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Delivering Good News on the Stork

• September 03, 2010 • 5:00 AM

Pushed by human development onto the endangered list, the American wood stork is wading back to its historical haunts in the swampy Southeast.

Despite horrific recent images of oil-soaked pelicans, the Southeast can boast a conservation bright spot — the ongoing recovery of the endangered American wood stork.

After decades of threat from development and poor hydrological management in south Florida, this wetland-dependent wading bird is permanently moving north.

The stilt-legged wood stork is experiencing a tentative rebound in its historical habitat in south Florida’s swamps and Everglades. At the same time, the stork is finding new homes along the coast of Georgia, South Carolina and even North Carolina.

“The current trend is that the wood stork’s population and breeding range is increasing and extending north,” said Bill Brooks, a U.S. Fish and Wildlife Service biologist in Jacksonville. “Those are all signs toward recovery,” he said, due in part to a long-term effort implemented by the USFWS.

The wood stork population is certainly doing better than three decades ago when, in 1978, it hit an estimated low of 2500 breeding pairs. But Larry Bryan, a research biologist at the University of Georgia’s Savannah River Ecology Laboratory says that today’s U.S. population of some 16,000 adult birds still doesn’t approach the estimated 100,000 of a century ago.

Development, not climate change, is the culprit this time. The stork’s decline has been due to hydrological change in south Florida, says Bryan, who studies the wood stork’s use of nesting areas at coastal Georgia’s Harris Neck National Wildlife Refuge. “Trying to hold back water for the dry times was good for humans,” he said, “but not for the wood stork.”

Storks breed when water levels drop and their prey concentrates in ponds, marshes and streams. By using their legs and web feet to stir up their prey by feel, they can feed on fish in foot-deep waters both night and day.

“It’s like the difference between trying to catch fish from a fish bowl versus a swimming pool,” said Rena Borkhataria, a research biologist at the University of Florida’s Everglades Research and Education Center. “When a fish strikes the stork’s bottom mandible, it triggers a bill snap reflex. But fish have to be sufficiently concentrated for this mechanism to pay off.”

For a given breeding season, a wood stork family of four — two adults and two nestlings – requires an average of 400 pounds of fish.

“Many storks are not initiating nesting until March,” said Borkhataria. “When storks begin nesting that late in the dry season, juveniles may not have had time yet to mature and to develop flight capabilities when the [late spring and summer] rainy season begins. Rising water levels disperse the prey. It’s crucial that wood storks begin nesting earlier in [south Florida's] dry season, preferably in November and December.”

Borkhataria notes that stork parents will frequently abandon the colony once the rainy season starts in earnest, leaving their chicks to starve.

Since Florida received statehood in 1845, it has lost nearly half its wetlands. But it wasn’t until the 1930s, when lumber interests moved into south Florida’s Big Cypress area, that destruction of the stork’s habitat began in earnest. Trees were often felled while storks were still nesting in their branches, decimating a significant portion of the birds’ then-estimated breeding population of 20,000 pairs.

By the 1950s, construction near southern Florida’s Lake Okeechobee had drained a good chunk of the Everglades.

Largely as a result, the USFWS listed the U.S. wood stork population as endangered in 1984. Even so, wood stork populations outside the U.S. – from as far south as Argentina up through Mexico, Central America and parts of the Caribbean remain healthy.

But the health of the U.S. stork population appears to be inextricably linked to the ecological fortunes of south Florida. The Everglades and nearby cypress wetlands appear to be very important to the Southeastern stork population as a whole, Borkhataria points out, and not just to the Florida colonies. Most of the storks she and colleagues tracked via satellite made use of the area’s cypress wetlands and estuaries before returning north to breed.

Although the Everglades National Park is protected, most of the wetlands in the stork’s core southwest Florida foraging area are on private lands still subject to land-use battles with developers and even governmental agencies.

“The willingness of all levels of government to grant permits to projects impacting significant wetland acreage within [southwest Florida's] core foraging area is readily apparent,” said Jason Lauritsen, assistant director at the National Audubon Society’s Corkscrew Swamp Sanctuary near Naples. He says one such project proposes destroying 645 acres of existing wetlands.

Yet in a 2007 internal USFWS five year-review, Brooks recommended that the stork’s status be upgraded from “endangered” to the more sanguine condition of “threatened.” Wood stork reclassification from endangered to threatened can be considered when, over a three year average, there are at least a population of 6,000 nesting pairs. That’s a criterion that is currently being met.

The USFWS isn’t the only entity tracking the rebound. Last year, it received a formal change-of-status petition from the Florida Home Builders Association with Brooks’ 2007 report attached.

Brooks says that the USFWS is still in the process of responding to the petition and emphasized that no deadline has been set for a final decision. But he also noted that there would be no change in the stork’s protection even if its status were upgraded from endangered to threatened.

Still, Bryan says the upgrade would mark the first step toward delisting the bird, a point that obviously hasn’t been lost on the home builders.

As the association’s general counsel, Keith Hetrick, explained, “Builders support appropriate species-protection measures supported by science, but builders do not support unwarranted restrictions on development activities resulting from unfounded designations that are either outdated or not supported by sound science.”

There’s no small irony that as the stork population fights its way back to something called normal, the human population around the Corkscrew sanctuary in Collier County has more than trebled – to over 300,000 — in just the last three decades.

“There can come a point where our property is rendered useless for development because of a species’ designation,” said Douglas Buck, the Florida Home Builders Association’s director of governmental affairs. “Environmental advocates never want to remove restrictions regardless of a species’ population. But when a species shows improvement and the regulations allow, then its status should reflect that.”

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Bruce Dorminey
Bruce Dorminey is an award-winning U.S.-based science journalist and author of Distant Wanderers: The Search for Planets beyond the Solar System. A former Hong Kong bureau chief for Aviation Week and Space Technology and former Paris-based technology correspondent for the Financial Times newspaper, he's covered everything from potato blight to dark energy.

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