The Nesting Mystery
Eagle enigma puzzles those who watch lakes
Copyright © 2001 Blethen Maine Newspapers Inc.
WAYNE — When Charles Todd looks for eagle nests, he scans the ground for clues.
People cannot see nests while walking through woods, according to the Department of Inland Fisheries and Wildlife biologist. Instead of peering into the air, he told members of the Androscoggin Lake Association, look down for small piles of sticks on the ground.
Then he pointed to a few close to where they stood amid a stand of trees.
"The constant rain of debris up above is not unusual," he said.
The sticks fall from the large nests eagles build. A good nest can last 30 years, through a couple of generations, Todd said.
Smaller clues blended in among dead leaves and pine needles on the forest floor — a pickerel jaw, the head of a bass and the pectoral bone of a horned pout. Todd began snapping up the bone fragments and identified each of them.
As he carefully put the bones in a clear plastic bag, he explained that bird bones are hollow and mammal bones are solid. He also told attendees how the bones connect back to eagles.
"You're looking at leftovers of eagle meals," he told them.
"This is a good, healthy diet."
The sticks and bones served as clues for a larger mystery. A pair of eagles on the lake have had nest failures the past three years.
"Something went wrong. We didn't know what it was," said Molly Saunders, president of the Androscoggin Lake Association. "When you have three in a row, that's a problem."
Eagles are not the only birds on the lake with nest failures. None of the 24 loon pairs on the lake had chicks this year.
The eagle nest failures follow a string of successes. When a pair of eagles reappeared on the lake in 1989, they successfully raised eaglets each season. Todd visited the eagles' home on Androscoggin Lake with members of the association this week as part of his investigation.
While the eagles' diet might have been healthy, Todd had a several other contributing factors to consider with the lakes association.
One factor in the nest failures could be dioxin, a byproduct of the bleaching process in paper making that is found in the sediment of the lake, according to Saunders. Fish can ingest the toxin, which is one reason people should not eat fish taken from the lake.
"It's less of a problem for us than the eagles. They have no choice," she said.
Other substances in the lake that might affect eagles are mercury and polychlorinated biphenyl, a chemical used in commercial and industrial electrical equipment, Saunders said.
Humans getting too close to a nest may also affect eagles, according to Todd. Eagles may leave their nest and eggs, circle and flap their wings at an approaching person.
But if an eagle leaves its eggs during a cold spring day for 10 minutes, the unhatched eggs can die, Todd said. Eagle eggs must be incubated for five weeks before they hatch.
He saw local awareness as a possible solution to people disturbing eagles.
"If you see somebody getting too close to eagles, speak to them. By the time the warden gets here, it's too late," Todd said.
The nest failures at Androscoggin Lake come amid the comeback of eagles in Maine. Since the early 1970s, eagle pairs increased from about 30 to an estimated 263 pairs to date, according to Todd.
A major factor in the declining eagle population was the use of the insecticide DDT in the United States. Although DDT helped halt the spread of malaria worldwide by killing mosquitos, the insecticide harmed other animals as well.
DDT has been banned in the United States since 1972.
"It's come a long way, but we're still in the early stages in western Maine of getting eagles back," he said.
After Todd visited the eagles' home Wednesday, he met with members of the lake association at Camp Androscoggin in Wayne to discuss strategies in finding the cause of a possible nest failure next year.
Although the mystery is not solved yet, Saunders was pleased that residents banded together to discuss the future of eagles on Androscoggin Lake.
"It's a great community of people around here," she said.
To reach Michael Reagan
Phone: 623-3811, ext. 431