Plains,
extending inland in floodplains of major rivers (eastern Texas,
Louisiana, Arkansas, bootheel of Missouri, Alabama, Georgia, North and
South Carolinas, Virginia, and flyovers in Florida). However, breeding
was documented only in northeast Arkansas, southeast Missouri,
southwest Kentucky, central Alabama, and
[[Page 54303]]
southeast South Carolina. Bachman's warbler was a neotropical migrant;
historically, the bulk of the species' population left the North
American mainland each fall for Cuba and Isle of Pines (Dingle 1953,
pp. 67-68, 72-73).
Available information indicates that migratory habitat preferences
differed from winter and breeding habitat preferences in that the bird
used or tolerated a wider range of conditions and vegetative
associations during migration. Historical records indicate the
Bachman's warbler typically nested in low, wet, forested areas
containing variable amounts of water, but usually with some permanent
water. While it is not definitively known, it is thought that they
preferred small edges created by fire or storms with a dense understory
of the cane species Arundinaria gigantea and palmettos. Nests were
typically found in shrubs low to the ground from late March through
June, and average known clutch size was 4.2 +/-0.7 (with a range of 3
to 5) (Hamel 2018, pp. 14-15). During the winter in Cuba, it was found
in a wider variety of habitats across the island including forests,
ranging from dry, semi-deciduous forests to wetlands, and even in
forested urban spaces (Hamel 1995, p. 5). Life expectancy is unknown,
but other warbler species live for 3 to 11 years (Klimkiewicz et al.
1983, pp. 292-293).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Bachman's warbler was one of the smallest warblers with a total
length of 11.0 to 11.5 cm. The bill was slender with a slight downward
curve in both sexes and was a unique feature within the genus. The male
was olive-green above with yellow forehead, lores, eye-ring, chin, and
underparts; a black throat and crown; and dusky wings and tail. Males
also had a yellow shoulder patch and bright rump. Generally, while
similar, plumage of females was paler. Females lacked any black
coloration and had olive green upperparts with yellow forehead and
underparts. The eye-ring was whiter than in the males, and the crown
was grayish. The dark patch on the throat was usually missing and the
eye-ring was pale. Females had a buffy or bright yellowish forehead and
a gray crown with no black; a whitish or white crissum; and less
pronounced white spots on the tail (Hamel and Gauthreaux 1982, pp. 235-
239; Hamel 1995, p. 2). Immature males resembled females. Males were
easy to distinguish from other warblers. However, the drab coloration
of the females and immature birds made positive identification
difficult (Hamel and Gauthreaux 1982, p. 235). Additionally, females
were much more difficult to identify because variability in plumage was
greater. Immature females were also most likely to be confused with
other similarly drab warblers. The song of the Bachman's warbler was a
zeep or buzzy zip given by both sexes (Hamel 2020, Sounds and Vocal
Behavior). This species may have been difficult to differentiate on
call alone, as its call was somewhat reminiscent of the pulsating trill
of the northern parula (Parula americana) (Curson et al. 1994, p. 95),
and only two recordings exist from the 1950s (Hamel 2018, p. 32) to
guide ornithologists on distinguishing it this way. Despite the fact
that it could be mistaken for the northern parula, Bachman's warbler
was of high interest to birders, and guides have been published
specifically to aid in field identification (Hamel and Gauthreaux 1982,
entire). As a result, substantial informal and formal effort has been
expended searching for the bird and verifying potential sightings as
outlined below (see ``Survey Effort'').
Survey Effort
Although Bachman's warbler was first described in 1833, it remained
relatively unnoticed for roughly the next 50 years. Population
estimates are qualitative in nature and range from rare to abundant
(Service 1999, pp. 4-448). Populations were probably never large and
were found in ``some numbers'' between 1890 and 1920, but afterwards
populations appeared to be very low (Hamel 2018, pp. 16-18). For
instance, several singing males were reported in Missouri and Arkansas
in 1897 (Widmann 1897, p. 39), and Bachman's warbler was seen as a
migrant along the lower Suwannee River in flocks of several species
(Brewster and Chapman 1891, p. 127). The last confirmed nest was
documented in 1937 (Curson et al. 1994, p. 96). A dramatic decline
occurred sometime between the early 1900s and 1940 or 1950. Recognition
of this decline resulted in the 1967 listing of the species (32 FR
4001; March 11, 1967) under the Endangered Species Preservation Act of
1966.
Between 1975 and 1979, an exhaustive search was conducted in South
Carolina, Missouri, and Arkansas. No Bachman's warblers were located
(Hamel 1995, p. 10). The last (though unconfirmed) sighting in Florida
was from a single bird observed near Melbourne in 1977. In 1989, an
extensive breeding season search was conducted on Tensas National
Wildlife Refuge in Louisiana. Six possible Bachman's warbler
observations occurred, but could not be documented sufficiently to meet
acceptability criteria established for the study (Hamilton 1989, as
cited in Service 2015, p. 4).
An experienced birder reported multiple, possible sightings of
Bachman's warbler at Congaree National Park, South Carolina, in 2000
and 2001. These included hearing a male and seeing a female. In 2002,
the National Park Service partnered with the Service and the Atlantic
Coast Joint Venture to investigate these reports. Researchers searched
over 3,900 acres of forest during 166 hours of observation in March and
April; however, no Bachman's warbler sightings or vocalizations were
confirmed. As noted previously, females and immature birds are
difficult to positively identify. Males (when seen) are more easily
distinguishable from other species. Researchers trying to verify the
sightings traced several promising calls back to northern parulas and
finally noted that they were confident the species would have been
detected had it been present (Congaree National Park 2020, p. 3).
In several parts of the Bachman's warbler's range, relatively
recent searches (since 2006) for ivory-billed woodpecker also prompted
more activity in appropriate habitat for Bachman's warbler. Although
much of the search period for ivory-billed woodpecker is during the
winter, the searches usually continue until the end of April, when
Bachman's warbler would be expected in the breeding range. Therefore,
because Bachman's warbler habitat overlaps ivory-billed woodpecker
habitat, the probability that Bachman's warbler would be detected, if
present, has recently increased (Service 2015, pp. 5-6). Further, in
general, substantial informal effort has been expended searching for
Bachman's warbler because of its high interest among birders (Service
2015, p. 5). In spite of these efforts, Bachman's warbler has not been
observed in the United States in more than three decades.
In Cuba, the species' historical wintering range, the last
ornithologist to see the species noted that the species was observed
twice in the 1960s in the Zapata Swamp: One sighting in the area of a
modern-day hotel in Laguna del Tesoro and the other one in the Santo
Tomas, Zanja de la Cocodrila area. Some later potential observations
(i.e., 1988) in the same areas were thought to be a female common
yellowthroat (Navarro 2020, pers. comm.). A single bird was reported in
Cuba in 1981 at Zapata Swamp (Garrido 1985, p. 997; Hamel 2018, p. 20).
However, additional surveys in Cuba by Hamel and Garrido in 1987
through 1989 did not confirm
[[Page 54304]]
additional birds (Navarro 2020, pers. comm.). There have been no
sightings or bird surveys in recent years in Cuba, and all claimed
sightings of Bachman's warbler from 1988 onwards have been rejected by
the ornithological community (Navarro 2020, pers. comm.). Curson et al.
(1994, p. 96) considers all sightings from 1978 through 1988 in Cuba as
unconfirmed.
Time Since Last Detection
After 1962, reports of the Bachman's warbler in the United States
have not been officially accepted, documented observations (Chamberlain
2003, p. 5). Researchers have been thorough and cautious in
verification of potential sightings, and many of the more recent ones
could not be definitively verified. Bachman's warbler records from
1877-2001 in North America are characterized as either relying on
physical evidence or on independent expert opinion, or as controversial
sightings (Elphick et al. 2010, pp. 8, 10). In Cuba, no records have
been verified since the 1980s (Navarro 2020, pers. comm.).
Other Considerations Applicable to the Species' Status
At breeding grounds, the loss of habitat from clearing of large
tracts of palustrine (i.e., having trees, shrubs, or emergent
vegetation) wetland beginning in the 1800s was a major factor in the
decline of the Bachman's warbler. Most of the palustrine habitat in the
Mississippi Valley (and large proportions in Florida) was historically
converted to agriculture or affected by other human activities
(Fretwell et al. 1996, pp. 8, 10, 124, 246). Often the higher, drier
portions of land that the Bachman's warbler required for breeding were
the first to be cleared because they were more accessible and least
prone to flooding (Hamel 1995, pp. 5, 11; Service 2015, p. 4). During
World Wars I and II, many of the remaining large tracts of old growth
bottomland forest were cut, and the timber was used to support the war
effort (Jackson 2020, Conservation and Management, p. 2). At the
wintering grounds of Cuba, extensive loss of primary forest wintering
habitat occurred due to the clearing of large areas of the lowlands for
sugarcane production (Hamel 2018, p. 24). Hurricanes also may have
caused extensive damage to habitat and direct loss of overwintering
Bachman's warblers. Five hurricanes occurred between November 1932 and
October 1935. Two storms struck western Cuba in October 1933, and the
November 1932 hurricane is considered one of the most destructive ever
recorded. These hurricanes, occurring when Bachman's warblers would
have been present at their wintering grounds in Cuba, may have resulted
in large losses of the birds (Hamel 2018, p. 19).
III. Analysis
As early as 1953, Bachman's warbler was reported as one of the
rarest songbirds in North America (Dingle 1953, p. 67). The species may
have gone extinct in North America by 1967 (Elphick et al. 2010, p.
619). Despite extensive efforts to document presence of the species, no
new observations of the species have been verified in the United States
or Cuba in several decades (Elphick et al. 2010, supplement; Navarro
2020, pers. comm.). Given the likely lifespan of the species, it has
not been observed in several generations.
IV. Conclusion
As far back as 1977, Bachman's warbler has been described as being
on the verge of extinction (Hooper and Hamel 1977, p. 373) and the
rarest songbird native to the United States (Service 1999, pp. 4-445).
The species has not been seen in the United States or Cuba since the
1980s, despite extensive efforts to locate it and verify potential
sightings. Therefore, we conclude that the best available scientific
and commercial information indicates that the species is extinct.
Bridled White-eye (Zosterops conspicillatus conspicillatus)
I. Background
The bridled white-eye (Zosterops conspicillatus conspicillatus, or
Nossa in the Chamorro language), was listed as endangered in 1984 (49
FR 33881; August 27, 1984), and was included in the Recovery Plan for
the Native Forest Birds of Guam and Rota of the Commonwealth of the
Northern Mariana Islands (USFWS 1990, entire). The species was last
observed in 1983, and the 1984 final listing rule for the bridled
white-eye noted that the species ``may be the most critically
endangered bird under U.S. jurisdiction'' (49 FR 33881, August 27,
1984, p. 49 FR 33883) and cited disease and predation by nonnative
predators, including the brown tree snake (Boiga irregularis), as the
likely factors contributing to its rarity (49 FR 33881, August 27,
1984, p. 49 FR 33884). Three 5-year status reviews were completed for
the bridled white-eye; the 2009 (initiated on March 8, 2007; see 72 FR
10547) and 2015 (initiated on March 6, 2012; see 77 FR 13248) reviews
did not recommend a change in status (USFWS 2009a, 2015). After
reevaluation of all available information, the 5-year status review
completed in 2019 (initiated on May 7, 2018; see 83 FR 20088)
recommended delisting due to extinction, based on continued lack of
detections and the pervasive rangewide threat posed by the brown tree
snake (USFWS 2019, p. 10).
At the time of listing, the bridled white-eye on Guam was
classified as one subspecies within a complex of bridled white-eye
(Zosterops conspiculatus) populations found in the Mariana Islands. The
most recent taxonomic work (Slikas et al. 2000, p. 360) continued to
classify the Guam subspecies within the same species as the bridled
white-eye populations currently found on Saipan, Tinian, and Aguiguan
in the Commonwealth of the Northern Mariana Islands (Z. c. saypani) but
considered the Rota population (Z. rotensis; now separately listed as
endangered under the Act) to be a distinct species.
Endemic only to Guam, within the Mariana Islands, the bridled
white-eye was a small (0.33 ounce or 9.3 grams), green and yellow,
warbler-like forest bird with a characteristic white orbital ring
around each eye (Jenkins 1983, p. 48). The available information about
the life history of the species is sparse, based on a few early
accounts in the literature (Seale 1901, pp. 58-59; Stophet 1946, p.
540; Marshall 1949, p. 219; Baker 1951, pp. 317-318; Jenkins 1983, pp.
48-49). Nonterritorial and often observed in small flocks, the species
was a canopy-feeding insectivore that gleaned small insects from the
twigs and branches of trees and shrubs (Jenkins 1983, p. 49). Although
only minimal information exists about the bridled white-eye's nesting
habits and young, observations of nests during several different months
suggests the species bred year-round (Marshall 1949, p. 219; Jenkins
1983, p. 49). No information is available regarding longevity of the
bridled white-eye, but lifespans in the wild for other white-eyes in
the same genus range between 5 and 13 years (Animal Diversity Web 2020;
The Animal Aging and Longevity Database 2020; WorldLifeExpectancy.com
2020).
The bridled white-eye was reported to be one of the more common
Guam bird species between the early 1900s and the 1930s (Jenkins 1983,
p. 5). However, reports from the mid- to late-1940s indicated the
species had perhaps become restricted to certain areas on Guam (Baker
1951, p. 319; Jenkins 1983, p. 50). By the early- to mid-1970s, the
bridled white-eye was found only in the forests in the very northern
portion of Guam (Wiles et al. 2003, p. 1353). It was considered rare by
1979, causing experts
[[Page 54305]]
to conclude that the species was nearing extinction (Jenkins 1983, p.
50).
By 1981, the bridled white-eye was known to inhabit only a single
395-acre (160-hectare) limestone bench known as Pajon Basin in a
limestone forest at Ritidian Point, an area that later became the Guam
National Wildlife Refuge. Nestled at the base of towering limestone
cliffs of about 426 feet (130 meters), the site was bordered by
adjoining tracts of forest on three sides, and ocean on the northern
side (Wiles et al. 2003, p. 1353). Pajon Basin was also the final
refuge for many of Guam's native forest bird species and was the last
place where 10 of Guam's forest bird species were still observed
together in one locality at historical densities (Savidge 1987, p. 661;
Wiles et al. 2003, p. 1353).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The bridled white-eye has been described as active and occurred in
small flocks of 3 to 12 individuals (Jenkins 1983, p. 48). Although
apparently not as vocal as its related subspecies on the other Mariana
Islands, the bridled white-eye was observed singing and typically
vocalized with ``chipping calls'' while flocking, less so during
foraging (Jenkins 1983, p. 48). Although perhaps not correctly
identified as a ``secretive'' or ``cryptic'' species (Amidon in litt.
2000, pp. 14-15), the detectability of the related Rota bridled white-
eye (Zosterops rotensis) is greatest during surveys when it is close to
the observer, relative to other species of birds that are detected at
further distances. While we are unaware of surveys for the bridled
white-eye using alternative methodologies specific for rare or
secretive bird species, we conclude there is still sufficient evidence
of extinction based upon the large body of literature confirming the
impacts of the brown tree snake on Guam (see discussion below under
``III. Analysis'').
Survey Effort
Variable circular plot (VCP) studies are surveys conducted at pre-
established stations along transects. Surveyor counts all birds seen
and heard during an 8-minute count period and estimates the distance
from the count station to each bird seen or heard. From this
information, an estimate of the number of birds in a surveyed area is
determined and the confidence interval for the estimate is derived.
During a multi-year VCP study at Pajon Basin consisting of annual
surveys between 1981 and 1987, observations of the bridled white-eye
drastically declined in just the first 3 years of the study. In 1981,
54 birds were observed, and in 1982, 49 birds were documented,
including the last observation of a family group (with a fledging) of
the species. One year later, during the 1983 survey, only a single
individual bridled white-eye was sighted. Between 1984 and 1987,
researchers failed to detect the species within this same 300-acre
(121-hectare) site (Beck 1984, pp. 148-149).
Between the mid- and late-1980s, experts had already begun to
hypothesize that the bridled white-eye had become extinct (Jenkins
1983, p. 50; Savidge 1987, p. 661). Although human access has become
more restricted within portions of Andersen Air Force Base since 1983,
the Guam DAWR has, to date, continued annual roadside counts across the
island as well as formal transect surveys in northern Guam in areas
previously inhabited by the bridled white-eye. The species remains
undetected since the last observation in Pajon Basin in 1983 (Wiles
2018, pers. comm.; Quitugua 2018, pers. comm.; Aguon 2018, pers.
comm.).
Time Since Last Detection
Researchers failed to observe the species at the Pajon Basin during
the annual surveys between 1984 and 1987, and during subsequent
intermittent avian surveys in northern Guam in areas where this species
would likely occur (Savidge 1987, p. 661; Wiles et al. 1995, p. 38;
Wiles et al. 2003, entire).
III. Analysis
The brown tree snake is estimated to be responsible for the
extinction, extirpation, or decline of 2 bat species, 4 reptiles, and
13 of Guam's 22 (59 percent) native bird species, including all of the
native forest bird species with the exception of the Micronesian
starling (Aplonis opaca) (Wiles et al. 2003, p. 1358; Rodda and Savidge
2007, p. 307). The most comprehensive study of the decline (Wiles et
al. 2003, entire) indicated that 22 bird species were severely impacted
by the brown tree snake.
The study also found that in areas newly invaded by the snake,
observed declines of avian species were greater than or equal to 90
percent and occurred rapidly, with the average duration just 8.9 years.
The study also examined traits of the birds that made them more or less
susceptible to predation by the brown tree snake, and determined that
the ability and tendency to nest and roost in locations where snakes
were less common (e.g., cave walls) correlated with greater likelihood
of coexistence with the snake. Large clutch size and large body size
correlated with a species' greater persistence, although large body
size appeared to only delay, but not prevent, extirpation. Measuring a
mere 0.33 ounces (9.3 grams), the bridled white-eye was relatively
small in size, and its nests were located in areas accessible to brown
tree snakes (Baker 1951, pp. 316-317; Jenkins 1983, pp. 49-50).
We used a recent analytical tool that assesses information on
threats to infer species extinction based on an evaluation of whether
identified threats are sufficiently severe and prolonged to cause local
extinction, as well as sufficiently extensive in geographic scope to
eliminate all occurrences (Keith et al. 2017, p. 320). Applying this
analytical approach to the bridled white-eye, we examined years of
research and dozens of scientific publications and reports that
indicate that the effects of predation by the brown tree snake have
been sufficiently severe, prolonged, and extensive in geographic scope
to cause widespread range contraction, extirpation, and extinction for
several birds and other species. Based on this analysis, we conclude
that the bridled white-eye is extinct and brown tree snake predation
was the primary causal agent.
IV. Conclusion
At the time of its listing in 1984, disease and predation by
nonnative predators, including the brown tree snake, were considered
the primary threats to the bridled white-eye. The best available
information now indicates that the bridled white-eye is extinct. The
species appears to have been vulnerable to the pervasive, rangewide
threat of predation from the brown tree snake. Since its last detection
in 1983, qualified observers have conducted surveys and searches
throughout the range of the bridled white-eye and have not detected the
species. Available information indicates that the species was not able
to persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial information indicates that
the species is extinct.
Ivory-Billed Woodpecker (Campephilus principalis)
I. Background
The ivory-billed woodpecker (Campephilus principalis) was first
described by Mark Catesby in 1731 (Tanner 1942, p. xv), under a
different taxonomic nomenclature. It was the
[[Page 54306]]
largest woodpecker in the United States and the second largest in North
America with an overall length of approximately 48-51 centimeters (cm)
(18-20 inches), an estimated wingspan of 76-80 cm (29-31 inches), and a
weight of 454-567 grams (g) (16-20 ounces); however, data from live
birds are lacking, so these estimates were based on observations by
ornithologists from the late 19th century who collected specimens
(Service 2010, pp. 1-2).
The ivory-billed woodpecker was listed as endangered throughout its
range on March 11, 1967 (32 FR 4001) under the Endangered Species
Preservation Act of 1966. Although no threats were identified at the
time of listing, land clearing and timber harvesting were known at the
time as threats acting on the species. A status review was announced on
April 10, 1985 (50 FR 14123) to determine if the species was extinct
and should therefore be proposed for delisting. We did not receive any
confirmed reports of live birds as a result of that review. In 1986, we
funded a large-scale survey that included coverage of potential sites
throughout the species' historical range (Jackson 1989, p. 74; Jackson
2006, p. 1-2, USFWS 2010, p. 69). The study also included soliciting
requests for new sightings and investigating those reports for
validity, as well as researching historical sources (Jackson 1989, p.
74). No conclusive evidence of ivory-billed woodpeckers was obtained
during that study.
Another status review was announced on November 6, 1991 (56 FR
56882) for all species (foreign and domestic listings) listed before
1991. In this review, the status of many species was simultaneously
evaluated with no in-depth assessment of the five factors or threats as
they pertain to the individual species. The document stated that the
Service was seeking any new or additional information reflecting the
necessity of a change in the status of the species under review. The
document indicated that if significant data were available warranting a
change in a species' classification, the Service would propose a rule
to modify the species' status. No change in the bird's listing
classification was found to be warranted. Each year, the Service
reviews and updates listed species information for inclusion in the
required Recovery Report to Congress. While considerable effort was
placed on confirming reported sightings after 2004 (details provided
below), no further sightings occurred. By 2013, the ornithological
community determined that these sightings could not be confirmed. Since
2013, our annual recovery data call included status recommendations
such as ``presumed extinct'' for the ivory-billed woodpecker.
A 5-year review was most recently announced on May 7, 2018 (83 FR
20092), with a 60-day public comment period ending July 6, 2018. During
the public comment period, the Service received and considered four
public comments describing reported, but not verifiable, encounters as
well as indications that the inability to conclusively document
existence does not mean that the species is extinct (Trahan 2020, pers.
comm.). The Service also reviewed a variety of additional resources,
including published and unpublished scientific information provided by
other Service offices, State wildlife agencies, stakeholders, and other
partners. Specific sources included the final rule listing this species
under the Act (32 FR 4001; March 11, 1967); the recovery plan (Service
2010, entire); peer-reviewed scientific publications; unpublished field
observations by Federal, State, and other experienced biologists;
unpublished studies and survey reports; and notes and communications
from other qualified individuals. The 5-year review was also sent to
four independent peer reviewers; one responded with comments. This 5-
year review was finalized on June 3, 2019, and recommended that the
ivory-billed woodpecker be delisted due to extinction (USFWS 2019,
entire).
Much of what we know about the ivory-billed woodpecker comes from
research in Louisiana during the late 1930s (Service 2010, pp. xv, vii,
10-22, 67). Suitable habitat for the ivory-billed woodpecker is thought
to be extensive forested areas with old-growth characteristics and a
naturally high volume of dead and dying wood, particularly in virgin
bottomland hardwoods that may sustain the species between disturbance
events (e.g., fires, storms, or other events expected to kill or stress
trees) (Tanner 1942, pp. 46-47, 52). The home range for the ivory-
billed woodpecker is thought to have been fairly large due to their
ability to fly long distances, up to at least several kilometers a day
between favored roost sites and feeding areas. The estimated ivory-
billed woodpecker density historically ranged from one breeding pair
per 6.25 square miles to one breeding pair per 17 square miles (Tanner
1942, p. 32).
Breeding was thought to occur between January and April (Tanner
1942, pp. 95-96). Clutch size reportedly ranged from 1 to 5 eggs with
an estimated incubation period of approximately 20 days (Service 2010,
p. 11). Both sexes of ivory-billed woodpecker incubated the eggs as
well as fed the young for a period of about 5 weeks until the young
fledged (Tanner 1942, pp. 101, 104). The young may have been fed by the
parents for an additional 2 months and roosted near and foraged with
the parents into the next breeding season. Dead or dying portions of
live trees, and sometimes dead trees, may have been excavated for nest
cavities. These cavities ranged from 4.6 meters (m) (15.1 feet (ft)) to
over 21 m (69 ft) up a nest tree, although rarely below 9 m (29.5 ft)
from a tree's base (Service 2010, p. 11). Ivory-billed woodpeckers not
only used nest cavities but excavated roost cavities as well, which are
similar in appearance to nest cavities. Pairs or group members were
found to roost in trees near each other, and they also were reported to
leave the roost after sunrise (Tanner 1942, pp. 57-59). The roosting
area is known to have been the center of activity for ivory-billed
woodpeckers; however, insect abundance (i.e., food availability) was
thought to be important to distribution as well (Tanner 1942, pp. 33-
36, 46, 52). Although it is not known for certain, lifespan for the
species was estimated to be in excess of 10 years (USFWS 2020, p. 24).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The ivory-billed woodpecker had a black and white plumage with a
white chisel-tipped beak, yellow eyes, and a pointed crest. It was
sexually dimorphic, with the sexes exhibiting different characteristics
(i.e., sizes, coloring, etc.). Females had a solid black crest, and
males were red from the nape to the top of the crest with an outline of
black on the front of the crest (Service 2010, p. 1). This large
woodpecker produced distinctive sounds and had distinctive markings
(e.g., large white patch on the wing that can be seen from long
distances (Tanner 1942, p. 1)), indicating a certain degree of
detectability during surveys, if present.
Survey Effort
The last commonly agreed-upon sighting of the species was on the
Singer Tract in the Tensas River region of northeast Louisiana in April
of 1944 (Service 2019, p. 9). Since this sighting, the most compelling
evidence of the existence of the ivory-billed woodpecker was in 2004 in
Arkansas (Fitzpatrick et al. 2005, pp. 1460-1462). From 2004 to 2005,
within the same area of Bayou DeView, located in the
[[Page 54307]]
Cache River National Wildlife Refuge (NWR) in Arkansas, observers
reported sightings, audio recordings, and a video interpreted to be an
ivory-billed woodpecker (Service 2010, p. 13). The original 2004
encounter as well as the other reports and video from Arkansas spurred
an extensive search effort in the area that was led by the Cornell
Laboratory of Ornithology and the Arkansas Nature Conservancy beginning
in 2005. Multiple approaches were used, including visual methods, aural
methods, and playback methods (alone and in combination), as well as
helicopter surveys. However, after completing analysis of detection
probabilities associated with all of the methods, researchers noted
few, if any, ivory-billed woodpeckers could have remained undetected in
the Big Woods of Arkansas during the period from 2005 to 2009
(Rohrbaugh and Lammertink 2016, p. 40). Further, although the bird in
the video was first interpreted as an ivory-billed woodpecker, there is
dispute among the ornithological community as to whether it was an
actual ivory-billed woodpecker or instead a pileated woodpecker
(Dryocopus pileatus). No conclusive videos gathered since then that
confirm the persistence of the ivory-billed woodpecker. After
additional extensive analysis of the recordings, it was determined that
these recordings do not constitute evidence of the presence of ivory-
billed woodpeckers (Charif et al. 2005, p. 1489; Fitzpatrick et al.
2005, p. 1462; Jackson 2006, p. 3).
Since the reported ivory-billed woodpecker in 2004/2005 at the
Cache River NWR, a survey design was developed and implemented during
search efforts throughout the species' historical range. Many State,
Federal, and private partners (e.g., State wildlife agencies, the
Service, and the Cornell Laboratory of Ornithology) collaborated over a
5-year period to conduct extensive searches for evidence of the
species' presence within the historical range; however, no individuals
were reliably located, and no conclusive evidence confirmed the
species' persistence (Service 2010, pp. V, VII, 2-9, 75-89). Since the
5-year survey effort was completed, other survey efforts based on
sightings and vocalizations reported by wildlife professionals and
other individuals have continued throughout the range through present
day. These efforts include:
2005-2013: Pearl River swamp, Louisiana and
Choctawhatchee River swamp, Florida--Approximately 1,500 hours were
spent surveying these two swamps with a kayak and video cameras. Three
video clips were produced from both areas; however, the blurred images
are inconclusive as to whether they are ivory-billed woodpeckers or not
(Collins 2017, entire; Donahue 2017, p. 2).
2007-2011: 30 additional areas in the
southeastern United States (Pascagoula Basin of Mississippi, Mobile
Basin of Alabama, Congaree and Coastal Basins of South Carolina,
Apalachicola Basin of north Florida, and Everglades/Big Cypress Complex
of south Florida) were surveyed with no presence of ivory-billed
woodpeckers found (Lammertink and Rohrbaugh 2016, p. 7).
2011: White River NWR, Arkansas--Searches were
completed a year and a half after a tornado; no evidence of ivory-
billed woodpecker presence was observed, further adding to negative
outcome of the 2005-2009 search efforts in this NWR (Lammertink and
Rohrbaugh 2016, p. 7).
2011: Avoyelles Parish, Louisiana--Survey on
private property and Pomme de Terre Wildlife Management Area (WMA). No
observations of ivory-billed woodpeckers were made (Lammertink and
Rohrbaugh 2016, p. 7).
2011: Lee River State Natural Area, South
Carolina--No evidence of ivory-billed woodpecker presence was found
during surveys (Lammertink and Rohrbaugh 2016, p. 7).
2009-present: Louisiana--A search group, Project
Coyote, was founded to search for ivory-billed woodpeckers in
Louisiana; no evidence has been offered that constitutes undeniable
confirmation that the species persists (Michaels 2018, p. 79).
2016: Cuba--An expedition to Cuba was initiated
in search of the ivory-billed woodpecker; no presence found (McClelland
2016, pp. 13-15).
Although there have been many sightings reported over the years
since the last unrefuted sighting in 1944, there is much debate over
the validity of these reports. Furthermore, there is no objective
evidence (e.g., clear photographs, feathers of demonstrated recent
origin, specimens, etc.) of the continued existence of the species.
Additionally, researchers analyzed the temporal pattern of the
collection dates of museum specimens from 1853 to 1932 throughout the
historical range to estimate the probability of the persistence of the
species into the 21st century, as well as the probability that the
species would be found at survey sites with continued efforts. The
probability of persistence in a 2011 analysis was less than 0.000064,
and this analysis estimated the probable extinction date to be between
1960 and 1980 (Gotelli et al. 2011, entire). While differing in
assumptions, treatment of data, and statistical methods used, other
analyses had qualitatively similar conclusions (e.g., Roberts et al.
2009, entire; Solow et al. 2011, entire).
Time Since Last Detection
The last unrefuted sighting of the ivory-billed woodpecker occurred
in April 1944 on the Singer Tract in the Tensas River region of
northeast Louisiana (Service 2015, p. 9).
III. Analysis
The decline of mature forested habitat with a high percentage of
recently dead or dying trees and widespread collection of the species
likely led to the extirpation of the population sometime after the
1940s. Although there have been potential sightings reported over the
years since the last agreed-upon sighting in 1944, there is much debate
over the validity of these reports. Furthermore, there is no objective
evidence (e.g., clear photographs, feathers of demonstrated recent
origin, specimens, etc.) of the continued existence of the species
despite extensive searches. Given the likely lifespan of the species,
this means it has not been indisputably observed in more than seven
generations.
IV. Conclusion
The ivory-billed woodpecker has not been definitively sighted since
1944, despite decades of extensive survey effort. The loss of mature
forest habitat and widespread collection of the species likely led to
its extirpation in the 1940s or soon thereafter. Therefore, we conclude
that the best available scientific and commercial information indicates
that the species is extinct.
Kauai akialoa (Akialoa stejnegeri)
I. Background
Kauai akialoa (Akialoa stejnegeri; listed as Hemignathus
stejnegeri), a Hawaiian honeycreeper, was listed as endangered on March
11, 1967 (32 FR 4001). It was included in the Kauai Forest Birds
Recovery Plan (USFWS 1983), and the Revised Recovery Plan for Hawaiian
Forest Birds (USFWS 2006, p. 2-86). At the time of listing, we
considered Kauai akialoa to have very low population numbers and to be
threatened by habitat loss, avian disease, and predation by rats
(Rattus spp.). The last confirmed observation of the species was in
1965, although there was an unconfirmed sighting in 1969 (Reynolds and
Snetsinger 2001, p. 142). Two 5-year status reviews have been
completed, in 2009 (initiated on July 6, 2005; see 70 FR 38972) and
2018 (initiated on February 13, 2015; see 80
[[Page 54308]]
FR 8100). The 2009 review did not recommend a change in status, though
there was some information indicating the species was already extinct.
The 5-year status review completed in 2019 recommended delisting due to
extinction based on consideration of additional information about the
biological status of the species, included in the discussion below
(USFWS 2019, pp. 5, 10).
The life history of Kauai akialoa is poorly known and based mainly
on observations from the end of the 19th century (USFWS 2006, p. 2-86).
There is no information on the lifespan of the Kauai akialoa nor its
threats when it was extant. The species was widespread on Kauai and
occupied all forest types above 656 feet (200 meters) elevation
(Perkins 1903, pp. 369, 422, 426). Its historical range included nearly
all Kauai forests visited by naturalists at the end of the 19th
century. After a gap of many decades, the species was seen again in the
1960s, when one specimen was collected (Richardson and Bowles 1964, p.
30). It has not been seen since, despite efforts by ornithologists
(Conant et al. 1998, p. 15) and birders, and intensive survey efforts
by wildlife biologists spanning 1968 to 2018 (USFWS 1983, p. 2; Hawaii
Department of Land and Natural Resources unpubl. data; Reynolds and
Snetsinger 2001, entire; Crampton et al. 2017 entire; Crampton 2018,
pers. comm.).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Kauai akialoa was a large (6.7 to 7.5 inches, or 17 to 19
centimeters, total length), short-tailed Hawaiian honeycreeper with a
very long, thin, curved bill, the longest bill of any historically
known Hawaiian passerine. The plumage of both sexes was olive-green;
males were more brightly colored, were slightly larger, and had a
somewhat longer bill (USFWS 2006, p. 2-86). The Kauai akialoa's
relatively large size and distinctive bill suggest that if it were
extant, it would be detectable by sight and recognized.
Survey Effort
A comprehensive survey of Hawaiian forest birds was initiated in
the 1970s using the VCP method (Scott et al. 1986, entire). VCP surveys
in Hawaii are conducted at pre-established stations along transects.
The surveyor counts all birds seen and heard during an 8-minute count
period and estimates the distance from the count station to each bird
seen or heard. From this information, an estimate of the number of
birds in area surveyed is determined and the confidence interval for
this estimate derived. VCP surveys have been the primary method used to
count birds in Hawaii; however, it is not appropriate for all species
and provides poor estimates for extremely rare birds (Camp et al. 2009,
p. 92). In recognition of this problem, the Rare Bird Search (RBS) was
undertaken from 1994 to 1996, to update the status and distribution of
13 ``missing'' Hawaiian forest birds (Reynolds and Snetsinger 2001, pp.
134-137). The RBS was designed to improve efficiency in the search for
extremely rare species, using the method of continuous observation
during 20- to 30-minute timed searches in areas where target species
were known to have occurred historically, in conjunction with audio
playback of species vocalizations (when available). Several recent
surveys and searches, including the RBS, have been unsuccessful in
detecting Kauai akialoa despite intensive survey efforts by wildlife
biologists from 1968 to 1973, and in 1981, 1989, 1993, 1994, 2000,
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018 pers. comm.). An unconfirmed 1969 report
may have been the last sighting of Kauai akialoa (Conant et al. 1998,
p. 15). Kauai akialoa has been presumed likely extinct for some time
(Reynolds and Snetsinger 2001, p. 142).
In addition, extensive time has been spent by qualified observers
in the historical range of the Kauai akialoa searching for the small
Kauai thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and
Kauai creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS)
were conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and
2018 (Paxton et al. 2016, entire). The Kauai Forest Bird Recovery
Project (KFBRP) conducted occupancy surveys for the small Kauai thrush
in Kokee State Park, Hono O NaPali Natural Area Reserve, Na Pali Kona
Forest Reserve, and Alakai Wilderness Preserve, from 2011 to 2013
(Crampton et al. 2017, entire), and spent over 1,500 person-hours per
year from 2015 to 2018 searching for Kauai creeper and akekee nests.
During the HFBS in 2012 and 2018, occupancy surveys and nest searches
did not yield any new detections of Kauai akialoa. The KFBRP conducted
mist-netting in various locations within the historical range for Kauai
akialoa from 2006 through 2009, and from 2011 through 2018, and no
Kauai akialoa were caught or encountered (Crampton 2018, pers. comm.).
Time Since Last Detection
Another approach used to determine whether extremely rare species
are likely extinct or potentially still extant is to calculate the
probability of a species' extinction based on time (years) since the
species was last observed (Elphick et al. 2010, p. 620). This approach,
when applied to extremely rare species, has the drawback that an
incorrect assignment of species extinction may occur due to inadequate
survey effort and/or insufficient time by qualified observers spent in
the area where the species could still potentially exist. Using 1969 as
the last credible sighting of Kauai akialoa, the authors' estimated
date for the species' extinction is 1973, with 95 percent confidence
that the species was extinct by 1984.
III. Analysis
The various bird species in the subfamily Drepanidinae (also known
as the Hawaiian honeycreepers), which includes Kauai akialoa, are
highly susceptible to introduced avian disease. They are particularly
susceptible to avian malaria (Plasmodium relictum), which results in
high rates of mortality. At elevations below approximately 4,500 feet
(1,372 meters) in Hawaii, the key factor driving disease epizootics
(outbreaks) of pox virus (Avipoxvirus) and avian malaria is the
seasonal and altitudinal distribution and density of the primary vector
of these diseases, Culex quinquefasciatus (Atkinson and Lapointe 2009a,
pp. 237-238, 245-246).
A recent analytic tool was consulted using information on threats
to infer species extinction based on an evaluation of whether
identified threats are sufficiently severe and prolonged to cause local
extinction, and sufficiently extensive in geographic scope to eliminate
all occurrences (Keith et al. 2017, p. 320). The disappearance of many
Hawaiian honeycreeper species over the last century from areas below
approximately 4,500 feet elevation points to effects of avian disease
having been sufficiently severe and prolonged, and extensive in
geographic scope, to cause widespread species' range contraction and
possible extinction. It is highly likely avian disease is the primary
causal factor for the disappearance of many species of Hawaiian
honeycreepers from forested areas below 4,500 feet on the islands of
Kauai, Oahu, Molokai, and Lanai (Scott et al. 1986, p. 148; Banko and
Banko 2009, pp. 52-53; Atkinson and Lapointe 2009a, pp. 237-238).
[[Page 54309]]
It is widely established that small populations of animals are
inherently more vulnerable to extinction because of random demographic
fluctuations and stochastic environmental events (Mangel and Tier 1994,
p. 607; Gilpin and Soul[eacute] 1986, pp. 24-34). Formerly widespread
populations that become small and isolated often exhibit reduced levels
of genetic variability, which diminishes the species' capacity to adapt
and respond to environmental changes, thereby lessening the probability
of long-term persistence (e.g., Barrett and Kohn 1991, p. 4; Keller and
Waller 2002, p. 240; Newman and Pilson 1997, p. 361). As populations
are lost or decrease in size, genetic variability is reduced, resulting
in increased vulnerability to disease and restricted potential
evolutionary capacity to respond to novel stressors (Spielman et al.
2004, p. 15261; Whiteman et al. 2006, p. 797). As numbers decreased
historically, effects of small population size were very likely to have
negatively impacted Kauai akialoa, reducing its potential for long-term
persistence.
Several recent surveys and searches (1981 to 2018), including the
RBS, have been unsuccessful in detecting Kauai akialoa despite efforts
by ornithologists (Conant et al. 1998, p. 15) and birders, and
intensive survey efforts by wildlife biologists in 1968 to 1973, 1981,
1989, 1994, 2000, 2005, and from 2011 to 2018 (Hawaii Department of
Land and Natural Resources unpubl. data; USFWS 1983, p. 2; Reynolds and
Snetsinger 2001, entire; Crampton et al. 2017, entire; Crampton 2018,
pers. comm.). Using 1969 as the last credible sightings, based on
independent expert opinion, the estimated date for the species'
extinction is 1973, with 95 percent confidence of the species having
become extinct by 1984 (Elphick et al. 2010, p. 620).
IV. Conclusion
At the time of listing in 1967, the Kauai akialoa faced threats
from habitat loss, avian disease, and predation by introduced mammals.
The best available information now indicates that the Kauai akialoa is
extinct. The species appears to have been vulnerable to introduced
avian disease. In addition, the effects of small population size likely
limited the species' genetic variation and adaptive capacity, thereby
increasing the vulnerability of the species to environmental stressors
including habitat loss and degradation. Since its last detection in
1969, qualified observers have conducted extensive surveys and searches
but have not detected the species. Available information indicates that
the species was not able to persist in the face of environmental
stressors, and we conclude that the best available scientific and
commercial information indicates that the species is extinct.
Kauai nukupuu (Hemignathus hanapepe)
I. Background
The Kauai nukupuu (Hemignathus hanapepe) was listed as endangered
on March 11, 1967 (32 FR 4001), and was included in the Kauai Forest
Birds Recovery Plan (USFWS 1983), as well as the Revised Recovery Plan
for Hawaiian Forest Birds (USFWS 2006). At the time of listing,
observations of only two individuals had been reported during that
century (USFWS 1983, p. 3). The last confirmed observation (based on
independent expert opinion and physical evidence) of the species was in
1899 (Eliphick et al. 2010, p. 620). Two 5-year status reviews have
been completed, in 2010 (initiated on April 11, 2006; see 71 FR 18345)
and 2019 (initiated on February 13, 2015; see 80 FR 8100). The 2010
review did not recommend a change in status, though there was some
information indicating the species was already extinct. The 5-year
status review completed in 2019 recommended delisting due to extinction
based on consideration of additional information about the biological
status of the species, included in the discussion below (USFWS 2019,
pp. 4-5, 10).
The historical record provides little information on the life
history of Kauai nukupuu (USFWS 2006, p. 2-89). There is no specific
information on the lifespan or breeding biology of Kauai nukupuu,
although it is presumed to be similar to its closest relative,
akiapolaau (Hemignathus munroi, listed as Hemignathus wilsoni), a
honeycreeper from the island of Hawaii. Similar to the akiapolaau, the
Kauai nukupuu uses its bill to extract invertebrates from epiphytes,
bark, and wood. The last confirmed observation (based on independent
expert opinion and physical evidence) of Kauai nukupuu was in 1899
(Eliphick et al. 2010, p. 620); however, there was an unconfirmed
observation in 1995 (Conant et al. 1998, p. 14).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Kauai nukupuu was a medium-sized, approximately 23-gram (0.78-
ounce), Hawaiian honeycreeper (family Fringillidae, subfamily
Drepanidinae) with an extraordinarily thin, curved bill, slightly
longer than the bird's head. The lower mandible was half the length of
the upper mandible. Adult male plumage was olive-green with a yellow
head, throat, and breast, whereas adult female and immature plumage
consisted of an olive-green head and yellow or yellowish gray under-
parts (USFWS 2006, p. 2-89). The long, curved, and extremely thin bill
of Kauai nukupuu, in combination with its brightly colored plumage,
would have made this bird highly detectable to ornithologists and
birders had it persisted (USFWS 2006, p. 2-89). No subsequent sightings
or vocalizations have been documented since the unconfirmed sighting in
1995, despite extensive survey efforts.
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Kauai nukupuu is unknown. A comprehensive
survey of Hawaiian forest birds was initiated in the 1970s using the
VCP method (Scott et al. 1986, entire) (see Survey Effort section for
the Kauai akialoa, above, for the description of the VCP surveys).
Several recent surveys and searches, including the RBS, have been
unsuccessful in detecting Kauai nukupuu despite intensive survey
efforts by wildlife biologists from 1968 to 1973, and in 1981, 1989
1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii Department of Land and
Natural Resources unpubl. data; Reynolds and Snetsinger 2001, entire;
Crampton et al. 2017, entire; Crampton 2018 pers. comm.). During the
RBS, Kauai nukupuu were not detected. The lack of detections combined
with analysis of detection probability (P >= 0.95) suggested that the
possible population count was fewer than 10 birds in 1996 (Reynolds and
Snetsinger 2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the Kauai nukupuu searching for the small Kauai
thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and Kauai
creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) were
conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018
(Paxton et al. 2016, entire). During the HFBS in 2012 and 2018,
occupancy surveys and nest searches did not yield any new detections of
the Kauai nukupuu. The KFBRP conducted mist-netting in various
locations within the historical range for the Kauai nukupuu from 2006
through 2009, and from 2011 through 2018, and no Kauai nukupuu were
caught or encountered (Crampton 2018, pers. comm.). Despite
contemporary
[[Page 54310]]
search efforts, the last credible sighting of Kauai nukupuu occurred in
1899.
Time Since Last Detection
Using 1899 as the last credible sighting of Kauai nukupuu based on
independent expert opinion and physical evidence, the estimated date
for the species' extinction was 1901, with 95 percent confidence that
the species was extinct by 1906 (Elphick et al. 2010, p. 620).
III. Analysis
Some of the reported descriptions of this species better match the
Kauai amakihi (Chlorodrepanis stejnegeri) (USFWS 2006, p. 2-90).
Although skilled observers reported three unconfirmed sightings of
Kauai nukupuu in 1995 (Reynolds and Snetsinger 2001, p. 142), extensive
hours of searching within the historical range failed to detect any
individuals. The last credible sightings of Kauai nukupuu was in 1899,
based on independent expert opinion and physical evidence (Elphick et
al. 2010, p. 620). It was estimated that 1901 was the year of
extinction, with 95 percent confidence that the species was extinct by
1906. The species was likely vulnerable to the persistent threats of
avian disease combined with habitat loss and degradation, which remain
drivers of extinction for Hawaiian forest birds.
V. Conclusion
At the time of listing in 1967, the Kauai nukupuu had not been
detected for almost 70 years. Since its last detection in 1899,
qualified observers have conducted extensive surveys and searches
throughout the range of the Kauai nukupuu and have not detected the
species. Available information indicates that the species was not able
to persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial information indicates that
the species is extinct.
Kauai `o`o (Moho braccatus)
I. Background
The Kauai `o`o (Moho braccatus) was listed as endangered on March
11, 1967 (32 FR 4001), and was included in the Kauai Forest Birds
Recovery Plan (USFWS 1983), as well as the Revised Recovery Plan for
Hawaiian Forest Birds (USFWS 2006). At the time of listing, the
population size was estimated at 36 individuals (USFWS 1983, p. 3).
Threats to the species included the effects of low population numbers,
habitat loss, avian disease, and predation by introduced mammals. The
last plausible record of a Kauai `o`o was a vocal response to a
recorded vocalization played by a field biologist on April 28, 1987, in
the locality of Halepaakai Stream. Two 5-year status reviews have been
completed, in 2009 (initiated on July 6, 2005; see 70 FR 38972) and
2018 (initiated on February 13, 2015; see 80 FR 8100). The 2009 review
did not recommend a change in status, though there was some information
indicating the species was already extinct. The 5-year status review
completed in 2018 recommended delisting due to extinction based on
consideration of new information about the biological status of the
species, included in the discussion below (USFWS 2019, pp. 5, 10).
The Kauai `o`o measured 7.7 inches (19.5 centimeters) and was
somewhat smaller than the Moho species on the other islands. It was
glossy black on the head, wings, and tail; smoky brown on the lower
back, rump, and abdomen; and rufous-brown on the upper tail coverts. It
had a prominent white patch at the bend of the wing. The thigh feathers
were golden yellow in adults and black in immature birds (Berger 1972,
p. 107). The Kauai `o`o is one of four known Hawaiian species of the
genus Moho and one of five known Hawaiian bird species within the
family Mohoidae (Fleischer et al. 2008, entire). Its last known habitat
was the dense ohia forest in the valleys of Alakai Wilderness Preserve.
It reportedly fed on various invertebrates and the fruits and nectar
from ohia, lobelia, and other flowering plants. There is no information
on the lifespan of the Kauai `o`o.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The vocalizations of this species were loud, distinctive, and
unlikely to be overlooked. The song consisted of loud whistles that
have been described as flute-like, echoing, and haunting, suggesting
that detectability would be high in remaining suitable habitat if the
Kauai `o`o still existed (USFWS 2006 p. 2-47).
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Kauai `o`o cannot be reconstructed. The
comprehensive surveys of Hawaiian forest birds are described in the
Survey Effort section of the Kauai akialoa. Several recent surveys and
searches, including the VCP and RBS, have been unsuccessful in
detecting Kauai `o`o despite intensive survey efforts by wildlife
biologists from 1968 to 1973, and in 1981, 1989 1993, 1994, 2000, 2005,
and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018 pers. comm.). During the RBS, coverage of
the search area was extensive; therefore, there was a high probability
of detecting a Kauai `o`o. None were detected, and it was concluded the
Kauai `o`o was likely extinct (P >= 0.95) (Reynolds and Snetsinger
2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the Kauai `o`o searching for the small Kauai thrush
(Myadestes palmeri), akekee (Loxops caeruleirostris), and Kauai creeper
(Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS) were conducted
in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and 2018 (Paxton et
al. 2016, entire). During the HFBS in 2012 and 2018, occupancy surveys
and nest searches did not yield any new detections of Kauai `o`o. The
KFBRP conducted mist-netting in various locations within the historical
range for Kauai `o`o from 2006 through 2009 and 2011 through 2018, and
no Kauai `o`o were caught or encountered (Crampton 2018, pers. comm.).
The last credible sighting was in 1987.
Time Since Last Detection
Using 1987 as the last credible sighting of the Kauai `o`o based on
independent expert opinion, the estimated date for the species'
extinction was 1991, with 95 percent confidence that the species was
extinct by 2000 (Elphick et al. 2010, p. 620).
III. Analysis
The various bird species in the subfamily Drepanidinae (also known
as the Hawaiian honeycreepers), which includes Kauai `o`o, are highly
susceptible to introduced avian disease, particularly avian malaria
(Plasmodium relictum). At elevations below approximately 4,500 feet
(1,372 meters) in Hawaii, the key factor driving disease epizootics of
pox virus (Avipoxvirus) and avian malaria is the seasonal and
altitudinal distribution and density of the primary vector of these
diseases, Culex quinquefasciatus (Atkinson and Lapointe 2009a, pp. 237-
238, 245-246). Because they occur at similar altitudes and face similar
threats, please refer to the Analysis section for the Kauai akialoa,
above, for more information.
IV. Conclusion
At the time of listing in 1967, the Kauai `o`o faced threats from
effects of
[[Page 54311]]
low population numbers, habitat loss, avian disease, and predation by
introduced mammals. The best available information now indicates that
the Kauai `o`o is extinct. The species appears to have been vulnerable
to introduced avian disease. In addition, the effects of small
population size likely limited the species' genetic variation and
adaptive capacity, thereby increasing the vulnerability of the species
to environmental stressors including habitat loss and degradation.
Since its last detection in 1987, qualified observers have conducted
extensive surveys and searches and have not detected the species.
Available information indicates that the species was not able to
persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial information indicates that
the species is extinct.
Large Kauai Thrush (Myadestes myadestinus)
I. Background
The large Kauai thrush (Myadestes myadestinus, or kama`o in the
Hawaiian language) was listed as endangered on October 13, 1970 (35 FR
16047), and was included in the Kauai Forest Birds Recovery Plan (USFWS
1983), as well as the Revised Recovery Plan for Hawaiian Forest Birds
(USFWS 2006). At the time of listing, the population size was estimated
at 337 individuals (USFWS 1983, p. 3). Threats to the species included
effects of low population numbers, habitat loss, avian disease, and
predation by introduced mammals. Two 5-year status reviews were
completed in 2009 (initiated on July 6, 2005; see 70 FR 38972) and 2019
(initiated on February 13, 2015; see 80 FR 8100). The 2009 review did
not recommend a change in status, though there was some information
indicating the species was already extinct. The 5-year status review
completed in 2019 recommended delisting due to extinction based on
consideration of additional information about the biological status of
the species, included in the discussion below (USFWS 2019, pp. 5, 10).
The large Kauai thrush was a medium-sized (7.9 inches, or 20
centimeters, total length) solitaire. Its plumage was gray-brown above,
tinged with olive especially on the back, and light gray below with a
whitish belly and undertail coverts. The large Kauai thrush lacked the
white eye-ring and pinkish legs of the smaller puaiohi (small Kauai
thrush, Myadestes palmeri) (USFWS 2006, p. 2-19). There is no specific
information on the life history of the large Kauai thrush; however, it
is presumed that it is similar to the more common and closely related
Hawaii thrush (Myadestes obscurus). Nests of the large Kauai thrush
have not been described but may be a cavity or low platform, similar to
those of the Hawaii thrush. Nesting likely occurred in the spring. The
diet of the large Kauai thrush was reported to include fruits and
berries, as well as insects and snails. The last (unconfirmed)
observation of the large Kauai thrush was made during the February 1989
Kauai forest bird survey (Hawaii Department of Land and Natural
Resources unpubl. data). However, the last credible sighting of the
large Kauai thrush occurred in 1987.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The large Kauai thrush was often described for its habit of rising
into the air, singing a few vigorous notes and then suddenly dropping
down into the underbrush. The vocalizations of this species varied
between sweet and melodic to lavish and flute-like, often given just
before dawn and after dusk (USFWS 2006 p. 2-19). These behaviors
suggest that detectability would be high in remaining suitable habitat
if the large Kauai thrush still existed. No subsequent sightings or
vocalizations have been documented despite extensive survey efforts by
biologists and birders.
Survey Effort
Several recent surveys and searches, including the VCP and RBS,
have been unsuccessful in detecting the large Kauai thrush despite
intensive survey efforts by wildlife biologists from 1968 to 1973, and
in 1981, 1989, 1993, 1994, 2000, 2005, and 2011 to 2018 (Hawaii
Department of Land and Natural Resources unpubl. data; Reynolds and
Snetsinger 2001, entire; Crampton et al. 2017, entire; Crampton 2018,
pers. comm.). During the RBS in 2001, coverage of the search area was
extensive; therefore, they had a high probability of detecting the
large Kauai thrush. None were detected, and it was concluded that the
large Kauai thrush was likely extinct (P >= 0.95) (Reynolds and
Snetsinger 2001, p. 142).
Extensive time has been spent by qualified observers in the
historical range of the large Kauai thrush searching for the small
Kauai thrush (Myadestes palmeri), akekee (Loxops caeruleirostris), and
Kauai creeper (Oreomystis bairdi). Hawaii Forest Bird Surveys (HFBS)
were conducted in 1981, 1989, 1994, 2000, 2005, 2007, 2008, 2012, and
2018 (Paxton et al. 2016, entire). During the HFBS in 2012 and 2018,
occupancy surveys and nest searches did not yield any new detections of
the large Kauai thrush. The KFBRP conducted mist-netting in various
locations within the historical range for the large Kauai thrush from
2006 through 2009, and from 2011 through 2018, and no large Kauai
thrush were caught or encountered (Crampton 2018, pers. comm.). The
last credible sighting of the large Kauai thrush occurred in 1987.
Time Since Last Detection
Using 1987 as the last credible sighting of the large Kauai thrush
based on independent expert opinion, the estimated date for the
species' extinction was 1991, with 95 percent confidence that the
species was extinct by 1999 (Elphick et al. 2010, p. 620).
III. Analysis
Several recent surveys and searches, including the RBS and HFBS,
have been unsuccessful in detecting the large Kauai thrush despite
intensive survey efforts by wildlife biologists in 1993, 1994, 2000,
2005, and 2011 to 2018 (Hawaii Department of Land and Natural Resources
unpubl. data; Reynolds and Snetsinger 2001, entire; Crampton et al.
2017, entire; Crampton 2018, pers. comm.). Using 1987 as the last
credible sighting based on independent expert opinion and the species'
observational record, the estimated date for the species' extinction
was 1991, with 95 percent confidence the species was extinct by 1999
(Elphick et al. 2010, p. 620). Another analysis determined that the
large Kauai thrush was probably extinct at the time of the RBS in 1994
(P >= 0.95) (Reynolds and Snetsinger 2001, p. 142).
IV. Conclusion
At the time of listing in 1970, the large Kauai thrush faced
threats from low population numbers, habitat loss, avian disease, and
predation by introduced mammals. The best available information now
indicates that the large Kauai thrush is extinct. The species appears
to have been vulnerable to the effects of small population size, which
likely limited its genetic variation, disease resistance, and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last credible detection in 1987, qualified
observers have conducted extensive surveys and searches throughout the
range of the
[[Page 54312]]
species but have not detected the species. Available information
indicates that the species was not able to persist in the face of
environmental stressors, and we conclude that the best available
scientific and commercial information indicates that the species is
extinct.
Maui Akepa (Loxops coccineus ochraceus)
I. Background
The Maui akepa (Loxops coccineus ochraceus, listed as Loxops
ochraceus) was listed as endangered on October 13, 1970 (35 FR 16047),
and was included in the Maui-Molokai Forest Birds Recovery Plan (USFWS
1984, pp. 12-13), and the Revised Recovery Plan for Hawaiian Forest
Birds (USFWS 2006, pp. 2-94, 2-134-2-137). At the time of listing, we
considered Maui akepa to have very low population numbers, and to face
threats from habitat loss, avian disease, and predation by introduced
mammals. Three 5-year status reviews have been completed; the 2010
(initiated on April 11, 2006; see 71 FR 18345) and 2015 (initiated on
March 6, 2012; see 77 FR 13248) reviews did not recommend a change in
status, though there was some information indicating the species was
already extinct (USFWS 2010, p. 12; USFWS 2015, p. 10). The 5-year
status review completed in 2018 (initiated on February 12, 2016; see 81
FR 7571) recommended delisting due to extinction, based in part on
continued lack of detections and consideration of extinction
probability (USFWS 2018, pp. 5, 10).
The Maui akepa was known only from the island of Maui in the
Hawaiian Islands. Maui akepa were found in small groups with young in
the month of June when the birds were molting (Henshaw 1902, p. 62).
The species was observed preying on various insects including small
beetles, caterpillars, and small spiders, as well as drinking the
nectar of ohia (Metrosideros polymorpha) flowers (Rothschild 1893 to
1900, pp. 173-176; Henshaw 1902, p. 62; Perkins 1903, pp. 417-420). The
species appeared to also use the ohia tree for nesting as a pair of
Maui akepa was observed building a nest in the terminal foliage of a
tall ohia tree (Perkins 1903, p. 420).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Maui akepa adult males varied from dull brownish orange to
ochraceus (light brownish yellow), while females were duller and less
yellowish (USFWS 2006, p. 2-134). Although the species was easily
identifiable by sight, its small body size (less than 5 inches (13
centimeters) long) and habitat type (dense rain forest) made visual
detection difficult. Songs and calls of Maui akepa could be confused
with those of other Maui forest bird species; therefore, detection of
the species requires visual confirmation of the individual producing
the songs and calls (USFWS 2006, p. 2-135).
Survey Effort
In the absence of early historical surveys, the extent of the
geographical range of the Maui akepa is unknown. Because the species
occupied Maui Island, one might expect that it also inhabited Molokai
and Lanai Islands like other forest birds in the Maui Nui group, but
there are no fossil records of Maui akepa from either of these islands
(USFWS 2006, p. 2-135). All historical records of the Maui akepa in the
late 19th and early 20th century were from high-elevation forests most
accessible to naturalists, near Olinda and Ukulele Camp on the
northwest rift of Haleakala, and from mid-elevation forests in Kipahulu
Valley (USFWS 2006, p. 2-134). This range suggests that the birds were
missing from forests at lower elevations, perhaps due to the
introduction of disease-transmitting mosquitoes to Lahaina in 1826
(USFWS 2006, p. 2-135). From 1970 to 1995, there were few credible
sightings of Maui akepa (USFWS 2006, p. 2-136).
The population of Maui akepa was estimated at 230 individuals, with
a 95 percent confidence interval of plus or minus 290 individuals
(Scott et al. 1986, pp. 37, 154) during VCP surveys in 1980. In other
words, the estimate projects a maximum population of 520 individuals
and a minimum population of zero. However, confidence intervals were
large, and this estimate was based on potentially confusing auditory
detections, and not on visual observation (USFWS 2006, p. 2-136). On
Maui, VCP surveys are conducted at survey stations spaced 328 to 820
feet (100 to 250 meters) apart, on transect lines spaced 1 to 2 miles
(1.6 to 3.2 kilometers) apart (Scott et al. 1986, pp. 34-40). It is
estimated that 5,865 8-minute point counts would be needed to determine
with 95 percent confidence the absence of Maui akepa on Maui (Scott et
al. 2008, p. 7). In 2008, only 84 VCP counts had been conducted on Maui
in areas where this species was known to have occurred historically.
Although the results of the 1980 VCP surveys find Maui akepa extant at
that time, tremendous effort is required using the VCP method to
confirm this species' extinction (Scott et al. 2008). For Maui akepa,
nearly 70 times more VCP counts than conducted up to 2008 would be
needed to confirm the species' extinction with 95 percent confidence.
Songs identified as Maui akepa were heard on October 25, 1994,
during the RBS in Hanawi Natural Area Reserve (Hanawi NAR) and on
November 28, 1995, from Kipahulu Valley at 6,142 feet (1,872 meters)
elevation, but the species was not confirmed visually. Auditory
detections of Maui akepa require visual confirmation because of
possible confusion or mimicry with similar songs of Maui parrotbill
(Pseudonestor xanthophrys) (Reynolds and Snetsinger 2001, p. 140). The
last confirmed record, as defined above, of Maui akepa was from Hanawi
NAR in 1988 (Engilis 1990, p. 69).
Qualified observers spent extensive time searching for Maui akepa,
po`ouli (Melamprosops phaeosoma), and Maui nukupuu (Hemignathus lucidus
affinis, listed as Hemignathus affinis) in the 1990s. Between September
1995 and October 1996, 1,730 acres (700 hectares) in Hanawi NAR were
searched during 318 person-days (Baker 2001, p. 147), including the
area with the most recent confirmed sightings of Maui akepa. During
favorable weather conditions (good visibility and no wind or rain)
teams would stop when ``chewee'' calls given by Maui parrotbill, or
when po`ouli and Maui nukupuu were heard, and would play either Maui
parrotbill or akiapolaau (Hemignathus munroi, listed as Hemignathus
wilsoni) calls and songs to attract the bird for identification. Six
po`ouli were found, but no Maui akepa were detected (Baker 2001, p.
147). The Maui Forest Bird Recovery Project (MFBRP) conducted searches
from 1997 through 1999 from Hanawi NAR to Koolau Gap (west of Hanawi
NAR), for a total of 355 hours at three sites with no detections of
Maui akepa (Vetter 2018, pers. comm.). The MFBRP also searched Kipahulu
Valley on northern Haleakala from 1997 to 1999, for a total of 320
hours with no detections of Maui akepa. However, the Kipahulu searches
were hampered by bad weather, and playback was not used (Vetter 2018,
pers. comm.). Despite over 10,000 person-hours of searches in the
Hanawi NAR and nearby areas from October 1995 through June 1999,
searches failed to confirm earlier detections of Maui akepa (Pratt and
Pyle 2000, p. 37). While working on Maui parrotbill recovery from 2006
to 2011, the MFBRP spent extensive time in the area of the last Maui
akepa sighting. The MFBRP project coordinator concluded that if Maui
akepa were present, they would have been detected (Mounce 2018, pers.
comm.).
[[Page 54313]]
Time Since Last Detection
The last confirmed sighting (as defined for the RBS) of the Maui
akepa was in 1988 (Engilis 1990, p. 69). Surveys conducted during the
late 1980s to the 2000s failed to locate the species (Pratt and Pyle
2000, p. 37; Baker 2001, p. 147). Using 1980 as the last documented
observation record for Maui akepa (the 1988 sighting did not meet the
author's criteria for a ``documented'' sighting), 1987 was estimated to
be the year of extinction of Maui akepa, with 2004 as the upper 95
percent confidence bound on that estimate (Elphick et al. 2010, p.
620).
III. Analysis
Reasons for decline presumably are similar to threats faced by
other endangered forest birds on Maui, including small populations,
habitat degradation by feral ungulates and introduced invasive plants,
and predation by introduced mammalian predators, including rats (Rattus
spp.), cats (Felis catus), and mongoose (Herpestes auropunctatus)
(USFWS 2006, p. 2-136). Rats may have played an especially important
role as nest predators of Maui akepa. While the only nest of Maui akepa
ever reported was built in tree foliage, the birds may also have
selected tree cavities as does the very similar Hawaii akepa (Loxops
coccineus coccineus). In Maui forests, nest trees are of shorter
stature than where akepa survive on Hawaii Island. Suitable cavity
sites on Maui are low in the vegetation, some near or at ground level,
and thus more accessible to rats. High densities of both black and
Polynesian rats (Rattus rattus and R. exulans) are present in akepa
habitat on Maui (USFWS 2006, p. 2-136).
The population of Maui akepa was estimated at 230 birds in 1980
(Scott et al. 1986, p. 154); however, confidence intervals on this
estimate were large. In addition, this may have been an overestimate
because it was based on audio detections that can be confused with
similar songs of Maui parrotbill. The last confirmed sighting of Maui
akepa was in 1988, from Hanawi NAR (Engilis 1990, p. 69). Over 10,000
search hours in Hanawi NAR and nearby areas including Kipahulu Valley
from October 1995 through June 1999 failed to confirm presence of Maui
akepa (Pratt and Pyle 2000, p. 37). Field presence by qualified
observers from 2006 to 2011 in the area Maui akepa was last known
failed to detect this species, and the MFBRP project coordinator
concluded that if Maui akepa were present they would have been detected
(Mounce 2018, pers. comm.). Further, using the method to determine
probability of species extinction based on time (years) since the
species was last observed (using 1980 as the last documented
observation record, as described above), the estimated year the Maui
akepa became extinct is 1987, with 2004 as the upper 95 percent
confidence bound on that estimate (Elphick et al. 2010, p. 620).
IV. Conclusion
At the time of listing in 1970, we considered the Maui akepa to be
facing threats from habitat loss, avian disease, and predation by
introduced mammals. The best available information now indicates that
the Maui akepa is extinct. The species appears to have been vulnerable
to the effects of small population size, which likely limited its
genetic variation, disease resistance, and adaptive capacity, thereby
increasing the vulnerability of the species to the environmental
stressors of habitat degradation and predation by nonnative mammals.
Since the last detection in 1988, qualified observers have conducted
extensive surveys in that same area with no additional detections of
the species. Available information indicates that the species was not
able to persist in the face of environmental stressors, and we conclude
that best available scientific and commercial information indicates
that the species is extinct.
Maui Nukupuu (Hemignathus lucidus affinis)
I. Background
The Maui nukupuu (Hemignathus lucidus affinis, listed as
Hemignathus affinis) was listed as endangered on October 13, 1970 (35
FR 16047), and was included in the Maui-Molokai Forest Birds Recovery
Plan (USFWS 1984, pp. 8, 10-12), and the Revised Recovery Plan for
Hawaiian Forest Birds (USFWS 2006, pp. 2-92-2-96). At the time of
listing, we considered Maui nukupuu to have very low population numbers
and to be threatened by habitat loss, avian disease, and predation by
introduced mammals. The 5-year status review completed in 2018
(initiated on February 12, 2016; see 81 FR 7571) recommended delisting
due to extinction (USFWS 2018, p. 11).
The Maui nukupuu was known only from the island of Maui in the
Hawaiian Islands. The historical record provides little information on
the life history of the Maui nukupuu (Rothschild 1893 to 1900, pp. 103-
104; Perkins 1903, pp. 426-430). Nothing is known of its breeding
biology, which likely was similar to its closest relative, the
akiapolaau (Hemignathus munroi) on Hawaii Island. The Maui nukupuu was
insectivorous and probed bark, lichen, and branches to extract insects,
foraging behaviors that resembled those of akiapolaau. Diet of the Maui
nukupuu was reported to be small weevils and larvae of orders
Coleoptera and Lepidoptera (Perkins 1903, p. 429). There is scant
evidence that Maui nukupuu took nectar from flowers. Maui nukupuu often
joined mixed-species foraging flocks (Perkins 1903, p. 429).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Maui nukupuu was a medium-sized (approximately 0.78 ounce, or
23 gram) Hawaiian honeycreeper with an extraordinarily thin, curved
bill that was slightly longer than the bird's head. The lower mandible
was half the length of the upper mandible and followed its curvature
rather than being straight (as in the related akiapolaau) (USFWS 2006,
p. 2-92). Adult males were olive green with a yellow head, throat, and
breast, whereas adult females and juveniles had an olive-green head and
yellow or yellowish gray under-parts. The species' coloration and bill
shape were quite distinctive, making visual identification of Maui
nukupuu relatively easy. The Maui nukupuu's song resembled the warble
of a house finch (Carpodacus mexicanus), but was lower in pitch. Both
the song and the ``kee-wit'' call resembled those of Maui parrotbill
(Pseudonestor xanthophrys), and audio detection required visual
confirmation (USFWS 2006, p. 2-92).
Survey Effort
Historically, the Maui nukupuu was known only from Maui, but
subfossil bones of a probable Maui nukupuu from Molokai show that the
species likely formerly inhabited that island (USFWS 2006, p. 2-92).
All records from late 19th and early 20th centuries were from locations
most accessible to naturalists, above Olinda on the northwest rift of
Haleakala, and from mid-elevation forests in Kipahulu Valley (USFWS
2006, pp. 2-134). Observers at the time noted the restricted
distribution and low population density of Maui nukupuu. As on Kauai,
introduced mosquitoes and avian diseases may have already limited these
birds to forests at higher elevations, and we can presume that the Maui
nukupuu once had a much wider geographic range (USFWS 2006, pp. 2-92).
In 1967, Maui nukupuu were rediscovered in the upper reaches of
Kipahulu Valley on the eastern slope of Haleakala, east Maui (Banko
1968, pp.
[[Page 54314]]
65-66; USFWS 2006, pp. 2-95). Since then, isolated sightings have been
reported on the northern and eastern slopes of Haleakala, but these
reports are uncorroborated by behavioral information or follow-up
sightings (USFWS 2006, pp. 2-95).
Based on a single sighting of an immature bird during VCP surveys
in 1980, the population of Maui nukupuu was estimated to be 28
individuals, with a 95 percent confidence interval of plus or minus 56
individuals (Scott et al. 1986, pp. 37, 131). On Maui, VCP surveys are
conducted at survey stations spaced 328 to 820 feet (100 to 250 meters)
apart, on transect lines spaced 1 to 2 miles (1.6 to 3.2 kilometers)
apart (Scott et al. 1986, pp. 34-40). It was estimated that 1,357 8-
minute point counts would be needed to determine with 95 percent
confidence the absence of Maui nukupuu on Maui (Scott et al. 2008, p.
7). In 2008, only 35 VCP counts had been conducted on Maui in areas
where Maui nukupuu could still potentially exist. Although the results
of VCP surveys in 1980 find Maui nukupuu extant at that time, a
tremendous effort is required to confirm this species' extinction using
VCP method (Scott et al. 2008). For Maui nukupuu, nearly 39 times more
VCP counts than conducted up to 2008 would be needed to confirm this
species' extinction with 95 percent confidence. The RBS reported an
adult male Maui nukupuu with bright yellow plumage at 6,021 feet (1,890
meters) elevation in 1996 from Hanawi Natural Area Reserve (Hanawi NAR)
(Reynolds and Snetsinger 2001, p. 140). Surveys and searches have been
unsuccessful in finding Maui nukupuu since the last confirmed sighting
by RBS. Based on these results, the last reliable record of Maui
nukupuu was from Hanawi NAR in 1996 (24 years ago).
Qualified observers spent extensive time searching for Maui
nukupuu, po`ouli (Melamprosops phaeosoma), and Maui akepa (Loxops
coccineus ochraceus, listed as Loxops ochraceus) in the 1990s. Between
September 1995 and October 1996, 1,730 acres (700 hectares) of Hanawi
NAR were searched during 318 person-days (Baker 2001, p. 147). Please
refer to the Maui akepa Survey Effort section above for the method used
in this survey. The Maui Forest Bird Recovery Project (MFBRP) conducted
searches from 1997 to 1999, from Hanawi NAR to Koolau Gap (west of the
last sighting of Maui nukupuu) for a total of 355 hours of searches at
three sites with no detections of Maui nukupuu (Vetter 2018, pers.
comm.). The MFBRP also searched Kipahulu Valley on northern Haleakala
from 1997 to 1999, for a total of 320 hours, with no detections of Maui
nukupuu. The Kipahulu searches were hampered, however, by bad weather,
and playback was not used (Vetter 2018, pers. comm.). Despite over
10,000 person-hours of searching in the Hanawi NAR and nearby areas
from October 1995 through June 1999, searches failed to confirm
detection in 1996 of Maui nukupuu, or produce other sightings (Pratt
and Pyle 2000, p. 37). While working on Maui parrotbill recovery from
2006 to 2011, the MFBRP spent extensive time in the area of the last
Maui nukupuu sighting. The MFBRP project coordinator concluded that if
Maui nukupuu were still present they would have been detected (Mounce
2018, pers. comm.).
Time Since Last Detection
The Maui nukupuu was last sighted in the Hanawi NAR in 1996
(Reynolds and Snetsinger 2001, p. 140). Surveys conducted during the
late 1990s and early 2000s were unable to locate the species (Pratt and
Pyle 2000, p. 37; Baker 2001, p. 147).
Elphick et al 2010 (p. 630) attempted to apply their method to
predict the probability of species extinction for the Maui nukupuu
based on time (years) since the species was last observed (see Time
Since Last Detection section for Kauai akialoa, above). Basing
extinction probability solely on the sighting record without physical
evidence has the drawback that an incorrect assignment of species
extinction may occur due to inadequate survey effort and/or
insufficient time spent by qualified observers in areas where the
species could still potentially exist. Therefore, observations in 1967,
1980, and 1996 were not considered for this analysis because they did
not meet the researchers' criteria for a confirmed sighting. Therefore,
using 1896 as the last observation of Maui nukupuu, under their
stringent criteria, the authors were unable to determine an estimated
date for species extinction.
III. Analysis
The Maui nukupuu is also affected by small population sizes and
other threats, as discussed above under the Analysis section for the
Maui akepa. The population of Maui nukupuu was estimated to be 28 birds
in 1980 (Scott et al. 1986, pp. 37, 131); however, confidence intervals
on this estimate were large. This population was vulnerable to negative
effects of small population size, including stochastic effects and
genetic drift that can accelerate the decline of small populations.
However, even rare species can persist despite having low numbers. The
last confirmed sighting of Maui nukupuu was in 1996, from Hanawi NAR
(Reynolds and Snetsinger 2001, p. 140). Over 10,000 person-search hours
in Hanawi NAR and nearby areas, including Kipahulu Valley, from October
1995 through June 1999 failed to confirm this sighting or to detect
other individuals (Pratt and Pyle 2000, p. 37). While working on Maui
parrotbill recovery from 2006 to 2011, the MFBRP spent extensive time
in the area of the last Maui nukupuu sighting; however, no Maui nukupuu
were observed, and the MFBRP project coordinator concluded that if Maui
nukupuu were still present they would have been detected (Mounce 2018,
pers. comm.).
IV. Conclusion
At the time of listing in 1970, Maui nukupuu had very low
population numbers and faced threats from habitat loss, avian disease,
and predation by introduced mammals. The species appears to have been
vulnerable to avian disease and the effects of small population size.
The latter likely limited the species' genetic variation and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last detection in 1996, qualified
observers have conducted extensive searches in the area where the
species was last sighted and other native forest habitat where the
species occurred historically, but have not detected the species.
Available information indicates that the species was not able to
persist in the face of environmental stressors, and we conclude that
the best available scientific and commercial data indicate that the
species is extinct.
Molokai Creeper (Paroeomyza flammea)
I. Background
The Molokai creeper (Paroreomyza flammea, or k[amacr]k[amacr]wahie
in the Hawaiian language) was listed as endangered on October 13, 1970
(35 FR 16047), and was included in the Maui-Molokai Forest Birds
Recovery Plan (USFWS 1984, pp. 18-20) and the Revised Recovery Plan for
Hawaiian Forest Birds (USFWS 2006, pp. 2-121- 2-123). At the time of
listing, the Molokai creeper was considered extremely rare and faced
threats from habitat loss, avian disease, and predation by introduced
mammals. Three 5-year status reviews have been completed; the 2009
(initiated on July 6, 2005; see 70 FR 38972) and 2015 (initiated on
March 6, 2012; see 77 FR 13248) reviews did not
[[Page 54315]]
recommend a change in status, though there was some information
indicating the species was already extinct (USFWS 2009, p. 11; USFWS
2015, p. 8). The 5-year status review completed in 2018 (initiated on
February 12, 2016; see 81 FR 7571) recommended delisting due to
extinction based in part on continued lack of detections and
consideration of extinction probability (USFWS 2018, p. 9).
The Molokai creeper was known only from Molokai in the Hawaiian
Islands. Only fragmentary information is available about the life
history of the species from the writings of early naturalists (Perkins
1903, pp. 413-417; Pekelo 1963, p. 64; USFWS 2006, p. 2-122). This
species was an insectivore that gleaned vegetation and bark in wet ohia
(Metrosideros polymorpha) forests and was known almost solely from
boggy areas of Molokai (Pekelo 1963, p. 64), although there is one
record in 1907 of the species from lower elevation forest of leeward
east Molokai (USFWS 2006, pp. 2-121).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Adult males were mostly scarlet in various shades, while adult
females were brown with scarlet washes and markings, and juvenile males
ranged from brown to scarlet with many gradations. The bill was short
and straight. Its calls were described as chip or chirping notes
similar to other creeper calls (USFWS 2006, pp. 2-122). Its closest
relatives are the Maui creeper (Paroreomyza montana) and the Oahu
creeper (P. maculata). The species' coloration and bill shape were
distinctive, and Molokai creeper was identified visually with
confidence.
Survey Effort
Molokai creeper was common in 1907, but by the 1930s, they were
considered in danger of extinction (Scott et al. 1986, p. 148). The
species was last detected in 1963, on the west rim of Pelekunu Valley
(Pekelo 1963, p. 64). Surveys and searches have been unsuccessful in
finding the Molokai creeper since the last sighting, including VCP
surveys on the Olokui Plateau in 1980 and 1988, and the RBS of the
Kamakou-Pelekunu Plateau in 1995 (Reynolds and Snetsinger 2001, p.
141). Following up on a purported sighting in 2005 of a Molokai thrush
(Myadestes lanaiensis rutha), a survey was conducted over 2 to 3 days
in Puu Alii Natural Area Reserve (Puu Alii NAR), the last place the
Molokai creeper was sighted in the 1960s (Pekelo 1963, p. 64; USFWS
2006, pp. 2-29). Using playback recordings for Molokai thrush,
searchers covered the reserve area fairly well, but no Molokai creepers
or Molokai thrush were detected (Vetter 2018, pers. comm.).
No Molokai creepers were detected during VCP surveys beginning in
the late 1970s to the most recent Hawaiian forest bird survey on
Molokai in 2010 (Scott et al. 1986, p. 37; Camp 2015, pers. comm.). On
Molokai, VCP surveys are 8-minute point counts conducted at stations
separated by a distance of 492 to 656 feet (150 to 200 meters) along
transect lines 1 to 2 miles (1.6 to 3.2 kilometers) apart (Scott et al.
1986, pp. 34-40). It was estimated that 215,427 8-minute point counts
would be needed to determine with 95 percent confidence the absence of
Molokai creeper on Maui (Scott et al. 2008, p. 7). In 2008, only 131
VCP counts had been conducted on Molokai in areas where Molokai creeper
could still potentially exist. For the Molokai creeper, nearly 1,650
times more VCP counts than conducted up to 2008 would be needed to
confirm the species' extinction with 95 percent confidence. Based on
species detection probability, the RBS determined the likelihood of the
Molokai creeper being extirpated from the Kamakou-Pelekunu plateau was
greater than 95 percent. The RBS estimated the Molokai creeper to be
extinct over the entirety of its range, but, because not all potential
suitable habitat was searched, extinction probability was not
determined (Reynolds and Snetsinger 2001, p. 141).
Time Since Last Detection
The last reliable record (based on independent expert opinion and
physical evidence) of Molokai creeper was from Pelekunu Valley in 1963
(Pekelo 1963, p. 64). Using 1963 as the last reliable observation
record for Molokai creeper, 1969 is estimated to be year of extinction
of the Molokai creeper with 1985 as the upper 95 percent confidence
bound (Elphick et al. 2010, p. 620).
III. Analysis
The Molokai creeper faces similar threats to the other Maui bird
species (see Analysis section for the Maui akepa, above). The last
confirmed detection of the Molokai creeper was in 1963 (Pekelo 1963, p.
64). Forest bird surveys in 1980, 1988, and 2010, and the RBS in 1994-
1996 (although not including the Olokui Plateau), failed to detect this
species. A 2- to 3-day search by qualified personnel for the Molokai
thrush in Puu Alii NAR in 2005, the last location where Molokai creeper
was sighted, also failed to detect the Molokai creeper. The estimated
year of extinction is 1969, with 1985 as the 95 percent confidence
upper bound (Elphick et al. 2010, p. 620). It is highly likely that
avian disease, thought to be the driver of range contraction and
disappearance of many Hawaiian honeycreeper species, was present
periodically throughout nearly all of the Molokai creeper's range over
the last half-century.
IV. Conclusion
At the time of listing in 1970, the Molokai creeper was considered
to be facing threats from habitat loss, avian disease, and predation by
introduced mammals. The best information now indicates that the Molokai
creeper is extinct. The species appears to have been vulnerable to
avian disease, as well as the effects of small population size. The
latter likely limited the species' genetic variation and adaptive
capacity, thereby increasing the vulnerability of the species to the
environmental stressors of habitat degradation and predation by
nonnative mammals. Since its last detection in 1963, qualified
observers have conducted extensive searches for the Molokai creeper but
have not detected the species. Available information indicates that the
species was not able to persist in the face of environmental stressors,
and we conclude that the best available scientific and commercial
information indicates that the species is extinct.
Po`ouli (Melamprosops phaeosoma)
I. Background
We listed the po`ouli (Melamprosops phaeosoma) as endangered on
September 25, 1975 (40 FR 44149), and the species was included in the
Maui-Molokai Forest Birds Recovery Plan (USFWS 1984, pp. 16-17), and
the Revised Recovery Plan for Hawaiian Forest Birds (USFWS 2006, pp. 2-
144-2-154). At the time of listing, we considered the po`ouli to have
very low abundance and to likely be threatened by habitat loss, avian
disease, and predation by introduced mammals. Three 5-year status
reviews have been completed; the 2010 (initiated on April 11, 2006; see
71 FR 18346) and 2015 (initiated on March 6, 2012; see 77 FR 13248)
reviews did not recommend a change in status, though there was some
information indicating the species was already extinct (USFWS 2010, p.
13; USFWS 2105, p. 8). The 5-year status review completed in 2018
(initiated on February 12, 2016; see 81 FR 7571) recommended delisting
due to extinction, based in part on continued lack of detections and
consideration of
[[Page 54316]]
extinction probability (USFWS 2018, pp. 4-5, 10).
The po`ouli was known only from the island of Maui in the Hawaiian
Islands and was first discovered in 1973, in high-elevation rainforest
on the east slope of Haleakala (USFWS 2006, p. 2-146). Fossil evidence
shows that the po`ouli once inhabited drier forests at lower elevation
on the leeward slope of Haleakala, indicating it once had a much
broader geographic and habitat range (USFWS 2006, p. 2-147). Po`ouli
were observed singly, in pairs, and in family groups consisting of both
parents and a single offspring (Pratt et al. 1997, p. 1). Po`ouli
foraged primarily on tree branches, making extensive use of the
subcanopy and understory. They seemed to have preferred the native
hydrangea (kanawao (Broussaisia arguta)), the native holly (kawau (Ilex
anomala)), and ohia (Metrosideros polymorpha) (Pratt et al. 1997, p.
4). Po`ouli gleaned from, probed, and excavated moss mats, lichen, and
bark for small invertebrate prey. Egg-laying took place in March and
April for two nests observed, and clutch size was probably two eggs
(Kepler et al. 1996, pp. 620-638). The female alone incubated eggs and
brooded chicks, but both parents fed the chicks. Throughout nesting,
the male fed the female at or away from the nest. Po`ouli often
associated with mixed species foraging flocks of other insectivorous
honeycreepers. Po`ouli were unusually quiet. Males rarely sang and did
so mostly as part of courtship prior to egg-laying. The maximum
lifespan of this species is estimated to be 9 years (The Animal Aging
and Longevity Database 2020, unpaginated).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The po`ouli was a medium-sized, 0.9 ounce (26 gram), stocky
Hawaiian honeycreeper, easily recognized by its brown plumage and
characteristic black mask framed by a gray crown and white cheek patch.
However, po`ouli were unusually quiet. Although distinctive visually,
because the species rarely vocalized, it was difficult to survey by
audio detections.
Survey Effort
The po`ouli was first discovered in 1973 (USFWS 2006, p. 2-146).
Total population was estimated at 140 individuals, with a 95 percent
confidence interval of plus or minus 280 individuals, during VCP
surveys in 1980 (Scott et al. 1986, pp. 37, 183), but estimates of
population size and density were likely inaccurate and considered
imprecise due to the species' low density and cryptic behavior (USFWS
2006, p. 2-147). In 1994, after nearly 2 years without a sighting, the
continued existence and successful breeding of five to six po`ouli in
the Kuhiwa drainage of Hanawi Natural Area Reserve (Hanawi NAR) was
confirmed (Reynolds and Snetsinger 2001, p. 141). Thorough surveys of
the historical range between 1997 and 2000, the Maui Forest Bird
Recovery Program (MFBRP) located only three birds, all in separate
territories in Hanawi NAR. These three po`ouli were color-banded in
1996 and 1997, and subsequently observed (see below), but no other
individuals have been observed since then (Baker 2001, p. 144; USFWS
2006, pp. 2-147-2-148). The MFBRP searched Kipahulu Valley on northern
Haleakala from 1997 to 2000, for a total of 320 hours, but failed to
detect po`ouli. These searches were hampered by bad weather, however,
and playback was not used (Vetter 2018, pers. comm.).
Time Since Last Detection
In 2002, what was thought to be the only female po`ouli of the
three in Hanawi NAR was captured and released into one of the male's
territories, but she returned to her home range the following day
(USFWS 2006, p. 2-151). In 2004, an effort was initiated to capture the
three remaining po`ouli to breed them in captivity. One individual was
captured and successfully maintained in captivity for 78 days, but died
on November 26, 2004, before a potential mate could be obtained. The
remaining two birds were last seen in December 2003 and January 2004
(USFWS 2006, pp. 2-153-2-154). While working on Maui parrotbill
(Pseudonestor xanthophrys) recovery from 2006 to 2011, the MFBRP spent
extensive time in the area of the last po`ouli sightings. No po`ouli
were seen or heard. The MFBRP project coordinator concluded that if
po`ouli were present, they would have been detected (Mounce 2018, pers.
comm.).
Using 2004 as the last reliable observation record for po`ouli,
2005 is estimated to be the year of extinction, with 2008 as the upper
95 percent confidence bound on that estimate (Elphick et al. 2010, p.
620).
III. Analysis
The Po'ouli faced similar threats to other Maui occurring bird
species (see the Analysis section for the Maui akepa, above). The last
confirmed sighting of po`ouli was in 2004 from Hanawi NAR (USFWS 2006,
p. 2-154). Extensive field presence by qualified individuals from 2006
to 2011 in Hanawi NAR, where po`ouli was last observed, failed to
detect this species, as did searches of Kipahulu Valley near Hanawi NAR
from 1997 to 1999 (USFWS 2006, p. 2-94). Using 2004 as the last
reliable observation record for po`ouli, the estimated year the species
went extinct is 2005, with 2008 the upper 95 percent confidence bound
on that estimate (Elphick et al. 2010, p. 620).
IV. Conclusion
At the time of its listing in 1975, we considered po`ouli to have
very low population abundance, and to face threats from habitat loss,
avian disease, and predation by introduced mammals. The best available
information now indicates that the po`ouli is extinct. Although the
po`ouli was last detected as recently as early 2004, the species
appears to have been vulnerable to the effects of small population size
since it was first discovered in 1973. The small population size likely
limited its genetic variation, disease resistance, and adaptive
capacity over time, thereby increasing the vulnerability of the species
to the environmental stressors of habitat degradation and predation by
nonnative mammals. Experienced staff with MFBRP conducted extensive
recovery work in po`ouli habitat between 2006 and 2011 and had no
detections of the species. Available information indicates that the
species was not able to persist in the face of environmental stressors,
and we conclude that the species is extinct.
Fishes
San Marcos Gambusia (Gambusia georgei)
I. Background
We listed the San Marcos gambusia (Gambusia georgei), a small fish,
as endangered throughout all of its range on July 14, 1980 (45 FR
47355). We concurrently designated approximately 0.5 miles of the San
Marcos River as critical habitat for the species (45 FR 47355, July 14,
1980, p. 47364). The San Marcos gambusia was endemic to the San Marcos
River in San Marcos, Texas. The San Marcos gambusia has historically
only been found in a section of the upper San Marcos River
approximately from Rio Vista Dam to a point near the U.S. Geological
Survey gaging station immediately downstream from Thompson's Island.
Only a limited number of species of Gambusia are native to the United
States; of this subset, the San Marcos gambusia had one of the most
restricted ranges.
We listed the species as endangered due to decline in population
size, low
[[Page 54317]]
population numbers, and possibility of lowered water tables, pollution,
bottom plowing (a farming method that brings subsoil to the top and
buries the previous top layer), and cutting of vegetation (43 FR 30316,
July 14, 1978, p. 30317). We identified groundwater depletion, reduced
spring flows, contamination, habitat impacts resulting from severe
drought conditions, and cumulative effects of human activities as
threats to the species (45 FR 47355, July 14, 1980, p. 47361). At the
time of listing, this species was extremely rare.
There has also been evidence of hybridization between G. georgei
and G. affinis (western mosquitofish) in the wild. Hybridization
between G. georgei and G. affinis continued for many years without
documented transfer of genes between the species that would have
resulted in the establishment of a new species (Hubbs and Peden 1969,
p. 357). Based on collections in the 1920s, a study in the late 1960s,
surmised that limited hybridization with G. affinis did not seem to
have reduced the specific integrity of either species. However, as
fewer G. georgei individuals existed in the wild and therefore
encountered each other, the chances of hybridization with the much more
common G. affinis increased.
All currently available scientific data and field survey data
indicate that this species has been extinct in the wild for over 35
years. The last known sighting in the wild was in 1983, and past
hybridization in the wild between G. georgei and G. affinis failed to
result in establishment of a hybridized species that would facilitate
the transfer of genes from one species to the other. Also, captive
breeding attempts of G. georgei failed. In 1985, the last captive
female San Marcos gambusia died. Because no males remained, we
concluded captive breeding efforts, and no individuals remain alive in
captivity today.
On March 20, 2008, we published a notice in the Federal Register
(73 FR 14995) that we were initiating a 5-year review of the species.
We did not receive any comments or new information, and the 5-year
review was not completed at that time. On May 31, 2018, we published a
notice in the Federal Register (83 FR 25034) initiating another 5-year
review of the species. The review relied on available information,
including survey results, fish collection records, peer-reviewed
literature, various agency records, and correspondences with leading
Gambusia species experts in Texas. That 5-year review recommended
delisting the San Marcos gambusia due to extinction.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Historically, the San Marcos gambusia had small populations, and
the pattern of abundance strongly suggests a decrease beginning prior
to the mid-1970s. Historical records indicate that San Marcos gambusia
was likely collected from the headwaters of the San Marcos River (Hubbs
and Peden 1969, p. 28). The highest number of San Marcos gambusia ever
collected was 119 in 1968. Because this species preferred sections of
slow-moving waters and had a limited historical range of a small
section of the San Marcos River, potential detection was not expected
to be difficult.
Survey Effort
In 1976, we contracted a status survey to improve our understanding
of the species and its habitat needs. We facilitated bringing
individuals into captivity for breeding and study. Many researchers
have been involved and have devoted considerable effort to attempts to
locate and preserve populations. Intensive collections during 1978 and
1979 yielded only 18 San Marcos gambusia from 20,199 Gambusia total,
which means San Marcos gambusia amounted to only 0.09 percent of those
collections (Edwards et al. 1980, p. 20). Captive populations were
established at the University of Texas at Austin in 1979, and fish from
that captive population were used to establish a captive population at
our Dexter National Fish Hatchery in 1980. Both captive populations
later became contaminated with another Gambusia species. The fish
hybridized, and the pure stocks were lost.
Following the failed attempt at maintaining captive populations at
Dexter National Fish Hatchery and the subsequent listing of the species
in 1980, we contracted for research to examine known localities and
collect fish to establish captive refugia. Collections made in 1981 and
1982 within the range of San Marcos gambusia indicated a slight
decrease in relative abundance of this species (0.06 percent of all
Gambusia). From 1981 to 1984, efforts were made to relocate populations
and reestablish a culture of individuals for captive refugia. Too few
pure San Marcos gambusia and hybrids were found to establish a culture,
although attempts were made with the few fish available (Edwards et al.
1980, p. 24). In the mid-1980s, staff from the San Marcos National Fish
Hatchery and Technology Center also searched unsuccessfully for the
species in attempts to locate individuals to bring into captivity.
Intensive searches for San Marcos gambusia were conducted in May,
July, and September of 1990, but were unsuccessful in locating any pure
San Marcos gambusia. The searches consisted of more than 180 people-
hours of effort over the course of 3 separate days and covered the area
from the headwaters at Spring Lake to the San Marcos wastewater
treatment plant outfall. Over 15,450 Gambusia were identified during
the searches. One individual collected during the search was visually
identified as a possible backcross of G. georgei and G. affinis
(Service 1990 permit report). This individual was an immature fish with
plain coloration. Additional sampling near the Interstate Highway 35
type locality has occurred at approximately yearly intervals since
1990, and no San Marcos gambusia have been found. No San Marcos
gambusia were found in the 32,811 Gambusia collected in the upper San
Marcos River by the Service from 1994 to 1996 (Edwards 1999, pp. 6-13).
Time Since Last Detection
Academic researchers, Texas Parks and Wildlife Department
scientists, and the Service have continued to search for the San Marcos
gambusia during all collection and research with fishes on the San
Marcos River. San Marcos gambusia have not been found in the wild since
1983, even with intensive searches, including the ones conducted in
May, July, and September of 1990, covering the species' known range and
designated critical habitat. Since 1996, all attempts to locate and
collect San Marcos gambusia have failed (Edwards 1999, p. 3; Edwards et
al. 2002, p. 358; Hendrickson and Cohen 2015; Bio-West 2016, p. 43;
Bonner 2018, pers. comm.). More recent surveys and analyses of fish
species already consider the San Marcos gambusia extinct (Edwards et
al. 2002; Hubbs et al. 2008). Additionally, hybridized individuals have
not been documented since 1990.
III. Analysis
Although the population of San Marcos gambusia was historically
small, it also had one of the most restricted ranges of Gambusia
species. San Marcos gambusia have not been found in the wild since
1983, even with intensive searches, including the ones conducted in
May, July, and September of 1990, covering the species' known range and
designated critical habitat. No San Marcos gambusia were found in the
32,811 Gambusia collected in the upper San Marcos River by the Service
from 1994 to 1996 (Edwards 1999, pp. 6-13).
[[Page 54318]]
Additional sampling near the Interstate Highway 35 type locality has
occurred at approximately yearly intervals since 1990. Since 1996, all
attempts to survey and collect San Marcos gambusia failed to find them
(Edwards 1999, p. 3; Edwards et al. 2002, p. 358; Hendrickson and Cohen
2015; Bio-West 2016, p. 43; Bonner 2018, pers. comm.). Additionally, no
detections of hybridized San Marcos gambusia with G. affinis is further
evidence that extinction has occurred.
In addition to the San Marcos gambusia not being found in the wild,
all attempts at captive breeding have failed. This is largely due to
unsuccessful searches for the species in attempts to locate individuals
to bring into captivity.
Due to the narrow habitat preference and limited range of the San
Marcos gambusia, and the exhaustive survey and collection efforts that
have failed to detect the species, we conclude there is a very low
possibility of an individual or population remaining extant but
undetected. Therefore, the decrease in San Marcos gambusia abundance,
and the lack of hybridized individuals in any recent samples, indicates
that the species is extinct.
IV. Conclusion
The San Marcos gambusia was federally listed as endangered in 1980.
At the time of listing, this species was rare. The last known
collections of San Marcos gambusia from the wild were in 1981 (Edwards
2018, pers. comm.), and the last known sighting in the wild occurred in
1983. In 1985, after unsuccessful breeding attempts with Gambusia
affinis from the upper San Marcos River, the last captive female San
Marcos gambusia died. All available information and field survey data
support a determination that the San Marcos gambusia has been extinct
in the wild for more than 35 years. We have reviewed the best
scientific and commercial data available to conclude that the species
is extinct.
Scioto Madtom (Noturus trautmani)
I. Background
The Scioto madtom (Noturus trautmani) was listed as endangered on
September 25, 1975 (40 FR 44149) due to the pollution and siltation of
its habitat and the proposal to construct two impoundments within its
range. Scioto madtom was included in 5-year reviews initiated on
February 27, 1981 (46 FR 14652), July 22, 1985 (50 FR 29901), and on
November 6, 1991 (56 FR 56882). These reviews resulted in no change in
the Scioto madtom's listing classification of endangered. Two
additional 5-year reviews were initiated in 2009 (74 FR 11600; March
18, 2009) and 2014 (79 FR 38560; July 8, 2014). The recommendations
from both of these reviews were to delist the species due to extinction
(Service 2009, p. 7; Service 2014, p. 6).
The Scioto madtom was a small, nocturnal species of catfish in the
family Ictaluridae. The Scioto madtom has been found only in a small
section of Big Darby Creek, a major tributary to the Scioto River, and
was believed to be endemic to the Scioto River basin in central Ohio
(40 FR 44149, September 25, 1975; Service 1985, p. 10; Service 1988, p.
1).
The species was first collected in 1943 (Trautman 1981, p. 504),
and was first described as a species, Noturus trautmani, in 1969
(Taylor 1969, pp. 156-160). Only 18 individuals of the Scioto madtom
were ever collected. All were found along one stretch of Big Darby
Creek, and all but one were found within the same riffle known as
Trautman's riffle. The riffle habitat was comprised of glacial cobble,
gravel, sand, and silt substrate, with some large boulders (Trautman
1981, p. 505) with moderate current and high-quality water free of
suspended sediments.
The Scioto madtom was an omnivorous bottom feeder that ate a wide
variety of plant and animal life, which it found with its sensory
barbels hanging down in front of its mouth. Little is known of its
reproductive habits, although it likely spawned in summer and migrated
downstream in the fall (Trautman 1981, p. 505).
The exact cause of the Scioto madtom's decline is unknown, but was
likely due to modification of its habitat from siltation, suspended
industrial effluents, and agricultural runoff (40 FR 44149, September
25, 1975; Service 1988, p. 2). At the time of listing, two dams were
proposed for Big Darby Creek, although ultimately they were never
constructed. It should also be noted that the northern madtom (Noturus
stigmosus) was first observed in Big Darby Creek in 1957, the same year
the last Scioto madtom was collected (Service 1982, p. 3; Kibbey 2009,
pers. comm.). Both species likely feed on small invertebrates and
shelter in openings in and around rocks and boulders. Given the
apparent small population size and highly restricted range of the
Scioto madtom in the 1940s and 1950s, it is possible that the species
was unable to successfully compete with the northern madtom for the
same food and shelter resources (Kibbey 2009, pers. comm.).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
The Scioto madtom looked similar to other madtom species but could
be distinguished by meristic and morphometric characters, such as the
number of pectoral and anal rays. The species, like other madtom
species, was relatively cryptic as they hid during the daylight hours
under rocks or in vegetation and emerged after dark to forage along the
bottom of the stream. Despite these detection challenges, many surveys
by experienced biologists have been undertaken to try to locate extant
populations of Scioto madtom.
Survey Effort
No Scioto madtoms have been observed since 1957, despite intensive
fish surveys throughout Big Darby Creek in 1976-1977 (Service 1977, p.
15), 1981-1985 (Service 1982, p. 1; Service 1985, p. 1), 2014-2015
(OEPA 2018, p. 48), and 2001-2019 (Kibbey 2009, pers. comm.; Zimmerman
2014, 2020, pers. comm.).
The fish surveys conducted in Big Darby Creek in 1976-1977 and
1981-1985 specifically targeted the Scioto madtom. The 1976-1977 survey
found 41 madtoms of 3 species and 34 species of fish in riffles at and
near the Scioto madtom type locality (Service 1977, pp. 13-15). The
1981-1985 survey occurred throughout Big Darby Creek and found a total
of 2,417 madtoms of 5 species (Service 1985, pp. 1, 5, 19-23). Twenty-
two percent (542 individuals) of the total madtoms were riffle madtoms
of the subgenus Rabida, which also includes the Scioto madtom (Service
1985, p. 1). None of the species identified were the Scioto madtom.
The 2014-2015 fish surveys occurred throughout the Big Darby Creek
watershed as part of the Ohio Environmental Protection Agency's
(OEPA's) water quality monitoring program. A total of 96,471 fish
representing 85 different species and 6 hybrids, were collected at 93
sampling locations throughout the Big Darby Creek study area during the
2014 sampling season. Fish surveys were conducted at numerous sites in
Big Darby Creek between 2001 and 2019, using a variety of survey
techniques, including seining, boat electrofishing, backpack
electrofishing, and dip netting (Zimmerman 2020, pers. comm.). Another
survey was also conducted annually in the Big Darby Creek from 1970 to
2005 (Cavender 1999, pers. comm.; Kibbey 2016, pers. comm.).
These surveys also included extensive searches for populations of
Scioto
[[Page 54319]]
madtoms outside of the type locality in Big Darby Creek (Kibbey 2016,
pers. comm.). In addition to fish surveys in the Big Darby Creek
watershed, the OEPA has conducted a number of fish studies throughout
the Upper, Middle, and Lower Scioto River watershed as part of the
agency's Statewide Water Quality Monitoring Program (OEPA 1993a, 1993b,
1999, 2002, 2004, 2006, 2008, 2012, 2019, entire). These surveys have
never detected a Scioto madtom.
Time Since Last Detection
No collections of the Scioto madtom have been made since 1957.
Given that the extensive fish surveys conducted since 1970 within the
species' historical location, as well as along the entire length of Big
Darby Creek and in the greater Scioto River watershed, have recorded
three other species of madtom but not the Scioto madtom, it is highly
unlikely that the Scioto madtom has persisted without detection.
Other Considerations Applicable to the Species' Status
The habitat that once supported the Scioto madtom has been
drastically altered, primarily via strong episodic flooding. Although
periodic flooding has historically been a part of Big Darby Creek's
hydrological regime, many of the original riffles where Scioto madtoms
were collected from just downstream of the U.S. Route 104 Bridge to
approximately one-half mile upstream have been washed out to the point
where they are nearly gone (Kibbey 2009, pers. comm.). Furthermore,
pollution sources throughout the Scioto River watershed, including row
crop agriculture, development, and urban runoff, have reduced the water
quality and suitability of habitat for madtoms (OEPA 2012, pp. 1-2).
III. Analysis
There has been no evidence of the continued existence of the Scioto
madtom since 1957. Surveys for the species were conducted annually
between 1970 and 2005, at the only known location for the species.
Additional surveys in the Big Darby Creek watershed have never found
other locations of Scioto madtom. After decades of survey work with no
individuals being detected, it is extremely unlikely that the species
is extant. Further, available habitat for the species in the only
location where it has been documented is now much reduced, which
supports the conclusion that the species is likely extinct.
IV. Conclusion
We conclude that the Scioto madtom is extinct and, therefore,
should be delisted. This conclusion is based on a lack of detections
during numerous surveys conducted for the species and significant
alteration of habitat at its known historical location.
Mussels
Flat Pigtoe (Pleurobema marshalli)
I. Background
The flat pigtoe (formerly known as Marshall's pearly mussel),
Pleurobema marshalli, was listed as endangered on April 7, 1987 (52 FR
11162) primarily due to habitat alteration from a free-flowing riverine
system to an impounded system. The recovery plan (``Recovery Plan for
Five Tombigbee River Mussels'') was completed on November 14, 1989. A
supplemental recovery plan (``Mobile River Basin Aquatic Ecosystem
Recovery Plan'') was issued on November 17, 2000. This plan did not
replace the existing recovery plan; rather, it was intended to provide
additional habitat protection and species husbandry recovery tasks. The
species' recovery priority number (RPN) is 5, indicating a high degree
of threat and low recovery potential. A 5-year review was announced on
November 6, 1991 (56 FR 56882); no changes were proposed for the status
of this mussel in that review. Two additional 5-year reviews were
completed in 2009 (initiated on September 8, 2006; see 71 FR 53127) and
2015 (initiated on March 25, 2014; see 79 FR 16366); both recommended
delisting the flat pigtoe due to extinction. The Service solicited peer
review from six experts for both 5-year reviews from State, Federal,
university, and museum biologists with known expertise and interest in
Mobile River Basin mussels (USFWS 2009, pp. 23-24; USFWS 2015, pp. 15-
16); we received responses from three of the peer reviewers, and they
concurred with the content and conclusion that the species is presumed
extinct.
The flat pigtoe was described in 1927, from specimens collected in
the Tombigbee River (USFWS 1989, p. 2). The shell of the flat pigtoe
had pustules or welts on the postventral surface, and the adults were
subovate in shape and approximately 2.4 inches long and 2 inches wide
(USFWS 1989, p. 2). Freshwater mussels of the Mobile River Basin, such
as the flat pigtoe, are most often found in clean, fast-flowing water
in stable sand, gravel, and cobble gravel substrates that are free of
silt (USFWS 2000, p. 81). They are typically found buried in the
substrate in shoals and runs (USFWS 2000, p. 81). This type of habitat
has been nearly eliminated within the historical range of the species
because of the construction of the Tennessee-Tombigbee Waterway in
1984, which created a dredged, straightened navigation channel and a
series of impoundments that inundated nearly all riverine mussel
habitat (USFWS 1989, p. 1).
The flat pigtoe was historically known from the Tombigbee River
from just above Tibbee Creek near Columbus, Mississippi, downstream to
Epes, Alabama (USFWS 1989, p. 3). Surveys in historical habitat over
the past three decades have failed to locate the species, and all
historical habitat is impounded or modified by channelization and
impoundments (USFWS 2015, p. 5). No live or freshly dead shells have
been observed since the species was listed in 1987 (USFWS 2009, p. 4;
USFWS 2015, p. 5).
The Tombigbee River freshwater mussel fauna once consisted of more
than 40 species (USFWS 1989, p. 1). Construction of the Tennessee-
Tombigbee Waterway adversely impacted some of the species (including
flat pigtoe), as evidenced by surveys conducted by the Service, the
Tennessee Valley Authority (TVA), the Mobile District Corps of
Engineers, and others (USFWS 1989, p. 1). The construction of the
Tennessee-Tombigbee Waterway was completed in 1984, and drastically
modified the upper Tombigbee River from a riverine to a largely
impounded ecosystem from Town Creek near Amory, Mississippi, downstream
to the Demopolis Lock and Dam (USFWS 1989, p. 1). Construction of the
Waterway adversely impacted mussels and eliminated mussel habitat by
physical destruction during dredging, increasing sedimentation,
reducing water flow, and suffocating juveniles with sediment (USFWS
1989, p. 6). The only remaining habitat after the Waterway was
constructed was in several bendways, resulting from channel cuts. These
bendways have all experienced reduced flows and increased sediment
accumulation, some with several feet of sediment buildup. Thus, no
remaining mussel habitat exists (USFWS 1989, p. 6; USFWS 2015, p. 8).
The species is presumed extinct by species experts (USFWS 2015, p. 8).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging and can be
[[Page 54320]]
affected by a variety of factors, including:
Size of the mussel (smaller mussels, including juvenile
mussels, can be more difficult to find in complex substrates than
larger mussels, and survey efforts must be thorough enough to try to
detect smaller mussels);
Behavior of the mussel (some are found subsurface, some at
the surface, and some above the surface, and position can vary
seasonally (some are more visible during the reproductive phase when
they need to come into contact with host fish; therefore, surveys
likely need to be conducted during different times of the year to
improve detection));
Substrate composition (it can be easier to see/feel
mussels in sand and clay than in gravel or cobble; therefore, surveys
need to include all substrate types because mussels can fall off host
fish into a variety of substrates);
Size of river (larger rivers usually have more expansive
habitat areas to search and are sometimes deep, requiring specialized
survey techniques such as self-contained underwater breathing apparatus
(SCUBA));
Flow conditions (visibility can be affected in very fast-
flowing, very shallow, or turbid conditions; therefore, surveys need to
use tactile or excavation methods, or delay until turbidity conditions
improve);
Surveyor experience (finding mussels requires a well-
developed search image, knowledge of instream habitat dynamics, and
ability to identify and distinguish species); and
Survey methodology and effort (excavation and sifting of
stream bottom can detect more mussels than visual or tactile surveys).
All of these challenges are taken into account when developing
survey protocols for any species of freshwater mussel, including the
flat pigtoe. The flat pigtoe was medium-sized (but juveniles were very
small) and most often found buried in sand, gravel, or cobble in fast-
flowing runs. However, mussels can be found in suboptimal conditions,
depending on where they dropped off of the host fish. Therefore, all of
the above-mentioned considerations need to be accounted for when trying
to detect this mussel species. Despite detection challenges, many well-
planned, comprehensive surveys by experienced State and Federal
biologists have not been able to locate extant populations of flat
pigtoe in the Tombigbee River (USFWS 2000, p. 81; USFWS 2015, p. 5).
Survey Effort
Prior to listing, freshly dead shells of flat pigtoe were collected
in 1980, from the Tombigbee River, Lowndes County, Mississippi (USFWS
2009, pp. 4-5), and a 1984 survey of the Gainesville Bendway of
Tombigbee River also found shells of the flat pigtoe (USFWS 1989, p.
4). After listing in 1987, surveys in 1988 and 1990 only found
weathered, relict shells of the flat pigtoe below Heflin Dam, thus
casting doubt on the continued existence of the species in the
Gainesville Bendway (USFWS 1989, p. 4; USFWS 2009, p. 5). Over the past
three decades, surveys between 1990-2001, and in 2002, 2003, 2009,
2011, and 2015, of potential habitat throughout the historical range,
including intensive surveys of the Gainesville Bendway, where adequate
habitat and flows may still occur below the Gainesville Dam on the
Tombigbee River in Alabama, have failed to find any live or dead flat
pigtoes (USFWS 2000, p. 81).
Time Since Last Detection
The flat pigtoe has not been collected alive since completion of
the Tennessee-Tombigbee Waterway in 1984 (USFWS 2000, p. 81; USFWS
2015, p. 5). Mussel surveys within the Tombigbee River drainage during
1984-2015 failed to document the presence of the flat pigtoe (USFWS
2015, p. 8).
Other Considerations Applicable to the Species' Status
Habitat modification is the major cause of decline of the flat
pigtoe (USFWS 2000, p. 81). Construction of the Tennessee-Tombigbee
Waterway for navigation adversely impacted mussels and their habitat by
physical destruction during dredging, increasing sedimentation,
reducing water flow, and suffocating juveniles with sediment (USFWS
1989, p. 6). Other threats include channel improvements such as
clearing and snagging, as well as sand and gravel mining, diversion of
flood flows, and water removal for municipal use. These activities
impact mussels by altering the river substrate, increasing
sedimentation, changing water flows, and killing individuals via
dredging and snagging (USFWS 1989, pp. 6-7). Runoff from fertilizers
and pesticides results in algal blooms and excessive growth of other
aquatic vegetation, resulting in eutrophication and death of mussels
due to lack of oxygen (USFWS 1989, p. 7). The cumulative impacts of
habitat degradation due to these factors likely led to flat pigtoe
populations becoming scattered and isolated over time. Low population
levels increased the difficulty of successful reproduction (USFWS 1989,
p. 7). When individuals become scattered, the opportunity for egg
fertilization is diminished. Coupled with habitat changes that result
in reduced host fish interactions, the spiral of failed reproduction
leads to local extirpation and eventual extinction of the species
(USFWS 1989, p. 7).
III. Analysis
There has been no evidence of the continued existence of the flat
pigtoe for more than three decades. Mussel surveys within the Tombigbee
River drainage from 1984-2015 have failed to document the presence of
the species (USFWS 2015, p. 8). All known historical habitat has been
altered or degraded by impoundments, and the species is presumed
extinct by most authorities.
IV. Conclusion
We conclude that the flat pigtoe is extinct and, therefore, should
be delisted. This conclusion is based on significant alteration of all
known historical habitat and lack of detections during numerous surveys
conducted throughout the species' range.
Southern Acornshell (Epioblasma othcaloogensis)
I. Background
The southern acornshell (Epioblasma othcaloogensis) was listed as
endangered on March 17, 1993 (58 FR 14330), primarily due to habitat
modification, sedimentation, and water quality degradation. The
recovery plan (``Mobile River Basin Aquatic Ecosystem Recovery Plan'')
was completed on November 17, 2000. Critical habitat was initially
determined to be not prudent (56 FR 58339, November 19, 1991, p. 58346)
and later not determinable (58 FR 14330, March 17, 1993, p. 14338), but
in 2001, in response to a legal challenge to the ``not determinable''
finding, the U.S. District Court for the Eastern District of Tennessee
issued an order requiring the Service to propose and finalize critical
habitat for 11 Mobile River Basin-listed mussels, including the
southern acornshell. We subsequently published a final critical habitat
rule on July 1, 2004 (69 FR 40084). Two 5-year reviews were completed
in 2008 (initiated on June 14, 2005; see 70 FR 34492) and 2018
(initiated on September 23, 2014; see 79 FR 56821), both recommending
delisting the southern acornshell due to extinction. We solicited peer
review from eight experts for both 5-year reviews from State, Federal,
university, nongovernmental, and museum
[[Page 54321]]
biologists with known expertise and interest in Mobile River Basin
mussels (Service 2008, pp. 36-37; Service 2018, p. 15); we received
responses from five of the peer reviewers, who all concurred with the
content and conclusion that the species is presumed extinct.
The southern acornshell was described in 1857 from Othcalooga Creek
in Gordon County, Georgia (58 FR 14330, March 17, 1993, p. 14331).
Adult southern acornshells were round to oval in shape and
approximately 1.2 inches in length (Service 2000, p. 57). Epioblasma
othcaloogensis was included as a synonymy of E. penita and was
considered to be an ectomorph of the latter (58 FR 14330, March 17,
1993, p. 14331). Subsequent research classified the southern acornshell
as distinct, belonging in a different subgenus; the species is
distinguished from the upland combshell (E. metastriata) and the
southern combshell (E. penita) by its smaller size, round outline, a
poorly developed sulcus, and its smooth, shiny, yellow periostracum (58
FR 14330, March 17, 1993, p. 14331). The Service recognizes Unio
othcaloogensis (Lea) and Unio modicellus (Lea) as synonyms of
Epioblasma othcaloogensis.
The southern acornshell was historically found in shoals in small
rivers to small streams in the Coosa and Cahaba river systems (Service
2000, p. 57). As with many of the freshwater mussels in the Mobile
River Basin, it was found in stable sand, gravel, cobble substrate in
moderate to swift currents. The species had a sexual reproduction
strategy and require a host fish to complete the life cycle.
Historically, the species occurred in upper Coosa River tributaries and
the Cahaba River in Alabama, Georgia, and Tennessee (Service 2000, p.
57). In the upper Coosa River system, the southern acornshell occurred
in the Conasauga River, Cowan's Creek, and Othcalooga Creek (58 FR
14330, March 17, 1993, p. 14331). At the time of listing in 1993, the
species was estimated to persist in low numbers in streams in the upper
Coosa River drainage in Alabama and Georgia, and possibly in the Cahaba
River (58 FR 14330, March 17, 1993, p. 14331; Service 2018, p. 6). The
southern acornshell was last collected in 1973, from the Conasauga
River in Georgia and from Little Canoe Creek, near the Etowah and St.
Clair County line, Alabama. It has not been collected from the Cahaba
River since the 1930s (Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The southern
acornshell was small-sized (with very small juveniles) and most often
found buried in sand, gravel, or cobble in fast flowing runs. However,
mussels can be found in sub-optimal conditions, depending on where they
dropped off of the host fish. Therefore, all of the detection
considerations need to be accounted for when trying to detect this
mussel species. Despite detection challenges, many well-planned,
comprehensive surveys by experienced State and Federal biologists have
not been able to locate extant populations of southern acornshell
(Service 2000, p. 57; Service 2008, p. 20; Service 2018, p. 7).
Survey Effort
Prior to listing, southern acornshell was observed during surveys
in the upper Coosa River drainage in Alabama and Georgia in 1966-1968
and in 1971-1973, by Hurd (58 FR 14330, March 17, 1993, p. 14331).
Records of the species in the Cahaba River are from surveys at Lily
Shoals in Bibb County, Alabama, in 1938, and from Buck Creek (Cahaba
River tributary), Shelby County, Alabama, in the early 1900s (58 FR
14330, March 17, 1993, p. 14331). Both the 2008 and 2018 5-year reviews
reference multiple surveys by experienced Federal, State, and private
biologists--17 survey reports from 1993-2006 and 6 survey reports from
2008-2017--and despite these repeated surveys of historical habitat in
both the Coosa and Cahaba River drainages, no living animals or fresh
or weathered shells of the southern acornshell have been located
(Service 2008, p. 19; Service 2018, p. 6).
Time Since Last Detection
The most recent records for the southern acornshell were from
tributaries of the Coosa River in 1966-1968 and 1974, and the Cahaba
River in 1938 (58 FR 14330, March 17, 1993, p. 14331; Service 2008, p.
19; Service 2018, p. 5). No living populations of the southern
acornshell have been located since the 1970s (Service 2000, p. 57;
Service 2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
Habitat modification was the major cause of decline of the southern
acornshell (Service 2000, p. 57). Other threats included channel
improvements such as clearing and snagging, as well as sand and gravel
mining, diversion of flood flows, and water removal for municipal use;
these activities impacted mussels by alteration of the river substrate,
increasing sedimentation, alteration of water flows, and direct
mortality from dredging and snagging (Service 2000, p. 6-13). Runoff
from fertilizers and pesticides results in algal blooms and excessive
growth of other aquatic vegetation, resulting in eutrophication and
death of mussels due to lack of oxygen (Service 2000, p. 13). The
cumulative impacts of habitat degradation likely lead to the southern
acornshell populations becoming scattered and isolated over time. Low
population levels mean increased difficulty for successful reproduction
(Service 2000, p. 14). When individuals become scattered, the
opportunity for a female southern acornshell to successfully fertilize
eggs is diminished, and the spiral of failed reproduction leads to
local extirpation and eventual extinction of the species (Service 2000,
p. 14).
III. Analysis
There has been no evidence of the continued existence of the
southern acornshell for over five decades; the last known specimens
were collected in the early 1970s. When listed in 1993, it was thought
that the southern acornshell was likely to persist in low numbers in
the upper Coosa River drainage and, possibly, in the Cahaba River.
Numerous mussel surveys have been completed within these areas, as well
as other areas within the historical range of the species since the
listing, with no success. Although other federally listed mussels have
been found by mussel experts during these surveys, no live or freshly
dead specimens of the southern acornshell have been found (Service
2018, p. 7). The species is presumed extinct.
IV. Conclusion
We conclude that the southern acornshell is extinct and, therefore,
should be delisted. This conclusion is based on significant alteration
of known historical habitat and lack of detections during numerous
surveys conducted throughout the species' range.
[[Page 54322]]
Stirrupshell (Quadrula stapes)
I. Background
The stirrupshell (Quadrula stapes) was listed as endangered on
April 7, 1987 (52 FR 11162), primarily due to habitat alteration from a
free-flowing riverine system to an impounded system. The recovery plan
(``Recovery Plan for Five Tombigbee River Mussels'') was completed on
November 14, 1989. A supplemental recovery plan (``Mobile River Basin
Aquatic Ecosystem Recovery Plan'') was completed on November 17, 2000.
This plan did not replace the existing recovery plan; rather, it was
intended to provide additional habitat protection and species husbandry
recovery tasks. A 5-year review was announced on November 6, 1991 (56
FR 56882); no changes were proposed for the status of the stirrupshell
in that review. Two additional 5-year reviews were completed in 2009
(initiated on September 8, 2006; see 71 FR 53127) and 2015 (initiated
on March 25, 2014; see 79 FR 16366); both recommended delisting the
stirrupshell due to extinction. We solicited peer review from six
experts for both 5-year reviews from State, Federal, university, and
museum biologists with known expertise and interest in Mobile River
Basin mussels (Service 2009, pp. 23-24; Service 2015, pp. 15-16); we
received responses from three of the peer reviewers, and they concurred
with the content and conclusion that the species is presumed extinct.
The stirrupshell was described as Unio stapes in 1831, from the
Alabama River (Stansbery 1981, entire). Other synonyms are Margarita
(Unio) stapes in 1836, Margaron (Unio) stapes in 1852, Quadrula stapes
in 1900, and Orthonymus stapes in 1969 (Service 1989, pp. 2-3). Adult
stirrupshells were quadrate in shape and reached a size of
approximately 2 inches long and 2 inches wide. The stirrupshell
differed from other closely related species by the presence of a sharp
posterior ridge and truncated narrow rounded point posteriorly on its
shell, and it had a tubercled posterior surface (Service 1989, p. 3;
Service 2000, p. 85). Freshwater mussels of the Mobile River Basin,
such as the stirrupshell, are most often found in clean, fast-flowing
water in stable sand, gravel, and cobble gravel substrates that are
free of silt (Service 2000, p. 85). They are typically found buried in
the substrate in runs (Service 2000, p. 85). This type of habitat has
been nearly eliminated in the Tombigbee River because of the
construction of the Tennessee-Tombigbee Waterway, which created a
dredged, straightened navigation channel and series of impoundments
that inundated much of the riverine mussel habitat (Service 1989, p.
1).
The stirrupshell was historically found in the Tombigbee River from
Columbus, Mississippi, downstream to Epes, Alabama; the Sipsey River, a
tributary to the Tombigbee River in Alabama; the Black Warrior River in
Alabama; and the Alabama River (Service 1989, p. 3). Surveys in
historical habitat over the past three decades have failed to locate
the species, as all historical habitat is impounded or modified by
channelization and impoundments (Tombigbee and Alabama Rivers) or
impacted by sediment and nonpoint pollution (Sipsey and Black Warrior
Rivers) (Service 1989, p. 6; Service 2000, p. 85; Service 2015, p. 5).
No live or freshly dead shells have been observed since the species was
listed in 1987 (Service 2009, p. 6; Service 2015, p. 7). A freshly dead
shell was last collected from the lower Sipsey River in 1986 (Service
2000, p. 85).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The stirrupshell
was medium-sized (with very small juveniles) and most often found
buried in sand, gravel, or cobble in fast flowing runs. However,
mussels can be found in sub-optimal conditions, depending on where they
dropped off of the host fish. Therefore, all of the detection
considerations need to be accounted for when trying to detect this
mussel species. Despite detection challenges, many well-planned,
comprehensive surveys by experienced State and Federal biologists have
not been able to locate extant populations of stirrupshell (Service
1989, pp. 3-4; Service 2000, p. 85; Service 2015, pp. 7-8).
Survey Effort
Prior to listing in 1987, stirrupshell was collected in 1978, from
the Sipsey River, and a 1984 and 1986 survey of the Sipsey River found
freshly dead shells; a 1984 survey of the Gainesville Bendway of
Tombigbee River found freshly dead shells of the stirrupshell (Service
1989, p. 4; Service 2000, p. 85). After listing, surveys in 1988 and
1990 only found weathered, relict shells of the stirrupshell from the
Tombigbee River at the Gainesville Bendway and below Heflin Dam, which
cast doubt on the continued existence of the species in the mainstem
Tombigbee River (Service 1989, p. 4; Service 2009, p. 6). Over the past
three decades, repeated surveys (circa 1988, 1998, 2001, 2002, 2003,
2006, 2011) of unimpounded habitat in the Sipsey and Tombigbee Rivers,
including intensive surveys of the Gainesville Bendway, have failed to
find any evidence of stirrupshell (Service 2009, p. 6; Service 2015, p.
7). The stirrupshell was also known from the Alabama River; however,
over 92 hours of dive bottom time were expended searching appropriate
habitats for imperiled mussel species between 1997-2007 without
encountering the species (Service 2009, p. 6), and a survey of the
Alabama River in 2011 also did not find stirrupshell (Service 2015, p.
5). Surveys of the Black Warrior River in 1993 and from 2009-2012 (16
sites) focused on finding federally listed and State conservation
concern priority mussel species but did not find any stirrupshells
(Miller 1994, pp. 9, 42; McGregor et al. 2009, p. 1; McGregor et al.
2013, p. 1).
Time Since Last Detection
The stirrupshell has not been collected alive since the Sipsey
River was surveyed in 1978 (Service 1989, p. 4); one freshly dead shell
was last collected from the Sipsey River in 1986 (Service 2000, p. 85).
In the Tombigbee River, the stirrupshell has not been collected alive
since completion of the Tennessee-Tombigbee Waterway in 1984 (Service
2015, p. 7). Mussel surveys within the Tombigbee River drainage during
1984-2015 failed to document the presence of the stirrupshell (Service
2015, p. 8). The stirrupshell has not been found alive in the Black
Warrior River or the Alabama River since the early 1980s (Service 1989,
p. 3).
Other Considerations Applicable to the Species' Status
Because the stirrupshell occurred in similar habitat type and area
as the flat pigtoe, it faced similar threats. Please refer to the
discussion for the flat pigtoe for more information.
III. Analysis
There has been no evidence of the continued existence of the
stirrupshell for nearly four decades; the last live individual was
observed in 1978 and the last freshly dead specimen was from 1986.
Mussel surveys within the Tombigbee River drainage (including the
Sipsey and Black Warrior
[[Page 54323]]
tributaries) from 1984-2015, and the Alabama River from 1997-2007 and
in 2011, have failed to document the presence of the species (Service
2015, pp. 5, 8). All known historical habitat has been altered or
degraded by impoundments and nonpoint source pollution, and the species
is presumed extinct by most authorities.
IV. Conclusion
We conclude that the stirrupshell is extinct and, therefore, should
be delisted. This conclusion is based on significant alteration of all
known historical habitat and lack of detections during numerous surveys
conducted throughout the species' range.
Upland Combshell (Epioblasma metastriata)
I. Background
The upland combshell, Epioblasma metastriata, was listed as
endangered on March 17, 1993 (58 FR 14330), primarily due to habitat
modification, sedimentation, and water quality degradation. The
recovery plan (``Mobile River Basin Aquatic Ecosystem Recovery Plan'')
was completed on November 17, 2000. Critical habitat was initially
determined to be not prudent (56 FR 58339, November 19, 1991, p. 58346)
and later not determinable (58 FR 14330, March 17, 1993, p. 14338), but
in 2001, in response to a legal challenge to the ``not determinable''
finding, the U.S. District Court for the Eastern District of Tennessee
issued an order requiring the Service to propose and finalize critical
habitat for 11 Mobile River Basin-listed mussels, including the upland
combshell. We subsequently published a final critical habitat rule on
July 1, 2004 (69 FR 40084). Two 5-year reviews were completed in 2008
(initiated on June 14, 2005; see 70 FR 34492) and 2018 (initiated on
September 23, 2014; see 79 FR 56821), both recommending delisting the
upland combshell due to extinction. We solicited peer review from eight
experts for both 5-year reviews from State, Federal, university,
nongovernmental, and museum biologists with known expertise and
interest in Mobile River Basin mussels (Service 2008, pp. 36-37;
Service 2018, p. 15); we received responses from five of the peer
reviewers, who concurred with our conclusion that the species is
presumed extinct.
The upland combshell was described in 1838, from the Mulberry Fork
of the Black Warrior River near Blount Springs, Alabama (58 FR 14330,
March 17, 1993, p. 14331). Adult upland combshells were rhomboidal to
quadrate in shape and were approximately 2.4 inches in length (58 FR
14330, March 17, 1993, pp. 14330-14331). The upland combshell was
considered to be a variation of the southern combshell (= penitent
mussel, Epioblasma penita), and they were considered synonyms of each
other (58 FR 14330, March 17, 1993, p. 14331). However, subsequent
research identified morphological differences between the two, and both
species were considered to be valid taxa; the upland combshell was
distinguished from the southern combshell by the diagonally straight or
gently rounded posterior margin of the latter, which terminated at the
post-ventral extreme of the shell (58 FR 14330, March 17, 1993, p.
14331). We recognize Unio metastriatus and Unio compactus as synonyms
of Epioblasma metastriata (58 FR 14330, March 17, 1993, p. 14331).
The upland combshell was historically found in shoals in rivers and
large streams in the Black Warrior, Cahaba, and Coosa River systems
above the Fall Line in Alabama, Georgia, and Tennessee (Service 2000,
p. 61). As with many of the freshwater mussels in the Mobile River
Basin, it was found in stable sand, gravel, and cobble in moderate to
swift currents. The historical range included the Black Warrior River
and tributaries (Mulberry Fork and Valley Creek); Cahaba River and
tributaries (Little Cahaba River and Buck Creek); and the Coosa River
and tributaries (Choccolocco Creek and Etowah, Conasauga, and Chatooga
Rivers) (58 FR 14330, March 17, 1993, p. 14331). At the time of listing
in 1993, the species was estimated to be restricted to the Conasauga
River in Georgia, and possibly portions of the upper Black Warrior and
Cahaba River drainages (58 FR 14330, March 17, 1993, p. 14331; Service
2008, p. 19). The upland combshell was last collected in the Black
Warrior River drainage in the early 1900s; in the Coosa River drainage
in 1986, from the Conasauga River near the Georgia/Tennessee State
line; and the Cahaba River drainage in the early 1970s (58 FR 14330,
March 17, 1993, p. 14331; Service 2000, p. 61; Service 2018, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The Upland
combshell was small-sized (with very small juveniles) and most often
found buried in sand, gravel, or cobble in fast flowing runs. However,
mussels can be found in sub-optimal conditions, depending on where they
dropped off of the host fish. Therefore, all of the detection
considerations need to be accounted for when trying to detect this
mussel species. Despite detection challenges, many well-planned,
comprehensive surveys by experienced State and Federal biologists have
not been able to locate extant populations of upland combshell (Service
2008, p. 19; Service 2018, p. 5)
Survey Effort
Prior to listing in 1993, upland combshell was observed during
surveys in the Black Warrior River drainage in the early 1900s;
repeated surveys in this drainage in 1974, 1980-1982, 1985, and 1990
did not encounter the species (58 FR 14330, March 17, 1993, p. 14331).
The upland combshell was observed in the Cahaba River drainage in 1938
and in 1973, but a 1990 survey failed to find the species in the Cahaba
River drainage (58 FR 14330, March 17, 1993, p. 14331). The species was
observed in the upper Coosa River drainage in Alabama and Georgia in
1966-1968, but not during 1971-1973 surveys; a single specimen was
collected in 1988 from the Conasauga River (58 FR 14330, March 17,
1993, p. 14331). Both the 2008 and 2018 5-year reviews reference
multiple surveys by experienced Federal, State, and private
biologists--18 survey reports from 1993-2006 and 10 survey reports from
2008-2017--and despite these repeated surveys of historical habitat in
the Black Warrior, Cahaba, and Coosa River drainages, no living animals
or fresh or weathered shells of the upland combshell have been located
(Service 2008, p. 19; Service 2018, p. 5).
Time Since Last Detection
The most recent records for the upland combshell are many decades
old: From tributaries of the Black Warrior in early 1900s, from the
Cahaba River drainage in the early 1970s, and from the Coosa River
drainage in the mid-1980s (58 FR 14330, March 17, 1993, p. 14331;
Service 2008, p. 19; Service 2018, p. 5). No living populations of the
upland combshell have been located since the mid-1980s (Service 2000,
p. 61; Service 2008, p. 20; Service 2018, p. 7).
Other Considerations Applicable to the Species' Status
Because the upland combshell occurred in similar habitat type and
area
[[Page 54324]]
as the southern acornshell, it faced similar threats. Please refer to
the discussion for the southern acornshell for more information on any
other overarching consideration.
III. Analysis
There has been no evidence of the continued existence of the upland
combshell for over three decades; the last known specimens were
collected in the late-1980s. When listed, it was thought that the
upland combshell was likely restricted to the Conasauga River in
Georgia, and possibly portions of the upper Black Warrior and Cahaba
River drainages. Numerous mussel surveys have been completed within
these areas, as well as other areas within the historical range of the
species since the late-1980s, with no success. Although other federally
listed mussels have been found by mussel experts during these surveys,
no live or freshly dead specimens of the upland combshell have been
found (Service 2018, p. 7). The species is presumed extinct.
IV. Conclusion
We conclude that the upland combshell is extinct and, therefore,
should be delisted. This conclusion is based on significant alteration
of known historical habitat and lack of detections during numerous
surveys conducted throughout the species' range.
Green Blossom (Epioblasma torulosa gubernaculum)
I. Background
The green blossom (pearly mussel), Epioblasma torulosa
gubernaculum, was listed as endangered on June 14, 1976 (41 FR 24062),
and the final recovery plan was issued on July 9, 1984. At the time of
listing, the single greatest factor contributing to the species'
decline was the alteration and destruction of stream habitat due to
impoundments. Two 5-year reviews were completed in 2007 (initiated on
September 20, 2005; see 70 FR 55157) and 2017 (initiated on March 25,
2014; see 79 FR 16366); both reviews recommended delisting due to
extinction. For the 2017 5-year review, the Service solicited peer
review from eight peer reviewers including Federal and State biologists
with known expertise and interest in blossom pearly mussels (the green
blossom was one of four species assessed in this 5-year review). All
eight peer reviewers indicated there was no new information on the
species, or that the species was presumed extirpated or extinct from
their respective State(s) (USFWS 2017, pp. 8-9).
The green blossom was described in 1865, with no type locality
given for the species. However, all historical records indicate the
species was restricted to the upper headwater tributary streams of the
Tennessee River above Knoxville (USFWS 1983, pp. 1-2). The recovery
plan described the green blossom as a medium-sized mussel with a
lifespan up to 50 years. The shell outline was irregularly ovate,
elliptical, or obovate. The green blossom was a sexually dimorphic,
medium-sized species. Females were generally larger than the males and
possessed a large, flattened, rounded swelling or expansion that
extends from the middle of the base to the upper part of the posterior
end. A comprehensive description of shell anatomy is provided in our 5-
year review and supporting documents (Parmalee and Bogan 1998, pp. 104-
107).
The green blossom was always extremely rare and never had a wide
distribution (USFWS 1984, p. 9). Freshwater mussels found within the
Cumberland rivers and tributary streams, such as the green blossom, are
most often observed in clean, fast-flowing water in substrates that
contain relatively firm rubble, gravel, and sand substrates swept free
from siltation (USFWS 1984, p. 5). They are typically found buried in
substrate in shallow riffle and shoal areas. This type of habitat has
been nearly eliminated by impoundment of the Tennessee and Cumberland
Rivers and their headwater tributary streams (USFWS 1984, p. 9).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are riverine, typically found only in streams
that are shallow with sandy-gravel substrate and rapid currents
(Stansbery 1972, pp. 45-46). Eight species of Epioblasma were presumed
extinct at the time of the recovery plan, primarily due to
impoundments, siltation, and pollution (USFWS 1984, p. 6).
Stream impoundment affects species composition by eliminating those
species not capable of adapting to reduced flows and altered
temperatures. Tributary dams typically have storage impoundments with
cold water discharges and sufficient storage volume to cause the stream
below the dam to differ significantly from pre-impoundment conditions.
These hypolimnial discharges result in altered temperature regimes,
extreme water level fluctuations, reduced turbidity, seasonal oxygen
deficits, and high concentrations of certain heavy metals (TVA 1980,
entire).
Siltation within the range of the green blossom, resulting from
strip mining, coal washing, dredging, farming, and road construction,
also likely severely affected the species. Since most freshwater
mussels are riverine species that require clean, flowing water over
stable, silt-free rubble, gravel, or sand shoals, smothering caused by
siltation can be detrimental. The recovery plan indicated that
siltation associated with poor agricultural practices and deforestation
was probably the most significant factor impacting mussel communities
(Fuller 1977, as cited in USFWS 1984, p. 12). The recovery plan also
documented numerous coal operations within the range of the green
blossom that have caused increased silt runoff, including in the Clinch
River, where the last live specimen was collected in 1982 (USFWS 1984,
pp. 12-13). Pollution, primarily from wood pulp, paper mills, and other
industries, has also severely impacted many streams within the
historical range of the species.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The green blossom
was a medium-sized mussel most often found buried in substrate in
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host
fish.
Survey Effort
As of 1984, freshwater mussel surveys by numerous individuals had
failed to document any living populations of green blossom in any
Tennessee River tributary other than the Clinch River. The recovery
plan cites several freshwater mussel surveys (which took place between
1972 and 2005) of the Powell River; North, South, and Middle Forks of
the Holston River; Big Moccasin Creek; Copper Creek; Nolichucky River;
and French Broad River, all of which failed to find living or freshly
dead green blossom specimens (USFWS 1984, p. 5). Annual surveys
continue to be conducted in the Clinch River since 1972. Biologists
conducting those surveys have not reported live or freshly dead
individuals of the green blossom (Ahlstedt et al. 2016, entire;
Ahlstedt et al. 2017, entire; Jones et al. 2014, entire; Jones et al.
2018, entire).
[[Page 54325]]
Time Since Last Detection
The last known record for the green blossom was a live individual
collected in 1982, in the Clinch River at Pendleton Island, Virginia.
III. Analysis
Habitat within the historical range of the green blossom has been
significantly altered by water impoundments, siltation, and pollution,
including at Pendleton Island on the Clinch River, the site of the last
known occurrence of the species (Jones et al. 2018, pp. 36-56). The
last known collection of the species was 38 years ago, and numerous
surveys have been completed within the known range of the species over
these 38 years. Although other federally listed mussels have been found
by these experts during these surveys, no live or freshly dead
specimens of the green blossom have been found (Ahlstedt et al. 2016,
pp. 1-18; Ahlstedt et al. 2017, pp. 213-225). Mussel experts conclude
that the species is likely to be extinct.
IV. Conclusion
We conclude the green blossom is extinct and, therefore, should be
delisted. This conclusion is based on lack of detections during surveys
and searches conducted throughout the species' range since the green
blossom was last observed in 1982, and the amount of significant
habitat alteration that has occurred within the range of the species,
rendering most of the species' historical habitat unlikely to support
the species.
Tubercled Blossom (Epioblasma torulosa torulosa)
I. Background
The tubercled blossom (pearly mussel), Epioblasma torulosa
torulosa, was listed as endangered on June 14, 1976 (41 FR 24062), and
the final recovery plan was completed on January 25, 1985. At the time
of listing, the greatest factor contributing to the species' decline
was the alteration and destruction of stream habitat due to
impoundments. Two 5-year reviews were completed in 1991 (initiated on
November 6, 1991; see 56 FR 56882) and 2011 (initiated on September 20,
2005; see 70 FR 55157); both reviews recommended the species maintain
its endangered status, although the 2011 review did conclude the
species was likely extinct. The most recent 5-year review was completed
in 2017 (initiated on March 25, 2014; see 79 FR 16366), indicated that
the species was presumed extinct, and recommended delisting. The
Service solicited peer review from three peer reviewers for the 2017 5-
year review from Federal and State biologists with known expertise and
interest in blossom pearly mussels (the tubercled blossom was one of
four species assessed in this 5-year review). All three peer reviewers
indicated there was no new information on the species, all populations
of the species were extirpated from their respective States, and the
species was presumed extinct.
The tubercled blossom was described as Amblema torulosa from the
Ohio and Kentucky Rivers (Rafinesque 1820; referenced in USFWS 1985, p.
2). All records for this species indicate it was widespread in the
larger rivers of the eastern United States and southern Ontario, Canada
(USFWS 1985, p. 2). Records for this species included the Ohio,
Kanawha, Scioto, Kentucky, Cumberland, Tennessee, Nolichucky, Elk, and
Duck Rivers (USFWS 1985, pp. 3-6). Historical museum records gathered
subsequently add the Muskingum, Olentangy, Salt, Green, Barren, Wabash,
White, East Fork White, and Hiwassee Rivers to its range (Service 2011,
p. 5). The total historical range includes the States of Alabama,
Illinois, Indiana, Kentucky, Ohio, Tennessee, and West Virginia. This
species was abundant in archaeological sites along the Tennessee River
in extreme northwestern Alabama, making it likely that the species also
occurred in adjacent northeastern Mississippi where the Tennessee River
borders that State (Service 2011, p. 5).
The tubercled blossom was medium-sized, reaching about 3.6 inches
(9.1 centimeters) in shell length, and could live as long as 50 years
or more. The shell was irregularly egg-shaped or elliptical, slightly
sculptured, and corrugated with distinct growth lines. The outer
surface was smooth and shiny; was tawny, yellowish-green, or straw-
colored; and usually had numerous green rays (Parmalee and Bogan 1980,
pp. 22-23).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are characteristic riffle or shoal species,
typically found only in streams that are shallow with sandy-gravel
substrate and rapid currents (Parmalee and Bogan 1980, pp. 22-23).
Eight species of Epioblasma were presumed extinct at the time of the
1985 recovery plan. The elimination of these species has been
attributed to impoundments, barge canals, and other flow alteration
structures that have eliminated riffle and shoal areas (USFWS 1985, p.
1).
The single greatest factor contributing to the decline of the
tubercled blossom is the alteration and destruction of stream habitat
due to impoundments for flood control, navigation, hydroelectric power
production, and recreation. Siltation is another factor that has
severely affected the tubercled blossom. Increased silt transport into
waterways due to strip mining, coal washing, dredging, farming,
logging, and road construction increased turbidity and consequently
reduced the depth of light penetration and created a blanketing effect
on the substrate. The 1985 recovery plan documented numerous coal
operations within the range of the tubercled blossom that were causing
increased silt runoff. A third factor is the impact caused by various
pollutants. An increasing number of streams throughout the blossom's
range receive municipal, agricultural, and industrial waste discharges.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The tubercled
blossom was a large-river species most often found inhabiting parts of
those rivers that are shallow with sandy-gravel substrate and rapid
currents. However, mussels can be found in sub-optimal conditions,
depending on where they dropped off of the host fish.
Survey Effort
All three rivers where the species was last located have been
extensively sampled in the intervening years without further evidence
of this species' occurrence, including Kanawha River, Nolichucky River,
and Green River (Service 2011, p. 5).
Based on this body of survey information in large rivers in the
Ohio River system, investigators have been considering this species as
possibly extinct since the mid-1970s. Probably the best reach of
potential habitat remaining may be in the lowermost 50 miles of the
free-flowing portion of the Ohio River, in Illinois and Kentucky. This
reach is one of the last remnants of large-river habitat remaining in
the entire historical range of the tubercled blossom. In our 2011 5-
year review for the tubercled blossom, we hypothesized that this mussel
might be found in this stretch of the Ohio River. Unfortunately, mussel
experts have not reported any new collections of the species (USFWS
2017, p. 8). Additionally, State biologists have conducted extensive
[[Page 54326]]
surveys within the Kanawha Falls area of the Kanawha River since 2005,
and have found no evidence that the tubercled blossom still occurs
there (USFWS 2017, p. 4). This species is presumed extirpated.
Time Since Last Detection
The last individuals were collected live or freshly dead in 1969,
in the Kanawha River, West Virginia, below Kanawha Falls; in 1968, in
the Nolichucky River, Tennessee; and in 1963, in the Green River,
Kentucky.
III. Analysis
The tubercled blossom has not been seen since 1969, despite
extensive survey work in nearly all of the rivers of historical
occurrence, prompting many investigators to consider this species as
possibly extinct. According to the last two 5-year reviews, experts
indicate that the species is presumed extinct throughout its range.
IV. Conclusion
We conclude the tubercled blossom is extinct and, therefore, should
be delisted. This conclusion is based on the lack of detections during
surveys and searches conducted throughout the species' range since the
tubercled blossom was last sighted in 1969, and the significant habitat
alteration that has occurred within the range of the species, rendering
most of the species' habitat unable to support the life-history needs
of the species.
Turgid Blossom (Epioblasma turgidula)
I. Background
The turgid blossom (pearly mussel), Epioblasma turgidula, was
listed as endangered on June 14, 1976 (41 FR 24062), and the final
recovery plan was completed on January 25, 1985 (USFWS 1985). At the
time of listing, the single greatest factor contributing to the
species' decline was the alteration and destruction of stream habitat
due to impoundments. Two 5-year reviews were completed in 2007
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated
on August 30, 2016; see 81 FR 59650); both reviews recommended
delisting due to extinction. The Service solicited peer review from
eight peer reviewers for the 2017 5-year review from Federal and State
biologists with known expertise and interest in blossom pearly mussels
(the turgid blossom was one of four species assessed in this 5-year
review). All eight peer reviewers indicated there was no new
information on the species, all populations of the species were
extirpated from their respective States, and the species was presumed
extinct.
The turgid blossom was described (Lea 1858; referenced in USFWS
1985, p. 2) as Unio turgidulus from the Cumberland River, Tennessee,
and the Tennessee River, Florence, Alabama. According to the recovery
plan, this species was historically relatively widespread with a
disjunct distribution occurring in both the Cumberlandian and Ozarkian
Regions (USFWS 1985, p. 7). It has been reported from the Tennessee
River and tributary streams including Shoal and Bear Creeks, and Elk,
Duck, Holston, Clinch, and Emory Rivers (Ortmann 1918, 1924, 1925;
Stanberry 1964, 1970, 1971, 1976a; Johnson 1978, as cited in USFWS
2017, entire). Additional records are reported from the Cumberland
River (Ortmann 1918; Clench and van der Schalie 1944; Johnson 1978, as
cited in USFWS 2017, entire) and from the Ozark Mountain Region,
including Spring Creek, and Black and White Rivers (Simpson 1914;
Johnson 1978, as cited in USFWS 2017, entire).
The turgid blossom was a medium-river, Cumberlandian-type mussel
that was also reported from the Ozarks. These mussels could live as
long as 50 years or more. The species was strongly dimorphic; males and
females differed in shape and structure. This species seldom exceeded
1.6 inches (4.1 centimeters) in shell length. Shells of the male tended
to be more elliptical or oval, while females tended to be more rounded.
Valves were inequilateral, solid, and slightly inflated. The outer
shell was shiny yellowish-green with numerous fine green rays over the
entire surface. The shell surface was marked by irregular growth lines
that are especially strong on females. The inner shell surface was
bluish-white (Parmalee and Bogan 1980, pp. 22-23).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are characteristic riffle or shoal species,
typically found only in streams that are shallow with sandy-gravel
substrate and rapid currents (Parmalee and Bogan 1980, pp. 22-23).
Eight species of Epioblasma were presumed extinct at the time of the
1985 recovery plan. The elimination of these species has been
attributed to impoundments, barge canals, and other flow alteration
structures that have eliminated riffle and shoal areas (USFWS 1985, p.
1). The last known population of the turgid blossom occurred in the
Duck River and was collected in 1972, at Normandy (Ahlstedt 1980, pp.
21-23). Field notes associated with this collection indicate that it
was river-collected 100 yards above an old iron bridge. Water at the
bridge one mile upstream was very muddy, presumably from dam
construction above the site (Ahlstedt et al. 2017, entire).
Additionally, surveys in the 1960s of the upper Cumberland Basin
indicated an almost total elimination of the genus Epioblasma,
presumably due to mine wastes (Neel and Allen 1964, as cited in USFWS
1985, p. 10).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The turgid blossom
was a small-sized mussel most often found buried in substrate in
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host
fish.
Survey Effort
This species has not been found in freshwater mussel surveys
conducted on the Duck River since the time of the Normandy Dam
construction (Ahlstedt 1980, pp. 21-23), nor has it been reported from
any other stream or river system. The most recent 5-year review notes
that the Tennessee Wildlife Resources Agency had completed or funded
surveys (1972-2005) for blossom pearly mussels in the Cumberland,
Tennessee, Clinch, Duck, Elk, Emory, Hiwassee, Little, and Powell
Rivers, yet there were no recent records of turgid blossom (USFWS 2017,
p. 4). Surveys in the Ozarks have not observed the species since the
early 1900s (USFWS 1985, p. 7).
Time Since Last Detection
The last known collection of the turgid blossom was a freshly dead
specimen found in the Duck River, Tennessee, in 1972 by a biologist
with the TVA. The species has not been seen in the Ozarks since the
early 1900s (USFWS 1985, p. 7).
III. Analysis
Habitat within the historical range of the turgid blossom has been
significantly altered by water impoundments, siltation, and pollution.
The last known collection of the species was more than 45 years ago.
Mussel experts conclude that the species is likely to be extinct.
Numerous surveys have been completed within the known range of the
species over the years. Although other federally listed mussels have
been found by experts during these
[[Page 54327]]
surveys, no live or freshly dead specimens of the turgid blossom have
been found.
IV. Conclusion
We conclude the turgid blossom is extinct and, therefore, should be
delisted. This conclusion is based on the lack of detections during
surveys and searches conducted throughout the species' range since the
turgid blossom was last sighted in 1972, and the significant habitat
alteration that occurred within the range of the species, rendering
most of the species' habitat unlikely to support the species.
Yellow Blossom (Epioblasma florentina florentina)
I. Background
The yellow blossom (pearly mussel), Epioblasma florentina
florentina, was listed as endangered on June 14, 1976 (41 FR 24062),
and the final recovery plan was completed on January 25, 1985. At the
time of listing, the single greatest factor contributing to the
species' decline was the alteration and destruction of stream habitat
due to impoundments. Two 5-year reviews were completed in 2007
(initiated on September 20, 2005; see 70 FR 55157) and 2017 (initiated
on March 25, 2014; see 79 FR 16366); both reviews recommended delisting
due to extinction. The Service solicited peer review from eight peer
reviewers for the 2017 5-year review from Federal and State biologists
with known expertise and interest in blossom pearly mussels (the yellow
blossom was one of four species assessed in this 5-year review). All
eight peer reviewers indicated there was no new information on the
species, all populations of the species were extirpated from their
respective States, and the species was presumed extinct.
The yellow blossom was described (Lea 1857; referenced in USFWS
1985, pp. 2-3) as Unio florentinus from the Tennessee River, Florence
and Lauderdale Counties, Alabama, and the Cumberland River, Tennessee.
According to the recovery plan, this species was a Cumberlandian-type
mussel historically widespread in the Tennessee and Cumberland Rivers
and tributaries to the Tennessee River. The yellow blossom was reported
from Hurricane, Limestone, Bear, and Cypress Creeks, all tributary
streams to the Tennessee River in northern Alabama (Ortmann 1925 p.
362; Bogan and Parmalee 1983, p. 23). This species was also reported
from larger tributary streams of the lower and upper Tennessee River,
including the Flint, Elk, and Duck Rivers (Isom et al. 1973, p. 439;
Bogan and Parmalee 1983, pp. 22-23) and the Holston, Clinch, and Little
Tennessee Rivers (Ortmann 1918, pp. 614-616). Yellow blossoms
apparently occurred throughout the Cumberland River (Wilson and Clark
1914, p. 46; Ortmann 1918, p. 592; Neel and Allen 1964, p. 448).
The yellow blossom seldom achieved more than 2.4 inches (6
centimeters) in length. The slightly inflated valves were of unequal
length, and the shell surface was marked by uneven growth lines. The
shell was a shiny honey-yellow or tan with numerous green rays
uniformly distributed over the surface. The inner shell surface was
bluish-white (Bogan and Parmalee 1983, pp. 22-23).
The genus Epioblasma as a whole has suffered extensively because
members of this genus are characteristic riffle or shoal species,
typically found only in streams that are shallow with sandy-gravel
substrate and rapid currents (Bogan and Parmalee 1983, pp. 22-23).
Eight species of Epioblasma were presumed extinct at the time of the
1985 recovery plan. The elimination of these species has been
attributed to impoundments, barge canals, and other flow alteration
structures that have eliminated riffle and shoal areas (USFWS 1985, p.
1).
The single greatest factor contributing to the decline of the
yellow blossom, not only in the Tennessee Valley but in other regions
as well, is the alteration and destruction of stream habitat due to
impoundments for flood control, navigation, hydroelectric power
production, and recreation. Siltation is another factor that has
severely affected the yellow blossom. Increased silt transport into
waterways due to strip mining, coal washing, dredging, farming,
logging, and road construction increased turbidity and consequently
reduced light penetration, creating a blanketing effect on the
substrate. The 1985 recovery plan documented numerous coal operations
within the range of the yellow blossom. A third factor is the impact
caused by various pollutants. An increasing number of streams
throughout the mussel's range receive municipal, agricultural, and
industrial waste discharges (USFWS 2017, p. 5).
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Detection of rare, cryptic, benthic-dwelling animals like
freshwater mussels is challenging, and can be affected by a variety of
factors. Please refer to the Species Detectability section for the flat
pigtoe above for the descriptions of these factors. The yellow blossom
was a small-sized mussel most often found buried in substrate in
shallow riffle and shoal areas. However, mussels can be found in sub-
optimal conditions, depending on where they dropped off of the host
fish.
Survey Effort
Since the last recorded collections in the mid-1960s, numerous
mussel surveys (1872-2005) have been done by mussel biologists from the
TVA, Virginia Tech, U.S. Geological Survey, and others in rivers
historically containing the species. Biologists conducting those
surveys have not reported live or freshly dead individuals of the
yellow blossom.
Time Since Last Detection
This species was last collected live from Citico Creek in 1957, and
the Little Tennessee River in the 1966 (Bogan and Parmalee, 1983, p.
23), and archeological shell specimens were collected from the
Tennessee and Cumberland Rivers between 1976-1979 (Parmalee et al.
1980, entire).
III. Analysis
Habitat within the historical range of the yellow blossom has been
significantly altered by water impoundments, siltation, and pollution.
The last known collection of the species was over 50 years ago. Mussel
experts conclude that the species is likely to be extinct. Numerous
surveys have been completed within the known range of the species over
the years. Although other federally listed mussels have been found by
these experts during these surveys, no live or freshly dead specimens
of the yellow blossom have been found.
IV. Conclusion
We conclude the yellow blossom is extinct and, therefore, should be
delisted. This conclusion is based on lack of detections during surveys
conducted throughout the species' range since the yellow blossom was
last sighted in the mid-1960s and on the significant habitat alteration
that occurred within the range of the species, rendering most of the
species' habitat unlikely to support the species.
Plants
Phyllostegia glabra var. lanaiensis
I. Background
Phyllostegia glabra var. lanaiensis was listed as endangered on
September 20, 1991 (56 FR 47686), and was included in the Lanai plant
cluster recovery plan in 1995 (USFWS 1995).
[[Page 54328]]
At the time of listing, no wild individuals had been seen since 1914,
although there was one questionable sighting from the 1980s that was
later considered to be P. glabra var. glabra (USFWS 1995; 2012).
Threats included habitat degradation and herbivory by feral ungulates,
the establishment of ecosystem-altering invasive plant species, and the
consequences of small population sizes (low numbers) (USFWS 1995). In
2000, designation of critical habitat was considered not prudent for P.
glabra var. lanaiensis because this plant had not been observed in the
wild in over 20 years and no viable genetic material was available for
recovery efforts (65 FR 82086; December 27, 2000). Two 5-year status
reviews have been completed; the 2012 review (initiated on April 8,
2010; see 75 FR 17947) recommended surveys within the historical range
and within suitable habitat on Lanai, with no change in status. Despite
repeated surveys of historical and suitable habitat by botanists since
2006, P. glabra var. lanaiensis has not been found (Plant Extinction
Prevention Program (PEPP) 2012; Oppenheimer 2019, in litt.). In 2012,
PEPP reported that P. glabra var. lanaiensis was likely extinct. The 5-
year status review completed in 2019 (initiated on February 12, 2016;
see 81 FR 7571) recommended delisting due to extinction.
Historically, P. glabra var. lanaiensis was known from only two
collections from Lanai, one from the ``mountains of Lanai,'' and the
other from Kaiholena Gulch, where it was last collected in 1914 (USFWS
1991, 1995, 2003; Wagner 1999; Hawaii Biodiversity and Mapping Program
2010). A report of this species from the early 1980s in a gulch feeding
into the back of Maunalei Valley probably was erroneous and likely P.
glabra var. glabra (USFWS 1995, 2003; Wagner 1999, p. 269). Very little
is known of the preferred habitat or associated species of P. glabra
var. lanaiensis on the island of Lanai. It has been observed in lowland
mesic to wet forest in gulch bottoms and sides, often in quite steep
areas, in the same habitat as the endangered Cyanea macrostegia ssp.
gibsonii (listed as C. gibsonii) (USFWS 1995).
Phyllostegia glabra var. lanaiensis was a short-lived perennial
herb. Flowering cycles, pollination vectors, seed dispersal agents,
longevity, specific environmental requirements, and limiting factors of
P. glabra var. lanaiensis remain unknown (USFWS 1995, 2003). P. glabra
var. lanaiensis was described as a variety of P. glabra from specimens
collected from Lanai by Ballieu, Munro, and Mann and Brigham. It
differed from P. glabra var. glabra in its longer calyx (the collection
of modified leaves that enclose the petals and other parts of a flower)
(0.3 inches or 10-11 millimeters) and narrowly lanceolate leaves
(Wagner et al. 1990, p. 816). No taxonomic changes have been made since
the variety was described in 1934.
II. Information on Detectability, Survey Effort, and Time Since Last
Detection
Species Detectability
Phyllostegia glabra var. lanaiensis was a short-lived perennial
herb. This taxon differed from the other variety by its longer calyces
and narrowly lanceolate leaves, suggesting that flowers should be
present in order to confirm identification. Most congeners tend to
flower year-round, with peak flowering from April through June,
indicating that it would be easier to detect and confirm the species
during this time period.
Survey Effort
The PEPP surveys and monitors rare plant species on Lanai;
botanical surveys are conducted on a rotational basis, based on the
needs for collections and monitoring. Opportunistic surveying is also
conducted when botanists are within the known range and suitable
habitat when other work brings them to that area. No observations of P.
glabra var. lanaiensis have been reported since 1914. By 2012, PEPP
determined that this variety was likely extirpated (PEPP 2012), with
very little chance of rediscovery due to the restricted known range,
thorough search effort, and extent of habitat degradation. However,
botanists were still searching for this taxon on any surveys in or near
its last known location and other suitable habitat, as recently as
January 2019 (Oppenheimer 2019, in litt.).
Time Since Last Detection
All P. glabra identified since 1914 have been determined to be P.
glabra var. glabra, and, therefore, P. glabra var. lanaiensis has not
been detected since 1914.
III. Analysis
Threats to the species included habitat degradation and herbivory
by feral ungulates, the establishment of ecosystem-altering invasive
plant species, and the consequences of small population sizes. Despite
repeated surveys of historical and suitable habitat by botanists from
2006 through 2019, P. glabra var. lanaiensis has not been found since
1914 (PEPP 2012; Oppenheimer 2019, in litt.). In 2012, PEPP reported
that P. glabra var. lanaiensis was likely extinct. In 2019, the species
was included on the list of possibly extinct Hawaiian vascular plant
taxa (Wood et al. 2019).
IV. Conclusion
At the time of listing in 1991, P. glabra var. lanaiensis had not
been detected in over 75 years. Since its last detection in 1914,
botanical surveys have not detected the species. Available information
indicates that the species was not able to persist in the face of
environmental stressors, and we conclude that the best available
scientific and commercial information indicates that the species is
extinct.
Required Determinations
Clarity of the Rule
We are required by Executive Orders 12866 and 12988 and by the
Presidential Memorandum of June 1, 1998, to write all rules in plain
language. This means that each rule we publish must:
(1) Be logically organized;
(2) Use the active voice to address readers directly;
(3) Use clear language rather than jargon;
(4) Be divided into short sections and sentences; and
(5) Use lists and tables wherever possible.
If you feel that we have not met these requirements, send us
comments by one of the methods listed in ADDRESSES. To better help us
revise the rule, your comments should be as specific as possible. For
example, you should tell us the names of the sections or paragraphs
that are unclearly written, which sections or sentences are too long,
the sections where you feel lists or tables would be useful, etc.
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
We have determined that environmental assessments and environmental
impact statements, as defined under the authority of the National
Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be
prepared in connection with regulations adopted pursuant to section
4(a) of the Act. We published a notice outlining our reasons for this
determination in the Federal Register on October 25, 1983 (48 FR
49244). This position was upheld by the U.S. Court of Appeals for the
Ninth Circuit (Douglas County v. Babbitt, 48 F.3d 1495 (9th Cir. 1995),
cert. denied 516 U.S. 1042 (1996)).
Government-To-Government Relationship With Tribes
In accordance with the President's memorandum of April 29, 1994
[[Page 54329]]
(Government-to-Government Relations with Native American Tribal
Governments; 59 FR 22951), Executive Order 13175 (Consultation and
Coordination with Indian Tribal Governments), and the Department of the
Interior's manual at 512 DM 2, we readily acknowledge our
responsibility to communicate meaningfully with recognized Federal
Tribes on a government-to-government basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
Federal-Tribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge our responsibilities to work directly with
Tribes in developing programs for healthy ecosystems, to acknowledge
that Tribal lands are not subject to the same controls as Federal
public lands, to remain sensitive to Indian culture, and to make
information available to Tribes. The Seminole Tribe of Florida and the
Miccousukee Tribe has expressed interest in the Bachman's warbler. We
have reached out to these tribes by providing an advance notification
prior to the publication of the proposed rule. We will continue to work
with these and any other Tribal entities that expressed interest in
these species during the development of a final rule to delist these
species.
References Cited
Lists of the references cited in in this document are available on
the internet at http://www.regulations.gov in the dockets provided
above under Public Comments and upon request from the appropriate
person, as specified under FOR FURTHER INFORMATION CONTACT.
Authors
The primary authors of this document are the staff members of the
Branch of Delisting and Foreign Species, Ecological Services Program,
as well as the staff of the Ecological Services Field Offices as
specified under FOR FURTHER INFORMATION CONTACT.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and
recordkeeping requirements, Transportation.
Proposed Regulation Promulgation
Accordingly, we hereby propose to amend part 17, subchapter B of
chapter I, title 50 of the Code of Federal Regulations, as set forth
below:
PART 17--ENDANGERED AND THREATENED WILDLIFE AND PLANTS
0
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; and 4201-4245,
unless otherwise noted.
Sec. 17.11 [Amended]
0
2. Amend Sec. 17.11(h), the List of Endangered and Threatened
Wildlife:
0
a. Under MAMMALS, by removing the entry for ``Bat, little Mariana
fruit'';
0
b. Under BIRDS, by removing the entries for ``Akepa, Maui'', ``Akialoa,
Kauai'', ``Creeper, Molokai'', ``Nukupuu, Kauai'', ``Nukupuu'', Maui'',
`` `O`o, Kauai (honeyeater)'', ``Po`ouli (honeycreeper)'', ``Thrush,
large Kauai'', ``Warbler (wood), Bachman's'', ``White-eye, bridled'',
and ``Woodpecker, ivory-billed'';
0
c. Under FISHES, by removing the entries for ``Gambusia, San Marcos''
and ``Madtom, Scioto''; and
0
d. Under CLAMS, by removing the entries for ``Acornshell, southern''
and ``Blossom, green''; both entries for ``Blossom, tubercled'',
``Blossom, turgid'', and ``Blossom, yellow''; and the entries for
``Combshell, upland'', ``Pigtoe, flat'', and ``Stirrupshell''.
Sec. 17.12 [Amended]
0
3. Amend Sec. 17.12(h), the List of Endangered and Threatened Plants,
under FLOWERING PLANTS, by removing the entry for ``Phyllostegia glabra
var. lanaiensis''.
Sec. 17.85 [Amended]
0
4. Amend Sec. 17.85(a) by:
0
a. In the heading, removing the word ``Seventeen'' and adding in its
place the word ``Fourteen'';
0
b. In the table, removing the entries for ``tubercled blossom (pearly
mussel)'', ``turgid blossom (pearly mussel)'', and ``yellow blossom
(pearly mussel)'';
0
c. In paragraph (a)(1)(i), by removing the number ``17'' and adding in
its place the number ``14'';
0
d. In paragraph (a)(1)(ii), by removing the number ``17'' and adding in
its place the number ``14''; and
0
e. In paragraph (a)(2)(iii), by removing the number ``17'' and adding
in its place the number ``14''.
Sec. 17.95 [Amended]
0
4. Amend Sec. 17.95 by:
0
a. In paragraph (e), removing the entry for ``San Marcos Gambusia
(Gambusia georgei)''; and
0
b. In paragraph (f), the entry for, ``Eleven Mobile River Basin Mussel
Species: Southern Acornshell (Epioblasma othcaloogensis), Ovate
Clubshell (Pleurobema perovatum), Southern Clubshell (Pleurobema
decisum), Upland Combshell (Epioblasma metastriata), Triangular
Kidneyshell (Ptychobranchus greenii), Alabama Moccasinshell (Medionidus
acutissimus), Coosa Moccasinshell (Medionidus parvulus), Orange-nacre
Mucket (Lampsilis perovalis), Dark Pigtoe (Pleurobema furvum), Southern
Pigtoe (Pleurobema georgianum), and Fine-lined Pocketbook (Lampsilis
altilis)'', revising the entry's heading, the first sentence of the
introductory text of paragraph (f)(1), the introductory text of
paragraph (f)(2)(i), the table at paragraph (f)(2)(ii), the
introductory text of paragraph (f)(2)(xiv), paragraph (f)(2)(xiv)(B),
the introductory text of paragraph (f)(2)(xv), paragraph (f)(2)(xv)(B),
the introductory text of paragraph (f)(2)(xx), paragraph (f)(2)(xx)(B),
the introductory text of paragraph (f)(2)(xxi), paragraph
(f)(2)(xxi)(B), the introductory text of paragraph (f)(2)(xxiii),
paragraph (f)(2)(xxiii)(B), the introductory text of paragraph
(f)(2)(xxvi), paragraph (f)(2)(xxvi)(B), the introductory text of
paragraph (f)(2)(xxvii), paragraph (f)(2)(xxvii)(B), the introductory
text of paragraph (f)(2)(xxviii), and paragraph (f)(2)(xxviii)(B) to
read as follows:
Sec. 17.95 Critical habitat--fish and wildlife.
* * * * *
(f) Clams and Snails.
* * * * *
Nine Mobile River Basin Mussel Species: Ovate clubshell (Pleurobema
perovatum), southern clubshell (Pleurobema decisum), triangular
kidneyshell (Ptychobranchus greenii), Alabama moccasinshell (Medionidus
acutissimus), Coosa moccasinshell (Medionidus parvulus), orange-nacre
mucket (Lampsilis perovalis), dark pigtoe (Pleurobema furvum), southern
pigtoe (Pleurobema georgianum), and fine-lined pocketbook (Lampsilis
altilis)
(1) The primary constituent elements essential for the conservation
of the ovate clubshell (Pleurobema perovatum), southern clubshell
(Pleurobema decisum), triangular kidneyshell (Ptychobranchus greenii),
Alabama moccasinshell (Medionidus acutissimus), Coosa moccasinshell
(Medionidus parvulus), orange-nacre mucket (Lampsilis perovalis), dark
pigtoe (Pleurobema furvum), southern pigtoe (Pleurobema georgianum),
and fine-lined pocketbook (Lampsilis altilis) are those habitat
components that support feeding, sheltering, reproduction, and physical
features for maintaining the natural processes that support these
habitat components. * * *
(2) * * *
(i) Index map. The index map showing critical habitat units in the
States of Mississippi, Alabama, Georgia, and Tennessee for the nine
Mobile River Basin mussel species follows:
[[Page 54330]]
(ii) * * *
----------------------------------------------------------------------------------------------------------------
Species Critical habitat units States
----------------------------------------------------------------------------------------------------------------
Ovate clubshell (Pleurobema perovatum)... Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, AL, GA, MS, TN.
12, 13, 17, 18, 19, 21, 24, 25, 26.
Southern clubshell (Pleurobema decisum).. Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 13, 14, AL, GA, MS, TN.
15, 17, 18, 19, 21, 24, 25, 26.
Triangular kidneyshell (Ptychobranchus Units 10, 11, 12, 13, 18, 19, 20, 21, 22, AL, GA, TN.
greenii). 23, 24, 25, 26.
Alabama moccasinshell (Medionidus Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, AL, GA, MS, TN.
acutissimus). 12, 13, 15, 25, 26.
Coosa moccasinshell (Medionidus parvulus) Units 18, 19, 20, 21, 22, 23, 24, 25, 26. AL, GA, TN.
Orange-nacre mucket (Lampsilis perovalis) Units 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, AL, MS.
12, 13, 14, 15.
Dark pigtoe (Pleurobema furvum).......... Units 10, 11, 12......................... AL.
Southern pigtoe (Pleurobema georgianum).. Units 18, 19, 20, 21, 22, 23, 24, 25, 26. AL, GA, TN.
Fine-lined pocketbook (Lampsilis altilis) Units 13, 16, 17, 18, 19, 20, 21, 22, 23, AL, GA, TN.
24, 25, 26.
----------------------------------------------------------------------------------------------------------------
* * * * *
(xiv) Unit 12. Locust Fork and Little Warrior Rivers, Jefferson,
Blount Counties, Alabama. This is a critical habitat unit for the ovate
clubshell, triangular kidneyshell, Alabama moccasinshell, orange-nacre
mucket, and dark pigtoe.
* * * * *
(B) Map of Unit 12 follows:
BILLING CODE 4333-15-P
[[Page 54331]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.004
(xv) Unit 13. Cahaba River and Little Cahaba River, Jefferson,
Shelby, Bibb Counties, Alabama. This is a critical habitat unit for the
ovate clubshell, southern clubshell, triangular kidneyshell, Alabama
moccasinshell, orange-nacre mucket, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 13 follows:
[[Page 54332]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.005
* * * * *
(xx) Unit 18. Coosa River (Old River Channel) and Terrapin Creek,
Cherokee, Calhoun, Cleburne Counties, Alabama. This is a critical
habitat unit for the ovate clubshell, southern clubshell, triangular
kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-lined
pocketbook.
* * * * *
(B) Map of Unit 18 follows:
[[Page 54333]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.006
(xxi) Unit 19. Hatchet Creek, Coosa, Clay Counties, Alabama. This
is a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
(B) Map of Unit 19 follows:
[[Page 54334]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.007
* * * * *
(xxiii) Unit 21. Kelly Creek and Shoal Creek, Shelby, St. Clair
Counties, Alabama. This is a critical habitat unit for the ovate
clubshell, southern clubshell, triangular kidneyshell, Coosa
moccasinshell, southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 21 follows:
[[Page 54335]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.008
* * * * *
(xxvi) Unit 24. Big Canoe Creek, St. Clair County, Alabama. This is
a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
(B) Map of Unit 24 follows:
[[Page 54336]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.009
(xxvii) Unit 25. Oostanaula, Coosawattee, and Conasauga Rivers, and
Holly Creek, Floyd, Gordon, Whitfield, Murray Counties, Georgia;
Bradley, Polk Counties, Tennessee. This is a critical habitat unit for
the ovate clubshell, southern clubshell, triangular kidneyshell,
Alabama moccasinshell, Coosa moccasinshell, southern pigtoe, and fine-
lined pocketbook.
* * * * *
(B) Map of Unit 25 follows:
[[Page 54337]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.010
(xxviii) Unit 26. Lower Coosa River, Elmore County, Alabama. This
is a critical habitat unit for the ovate clubshell, southern clubshell,
triangular kidneyshell, Alabama moccasinshell, Coosa moccasinshell,
southern pigtoe, and fine-lined pocketbook.
* * * * *
(B) Map of Unit 26 follows:
[[Page 54338]]
[GRAPHIC] [TIFF OMITTED] TP30SE21.011
* * * * *
Martha Williams,
Principal Deputy Director, Exercising the Delegated Authority of the
Director, U.S. Fish and Wildlife Service.
[FR Doc. 2021-21219 Filed 9-29-21; 8:45 am]
BILLING CODE 4333-15-C