A Wing and a Prayer
The roseate spoonbill is barely hanging on in Florida Bay. And the biologist who knows it best is fighting for its survival. By Frank Graham Jr.
The roseate spoonbill invites rhapsody even ahead of study. "Rosy pink, with wing and tail coverts of deeper carmine," an early observer enthused. "It is as though an orchid had spread its lovely wings and flown." Jerry Lorenz, a contemporary admirer of this bird's flaming beauty, is the latest in a succession of Audubon biologists who have tracked its troubled existence for more than 60 years in Florida Bay.
"The spoonbill is an indicator species," Lorenz told me as we toured the bay recently in an open boat. "The ups and downs the bird has experienced over time closely reflect the health of its environment here. As we try to restore some semblance of natural conditions, the way the spoonbill responds will tell us if we're getting it right." Lorenz studies the interactions between spoonbills and the small fish they prey on in the bay, an estuary bounded by the southern tip of the Everglades and the long arc traced by the coral and limestone islets called the Florida Keys. Burly and sunburned, Lorenz stood in the boat, looking for all the world like a movie corsair, with his reddish-blond pigtail poking out of the blue-spotted bandanna knotted around his head. If his expression was correspondingly fierce, it was chiefly because the bay's spoonbills were responding badly.
"We see a lot of local publications that put pretty pictures of spoonbills on the cover," he said grimly. "Even worse are the fuzzy, feel-good stories about them. But I'm down here watching the birds go all to hell."
In scholarly articles and a doctoral dissertation for the University of Miami, Lorenz has documented the impact of changes in water flow and salinity on the salt- and freshwater fish that sustain the local spoonbill population. Tern Key, toward which we were headed, revealed part of the problem. One of the myriad compact clumps of mangrove trees rising tiptoe above the shallow bay on clawlike prop roots, the key seemed to undulate on the gentle surface ripples. This impression was reinforced when Lorenz anchored and we slogged in among the mangroves. With each step I sank knee-deep into gray marl, the consistency of oatmeal, from which the mangroves rose. Only by grasping the prop roots and pulling myself along could I keep up with the indefatigable Lorenz.
Inside the tangled miniature forest, however, Tern Key came alive. Mature spoonbills (long drooping legs, an eye-catching pink blur) burst repeatedly from the veil of leaves ahead and flapped toward the key's interior. Nests, concave platforms built of sticks, perched in the mangroves, well above the water. Gangly and still unable to fly, this year's offspring made the best of the situation. They were already out of the nests, clinging to bobbing branches and craning their pale, slender necks for a view of the intruders.
"I've seen 25, maybe 30 of the young birds here," Lorenz said. "But a great many nests have failed on the other keys. Since the late 1970s spoonbills in the bay have re-nested if things have gone wrong, and I see signs that some failed nesters have moved over here to try again. Let's hope."
The spoonbill's pale-green head, bare of feathers by the time the bird reaches maturity, grades into a soft, spoon-shaped bill. To feed, a spoonbill walks through shallow water, sweeping its sensitive, half-open bill from side to side and snapping it shut when it "feels" a fish, insect, or other small organism. To feed itself and its insatiable young using this technique, the spoonbill needs a dense concentration of prey. Under natural conditions the bay teemed with small fish. Minnows, killifish, and other prey found cover in the dense mangrove forests that rimmed all of the larger keys before World War II.
"The spoonbills' nesting cycle is tied to the region's wet-dry cycle," Lorenz explained. "They arrive in Florida Bay toward the end of the rainy season--a time when prey fish are thriving in the marshes and mangroves. Then, as rains diminish in early winter, higher parts of the landscape go dry, and the fish are concentrated by falling water levels. This superabundance of prey stimulates the spoonbills to begin breeding. As water levels go on dropping in late winter and early spring, the fish become more and more concentrated. The spoonbills can quickly gather enough food for their nestlings. Then, when young spoonbills leave the nest, they find a good supply of easily caught prey in the shallow water to tide them over while they learn to survive on their own."
This natural cycle was disrupted in the postwar era. The human population on the Florida Keys surged from a sparse 14,000 to more than 90,000 last year, and the flood of residents and visitors goes on rising. Dredge-and-fill projects for building and the conversion of mangrove wetlands into boat channels destroyed much of the birds' old feeding grounds in the southern and western parts of Florida Bay. Parent spoonbills flew north to the Everglades, 20 miles or more, to locate adequate food, though sources there were also becoming uncertain. Today 1,000 spoonbill pairs breed in Florida, mainly in Florida Bay but also around Tampa Bay, on Florida's Gulf Coast, and near the Kennedy Space Center, on the Atlantic Ocean. Separate breeding populations exist farther west: 1,500 pairs along the Texas coast and 1,500 pairs in Louisiana.
"South Florida is the only place in the world where, when it rains, somebody always sues the government. It's insane. If you live in Minnesota, can you sue because it snowed on your property?"
A century ago the roseate spoonbill had almost disappeared from the United States, as hunters killed many kinds of wading birds to procure their feathers for the millinery trade. The shooting disrupted and ultimately destroyed the spoonbill colonies. A successful preservation campaign launched by the early Audubon societies stopped much of the killing and restored healthy populations of some species. But the spoonbill continued to decline. By 1920 ornithologists knew of only 20 or 25 spoonbill nests in the entire United States.
In 1939 Audubon's executive director, John Baker, turned to science to uncover the reasons for the species' plight. He chose biologist Robert Porter Allen to begin the society's now-62-year involvement with this remarkable bird in Florida Bay. At the time, a single nesting colony, with a total of 15 pairs, survived in Florida, on Bottlepoint Key. For three years (including a season spent studying spoonbills on the Texas coast) Allen lived under primitive conditions, almost like a spoonbill himself, studying the birds as well as the humans and other animals that affected their lives. "No snail that crawled, no worm that squirmed, no leaf that grew would escape my ardent attentions," he later wrote.
One of Allen's discoveries was that spoonbills fed primarily on killifish and minnows rather than on mollusks, as he had previously thought. The birds often fed at night, and Allen's dredging and netting revealed the reason: That was the time when dense shoals of fish poured into the shallows. Food, he decided correctly in that time of natural water flow, was not a limiting factor on their population.
But his most important discovery was to pinpoint the continued illegal shooting by local people and the taking of spoonbill eggs and young for food as the chief cause of the birds' scarcity. After most of the bay's small keys became part of Everglades National Park in 1948, roseate spoonbill numbers began to double every decade. Audubon researchers counted 1,254 breeding pairs in the bay and its mainland fringes in 1978-1979.
But by then intensive water management was under way far to the north, designed to provide flood control for the housing and agricultural development invading the Everglades. Much of the flow of water to which the spoonbills had adapted their life cycle was diverted through canals to the Atlantic Ocean. Creeks from the interior Everglades, which had once delivered large volumes of fresh water to Florida Bay, dwindled to insignificance. In 1987 the bay's seagrasses, important as nurseries for shrimp and fish, began to die. Huge algal blooms erupted in the 1990s.
Under pressure from environmentalists, state and federal authorities have tinkered with South Florida's water-management system to provide some relief to the water-starved national park. Between 1983 and 1999, part of the flow formerly diverted into the Atlantic was held north of the park, then released seasonally into the Everglades to mimic natural conditions. But agricultural interests were concerned that the rains, combined with the released water, would cause flooding, and sued to disrupt the plan. Under the threat of legal action, water managers opened the floodgates, inundating wetlands to the south just when young spoonbills left the nest. Today, roseate spoonbills hang on precariously in Florida Bay, with 500 to 700 pairs
Trying to produce young, with varying success. "South Florida is the only place in the world where, when it rains, somebody always sues the government," said Lorenz. "It's insane. If you live in Minnesota, can you sue because it snowed on your property?"
Lorenz joined Audubon's research staff in 1989, primarily to study the spoonbills' prey fish. But he soon found himself watching the spoonbills, too. The connections he has discovered between birds and fish provide ammunition for the administrators and environmentalists working to restore the Everglades and Florida Bay. In addition to counting breeding birds on the nesting keys to determine nesting results, he designed a unique drop net to sample the makeup of fish populations in what have become prime feeding grounds at the southern tip of the Florida mainland.
"Withholding fresh water from the north changed the landscape where the Everglades meet Florida Bay," Lorenz said. "Formerly, mangroves grew only in a narrow strip along the shore. But now salt water creeps farther and farther inland and brings the saline-loving mangroves with it, replacing the freshwater marshes. Though there have been some recent adjustments in management, they are too sporadic to let freshwater habitat recover."
Lorenz has correlated water conditions in the lower Everglades--fresh, lightly salty, and marine--with the kinds of minnows and other prey fish they support. (Spoonbills feed on fish in all three kinds of aquatic habitat.) "The species that thrive in fresh water are more abundant and have greater biomass," he explained, "so they provide more food for the spoonbills. But if they're going to build up to big numbers, these prey fish need extensive fresh water in the sloughs and creeks where they breed."
Backed by such evidence, Lorenz and his colleagues link the spoonbills' present instability in Florida Bay to out-of-sync water levels. Attempts by many of the bay's breeding pairs to nest or re-nest often fail, as (despite Lorenz's hopes) they did this spring. Last year Congress approved the Comprehensive Everglades Restoration Plan to put the whole system back together, but funding is already running behind schedule. Money promised for pilot projects and land acquisition has not materialized.
"I made a video of young spoonbills that isn't pretty," Lorenz said. "They're draped over mangrove roots, starving and barely moving, or already dead. Fish are scattered in the deeply flooded mangroves, and the birds can't get enough to eat."
Lorenz takes his video to meetings where water managers, biologists, and administrators are trying to figure out how to fulfill the Comprehensive Everglades Restoration Plan. At this point, the plan still does not address the spoonbill's complex needs. But the documented problems of an indicator species such as the roseate spoonbill, Lorenz points out, prove that the future of wildlife in one of the most incredibly diverse wetlands on the planet is at stake.
"Let's fix the system," he said to me in the boat off Tern Key. "Given the loss of foraging habitat around Florida Bay, a return to the spoonbills' highest nesting success of the past is highly unlikely. But we might at least restore the nesting effort and success rates of the 1970s."
As he spoke, two mature spoonbills rose over the key, splashes of glorious pink against the blue Florida sky. We watched them as they flew with their deep, slow wing beats, their long necks and curious bills pointed north toward their feeding grounds in the Everglades. Statistics aside, the beauty of Florida's "flame birds" may be the best argument of all for fixing the system.
Frank Graham Jr., an Audubon field editor since 1969, calls himself "a 19th-century naturalist." Besides birds, objects of his devoted attention include plants, spiders, and true flies.
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© 2001 NASI
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