ANCHORAGE, Alaska -- Young golden eagles migrating for the first time don't return to their birthplace in Denali National Park and Preserve in central Alaska, but summer instead in oil-rich areas in the Arctic.
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A golden eagle makes a meal of a tundra swan at an Oregon wildlife refuge. The eagles winter in a range from southern Canada to northern Mexico. (Associated Press) |
The surprise finding was part of a four-year study to track for the first time the migration routes of Alaska's golden eagles. The finding again raises concerns about oil development on Alaska's North Slope and in the National Petroleum Reserve-Alaska, and about the increased pressure to open the Arctic National Wildlife Refuge to drilling.
"We are really afraid we will lose what's special about the western Arctic before we even understand what is there," said Sara Chapell, spokeswoman for the Sierra Club in Alaska.
After wintering in the south, the young eagles headed north, bypassing the 6 million-acre national park and flying another 450 to 600 miles to summer on the Arctic coastal plain. A few ended up near the Alaska Range in the Interior or on the Kenai Peninsula south of Anchorage, but most flew north.
"They were all across the North Slope," said Carol McIntyre, a wildlife biologist at Denali who has been studying eagles since 1987. The park is home to at least 100 breeding pairs of golden eagles.
Golden eagles weigh 8 to 12 pounds and have gold and buff-colored feathers on the crown and nape of the neck. They are found in the northern part of the Northern Hemisphere and have been protected in the United States since 1963.
The $250,000 study was funded by the National Park Service and the U.S. Geological Survey.
McIntyre said in 1997 and 1999 tiny Teflon backpacks containing small satellite transmitters costing $2,500 each were attached to the backs of 45 golden eagles just before their first migration.
Weights and measurements were taken on the young birds before they left their nests in late July to mid-August. The eagles didn't depart Denali until late September and early October, a time when the parents continue to feed and protect them and the young practice their flying and hunting skills.
McIntyre and Michael Collopy, a former USGS scientist, tracked the birds as they flew south from central Alaska, wintering anywhere from southern Canada to northern Mexico.
Scientists don't know why some birds stop in Canada and others fly all the way to Mexico. Some could be looking for food. Weather could be a factor. Maybe they simply "feel the need to keep going," said Collopy, now department chairman of Environmental and Resource Sciences at the University of Nevada in Reno.
Twelve of the 45 eagles survived their first year, often migrating more than 5,000 miles. Most of those that died starved, but some also were hit by cars, electrocuted by power lines, accidentally poisoned and shot, McIntyre said. Most of them died in Canada, where necropsies were performed and the tiny transmitters sent back to McIntyre for reuse.
Not all the young eagles made the trip the same way. Some flew just a few dozen miles a day while others flew nearly 200 miles a day.
"Some really just bee-lined right to where they were going and some meandered along the way," McIntyre said.
He said the young eagles probably bypass Denali because the park's adult eagles would drive them off. Their Arctic destination holds a wealth of immature waterfowl, Arctic ground squirrels and caribou calves that make easy prey for the inexperienced hunters.
Drilling for oil in the Alaska refuge is a key part of the Bush administration energy plan, which likely has a better chance of passing next session with Republicans controlling the House and Senate.
McIntyre worries that golden eagles, which are much less tolerant of human beings than bald eagles, won't be able to adapt to increased development in the wilderness, whether it's on Alaska's North Slope or wintering grounds in Canada, northeastern Washington, Idaho, Montana, North and South Dakota, Colorado, Wyoming, Kansas and New Mexico.
"We are kind of choking them out of where they live," she said.
