When a bald eagle gets angry enough to scream, you expect to hear something fierce enough to scare rabbits into foxholes. But here was Tony Steffers, manhandling two 8-week-old eagle chicks in their nest and Mama was flying lazy circles overhead, making noises like a squeaky gate.

"It's a strange sound coming out of an eagle," said Keith Cline, providing ground support for Steffers, who was tied to the trunk of a loblolly pine, 58 feet above the ground. "But I guess it sounds just right to another eagle."

For the last seven years, Cline and a crew of wildlife workers have spent each spring climbing tall trees around the Chesapeake Bay to put identification tags around the legs of young birds that, with luck, will grow up to be national symbols.

Cline is the field crew director for the Chesapeake Bay Bald Eagle Banding Project, which is funded by the U.S. Fish and Wildlife Service and the National Wildlife Federation, a private conservation group. After state wildlife workers in Virginia, Maryland and Delaware conduct aerial surveys to spot nests, Cline and his climbers are sent out to do more detailed snooping.

This spring, the news from the nests is very good.

"As of yesterday, we had banded 75 nestlings in 66 nests," said Cline at the end of last week. "And a lot of pairs nested late because of the cold and rain."

The last few years have been fertile for bald eagle lovers. After decades of a population decline that threatened the giant raptors with extinction in the lower 48 states, there lately has been a baby boom in the high rise nests that surround the bay.

In 1962 a survey of Chesapeake bald eagles found only 13 chicks; last year, Cline and his climbers counted 98. Just 10 years ago, there were only an estimated 1,000 bald eagles in the contiguous United States. There are now thought to be more than 4,500.

A ban in 1972 on the use of pesticides such as DDT and passage of the Endangered Species Act one year later are credited by officials with beginning that reversal. The pesticides, which entered the eagles' food chain through fish that make up about 90 percent of their diet, were blamed for the sudden appearance of thin, brittle egg shells that did not survive incubation.

Federal legislation, stipulating fines of $5,000 and jail sentences of up to a year for anyone convicted of killing or maiming an eagle, helped protect the birds that were once routinely shot by feather hunters and western ranchers. Where others saw awesome beauty and skill in the eagle's swoop, the ranchers saw another barnyard fowl disappear.

"When I started working with eagles in 1965 they were on the skids," said Jack Holt, the most experienced of Cline's banding crew. "They bottomed out in '69 and '70 and have been on the increase ever since."

Holt wears a green long-billed cap that might once have sported a propeller. His backpack is a 30-year-old Boy Scout model. His patched jeans may be older. He is comfortably round and generally slow moving, until he starts climbing a tree. Then he seems to plug into a current below the bark.

During May, Holt bands eagles around the Chesapeake. For the rest of the year he is in Pennsylvania, Michigan or Canada, banding eagles and hawks, or studying great horned owls. For half the year he lives out of a Volkswagen bus that sports a "Don't Shoot Hawks" bumper sticker and a spare tire cover emblazoned with a bald eagle about to strike.

Cline is 29, a staff member of the National Wildlife Federation's Raptor Information Center. Because his eyes are set deep behind bushy brows and his nose has a slight hook to it, his face has an attractive touch of bird about it.

The other climber on this trip is Steffers, a tall, dark-haired biologist who makes his living as a stained glass artist. Steffers met his wife, another tree climber, on an eagle banding project. Now he spends five weeks each spring separated from her and their two children for the sake of eagles.

Much of their work, say this crew, is less than glamorous. To find nests spotted during aerial observations, they must often trek through acres of swamp and briars, fending off mosquitoes and blood-sucking flies as they go. Once at the nest, they have to worry only about falling from a tree or getting slashed by a razor-sharp talon or hooked beak.

This day, though, all goes well. With the help of Chuck and Anne Geyer, the caretakers of a 1,650-acre estate beside the Rappahannock River, the crew finds the eagle's nest after a search of only half an hour. The tree is relatively easy to climb and the nest is holding two eagle chicks, already big enough to have wing spans of five feet.

"This is the way you would like all of them to work out," said Cline after the birds had been banded and left to wonder at the strange-looking creatures that share their world.