One morning this month, a stinging wind scoured the stubbly marsh and shallow waters of the Blackwater National Wildlife Refuge on Maryland's Eastern Shore.
Just beyond a 40-foot observation tower, a large flock of Canada geese huddled along the icy shore of the Little Blackwater River. But a much smaller group of birds several hundred feet away drew the attention of assistant refuge manager Buddy Johnson.
West of the tower, two adult bald eagles, flashing white heads and tail feathers, wheeled in the air above a frozen finger of marsh. On the ice below were five immature eagles, their mottled plumage ruffled by the lashing wind. Further out from shore, four more eagles were silhouetted against the glinting sun.
From the tower, Johnson radioed his sightings to other wildlife officials scanning the refuge's 15,615 acres of woods and marsh for more eagles. In less than an hour, officials counted 29 eagles. It was a sight that heartens many of the wildlife officials who not so long ago watched as the population of eagles declined dramatically.
Biologist Bill Giese remembers those days when bald eagles were a much rarer sight on the Blackwater refuge, and when their mating resulted in broken or unhatched eggs riddled with a deadly contaminant.
"We've seen a tremendous recovery," he said.
Although some officials worry about the bird's long-term prospects, most agree the bald eagle is making a strong comeback in its traditional stronghold of the Chesapeake Bay region, the second largest breeding area for eagles east of the Mississippi River. In Maryland, its two prime habitats are the Blackwater refuge and the Aberdeen Proving Grounds, a military testing installation northeast of Baltimore.
If the eagle population grows at current rates for the next few years, the eagle may move off the list of the region's endangered species, wildlife officials speculated.
Fifteen years ago, the bird that serves as our national symbol was sliding toward extinction in the lower 48 states. Wildlife officials blamed the pesticide DDT, which had saturated the environment after coming into widespread use in the 1940s. Eagles, preying on animals whose tissues were tainted with DDT, were being poisoned in large numbers. DDT also caused breeding females to lay thin-shelled eggs that cracked under the weight of the adult birds.
"Most eagles in the bay had picked up DDT, and the reproduction was down to almost nothing," said Maurice LeFranc, a researcher affiliated with the National Wildlife Federation.
Other birds of prey, such as the peregrine falcon and osprey, also were affected by DDT. The osprey never declined as sharply as the eagle, and the much rarer peregrine falcon has been bred in captivity and released in the eastern United States.
The bald eagle's decline helped lead to the ban on DDT in this country in 1972. The next year the eagle was given additional protection under a federal law on endangered species.
In 1977, wildlife officials found that nesting pairs of eagles in the Chesapeake Bay region, including Maryland, Virginia and Delaware, had dropped to 77 from an estimated 600 pairs in the 1930s. Ten years after that dismal count, officials reported that nesting pairs in the region had climbed to 160.
"They're increasing at a very encouraging rate that's more than enough to sustain the population," said Glenn Therres, an administrator with Maryland's Forest, Park and Wildlife Service.
Eagles have benefited not only from the DDT ban, but also from regulations to protect their habitat and from increased monitoring by wildlife officials.
The National Wildlife Federation, in cooperation with most of the 48 contiguous states, sponsors winter counts to learn where the birds congregate and migration patterns of eagles traveling south from Canada and New England.
The January count found 85 birds at Aberdeen Proving Grounds, in addition to the 29 eagles at the Blackwater refuge.
Maryland's Critical Areas Program, inaugurated under a 1984 law to protect the Chesapeake, restricts development on land near active eagle nests, said the wildlife service's Therres. Although many landowners are eager to protect nesting eagles on their property, the restrictions have drawn a lawsuit from one Talbot County developer prevented from clearing land for a housing project. The suit, filed more than a year ago, still is pending, Therres said.
Wildlife officials hope their efforts, coupled with the eagle's population rebound, will result in the bird moving off the endangered species list in the Chesapeake Bay before long. A six-year-old recovery plan has as its goal a bay population of 175 to 250 nesting pairs before the species is reclassified.
At its current population growth, the eagle may reach the lower figure in another year or two, said Mitchell Byrd, a Virginia biology professor who worked on the recovery plan.
Although the eagle now is doing well, Byrd worries about the species' fate 20 years from now. "I think habitat is going to be the limiting thing," he said.
Continued development along the bay and its tidal rivers will eliminate the forests and undisturbed shores eagles need for hunting and raising their young. Shrinking habitat has had a disastrous effect on North American ducks, whose population is at all-time lows as marshy breeding grounds in the northern Midwest and Canada are converted to farmland.
"Nobody is creating more habitat that I know of," said Don Perkuchian, manager at the Blackwater refuge.
Although DDT is no longer a serious threat, pesticides still take their toll on eagles. In the past two years, officials have found several eagles in Maryland and Virginia poisoned by carbofuran, an insecticide commonly used on corn. In addition, officials occasionally find eagles shot to death.
"We're still not totally out of the woods," said the Blackwater refuge's Giese. "We still lose birds."