WEATHER

Wood storks, the bellwether of Everglades health: They're surviving on hot dogs and chicken wings

Rains and human-ruined landscapes led almost all wood stork nests to fail in the Everglades this year. But a new FAU study found that wood storks are adapting by becoming urban eaters.

Kimberly Miller
Palm Beach Post
Wood stork chicks are seen eating chicken wings. [Provided by Betsy Evans]

A tragedy of ill-timed rains and human-ruined landscapes led 98.5% of wood stork nests to fail in the Everglades this year, with nearly grown chicks starving to death as vultures circled.

But a new Florida Atlantic University study found a nascent trend in urban colonies may assuage down years as the threatened species knots together a life on the periphery of the Everglades and in the trashcans of mankind.

The three-year study discovered that despite a narrowly evolved diet of fish, wood storks will subsidize their meal plan with fast food favorites such as chicken wings, hot dogs and cold cuts when traditional fare is scarce.

The lanky birds also had a taste for penne pasta, chicken nuggets and pollywogs.

Wood Stork babies peek out of their nest under the protective cover of their mother at Wakodahatchee Wetlands in Delray Beach in 2018. [GREG LOVETT/palmbeachpost.com]

“It’s maybe not the best food items, but it’s better than nothing and they end up producing at least one young per pair,” said Dale Gawlik, an FAU biology and environmental science professor who co-authored the study. “They can’t make a go of it just by feeding in urban areas, but it’s a relief valve when things are really bad.”

Betsy Evans, a natural resources specialist with the U.S. Army Corps of Engineers and lead author of the study, said examining the diet of wood storks is relatively easy because they regurgitate when nervous, such as in the presence of humans or predators.

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She said about 90 percent of the boluses – balls of puke found in nests – could easily be identified as food items. From 2015 through 2017, 643 boluses were reviewed.

“They are really vomity,” Evans said about wood storks. “In one nest a chick regurgitated a hot dog and the other had the bun.”

Two wood stork colonies in natural areas and three urban colonies, including one in Palm Beach County, were involved in the study. In total, 160 nests were studied.

Ballenisles Country Club in Palm Beach Gardens was the home to one of the urban colonies, which nested on an island in a golf course pond. One urban colony was in a Broward County park. Another was behind a car dealership on a spill island in a manmade lake.

Wood stork study area

Gawlik said it’s the first study he knows of that looks at the diets of the urbanized wood storks.

Although white ibis have long been city feeders, plucking crickets and worms from front yards, as well as the random parking lot French fry or bread crust, wood storks are more selective.

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The big birds, which can stand 45 inches tall and weigh as much as 8 pounds, feed by touch, swishing their beaks back and forth in the water and then snapping them shut with a 25-millisecond reflex action when they feel a fish. A pair of nesting wood storks needs an ample bounty of fish to raise their chicks and can eat more than 400 pounds during a breeding season.

They also evolved to thrive in the unique environment of the Everglades where wet season deluges spread fish throughout the landscape, which are then consolidated in easy-catch pools when the waters recede during the dry season.

The 2019 rainy season was the shortest in 88 years of records kept by the South Florida Water Management District, with September being the driest on record. That meant no water on the high-ground marl prairies that typically dry down in the fall to provide easy fishing for the storks.

So the wood storks waited until February and March to nest when the deeper Everglades sloughs began to dry.

Wood stork chicks on a golf course. [Provided by Betsy Evans]

The delay caused nesting season to bleed into the rainy season, which cut off the wood storks' food supply when the fish spread throughout the landscape again, making them harder to catch. A wood stork's nesting period is about four months.

Parents couldn’t feed the fledgling storks that were just weeks from adulthood. Of about 1,360 nests counted by the South Florida Water Management District, 98.5 percent failed. Wood storks are called the bellwether of Everglades health because they prosper when the natural conditions – pre-flood control – are in place.

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“The urban colonies are essentially cutting down the bust years so instead of boom and bust, it’s like boom and average,” Gawlik said. “And that’s not a small thing when you think about it generation after generation.”

Urban wood storks also fed more on tadpoles, the study found, which were abundant in roadside-created wetlands such as swales, ponds and canals.

An urban wood stork colony. [Provided by Betsy Evans]

Evans said the health of the urban wood storks was not much different than that of the storks in the natural areas.

One characteristic of wood storks that allows them to thrive in urban environments is they can fly long distances – up to 50 miles – to search for food, which gives them options of traveling to natural marsh areas or supplementing with fast food scraps.

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Future studies may look at a specific gene in wood storks that accounts for how daring they are as far as trying different food or being willing to move into urban areas. If bolder birds are more likely to survive because they can expand their range and diet, it could mean an evolutionary tweak in the wood stork’s behavior.

“It’s a firehose of change we are throwing at animals,” Gawlik said. “Over time, if a species isn’t adapting or making unconventional choices, then they are gone.”

Kmiller@pbpost.com

@Kmillerweather