Naturalist Tracks Eagles, and by Her Count, There Is Cause for Alarm

Libby Mills spends Thursdays surrounded by bald eagles: eagles tearing salmon carcasses on the riverside gravel bar, eagles resting in alder and cottonwood, eagles soaring over snow on the ridge top.

Mills, a naturalist, has been taking a weekly eagle census along a seven-mile stretch of the Skagit River at the edge of the North Cascades, where scores of bald eagles congregate every year from December to March. Most of the birds return north this month and next.

More bald eagles winter in Washington than in any other state in the Lower 48, according to statistics from the state Game Department. About 1,500 eagles return year after year for spawned-out chum salmon carcasses and nearby roosting spots in old-growth Douglas fir, Western hemlock and cedar.

Numbers on Rise

Many who study eagles say the national bird, which once numbered 1 million, is slowly gaining in numbers.

Today, there are an estimated 25,000 bald eagles in the United States, as many as 15,000 of them in Alaska. The eagle population in the Lower 48 reached a low point of 6,000 to 9,000 birds in the 1960s, largely because of the effects of the insecticide DDT, authorities say.

Besides Washington, major wintering spots are Lake Coeur d’Alene and Lake Pend Oreille in Idaho, Yellowstone and Glacier national parks, the Mississippi River flyway, the Great Lakes and Florida.

Still, the bald eagle is an endangered species in all but a few states.

A ban on DDT in the 1970s has helped the eagles survive in the egg, but Mills worries that logging, overfishing and other pressures of development threaten their long-term prospects.

Dams for the Northwest’s hydroelectric power block fish migration routes, and rivers that are channeled to improve boat passage are no good for the eagles because the birds do not dive in deep water, she said.

Clear-cutting--the felling of all trees in a particular area--along the coastal waters of Canada and Alaska also threatens the birds’ nesting grounds, Mills said.

She sees the eagles in a “downward spiral--hopefully a slow one . . . . They can’t have a real bright future.”

Others are more hopeful.

Richard Taylor, a statistician with the state Game Department, said eagles are hard to count, but he is confident that their numbers are increasing.

Cites Change in Attitude

Although it may take a long time for the chemicals that contributed to the devastation of the bald eagle population to work out of the environment, man’s attitude toward the birds is changing in their favor, he said. Environmental protection is widely implemented, and fewer birds are being shot as people begin to appreciate them more, he said.

“As long as we have that kind of an attitude, I think things will get better,” Taylor said.

Plentiful food and big trees attract eagles, mostly from British Columbia, to this spot along the Skagit, Mills said.

She has been counting the eagles for five years for the Nature Conservancy, a private nonprofit organization that buys land to preserve it. The conservancy owns an eagle preserve here on the Skagit, about 70 miles northeast of Seattle, and hopes to buy nearby land to save eagle roosts, because old-growth Forest Service land in the area could be slated for logging.

The Forest Service is conducting a study of eagle roosting patterns to determine which stands of trees to protect. The state Game Department also studies eagle nesting patterns and takes a midwinter census.

Of the estimated 1,500 eagles wintering in Washington, about 500 nest in the state, Taylor said.

Eagles can fly hundreds of miles to feed, said Kathy Sider, a biologist who started the Seattle Aquarium’s float trips down the Skagit in 1984. Some tagged eagles have been known to take weekend trips from the Skagit to San Francisco and back, she said.

Eagles are designated merely “threatened” here and in Oregon, Minnesota, Wisconsin and Michigan. In all other states except Alaska, the eagle remains an endangered species.

Breeding Programs

Many states have successful programs to breed the birds and introduce them into the wild when they are about 3 months old.

At least a dozen states in the East have sent chicks back into the wild, said Matthew Perry, a fish and wildlife spokesman at the Patuxent National Wildlife Refuge in Maryland. There are signs that breeding pairs of eagles are producing two and three chicks per nest, a high percentage.

“We think they’re doing well,” he said. “They’ve certainly made good increases in the East.”

Habitat pressures continue, but he said that at least in the Chesapeake Bay area, new laws require more land to be dedicated to green areas, which will accommodate eagles.

On a census day a few weeks ago, Mills had counted 79 eagles by late morning when she reached an overlook in Rockport State Park. She used binoculars to scan the valley--taking in the wide, shallow Skagit, a grassy field, hillsides of conifers and 33 more eagles.

Eagles prefer the tops of big trees, probably for the view, Mills said. On warm, sunny afternoons, they’re likely to leave the trees to soar, often along the top of a ridge.

“They get so high up,” she said, “I think they’re just goofing off.”