Eagle count finds 855, fraction of total gathering
How many bald eagles are in Haines this week?
Counts conducted around the Chilkat Valley on Nov. 3 found 855, but that’s only a fraction of the total.
Since 2009, surveys of eagles have been done by Haines High School science students, using spotting scopes at 10 locations along the local road system. The counts don’t include birds on the west side of the Chilkat River and other areas difficult to reach, said Pam Randles, who leads the class.
After a recent dip in the count by students, Randles traveled to Herman Creek, a salmon-spawning site inside the preserve, and found scores of birds. “That’s where the eagles were. The fish there were pulling birds away from our count. That can happen anytime, with eagles moving to different areas of salmon returns.”
Randles said this year’s count is “in the ballpark” for numbers since 2009, although it’s the first year in four that her count hasn’t topped 1,000 before the festival. Randles’ class counted 1,264 birds here on Oct. 23, 2011.
The highest counts of eagles in the Chilkat Valley were made by the U.S. Fish and Wildlife Service, which used airplanes between 1986 and 2000 to spot the birds from above. The agency flew in mid-November, when the gathered population tends to peak, and counted 3,444 eagles in 2000.
But on the same week in 1986, the agency counted only 600.
The number of eagles here during the annual fall migration changes from year to year depending on conditions, including weather and the relative abundance of salmon. Colder temperatures freeze river channels, keeping eagles from carcasses and causing them to leave the valley in search of food elsewhere.
What’s more, the birds that migrate here move from one valley location to another during the course of the fall, as salmon return to various locations, then dissipate.
Randles and the Haines School’s Citizen Science class have been making ground counts of eagles since 2009, starting in September when the birds start arriving here from other places.
On Oct. 6 this year, there were 775 eagles in the valley, with 229 – the greatest concentration – on the lower Chilkoot River, where the waning pink salmon run provided an easy raptor meal. A week later, the greatest concentration (300-plus of 800 total) was on the upper Klehini River, where chum salmon numbers were peaking.
By Nov. 3, the top concentration was centered on the eagle preserve’s Council Grounds, a riverside stretch between 19 Mile and 21 Mile Haines Highway. Randles and students found 725 of their 855 total count in the trees, sandbars and riverbanks known as the “critical habitat area” where the confluence of three rivers and certain geological features keep channels from freezing.
The eagle festival’s timing capitalizes on this concentration of birds, which makes for a spectacle regardless of how many eagles show up in total.
Randles said relative numbers are more important than actual ones, in gauging what’s going on with the ecosystem.
“We take a sample. If our sample shows a drastic drop, we’d have something to worry about. Eagles are at the top of the food chain. If their numbers drop, there are problems further down the food chain. As long as the trends are staying the same year after year, the system is not changing,” she said.
State parks ranger Bill Zack conducted ground counts of eagles between 1986 and 2000. His highest count, 2,984, came on Dec. 1.
Toward bringing some uniformity to count numbers, Randles said a next step for researchers would be to learn the methodology Zack used in making his counts, as well as how aerial counts were made. Zack’s numbers don’t correlate directly to aerial counts made on the same years, she said.