Bald Eagle Ailment Puzzles Experts

Monday, February 9, 2004
Duluth News Tribune (AP)

MILWAUKEE - A disease infecting bald eagles along the lower Wisconsin River has wildlife experts puzzled, nearly a decade after it first appeared. No one knows what causes the ailment, which wildlife specialists say generally manifests itself in live animals as grand mal seizures.

Experts say the limited scope and area of the disease indicate something peculiar to the lower Wisconsin is contributing to the ailment.

The Wisconsin Department of Natural Resources and National Wildlife Health Center have conducted investigations to look for infectious agents, environmental pollutants and poisons in the eagles' forage.

Nothing has surfaced so far, said Julie Langenberg, DNR wildlife veterinarian. "The bottom line is nobody knows what is going on," she said.

The disease is suspected in at least 11 eagles in the past year. Four survived and are getting rehabilitated at the Raptor Education Group Inc. in Antigo. There they are watched 24 hours a day and given anti-seizure medications as soon as they start having spasms.

"We literally sleep next to them so that we're right there if the symptoms start," said Marjorie Gibson, the raptor group's executive director.

She also works to teach the surviving birds how to fly and hunt again.

The disease first appeared in the winter of 1994 and 1995. It then vanished and reappeared in the winter of 2000. Since then the severity has fluctuated, killing between six and 20 eagles each year.

The disease has alarmed wildlife specialists even though it seems to have affected only a small number of eagles - only 11 out of 614 pairs between Adams and Juneau counties, Langenberg said.

According to pathology work done at the U.S. Geological Survey's National Wildlife Health Center in Madison, "changes in these birds do not point to any clear cause," said Carol Meteyer, a wildlife pathologist.

No other birds or mammals appear to be involved, Meteyer said.