Living Dangerously: Eagles In Maine

The Nature Conservancy has protected dozens of bald eagle nesting sites in Maine. Our efforts have been directed toward protecting their habitat from encroaching development and reducing human disturbance during the critical nesting season. Working with the University of Maine and the state Department of Inland Fisheries and Wildlife, we have sought to provide eagles with the essential habitat they need to reproduce and prosper.

The Nature Conservancy's role is central to eagle protection, but other factors must be addressed as well if Maine's eagle population is to continue to grow.

The eagle is a good indicator of the richness, productivity and health of a natural system. It carries this status because of its high visibility, the fact that its needs are relatively well understood, and particularly because it lives high on the food chain. Dangerously high.

Chemical contaminants

This was painfully clear in 1965 when only four eaglets fledged in all of Maine. As fish and carrion eaters, eagles were consuming just those creatures in which the chemical DDT had been accumulating. High concentrations of a DDT byproduct, DDE, damaged the eagles' ability to retain calcium, dooming them to produce eggs with shells so thin they collapsed under the weight of the brooding eagles. Eggs that did survive simply never hatched.

When DDT was banned in 1972, many thought the problem was solved. As the years went by, we believed the eagles would rebound, and they did. This season, 115 eaglets fledged successfully in Maine. That is progress -- but in terms of the productivity of nesting eagles -- the number of eaglets per pair -- it is the least progress seen anywhere in the country. One reason may be that in Maine, perhaps because of the cold, the short growing season and the acidic soil, contaminants such as byproducts of DDT last longer. While we wait to find out just how much longer, new chemical threats have appeared: a blood sample taken from one coastal eagle was called "a slurry of toxic pollutants" in a recent news article.

"These eagles are growing up laced with contaminants," says Maine's chief eagle expert Charlie Todd, an endangered species biologist with the Department of Inland Fisheries and Wildlife. "All coastal eagles now have PCB levels, some remarkably high. Inland, the problem is mercury, and perhaps half of all eagles still carry DDT."

Habitat

While researchers continue testing the content of eagles' blood and monitoring their productivity, others are undertaking research that will directly influence The Nature Conservancy's role in habitat protection.

To date, we have focused our protection efforts on the nesting site. For most mainland eagles, nesting, roosting and feeding take place in close proximity. Protecting one site goes a long way towards protecting all. This is not true for eagles nesting on coastal islands. They often travel far from their nests to feed. But how far and to where? To begin answering that question, the University of Maine has attached tiny radio transmitters to two adult eagles (one from the Conservancy's Long Porcupine Island Preserve). With a range of 100 miles, the radio transmitters will help us understand the territory and feeding habits of coastal eagles.

Meanwhile, Todd feels there is a renewed urgency in studying Maine eagles. Success elsewhere is placing yet another pressure on Maine's bald eagles and on those who would see them prosper. The rebound by eagle populations elsewhere has prompted a change in the federal protected status of eagles in this country from 'endangered' to 'threatened'. The eagles represent the kind of high-profile success story endangered species advocates may need to promote right now. And although bald eagle productivity is on the upswing in Maine as well, it remains on the state's endangered list. There is concern here that the upswing may be a short-lived phenomenon if regulatory protection is removed before the eagles are provided with what Todd calls "a safety net of secure habitats."

The Maine Chapter continues to make that sure just such a net is in place. As regulatory and environmental factors change, it will give the eagles a fighting chance. "Eagles are out there in the real world," says Todd. "Their lasting recovery depends on their ability to fend for themselves."

*Adapted from an article appearing in The Maine Legacy, the quarterly newsletter of the Maine Chapter.