Spoonbills an indicator of health for Florida Bay
Of the many ways used to diagnosis the health of the Everglades, the most bizarrely beautiful by far, with red beady eyes and bald greenish head, is the scarlet-plumed roseate spoonbill nearly wiped off the planet by feather hunters a century ago.
On a blustery morning in Florida Bay earlier this week, two adults and four chicks in training also demonstrated the birds’ tenacity.
As winds whipped the bay in advance of a late-season cold front, the birds repeated an evolutionary recon mission known as a weaning flight. Over and over, the adults spread their cotton candy-colored wings, flapped skyward and hoped the chicks, now about three months old, would follow. With gusts topping 20 mph, the chicks pursued for as long as they could before returning to their swaying perches among the mangroves on South Nest Key to rest. It’s a feat unique to the spoonbills among wading birds and a sight that still dazzles the biologist who has been tracking their movements for nearly 30 years.
“Once this wind dies, they’ll be out of here,” Audubon Florida’s Jerry Lorenz mused from the wheel of his boat. “They’ll be gone by the weekend.”
Lorenz considers the spoonbills Florida’s most telling canary in a coal mine, and the song they’re singing is pretty telling: changing water patterns linked to Everglades flood control compounded by rising sea levels are driving the birds away. It’s also likely propelling an overall decline in other wading bird species in the Everglades that last year reached a decade-long low. Lorenz worries if changes aren’t made soon, the sight of spoonbills in Florida Bay might be doomed.
We don’t have a quote, unquote dry season in the bay anymore.
Audubon Florida State Research Director Jerry Lorenz
“We don’t have a quote, unquote dry season in the bay anymore,” he said, describing the time of year when the bay becomes a massive nursery for spoonbills and all kinds of wading birds.
Nest Key and the surrounding keys in Northeast Florida Bay once contained the highest number of nests in the state. The population was all the more remarkable for the birds’ dramatic comeback: after plume hunters reduced their numbers to just 25 breeding pairs, Florida banned the trade in 1901 and set a national example for wildlife preservation. By the late 1970s, nearly 1,300 nests were spread across the bay, with most at the mouth of Taylor Slough, where seasonal surges of fresh water turned the estuary into a fish smorgasbord. Spoonbills feed by shuffling across the shallows to stir up mud and use their beaks to feel, rather than their eyes to see, prey.
Then Florida began installing the final piece of its massive flood control system south of Miami in the 1980s. The shifting water patterns slammed the birds, Lorenz said.
By 1990, the area that had once provided the best place to breed and raise chicks produced just over 200 nests. Accelerating sea rise only made things worse. Since 2000, water levels have risen around the bay by five inches, Lorenz said, essentially eliminating the season when subsiding waters pool and collect prey like fish in a barrel, perfect for parents feeding young chicks.
5 inchesThe increase in sea level in Florida Bay since 2000
This year, northeast Florida Bay had colonies on only two keys, South Nest and Duck keys, he said.
More and more, the bay’s birds — which historically nested on islands — are packing up and moving inland. A large colony was found on the mainland in Madeira Bay and far inland in Everglades National Park around Paurotis Pond, off the park’s main road, last year. And for the first time, spoonbills were found nesting as far north as South Carolina as they move north in search of fresher water.
They are also nesting later in the bay, an indication that they’re waiting for a dry season that never comes, and nesting longer than the two to three weeks it historically took for a colony to lay its eggs. Last year, the first chicks that hatched on South Nest Key all died, Lorenz said. It was early enough that the birds nested again and the second batch of chicks survived.
What I think is happening is the water levels are so high because of sea level rise, they’re missing their cues.
Audubon Florida State Research Director Jerry Lorenz
“What I think is happening is the water levels are so high because of sea level rise, they’re missing their cues,” he said.
Lorenz said last year’s 20 percent increase in spoonbills statewide was likely driven by a wet 2016 El Niño that followed a 2015 drought. Droughts typically lead to a drop in the number of big fish that compete with spoonbills for little fish. And while it might be a short-term boon for the birds, droughts can cause long-term problems like the seagrass die-off that covered about 25 square miles in the bay.
“When this happens, I’m just thrilled. But at the same time I know this is an anomaly,” he said. “We have not corrected the problems that started this.”
Spoonbills earned their place as an umbrella species — one targeted by scientists to measure the health of everything else — because of all the reasons above. Species that are easy to spot and inspire public curiosity make it easier for scientists to tell their story. The long record of observations also reveal changes and patterns. The spoonbills also occupy a special place in bird history.
Robert Porter Allen, the early ornithologist credited with saving the whooping crane, first landed on the idea of tracking the birds, Lorenz said. After plume hunting was banned, he wanted to find out why some birds seemed to rebound and others did not. So he headed to the Florida Keys in the late 1930s, began pitching a tent on the buggy islands and tracking their movements up close.
Allen was the first to document their weaning flights — a discovery Lorenz made last month when he was researching a paper and came across a February 1962 National Geographic story.
Allen, who opened Audubon’s Everglades Research Center in Tavernier, also discovered how inextricably tied the birds’ nesting patterns were to the bay’s hydrology. Historically, the birds flocked to the mangrove islands in the bay to nest, where they were protected from raccoons, alligators and other animals that might eat them or their young. The islands were also close enough to foraging grounds, which inspired Allen’s pioneering breakthrough in research.
At the time, biologists killed birds to examine their stomach contents. So few spoonbills remained by the time he arrived that Allen instead began observing their habits. In 1989, Audubon hired Lorenz to study that prey.
After Everglades Restoration came along in 2000, Lorenz helped convince planners that the spoonbills could provide a way to measure progress in part because their decline coincided with a specific event: the completion of the South Dade Conveyance System in 1983.
The system was the final piece in a maze of canals, levees and pumps that carved up the transverse glades and instead redirected water around farm fields and Everglades National Park. Nesting reached a peak in 1978, with more than half the nests on islands near the mouth of Taylor Slough. After the project was finished, the number dramatically dropped, from 688 to about 100.
What that tells Lorenz is that this corner of the bay, at the bottom of a dried up slough that once nourished seagrass beds and freshened water to make fish more plentiful, continues to be an inhospitable home.
While it’s good that the birds are able to move and adapt, scattering across the state means their numbers will likely never recover to historic heights, he said. Roseate spoonbills are one of six species and the only one with the mysterious bubblegum color. Around the world, they thrive in massive colonies centered around estuaries. By the 1990s, Florida’s spoonbills lived mostly in three estuaries: Florida Bay, Tampa Bay and on Merritt Island east of Orlando, he said. Now, they live like nomads, nesting in a patchwork of about 20 smaller colonies.
“I accept that Florida Bay may not be the center of spoonbills like they were in the 70s,” Lorenz said. “But there should always be a place like this. These birds should have a home.”
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