seen most frequently near water.
More and more people in Maryland do each year, as the bald eagle becomes somewhat common here and throughout the country.
Once endangered, our national symbol's numbers have increased dramatically over the past two decades. In Maryland, the number of nesting eagles has increased sixfold since the mid-1970s, with 260 pairs nesting in 1999 (compared to 41 pairs in 1977).
Why such a significant increase? The ban on the use of DDT and other organochlorine pesticides in 1972 by the U.S. Environmental Protection Agency started the recovery. DDT caused the eagles to lay thin-shelled eggs, which cracked when the eagles incubated them. Cracked eggs do not produce young.
Once this pesticide was no longer used, the environment was able to slowly rid itself of the contaminant and eagles started to nest successfully. Nest sites were protected by the Maryland Department of Natural Resources (DNR), the U.S. Fish & Wildlife Service, and others under the authority of the Endangered Species Act and, in Maryland, under the authority of the State's Endangered Species Act and the Critical Area Program.
In the Chesapeake Bay area, the eagle recovery was further enhanced by efforts to restore the bay. Better water quality helps sustain fish populations ¯ the principal diet of eagles.
Today, more than 2,000 bald eagles make their home in the Chesapeake Bay area. In 1999, Maryland's 260 nesting pairs of eagles produced 370 young; that's 890 nesting eagles and young in Maryland alone, and Virginia had comparable numbers. And these totals do not include the numerous immature eagles, one to four years old, wandering around the bay.
Bald eagles in Maryland are found primarily in association with the Chesapeake Bay and its tidal tributaries. Most nests are within one mile of these tidal waters, with many located along the shorelines of large rivers, such as the Chester, Choptank, Patuxent and Potomac. In 1999, eagles nested in 19 Maryland counties, including all that border the Chesapeake Bay. Dorchester County had the most with 58 nesting pairs, and Charles County was second with 37 pairs nesting mainly along the Potomac River.
Though most eagles nest near tidal waters, several pairs are associated with large reservoirs and nontidal portions of the Potomac and Susquehanna rivers. Nesting pairs are known at both Loch Raven and Triadelphia reservoirs. Just last year, a new pair was found on the shoreline of the Potomac in Frederick County, making this the westernmost nesting pair of bald eagles in Maryland.
Bald eagles nest in large trees, either pines or hardwoods, usually at the edge of a wooded area. Many nests border active farm fields or shoreline. Since eagles have such a large wingspan they cannot fly through woods easily, so they build nests where there is easy access. Nests ¯ 4 to 5 feet wide and more than 3 feet deep ¯ are made of large sticks and located in the upper crotch of trees.
In Maryland, eagles start courting in December. By March, they lay their clutch of one to three eggs and begin incubating immediately. (Since this is usually the coldest time of the year, nesting eagles should never be disturbed as they safeguard their eggs against adverse weather.)
After hatching in April, young eagles remain in the nest for about 12 weeks. They start to fly in June, and by August have learned to hunt and fish on their own.
Immature bald eagles are the same size as adults, standing nearly three feet tall. They are dark brown in color ¯ including their heads and tails ¯ and some have white mottling on their bellies and under their wings. Juveniles can be mistaken for large hawks or vultures. Immature eagles wander around the bay area looking for food and a safe place to roost.
Some eagle roosts in the area have populations of more than 100. Blackwater National Wildlife Refuge on Maryland's Eastern Shore is one such place; Aberdeen Proving Ground at the head of the Chesapeake Bay is another, where eagles frequently feed along the Susquehanna River below Conowingo Dam.
During the winter months our own population increases, when bald eagles from Maine, eastern Canada and the northeastern United States come to Maryland. Our eagles usually do not migrate, though they will wander around the bay area when not nesting.
Interested in checking out this majestic bird of prey first-hand? In Maryland, a pair of binoculars, patience and a good viewing location along the shoreline of a tidal waterway are all you need.
Glenn Therres is the DNR Program Manager for Heritage and Biodiversity Inventory, Research & Monitoring.