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Winter 1997

Research Magazine > ARCHIVE > Spring 96 > Article

Secrets of Stork Survival
by Jane M. Sanders

To wood stork chicks at Birdsville in Middle Georgia, Larry Bryan looks more like a villain than a hero.

The ecologist invades their treetop nests, snaps identification bands around their legs and collects blood samples before retreating. Bryan is among the researchers at the University of Georgia's Savannah River Ecology Laboratory (SREL) in Aiken, S.C., who are on a mission to save the endangered wood stork.

"Ultimately, we want to aid in the recovery of this species," Bryan said. "Banding birds, taking blood samples and learning about wood storks' basic biology will help us do that."

For nearly 14 years, UGA ecologists like Bryan have scaled towering cypress trees -- from an inland swamp in Birdsville to coastal barrier islands -- to study wood storks where they roost and nest.

"It is labor-intensive, but we place leg bands on chicks because it is the best way of documenting wood stork survival and movement," he said. "Wood storks move about in a large geographic area, and following them for observation and study is a difficult task."

Information gathered from these studies may be critical to the survival of wood storks, whose numbers have dwindled from more than 18,000 nesting pairs 60 years ago to approximately 7,000 pairs today. The wood stork is a highly specialized feeder with a big appetite found in South Carolina, Georgia and Florida, and depends on shallow wetlands with high densities of fish.

SREL research also will aid efforts to restore natural wetlands and create artificial ones, such as the Department of Energy's Kathwood ponds in South Carolina. Among SREL's findings are:

Wood storks fly as many as 50 miles to forage.

Chicks often return to their natal colony from one breeding season to the next.

In some settings, wood storks feed as often at night as during the day.

Although banding storks enables Bryan and other scientists to track individual birds from season to season and year to year, it also has its drawbacks. For one, it requires visual identification of each banded bird.

"For all the work we did to band 65 birds in Georgia in the summer of 1995, we only saw one banded bird at Kathwood -- a stork from the Harris Neck National Wildlife Refuge on the coast of Georgia," Bryan said.

Nor can banding data alone account for why populations of these large wading birds are on the rise in Georgia and South Carolina but are declining in Florida. Are the recent population shifts fueled by a northward migration of birds from Florida, where wetland habitats are in short supply because of urbanization and agricultural development? Or could it be that storks are adapting to the inland and coastal wetlands of Georgia and South Carolina?

"If Georgia and South Carolina are such great areas for storks, why haven't many of them been here for the past 100 years? We hope to find out," Bryan said.

Blood samples -- both those he collected and those donated by the Florida Freshwater Fish and Game Department -- may help provide the answer. Bryan is working with scientists at Texas Tech to analyze samples from wood storks in both states in search of a genetic marker. Such a marker would enable scientists to track individual birds by their shed feathers.

"If we can determine genetic markers for Georgia and Florida storks, we could just analyze genetic materials in shed feathers to determine where the birds came from rather than taking days at a time and climbing trees to band birds and draw blood samples," Bryan said. "Determining whether the Georgia colonies represent one population or several different ones will tell us how to better manage wetlands for the wood stork."

In the process, Bryan might show if these birds of a feather really do flock together.


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