Bald eagles back in the news

by Roland D. Hallee

Bald eagles are in the news again. It seems they have made such a historic recovery from near extinction, that they once again are becoming a nuisance in rural areas, especially among chicken farmers. Unfortunately, that has led to the killing of many bald eagles, illegally of course, but still, a recurring problem. Eagles are still protected despite the fact they have been removed from the endangered wildlife list. Farmers hands are literally tied when it comes to dealing with the problem of poaching bald eagles. Federal law protects them, unlike foxes, coyotes, and the like.

They are strong fliers, and can reach speeds of 35-43 mph when gliding and flapping, and about 30 mph while carrying fish. Its dive speed is between 75-99 mph.

Sightings of bald eagle are happening more frequently now because of the efforts produced by the Endangered Species Preservation Act of 1966.
Accounts suggest at least 50,000 breeding pairs of eagles lived in the lower 48 states before European settlement. Historic numbers are unknown in Maine, but eagles were widespread in the state and locally in some coastal regions. Eagles were fed to hogs by Casco Bay settlers in the 1700s. In 1806, there was a bounty on eagles in a Knox County town. Nesting colonies were reported along the Maine coast from Swan Island to Roque Island. Swan Island was named after “sowangan,” which is an Abenaki word meaning “bald eagle.”

The bird itself gets its species name from bald, in English derived from the word piebald, and refers to the white head and tail feathers in contrast with the darker body. The scientific name is derived from Haliaeetus, a Latin word for sea eagle.

In 1967, a comparative study of eagle nesting in five states, including Maine, revealed relatively low numbers and chronically poor reproduction, especially in Maine’s remnant population. In 1962, two biologists with the National Audubon Society, Charlie Brookfield and Frank Ligas, began annual monitoring of bald eagles in Maine. Early efforts were limited, but their counts could only document 21-33 pairs of nesting eagles and only 4-15 eaglets fledged each year between 1962 and 1970. Average productivity among Maine eagles during the 1960s was only 0.34 eaglets per nesting pair.

By 1978, the bald eagle was listed as an endangered species in 43 of the lower 48 states. It was listed as threatened in the remaining five states, Michigan, Minnesota, Oregon, Washington and Wisconsin.

Bald eagles, Haliaeetus leucocephalus, continued to decline in western Maine through the 1970s. By 1979, only two pairs remained in the western half of the state’s vast coastline. None were in northern most Maine. Only easternmost coastal regions of Washington County supported viable eagle numbers and productivity.

The defining moment came at a time when various agencies anguished over a $1 billion oil refinery proposal in this last stronghold in the northeast. That would have been the worst case scenario, from potential oil spills, and likely jeopardy for Maine’s endangered bald eagles. The project was never developed, and eagle numbers began to rebound in Maine from that point forward.

Meanwhile, bald eagles were absent from all other New England states; New York could only account for a single nesting pair, and New Brunswick, was the only Canadian province to recognize bald eagles as endangered.

In the 1970s and early 1980s, biologists in Maine worked to increase eagle productivity and survival. Egg transplants attempted to bolster productivity at nests with chronic failure, especially in western Maine where the population was nearly extirpated. Public outreach, educational initiatives, and intensified law enforcement sought to reduce human-caused mortality: illegal shooting was the leading cause of documented eagle mortality in this era. Trappings, poisonings and electrocutions also took a toll.

The diminished use of DDT is broadly correlated with the comeback of the bald eagles. Extensive use of the toxin during the 1970s and 1980s has been linked with the decline of the bald eagle population. The insecticide would soften the eagle egg shells, causing them to crush when the adult eagles attempted to incubate them.

By 2006, in Maine, the breeding population had rebounded to 414 eagle pairs. Bald eagles now breed in all 16 counties.

The average life expectancy of a bald eagle is 20 years, with the oldest living up to 30 years. One in captivity in New York lived to be 50 years old.
Contaminants, dioxins, mercury and lead appear in Maine bald eagles. Breeding populations in the northeast, as of 2006, is tied intimately to the fate of Maine’s population.

As of 2006, 74 percent of the northeast population of bald eagles was located in Maine.

Eagles are a magnificent bird to watch in their environ. I seem to have this knack for seeing rare occurrences in nature during my travels. Recently, while on my way home from work, I was approaching the Carter Memorial Bridge from the Winslow side when I noticed a bald eagle flying very low over the bridge. Once I reached the spot where I had seen the eagle, I looked north up the river to see if I could spot where it was going. To my surprise, it was now below the deck of the bridge and flying directly upriver. What a sight to actually observe a bald eagle in flight, from above. It was gliding majestically, obviously looking for prey.