Originally created 08/12/01

Home is where the food is



JACKSON, S.C. - Paul Koehler sees plenty of birds at the Silver Bluff Audubon Center and Sanctuary, but none are as pampered - or as unusual - as the delicate wood storks that appear during the hottest days of summer.

"They usually arrive in July," said Koehler, assistant manager at the 3,154-acre preserve along the Savannah River. "And they're always hungry."

The rare birds were added to the federal Endangered Species List in 1984 after their numbers in the Florida Everglades - their largest surviving habitat - dwindled from 6,000 in 1960 to a mere 500 birds.

Wood storks stand three feet tall and have wings that span more than five feet.

"But they can't survive just anywhere," Koehler said. "They need a lot of help."

To start with, storks have a voracious appetite. A nesting pair of adult birds requires 440 pounds of fish during the March-to-August breeding period.

Typically, storks seek out wetlands habitat that partially dries out in late summer, concentrating small fish and crustaceans that make up the bird's diet.

Because those habitats have vanished, storks have, too.

Silver Bluff, owned by the National Audubon Society, is home to one of the nation's northernmost feeding colonies of wood storks. The birds gather at specially built ponds financed in part by the U.S. Department of Energy.

"We have four ponds the storks use, but we can only manipulate the water level in three of them," Koehler said.

Last year - and again this year - the U.S. Fish & Wildlife Service provided 500,000 bluegill and sunfish from a fish hatchery near Orangeburg, S.C.

All year long, the fish are fed and fattened. When the storks arrive, water levels in three of the ponds are lowered to a depth of 12 to 18 inches - just right for foraging storks to gorge themselves.

"The way we manage the ponds is to bring them down to about that level," he said. "The storks show up, often within a matter of hours. They fly so high up in the air that you can't even see them."

Storks have keen eyesight and can spot exposed mud flats, which indicate a shrinking water supply that concentrates fish into smaller pools.

The birds that feed at Silver Bluff are from a nesting colony called Big Dukes Pond, a 1,220-acre site in Jenkins County, Ga., acquired two years ago by the state and set aside as a preserve for the unusual birds.

While feeding, storks rely not on their eyesight, but on "tacto-location," a process in which they catch and eat fish by touch.

They wade through shallow, muddy water while sweeping their long, submerged bills from side to side. When the bill touches prey, it snaps shut with a 25-millisecond reflex action - the fastest known for vertebrates.

"They feed by touch, and sometimes a stork will swallow anything it bumps into," Koehler said. "There was one mixed up stork that had swallowed a pine cone."

This summer, a stork at Silver Bluff was found dead - after it tried to swallow a cottonmouth that struck it repeatedly on the neck and head. But mostly they just gulp down small fish.

"One of their adaptive advantages is, since they don't rely on their eyesight to feed, they often feed in the dead of night," Koehler said.

This year, the highest number of storks counted at Silver Bluff has been 77, Koehler said. "The record high was 305, some years back, and our average is usually 180 to 220."

Wood Stork Facts:

* Added to Endangered Species list in 1984.

* Stork numbers declined 70 percent since 1960.

* Nesting pairs require 440 pounds of fish during breeding season.

* Storks soar so high they are often invisible from the ground.

* Storks feed in shallow, drying wetlands that concentrate food.

* Their bills snap shut reflexively - the fastest among all vertebrates.