A federal biologist plans to climb 80 feet into an ancient oak tree near Glenn L. Martin State Airport this morning to knock down a nest built by a breeding pair of bald eagles.
The eviction is part of an effort to drive the nesting birds away from the airport, where they have been judged a hazard to aircraft operations.
"Apparently it's an attractive tree for eagles," said Jonathan Dean, a spokesman for the Maryland Aviation Administration. It's a tall, sturdy perch, close to the food resources of the Chesapeake Bay and its tributaries.
Nevertheless, he said, "birds and aircraft don't mix."
Biologists say there is a better-than-even chance the birds are already incubating eggs, but bad weather prevented officials from acting sooner. Any eggs in the nest will be lost. But officials expect the eagles will find another nesting site in time to reproduce again this spring. That often occurs when an eagle nest is hijacked by great horned owls.
It's the second time these eagles have been shooed from the same tree. Officials lopped off several limbs last year to discourage the birds' return. The pair then built a nest in a tree some distance away on Frog Mortar Creek and raised at least one chick.
But, to the biologists' amazement, the birds returned to the old oak this winter and found a new way to anchor and build a nest alongside the airport runway. The hope is that as soon as this new nest is demolished, the pair will return to their old one on Frog Mortar Creek and start a new family.
"It's a bit windblown. It needs some work, but they can do that in three or four days, no problem," said Craig A. Koppie, a raptor specialist with the U.S. Fish and Wildlife Service's Chesapeake Bay field office in Annapolis.
Koppie will use a bucket truck to lift himself halfway up the tree this morning, then climb the rest of the way with spiked shoes and ropes. He expects the eagles will "do some clucking" but won't try to harm him.
The danger of mixing birds and aircraft was driven home Jan. 15 when a US Airways jetliner struck a flock of Canada geese shortly after departure from New York's LaGuardia Airport and lost power in both engines. The crew ditched the plane in the Hudson River, and everyone on board survived.
Martin State Airport is located on Middle River, an arm of the Chesapeake Bay, nine miles east of Baltimore. It is used by civilian flights and the Maryland Air National Guard, with almost 80,000 takeoffs and landings each year.
The airport has grappled with bird problems for years. It has more than a dozen propane cannons around the airfield that can be fired by remote control to shoo gulls and waterfowl from the runways. The devices are allowed by federal authorities, but they have not bothered the eagles, Dean said.
The birds' aerie rests 80 feet up in an oak tree on the northeast sector of the airfield, about 150 feet from a taxiway and 900 feet from the main runway.
Eagles can weigh up to 14 pounds, and they have been observed standing and "loafing" on or near the runway, officials said. Their flights to and from the nest sometimes take them across the runway at altitudes that could intersect with arriving or departing aircraft.
As bald eagle populations around the Chesapeake Bay continue to climb, such conflicts are increasing, biologists say. An eagle nest was removed from a tree near Norfolk International Airport in Virginia several years ago after a light aircraft there was struck.
The plane landed safely. The dead eagle's mate found a new partner and a safer nesting site near the Norfolk Botanical Garden, said Bryan D. Watts, director of the Center for Conservation Biology at the College of William and Mary.
Authorities are discussing the fate of another eagle nest along a runway at Fort Eustis, near Newport News. A nest at Langley Air Force Base also is being watched.
The bald eagle population declined after World War II, largely due to the pesticide DDT. The chemical weakened their eggs.
Federal protection in 1967, and the DDT ban in 1972, put the species on the road to recovery. In 2007, bald eagles were removed from protection under the Endangered Species Act. But they are still protected under the Bald and Golden Eagle Protection Act of 1940.
Today, biologists estimate there are 1,000 to 1,100 nesting pairs of bald eagles around the Chesapeake Bay. They're producing 1,200 to 1,500 chicks a year, Watts said. Of those, 70 to 80 percent are likely to survive their first year.
"The Chesapeake Bay, we believe, is beginning to reach saturation," he said. As the best territories are taken, birds are vying for space. More are moving into places they once would have shunned, including those in potential conflict with human activity.
"This is just another chapter in the recovery of the species," Watts said. "It suggests they're doing OK."