WENATCHEE -- From helicopters and other vantage points, state biologists across Eastern Washington have been visiting golden eagle nests this month and counting the furry white chicks inside.
The information they’re gathering will help determine whether this dark brown raptor with a golden crown and a seven-foot wingspan needs more protections in Washington.
“There’s a lot of interest in the status of golden eagles right now, both at the state level, and regionally, if not nationally,” said Gerry Hayes, wildlife diversity biologist who is coordinating the survey for the state Department of Fish and Wildlife.
About 60 breeding pairs of golden eagles are estimated to live year-round in Washington. And while it’s too soon to say whether those numbers are declining, two potential concerns are emerging.
First, preliminary results after the second year of the two-year survey show that about half of the nesting sites used year after year were occupied.
And second, more than half of 18 golden eagles that were captured and tested in a separate study for several years had elevated levels of lead, a toxic substance commonly used in ammunition.
Although the elevated lead levels in Washington’s golden eagles has not been tied to ammunition, the Humane Society of the United States this month petitioned the U.S. Department of the Interior to require the use of nonlead ammunition on more than 160 million acres of federal lands managed by the National Park Service and U.S. Fish and Wildlife Service. The group estimates that 10 million to 20 million birds and other animals die each year from lead poisoning, either by eating lead shot or lead fragments from bullets, or by feeding on lead-contaminated prey.
The golden eagle is a state candidate species in Washington, and is reviewed periodically to determine if its status should be changed to endangered, threatened or sensitive.
Hayes said the last comprehensive survey was 10 years ago. These surveys include sending biologists into the field several times during the spring and early summer to look at a large portion of the eagles’ nesting territories. They determine whether the nests are occupied, and if they are, finding out whether there are eggs, and chicks, and eventually whether those chicks leave the nest.
Hayes said the 50 percent overall occupancy of nests found so far is considered low, but that’s not necessarily an indication that the number of resident golden eagles in Washington is declining.
“We’re not really sure. That’s part of our assessment,” he said. “Maybe there are some things in how we’re doing the survey that might contribute to that lower level.”
If they are declining in numbers, lead poisoning is just one of several possible reasons, said Jim Watson, a raptor research scientist for the state Department of Fish and Wildlife who is studying elevated lead levels in golden eagles.
Watson said his study documented significantly elevated levels of lead in 61 percent of golden eagles sampled, but he has not yet found the source of lead contamination.
Studies in other states, however, have identified ammunition as a potential source of the contamination. His study will continue to explore which animals the eagles with high levels of lead preyed on, and try to determine how that prey was contaminated.
Banning lead-based ammunition -- at least on some federal lands -- is a goal that The Humane Society of the United States believes is achievable and not overly burdensome, said Dan Paul, director of the group’s Washington office.