An ailing bald eagle found by a southwestern Indiana farmer tested positive for mercury poisoning, but state wildlife officials say it's unclear if the bird was poisoned by eating tainted fish it caught in Indiana waterways.

An environmental watchdog group says Indiana ranks fourth nationally in mercury emissions from coal-fired power plants that eventually end up in the food chain.

"To me, this eagle is sending a very strong message that people should pay attention to," said Catherine Bowe of the National Wildlife Federation.

But Mark Pochon, property manager at Hovey Lake, said the bird might have traveled a great distance.

"She could have picked that up anywhere in country; they're travelers," he said. "Our hope is she picked it up over a very long time, but we will keep looking to see if there are any other (cases)."

The eagle, an older female, was lethargic and unable to fly when a farmer found it in June and turned over to officers at the Hovey Lake Fish and Wildlife Area in southwestern Indiana.

Evansville veterinarian Gregg Gormley examined the eagle, and at first suspected the bird might have suffered lead poisoning from eating fish contaminated with lead shot or sinkers.

Instead, blood tests found normal lead levels but elevated levels of mercury, he said.

The eagle was released weeks later after being treated with medicine to rid its body of the toxic metal.

Indiana ranked fourth nationally in mercury emissions from power plants that fouled waterways, according to a report issued last week by the U.S. Public Interest Research Group, an environmental group.

The area where the eagle was found, tucked near the Kentucky and Illinois borders at the confluence of the Wabash and Ohio rivers, has among the greatest concentrations of coal-fired power plants in the nation.

David Evers, director and chief scientist at the Maine-based Biodiversity Research Institute, said he doubts that mercury caused the Indiana eagle's problems. Damage done by mercury is irreversible, he said, but the eagle recovered and was released in July after Gormley treated it with a chemical to which mercury binds and passes out of the body.

"I don't know what else it could be," said Gormley, who has treated wild birds for a decade. "There were no other physical changes" besides neurological problems, "and it's no secret there are sources of fish laden with mercury."

Source: Associated Press