KEEPING AN EYE ON EAGLES
Fewer bald eagles may be descending upon the Grande Ronde Valley this winter.
Don't sound the environmental alarm, though.
The apparent drop likely reflects the mild winter Northeast Oregon is
A count on a upper Grande Ronde River route by Forest Service biologists Arlene Blumton and Mark Penninger found only four bald eagles this month. The count was part of the annual national Mid-Winter Bald Eagle Survey conducted by the Forest and Range Ecosystem Science Center of the U.S. Geological Survey.
Since 1989, up to 18 bald eagles have been spotted annually along the upper Grande Ronde River route during the annual winter survey, Blumton said. The numbers sometimes fluctuate widely. For example, in 1997 only four bald eagles were spotted, but the next year 18 were recorded.
Bald eagles are less likely to come into valleys during mild winters because there is less to feed on, said Frank Isaacs of Philomath, a senior faculty research assistant at Oregon State University. Isaacs coordinates the Oregon portion of the Mid-Winter Bald Eagle Survey.
Isaacs said that in harsh winters waterfowl, which eagles feed on, are more likely to concentrate in areas such as Hot Lake and the city of La Grande's sewage lagoons. Bald eagles follow them into the Grande Ronde Valley.
In addition, more deer and elk come into the valley during hard winters and a number die from the elements or are hit by vehicles, giving eagles more to feed on.
A Mid-Winter Bald Eagle Survey count was also conducted in a portion of Wallowa County by the husband and wife team of Frank and Sue Conley of Joseph. The Conleys spotted 20 bald eagles, 13 of which were adults.
"It was an average count,'' said Frank Conley, who has conducted the annual count for the survey since the early 1990s.
The Conleys usually spot between 12 and 35 bald eagles during their survey. Their count route runs from Wallowa Lake along the Wallowa River to Minam.
Frank Conley believes the mild winter weather affected what he saw.
"Eagles have been scattered. They have not concentrated because of the drier, mild winter weather,'' Conley said.
One of the challenges counters face is distinguishing golden eagles from immature bald eagles. The birds look similar at first glance but, Conley said, there are some key differences. For example, a bald eagle has a larger head and its wings are not quite as wide
In addition bald eagles don't move in the same manner.
"They flap their wings differently,'' Conley said.
The Joseph birder is fascinated by bald eagles in part because of their keen environmental awareness. Temperature is an example.
"They have an acute sense of temperature. They roost where it is warmest,'' Conley said.
He noted when an inversion produces warmer temperatures at high elevations, eagles quickly respond.
"Eagles know this and will fly up 2,000 to 3,000 feet to get to higher temperatures,'' Conley said.
Eagles may roost in trees at 7,000 to 8,000 feet one night, Conley said, and the next night they will return to Wallowa Lake after the inversion ends.
It is easy for eagles to do this at Wallowa Lake, which has an elevation of about 4,500 feet. Conley explained that an eagle can fly from Wallowa Lake to a roosting site 2,000 to 3,000 feet higher in about 90 seconds.
Bald eagles come to Northeast Oregon in the winter from interior Canada, Arizona, Yellowstone National Park and Idaho, Isaacs said.
"They come from all directions looking for food,'' he said.
Wallowa, Union and Baker counties have nine nesting pairs of bald eagles. Wallowa County has four, Union County has two and Baker County has three.
Oregon had a total of 441 nesting pairs in 2004. About 95 percent are in the western half of the state, Isaacs said. The majority are at Klamath Lake and near the lower Columbia River.
Oregon had only 82 known nesting pairs in 1979 but since then the number has steadily climbed.
"It has been increasing about 6 percent a year,'' Isaacs said.
The increase is a credit to two major factors:
Continued protection under the Endangered Species Act.
The banning of the pesticide DDT in the United States. DDT, which is particularly harmful to birds, was banned in the U.S. in 1972.
Watching Oregon's bald eagle numbers increase has been heartening for Isaacs, who has coordinated the Oregon portion of the Mid-Winter Bald Eagle Survey since 1988. Isaacs said that he never tires of them.
"I still love watching them.
Searching for a nest is like a treasure hunt.''