The Eagles Have Landed Here!
Special to The Washington Post
Wed., Aug. 12, 1998; Page H01
Rosy orange fingers of first light shimmer across a marshy inlet on Hoskins Creek, a tributary of Virginia's Rappahannock River, which in turn flows into Chesapeake Bay.
A boat ramp leads into the creek from a parking lot in the town of Tappahannock about 65 miles southeast of Fredericksburg. At the top of the ramp, biologists Bryan Watts and Keith Cline wait to back their research skiff into the creek while, just ahead of them, two early-morning fishermen roll a trailered boat down the ramp.
"Those guys are going to have competition, though," Watts says, "from some of the best fish-spotters on the bay -- bald eagles."
The Rappahannock and neighboring James rivers support two of the largest summer concentrations of bald eagles in North America.
"Last July, in one stretch of river along the James, we counted more than 400," says Watts, director of the Center for Conservation Biology at the College of William and Mary. "Few, if any, other places on this continent have as many bald eagles during the summer months."
In fact, there now are more bald eagles along the Chesapeake within a few dozen miles of Washington than there were in the entire continental United States in the mid-1960s. "The Chesapeake's heavily forested shorelines and abundance of fish make this region extremely attractive to bald eagles since they perch in trees right next to the water and from there hunt for fish." explains Cline, a wildlife biologist with the Virginia Department of Game and Inland Fisheries.
Watts and Cline are conducting a census of bald eagles on Chesapeake tributaries and are monitoring boats and people along or on the rivers to determine how our national symbol since 1782 is faring.
"Bald eagles have made a remarkable comeback since 30 years ago when DDT was responsible for a huge decline in their numbers," Cline says. "But now there's a new problem for eagles. They like the same places as humans, shorelines with waterfront views. When our needs and those of bald eagles conflict, the situation often ends up with the eagles as losers."
The 1972 U.S. ban on DDT likely is responsible for the birds' comeback, according to eagle experts. After World War II, the toxic pesticide was sprayed extensively along the coast to control salt marsh mosquitoes and then accumulated in fish and other bald eagle prey such as waterfowl.
Because of that biomagnification -- the increasing concentration of a pollutant as it moves up the food chain -- predators such as bald eagles and peregrine falcons were exposed to large amounts of DDT in a single meal. One result was that the shells of eagles' eggs became so thin that they could not support the weight of a parent bird, which must sit on the eggs to incubate them.
Other raptors, or birds of prey, also were affected, and the numbers of peregrine falcons and ospreys crashed, along with some sea birds such as brown pelicans.
Today, about 5,290 pairs of bald eagles nest in the continental United States, up from about 450 pairs three decades ago. A significant number, 2,067 pairs, are in the northern tier states from Maine to the Dakotas, according to Jody Millar, national bald eagle project coordinator for the U.S. Fish and Wildlife Service, with large numbers also in the Pacific region (1,379 pairs); the southeastern region, including Florida (1,319); and the Chesapeake (489).
"The Chesapeake is a small region in terms of the land area allotted to it for management purposes," Millar explains, "so in a ratio of eagles-to-area, it probably has one of the highest overall concentrations of nesting pairs of bald eagles."
About a century ago, there was one eagle nest for every one of the 5,620 miles of shoreline along Chesapeake Bay, according to Jon Gerrard and Gary Bortolotti, authors of The Bald Eagle: Haunts and Habits of a Wilderness Monarch. But by 1962, a census of half of the bay produced only 28 active bald eagle nests, or eyries.
Since 1962, bald eagle numbers have increased gradually. In 1995, the Fish and Wildlife Service "downlisted" the bald eagle, protected since 1973 by the Endangered Species Act, from "endangered" to "threatened." Now, removing the bird from the list is being considered.
Loss of habitat, however, may be the DDT of the 1990s. "Habitat loss is the single biggest reason a species becomes endangered today," Watts says. The Environmental Defense Fund estimates that as the culprit in about 88 percent of such cases.
Just before 6:30 a.m., Watts shimmies a Boston Whaler down the boat ramp. Gear is loaded hastily, and the biologists are ready to go. They putt out of Hoskins Creek and into the wider Rappahannock.
Watts throttles up and skims through weed-green mist that rises from the river on hot days. As the boat reaches the far shore, he slows to an idle and turns north. "We'll survey the area from Tappahannock to Port Royal today," he explains, "which is about 25 miles of great eagle territory."
The boat drifts under the Downing Bridge over the Rappahannock. The early hour and rocking motion conspire to keep the biologists in slow motion, but not for long. Just ahead is the first bald eagle of the day, walking, improbably enough, along a narrow spit of exposed river-bottom along a cordgrass marsh.
"Well, there's number one," Cline says, noting the bird's location on a map. Before the scientists can reach a spot near the eagle, though, it's up and away, winging over the marsh, white head and tail in stark contrast to the brownish-green of the grasses.
The bald eagle's scientific name, Haliaeetus leucocephalus, means "sea eagle with a white head." Sea eagles are large, powerful birds of seacoasts, lakes and rivers. Bald eagles, one of the world's eight species of sea eagles, usually are about five years old when they attain the bright white head and tail plumage of adults, which can live 25 to 30 years.
Younger birds sport a mix of dark brown and buff white feathers, their heads and tails becoming progressively whiter as they grow older. When they first leave the nest as youngsters, bald eagles usually are dark brown or a mottled dark and medium brown.
Features that make bald eagles noticeably different from other eagles are their large, taloned feet, used to grasp and kill prey, and massive hooked beaks that have evolved to tear chunks of flesh. Bald eagles also use their yellow bills in courtship rituals to catch the eye of potential mates.
"The adult on the riverbank was probably feeding on a fish, maybe a dead one that washed up," Cline says. "Bald eagles prefer live fish to dead ones, but they'll take what they can get." An eagle spends much time perching. Once it sights a fish, it descends quickly. At the water's surface, the eagle reaches a foot -- or both feet, if the fish is a large one -- down to scoop up the prey.
Eagles on Virginia waterways and along most of Chesapeake Bay feed on shad, catfish, carp, menhaden and eels. Unlike ospreys, which usually fish "on the wing," bald eagles hunt from prominent perches along the shore, using their sharp sight to spy a fish as it swims just beneath the surface.
"Like that eagle, our second one of the day, is doing," Cline says, pointing toward a tree snag with a dark silhouette on an upper branch. "This one's an immature bird, probably born this year, judging from its dark color and lack of white plumage."
The youngster, like the adult, takes off over the marsh as it sights the boat.
"There's an eagle nest back about a quarter-mile into the marsh," Cline says, "so these birds may have been from that nest, but it's hard to say for sure." Bald eagles begin to breed when they reach full adulthood at age 5. In the mid-Atlantic region, their nest-building activities begin in November.
Eggs are laid between mid-January and late March and hatch by early May. Eaglets remain in the nest for 11 to 12 weeks, fledging by late July. "Bald eagles almost always nest in the vicinity of water bodies, and they prefer areas with undeveloped shoreline," Cline says. The eagles build large, often conspicuous eyries made of sticks and situated where a tree's trunk meets its upper limbs. Some nests remain in continuous use for more than 25 years.
Bald eagles are most sensitive to human disturbance in the early stages of nesting. "That's when a lot of activity near the nest site can scare off the eagles for good," Watts says. But some nests, including one Cline has tracked for eight seasons in a farmer's front yard in Westmoreland County, are surprisingly close to human habitation. "That's definitely the exception, not the rule, though," he says.
The Boston Whaler putters along and soon reaches a section of the river known as Mulberry Island. Here eagles are abundant. "Over there, three birds on the beach, all immatures," Watts says. "And two young and one adult, just above them in those trees along the river."
By the time they pass Mulberry, the biologists have counted 34 eagles. "Eagles love this area's border of tall trees because the trees have no sub-canopy [lower trees and shrubs growing beneath]. That way, they can fly right in and out," Cline explains. "Forested shorelines are probably the number one reason there are so many eagles in the Chesapeake Bay region.
"Past Smoot's Landing, the river's edge is increasingly dotted with pines and oaks. Soon they reach Fones Cliff, centerpoint of the bald eagle concentration area on the Rappahannock. "Many of the eagles that are here in summer are birds up from Florida and the southeast," Watts says. "We have a growing amount of information from radio transmitters placed on eagles in Florida. After their nesting season ends, these eagles mostly come to the Rappahannock and James rivers.
"Eagles farther south breed earlier than those in the Chesapeake; those farther north breed later. Watts and Cline believe that this difference results in an influx of birds into the bay in midsummer. In winter, the Chesapeake again is home to large numbers of eagles that migrate south from New England and farther north to winter on waters rarely covered with ice.
As the boat meanders along the river beneath Fones Cliff, eagles almost too numerous to count take flight from the upper branches of Virginia pines along the cliff edge. One by one, they wheel over the river, slowly whooshing just above the biologists. As the poet John Keats once wrote, the eagles seem to sleep, wing-wide upon the air.
"They're impressive birds," Cline says, "especially when you see so many of them together like this." To the naturalist and artist John James Audubon, bald eagles' majestic soarings were "the mightiest of the feathered tribe." He believed that "Americans have reason to be proud of their great eagle.
"It's now almost 10 a.m., and the sun is beginning to burn off the river mist. "Pretty soon, the eagles will start moving farther back into the foliage," Cline says. "Once it gets really hot, they stop feeding and roost for the rest of the day in shaded areas, becoming active again at sunset."
The biologists motor past Carter's Wharf and on to Leedstown, where signs of development appear. They round a bend and spot a placard in the middle of a field. "Leedstown Landing" it reads, a harbinger of waterfront town houses and condominiums. "We've found that, when people move in, eagles move out," Cline says. "Once trees are felled and marsh paved over, there's really nowhere for the eagles to go."
In a few more miles, the boat reaches Virginia's Lands End Wildlife Management Area. "Here's another potential problem for eagles," Cline says. "This [adjacent] area is slated to become the site of the Virginia Naval Academy. If that happens, bald eagles in this vicinity will definitely be displaced."
Cline and Watts said they hope that development on the Rappahannock is halted before it reaches the extent seen on some other Chesapeake tributaries. "The Rappahannock is an example of what the James and Potomac might have been," Cline says, "if large areas on those rivers had been preserved."
In the distance, the James Madison Memorial Highway bridge shimmers in the heat. "That's our turnaround place," Watts says. "The tide's going out now, and it gets hard to keep from running aground if we don't get back down river before it's out completely. The Rappahannock is a tidal river up until about Port Royal." From Tappahannock to Port Royal, the biologists have counted more than 150 eagles.
Watts revs up the boat, slices a turn and zooms back down the river, passing Mill Creek, Marsh Point and Toby's Point. As he rounds a bend known as Devil's Elbow, a bass-fishing boat arcs around from the far side.
"There's another of the likely problems for eagles on the Rappahannock," he says. "Now that it's late morning, boaters are up. We're going to see lots of bass-fishing boats and jet skis on the way back to Hoskins Creek, many more than the few we saw on the way out." Indeed, numbers of eagles on the return trip only slightly exceed numbers of boats.
Within two hours, the scientists are chugging back up Hoskins Creek. Sweat drips down their backs, and even the boat engine shows signs of overheating. Watts and Cline are elated, however, because bald eagle sightings today along the Rappahannock total 232, "even more than we thought we'd find," Cline says.
At the Tappahannock boat ramp, a queue of watercraft awaits entry. "Bald eagles are definitely coming back," Cline says, "but with all the boats out here, we're looking at a future for eagles that may not be very bright."
Rappahannock River Cruises in Tappahannock offers boat trips to see the summer concentration of bald eagles. The sightseeing vessel, Capt. Thomas, leaves Tappahannock at 10 a.m. and returns at 5 p.m. every day but Monday from May through October. Reservations are necessary. 804-453-2628.
A land-based alternative trip on the lower Potomac River is available through Caledon Natural Area in King George County, Va., about 22 miles southeast of Fredericksburg. Caledon's 2,579 acres host large numbers of eagles in summer. A 90-minute tour takes visitors by minibus to prime eagle-foraging areas on Saturdays and Sundays at 10 a.m. and 2 p.m., from mid-June through Labor Day. Call 540-663-3861 for reservations.
Cheryl Lyn Dybas is a science writer specializing in marine and aquatic biology.
© Copyright 1998 The Washington Post Company