I saw my first bald eagle almost 30 years ago on school trip to Blackwater National Wildlife Refuge. Bald eagles were not a common site back then and I was enthralled with this rare bird.
Since then, as bald eagles have made a comeback in the Bay region, I’ve spotted more eagles, especially while canoeing the many creeks and rivers in the watershed.
As adults, bald eagles are easily recognized by their brown bodies and white heads and tails. The scientific name, Haliaeetus leucocephalus, means “white-headed sea eagle.” Immature birds are dark brown, mottled with white. The white head and tail begin to appear at 3-4 years of age and are complete by 4-5 years.
Adult males measure about 3 feet from head to tail, weigh 10-12 pounds and have a wingspan of 6-7 feet. Female birds are slightly larger.
In flight, the bald eagle has a distinctive, flat-winged profile, unlike the “V” shape of a vulture.
Breeding pairs usually build their nests high in mature loblolly pines, tulip poplars and oak trees along the shores of the Bay and its tributaries.
Eagle nests tower 80-110 feet above the ground. The massive nests are often used year after year, growing to 6-8 feet in width and averaging 4 feet deep, although some nests may grow to 10 feet deep. They are built with large sticks and plants with a soft inner lining of broom sedge and pine sprigs.
Bald eagles usually lay one clutch of one to three eggs in late winter which hatch after 35 days. In 1986, an unprecedented four-egg clutch occurred at a nest in Kent County. All four eggs hatched and were successfully raised to fledglings.
The young are covered with soft down but soon grow feathers and are flying within three months. By the fourth month, they are on their own.
Like eagles elsewhere, Chesapeake birds feed primarily on fish, but also eat ducks, geese, small mammals, rodents, snakes and turtles, as well as carrion.
Bald eagles were once pretty common around the Bay, averaging one pair for every five miles of shoreline. Just prior to the 1940s, though, bald eagles began to decline because of the direct killing of birds and loss of habitat.
In 1940, the Bald Eagle Protection Act made it illegal to kill, harm, harass or possess bald eagles, alive or dead, including eggs and feathers. They began to recover but then another culprit entered the picture.
Just before World War II, the use of the pesticide DDT to control mosquitoes was widespread in coastal areas. Bald eagles were feeding on prey contaminated with this pesticide.
By the late 1960s and early ’70s, researchers determined that DDE, a breakdown product of DDT, built up in the tissue of adult female bald eagles. This prevented the calcium release needed to produce strong eggs and caused reproductive failures.
Surveys of the Chesapeake Bay area revealed a drop in active eagle nests and the number of eaglets fledged. In the 1930s, one to two eaglets were produced per nest, but in the early 1960s, the average dropped to one eaglet for every five active nests.
The use of DDT was banned in the United States in 1972, but our nation’s symbol was still in trouble. By that time, there were fewer than 90 breeding pairs of eagles in the Chesapeake area. In 1973, under the Endangered Species Act, the bald eagle was listed as endangered throughout the lower 48 states except Michigan, Minnesota, Wisconsin, Washington and Oregon, where it was listed as threatened.
ince the late 1970s, the amount of DDE found in Bay eagle eggs has dropped, and more young eagles have hatched. In 1977, 44 nests in Virginia and Maryland (combined) produced 63 young. Nesting success has steadily increased each year.
In August 1995, the bald eagle was reclassified from endangered to threatened. By 2003, there were 760 active bald eagle nests in the Chesapeake Bay watershed.
During the last 25 years of recovery, eagles have rebounded in part because of the replacement of healthy adult nesting pairs.
Bald eagles in the United States have responded to the protection afforded by the Endangered Species Act as well as several other actions. The DDT ban, Bald Eagle Protection Act, and the protection of habitat through land acquisitions and landowner agreements have all helped the bald eagle to recover.
The U.S. Fish and Wildlife Service first initiated a proposal to delist the bald eagle in 1999. Because of the complexity of the issues, including the large-scale distribution of this species, the service is completing the steps for a re-proposal to delist the bald eagle.
The Chesapeake Bay now has one of the highest concentrations of bald eagles in the lower 48 states. In addition to the breeding population, biologists in Maryland and Virginia have documented approximately 10 key communal roost areas, or concentration areas, which support hundreds of winter migrants from as far north as Canada and summer migrants from Florida.
Although Chesapeake bald eagles have fully recovered, it is believed that the full extent of the carrying capacity for the Bay area has yet to occur.
The population is expected to grow for many more years. The maximum size of the breeding population will be predicted by future land and water development projects, especially if these occur in areas near forested shorelines where eagles forage, roost and nest.
In order for bald eagles to remain, they need access to adequate habitat, including suitable nesting trees near open water, isolation from human activity and a stable food supply that includes mostly fish, other birds, mammals and reptiles and amphibians.
Biologists are working so that one day bald eagles in the Chesapeake Bay area will no longer need the protection of threatened status.
Through habitat protection, the identification of important nesting, roosting and feeding sites, and the monitoring of potential contaminants, the bald eagle will continue to thrive in the Chesapeake Bay and beyond.
Do Not Disturb!
Always avoid activities that might disturb bald eagles, especially during the nesting season (Dec. 15 through June 15).
If you should stumble into a nesting territory during this period, adults will usually sound a high-pitched cry. This is an indication that you are too close to an active nest and your presence is disturbing the pair. The first seven weeks after eggs are laid are the most critical for the survival of the eaglets.