A few weeks ago, while checking reports of schooling hickory shad at the Deer Creek Bridge on Stafford Road, I was pleasantly surprised to see the return of two old friends, a pair of bald eagles.
They were perched atop their huge nest, which they carefully built among the branches of a mature oak nearly three years ago. In March 1989, an army of bird watchers, armed with spotting scopes, cameras, telephoto lenses and binoculars, swarmed to the site and watched for several weeks as the eagles transformed hundreds of sticks into a nest measuring nearly 6 feet in diameter.
Throughout April and well into May, both birds spent most of their time winging to and from the base of Conowingo Dam, where they caught gizzard shad, herring, hickory shad and other forage species to feed their young. By the end of May, two fluffy, dark brown, juvenile eagles could be seen standing on the nest's edge, exercising their wings before making their first attempt at flight. Within the next two weeks, they were gone.
Just a decade ago, your chances of seeing an eagle in the wild around here were slim to none. Last year, however, eagles nested in 17 Maryland counties, and the breeding population of 128 pairs produced 169 young. The 1977 population was only 41 pairs. Although it may be difficult to believe, Maryland boasts the second-largest eagle population on the East Coast, where only Florida holds more eagles.
Why do eagles thrive in Harford County? A quick trip to the base of Conowingo Dam provides the answer: food. The fertile waters of the lower Susquehanna River teem with spawning fish during early spring and summer. When cold weather returns to the Susquehanna Basin and fish are less abundant, eagles switch to waterfowl, rodents and dead deer.
Until 1972, when the U.S. Environmental Protection Agency banned use of the pesticide DDT, eagle populations sunk to an all-time low. The highly toxic pesticide had leached into ground water, contaminated hundreds of fish species and was thought to be responsible for a host of serious ailments affecting humans. Trace amounts of the chemical are still found in most species of fish in the Chesapeake Bay.
Glenn Theres, of the state Department of Natural Resources, says the chemical interfered with female eagles' ability to produce sufficient calcium during early stages of egg development. This resulted in paper-thin shells, crushed by the weight on an incubating adult.
A half dozen eagles now can be seen daily near the base of Conowingo Dam. Although most are easily recognizable adults, some are 1- to 3-year old birds often mistaken for large hawks.
Bald eagles do not develop their characteristic white head and tail plumage until they're about 4 1/2 years old. In their first four years, young birds are dark brown with some minor patches of white on breast feathers. They're about the same size as adults, standing nearly a yard tall with a wing span of more than 6 feet.
When the head and tail feathers change from mottled brown to bright white, the bird becomes sexually mature, seeks a lifelong mate and establishes a nesting territory where it spends most of its adult life.
The best time to observe eagles is during early morning and late afternoon, when they're actively searching for an easy meal. Most of the time, they're congregated near Rowland Island, about a quarter-mile downstream from Conowingo Dam and frequently observed from the parking lot at the end of Shures Landing Road.
All you need is a good pair of binoculars or a small telescope. If you're thinking about photographing an eagle, you'll need a good-quality 35mm camera, a 1,000-millimeter lens, a sturdy tripod and lots of luck.
This equipment can cost $10,000 to $12,000.
The U.S. Fish and Wildlife Service, a federal agency responsible for all endangered species, is considering a change in the eagle's status to threatened. The birds would still receive protection under the Endangered Species Act, but the new status would signal that federal officials believe a substantial improvement in the health of eagle populations has occurred nationally.