Newspaper article The Florida Times Union

Bald Eagle Faces New Threat Deaths Traced to Toxin of Unknown Origin

Newspaper article The Florida Times Union

Bald Eagle Faces New Threat Deaths Traced to Toxin of Unknown Origin

Article excerpt

AUGUSTA -- A U.S. Forest Service ranger encountered a disturbing scene while patrolling a remote access road at 310-square-mile Savannah River Site just before Christmas.

It was a bald eagle -- a female on the verge of reproductive maturity. It was almost 5 years old with full, white plumage.

And it was quite dead.

The bird was taken to the Savannah River Ecology Laboratory, where its death could not be explained. Then it was sent to a research lab in Wisconsin, where its brain was examined with a powerful electron microscope.

"The news wasn't good," said Karen Gaines, a research coordinator at the ecology lab.

Scientists at the U.S. Interior Department's National Wildlife Health Center in Madison, Wis., confirmed what Gaines and her colleagues already feared.

The bird -- and another eagle found days earlier along Thurmond Lake in Lincoln County -- were the newest victims of a mysterious, always-fatal toxin whose origin remains unknown.

The disease, which also affects small waterfowl called coots, surfaced at DeGray Lake, Ark., in 1994, where 58 bald eagles have died. The eagles at the Savannah River Site and Thurmond Lake were the first eagle deaths outside Arkansas, but others have since been reported at Lake Juliette, Ga., and Wood Lake, N.C.

Now scientists fear the unknown affliction, which is gradually affecting ducks and other waterfowl, could threaten the once-endangered bald eagle which was rescued from the brink of extinction decades ago.

"When you have an endangered species like the bald eagle coming back so well, and you have a major die-off, it's a major concern," said Gaines, who is launching new studies at the ecology lab this year to learn more about the toxin -- dubbed avian vacuolar myelinopathy, or AVM.

"It could be an algae or something in the lower end of the food chain," said Gaines, who is working with a colleague, raptor rehabilitation specialist Lara Hopkins, on the project. "But it'll be hard to identify. We know it's unpredictable. And it doesn't last long."

Like detectives sifting through evidence -- both circumstantial and forensic -- the two scientists hope to develop leads to pin down the cause for the disease and perhaps a cure.

Kimberli Miller, a wildlife disease specialist at the National Wildlife Health Center, has studied AVM since it surfaced in 1994.

"The thing we don't typically see is multiple eagles in one location dying," Miller said. "Even with ducks you can have die-offs, because ducks are gregarious. They flock and feed together. Eagles are loners."

The theory for transmission of the disease is that coots eat toxic plants and in turn are consumed by eagles. But that has not been proved, said Gaines, who is planning experiments involving coots.

In the complex science of disease study, solutions are often found through the process of elimination. …

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