With plumage pink as a blushing cheek and a bill that resembles a wooden kitchen utensil, the roseate spoonbill always stands out — even among the many and beautiful wading birds of the Everglades.
But its striking appearance is not why National Audubon Society scientists like Jerry Lorenz have spent nearly 80 years monitoring the bird’s habits in a shallow bay wedged between the southern the Everglades and the Florida Keys.
The spoonbill, which nests on mangrove islands, serves as something of a flying barometer of the health of the bay and the Everglades system that flows into it. So a sudden, mysterious plunge in nesting last year to the lowest numbers in more than a half century had Lorenz and fellow scientists anxious about what might unfold this year.
The prognosis midway through breeding season: Spoonbills are back — though still in numbers far too small to suggest its future is rosy in the bay.
“I’m encouraged,’’ said Lorenz, after snaking through mangroves to check spoonbill nests on an island near Audubon’s research lab in Tavernier. “Last year, we had a massive abandonment of Florida Bay and I have no idea why. I’m hoping it was just a weird blip.’’
Other pink birds, a flock of 19 migrating flamingo, also have been popped up in Lake Ingraham in the western reaches of Everglades National Park this winter. But unlike the native spoonbills, these sporadic visitors have only feeding, not breeding, on their minds.
In an Everglades system driven by ever-changing water levels, weird blips are sort of the norm. Even before development chewed up half the historic wetlands and canals and levees altered the flow of the River of Grass, wildlife and bird populations often rollercoastered with rainfall, said Sonny Bass, supervisory wildlife ecologist at Everglades National Park.
“The system here is really a boom or bust system,’’ Bass said. “You can either have a really good year when everything comes off right or you can have a really bad year. Historically, that’s been the case but it’s probably exaggerated now on both ends.’’
The last few years alone illustrate that. In 2009, coming off a deep drought, wading birds across South Florida went into a breeding frenzy, producing nearly 78,000 nests — the most since the 1940s. The next year, heavy rains flooded out many nests, producing some of the lowest nesting numbers in decades. Last year, another drought — but no corresponding jump in breeding activity this time. Instead, it proved mediocre, with nesting across the region down by 40 percent from the 10-year average, according to an annual survey compiled by the South Florida Water Management District.
The working theory is that two droughts sandwiched around a very wet year threw off the timing of seasonal drying cycles across much of the Everglades that concentrate fish and other tiny things that wading birds fatten up on during breeding.
But that doesn’t explain the spoonbill’s decline in Florida Bay, Lorenz said.
Spoonbills have historically foraged where freshwater Everglades meets brackish Florida Bay, methodically sweeping their bills through shallow pools in tidal flats and coastal estuaries to snatch minnows and crabs. Audubon surveys showed those areas were packed with record amounts of prey, Lorenz said.
Even so, most spoonbills, which Lorenz said typically return to nest on the islands where they were born, took wing from Florida Bay last year. The birds built only 69 nests in the bay, roughly a third of the previous year, which had been an all-time low. In an unusual move, some went north to try nesting in the water conservation areas of western Broward County.
“What was so scary was that it was such a precipitous drop,’’ said Lorenz, Audubon’s state director of research.
He doesn’t have a good explanation. A record cold spell in early 2011 is a possibility, he said, but one he mostly discounts because birds have nested in colder weather in the past.
Whatever the cause, many spoonbills have returned. Since January, at least 160 nests have been spotted on bay islands, more than double the number last year, and there may be more. Just last week, Lorenz and his small team of researchers tallied another 160-plus nests in Taylor Slough, first spotted during a fly-over by Everglades National Park biologists.
Nesting spoonbills are rarely seen from the air. The species builds its nests so deep under the mangrove canopy, it’s hard to catch even a glimpse of pink from a boat or plane. So several times a month during breeding season, Audubon researchers head out in small boats to wade through shoe-sucking mud and crawl through tangles of mangroves to count birds, eggs and fledglings.
Wading quietly onto East Key, Lorenz heard the spoonbills before he spotted them, a deep croaking not unlike a bullfrog.
“Hear that?” he said. “They’re barking at me.”
Audubon’s spoonbill studies date back to the 1930s, when the society dispatched an ecologist named Robert Porter Allen to help rescue a bird nearly obliterated by poachers who sold the prized pink plumes to hat makers. Allen would devote 38 years to studying their habits and flight patterns, producing a 1947 book, “The Flame Birds.’’
If the colorful name didn’t stick, Allen’s research showed the birds to be key gauges of the Glades’ complex and interconnected ecosystems. He charted the birds’ comeback after hunting was halted and Everglades National Park was created in 1947. Then he chronicled the birds’ decline again, as a building boom swept the Florida Keys in the 1970s, dredging up once rich feeding grounds.
Lorenz has been monitoring spoonbills for Audubon since 1989, linking the species’ continuing decline to roads, development and drainage projects that have siphoned off and altered the flow of fresh water to Florida Bay.
One project, the C-111 canal, has been particularly damaging. Dug in the 1960s to carry rockets from the defunct Aero-Jet plant in South Miami-Dade and increased in capacity in the 1980s to protect farms from flooding, the canal diverts fresh water that once flowed down Taylor Slough into Florida Bay, instead funneling it 20 miles east into Barnes Sound.
The C-111, which left the park’s southern wetlands too dry and northeast Florida Bay too salty, is now undergoing state and federal alterations to return water to areas abandoned by the spoonbill — help that Lorenz says can’t come soon enough.
Spoonbills, while ranked as a “species of special concern’’ by the state, aren’t considered endangered. Another population around Tampa Bay has steadily grown and now outnumbers the one in Florida Bay, which has steadily declined for decades.
Audubon’s annual surveys show that since a peak nesting count of 1,260 in 1979, nesting numbers fell to an average of around 500 from 2000 to 2005 and have continued slipping since. The 300-plus nests this year by no means amount to a major rebound but after last year, they do represent a pink flash of hope.
“It’s not just the birds we’re concerned about,’’ he said. “The spoonbill is the canary in the coal mine for Florida Bay.’’
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