State's Baby Eagle Boom Could Restock Rest Of U.s.

September 29, 1985|By Mike Thomas of The Sentinel Staff

Wildlife experts plan to expand an eagle-moving experiment that could make Florida the major supplier of the endangered birds for the rest of the country.

The experiment is possible because Florida has more eagles than any other state except Alaska, and the population is growing, said Stephen Nesbitt, a Florida Game and Fresh Water Fish Commission biologist in Gainesville.

Florida has about 1,500 eagles. Last winter they had a record nesting season, producing 435 chicks.

In the experiment, eggs are taken from Florida nests and hatched in an Oklahoma incubator. The hatchlings then are released in states with depleted eagle populations.

The Florida birds, meanwhile, lay a second clutch of eggs to replace those that are taken.

''We can rob the first eggs shortly after they are laid, making the adults lay a second clutch -- giving us double service from those birds,'' Nesbitt said.

University of Florida zoologist Mike Callopy said that before the experiment only captive eagles had laid back-to-back clutches of eggs.

Until now only eggs from captive birds had been used in release programs, Callopy said. But there aren't enough captive birds to produce all the eggs that are needed.

If the experiment continues to work, Florida's wild eagles could become breeding stock for the rest of the country, Callopy said.

Alaskan eagles aren't being used because the birds are bigger than those in the continental United States and could have problems adjusting to the heat, Nesbitt said.

The experiment began in December when biologists took 18 eggs from nine eagle nests. One egg was infertile, and four baby eagles died from a vitamin deficiency, a problem that biologists say won't happen again.

The 13 surviving eagles were released in Georgia, Alabama and Oklahoma, said Alan Jenkins, assistant director of the Sutton Avian Research Center in Bartlesville, Okla. The center is a non-profit research organization that helps endangered birds.

The baby eagles are put in towers in woods where they are fed until they learn to catch their own food, Jenkins said.

Biologists have been able to trace only two of the 13 released eagles. One was shot and will remain in captivity the rest of its life. A second was having problems finding food, so it was captured and will be released again, Jenkins said.

Only about 10 percent of baby eagles survive, Nesbitt said.

In three months, biologists will almost almost double the size of the experiment by removing 35 eggs. When the results from this second phase are tabulated, the state will decide whether to continue, Nesbitt said.

Florida's eagle population has been slowly growing and is about half what it was 50 years ago.

The population may be rebounding because the pesticide DDT was banned in the early 1970s. DDT, which was passed to eagles through their food chain, caused the birds to lay eggs that cracked.

The state's largest concentration of eagles is along the Kissimmee chain of lakes in Central Florida, where the birds feed on fish. Their numbers are declining in developing areas along the southwest and east coasts.

During the most recent nesting season, which began in November and ended in March, 280 eagle pairs had 435 young, Nesbitt said. During the previous four years the number was 350 to 375.

Pairs that usually have one or two chicks are now producing two and three, said Herb Kale, a Florida Audubon Society ornithologist.

Nesbitt said one theory for the increased production is that freezes during the past two winters stunned shad, a trash fish that abounds in lakes, providing an easy food source for the birds.

''Eagles aren't exactly proud,'' Nesbitt said. ''They'll take anything.''

Another bird that biologists once feared was on a flight toward extinction, the brown pelican, also had a record nesting season.

About 9,078 pelican pairs produced young, compared with the previous record of 8,942 breeding pairs.

More than 1,000 pelicans from Florida were transplanted to other states in the early 1970s to boost their dwindling populations.

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