Roseate Spoonbills Send Warning Signs About the Florida Everglades
Decades after they staged a major comeback from plume hunting, one of the world's most bizarre and beautiful birds is struggling in South Florida. Does this spell trouble for the entire Everglades ecosystem?
Once the spoonbills regained a toehold in Florida Bay, their numbers climbed steadily until 1979, when they peaked at roughly 1,260 nests. They then began a precipitous decline. Wetlands throughout the Keys were ditched and drained to create new housing developments offering residents both direct waterfront and road access, wiping out roughly 80 percent of the birds' foraging grounds. "The Keys were covered in so much dust, it looked like a fog bank," Lorenz recalls being told by an U.S. Army Corps of Engineers scientist who was working in the area at the time.
The spoonbills responded to such unprecedented development by shifting to more northern nesting areas in Florida Bay. They might have hung on there, if not for the drastic changes in water management that followed, including upgrading the canal system to three times its former size and increasing the number of pump stations to support booming agriculture in southern Dade County.
Lorenz's research helped reveal the extent to which the spoonbills' needs were quickly becoming at odds with development and water management. For one, water depth plays an important role in spoonbill survival. When water levels drop very quickly, as they are supposed to do naturally in November and December, it signals to the spoonbills that it is time to start nesting. If all is well, 22 days after the birds lay their first egg the conditions will be ripe for foraging--fish will be concentrated in shallow waters, where spoonbill parents can quickly suck them up and return to the nest to feed their chicks.
If something happens to significantly affect water levels during that time, it can be catastrophic. Say, for instance, it is an unusually wet year when water managers need to mitigate flooding. The standard course has been to pump large amounts of water into the bay, which floods the grassy flats where spoonbills would be feeding.
"All the spoonbill chicks hatched that year will likely die," says Lorenz. "Parents go out looking for food. If they don't find it, they don't come back. The chicks get cold and eventually become weak. They nest mostly over water. If the chicks fall out of the nest, they will be dead within the hour."
He's seen it happen. During the 2000-2001 nesting season, one island's entire colony--130 nests holding nearly 400 chicks--went under when water levels rose rapidly. "There was a wrack line of hundreds of dead spoonbill chicks just lining the island," Lorenz says. "I have some pretty gruesome pictures." Most recent surveys count only about 350 spoonbill nests remaining in all of Florida Bay.
As Lorenz approaches another island, he stops mid-paddle. "If you were to sit here 20 years ago, you would see a steady stream of spoonbills coming and going. There was hardly ever a time when there wasn't a spoonbill overhead."
Lorenz hasn't completely lost hope, however. Lately there have been some promising developments. In response to his research, the governing board of the water management district directed one of its engineers to communicate with Lorenz and his staff on a weekly basis during nesting season. "They would call anytime there is a proposed change in management," he says, brightening. "They would say, 'Hey, Jerry, how are the birds doing? What's going to happen to those birds if we open the S18C gate?' And I'd say, 'Well you'd kill my birds.' Then they'd ask, 'What happens if we only open it partially?' 'Well, then, that would be okay.' Those were the conversations we were starting to have, and as a result, we've had successful spoonbill nesting for five of the last six years [giving the population a boost, though the overall numbers remain drastically low]. These birds can be resilient."
We forge our way through pounding waves and stinging salt spray for more than an hour until we reach Little Madeira Bay, where we board a small johnboat and begin an hour-long slalom up the Taylor River. Robinson ties a bandana around her mouth and nose to avoid eating spider webs as we zigzag through a long tunnel created by a tight mangrove canopy.
Two hours after leaving the dock by moonlight, we arrive at her study site, where she works well into the afternoon dropping large tentlike nets to survey the types and densities of tiny fish swimming these shallow waters. "Usually the mudflats would be dry by now and fish would be concentrated in the creek," she tells me. "The spoonbills would be feeding in there."
But the water is much higher than it should be, partly because of the recent wet weather. A spoonbill streams over, flying fairly low. "Probably looking for a place to eat," she says, leaning way out of the boat with the ease of a sailor.
Over and over, Robinson methodically sets the nets and gondoliers the boat to the next one, eventually returning to collect the fish. She is halfway through her morning rounds when Peter Frezza arrives to pick me up for one last bay cruise, and a lesson on fish economics. That is, how much a fish, or a spoonbill for that matter, is worth to the state of Florida.