Historic Review of North American Bald Eagle Gatherings and Numbers
Saturday, September 15 2012 @ 01:54 AM EDT
Contributed by: davidh
Background of Counts: In most northwest geographical areas the largest gatherings of bald eagles are associated with spawning salmon, oolachin and herring spawns and a few tidal bores, where fish are sometimes so disturbed by the fast turbulent waters that several thousand eagles occasionally gather to feast on the unorganized fish. Over the years, due to changing river conditions and also due to public awareness, different areas can legitimately claim the seasonal, local or regional title for having the most eagles.
The count methods are quite simple: The supervisor selects several geographic locals in the defined area and attempts to count, one or two at a time, all the eagles in each area. These numbers are written down every few minutes or section of the panorama being counted. The figures are simply totalled and that constitutes a count on that date or time. While it is desirable to keep the same people doing the counts and from the same locations this does change as an area becomes better known and the locations of the fishing or loafing eagles is better known. A bad weather day can simply obliterate eagles at almost any distance. Many eagles may not be counted because they are hidden out of sight below a stream bank or sitting on the wrong side of a tree. The challenge of the count is a consistency of right timing and methodology to show some comparative measure of daily, seasonal or annual counts to illustrate eagle movements or show trends in eagle numbers.
I have undertaken counts where over 1500 eagles were present on the Chehalis Flats and then 10 minutes later only a hundred or so could be seen flying or perched in adjacent trees. A canoeist paddled out onto the flats and drove off the entire feeding flock. If the day is good for soaring then the eagles’ flight can be extensive and endured without much expenditure of energy. Thousands of eagles can move many miles by soaring, gliding and drifting in a few minutes -- a major reason why and how eagles are so adaptable. USF&WS Satellite tracking data has recently shown eagles can move over 500 miles in three days. I suspect time will show that eagles can move greater distances than that in a single day.
The Three major locations for seeing Bald Eagles in North America:
Chilkat - Haines Bald Eagle Festival: The Alaska - Yukon Chilkat River system, beside the town of Haines Alaska was and is a great salmon spawning and eagle wintering area. It became famous through a National Geographic article and our annual Haines Chilkat Bald Eagle Festivals. The numbers of wintering eagles has recently declined from highs about 3000 eagles down to just under one thousand during the November Bald Eagle Festival counts. I am a Trustee of the American Bald Eagle Foundation and have attended the annual eagle gathering for many years, actually undertaking many of the wintering eagle counts. Some of the counts have focused on the entire 20 miles of Chilkat River along the Bald Eagle Preserve, others on the 5 miles where most of the eagles congregate. This is Alaska's largest bald eagle gathering. See the American Bald Eagle Foundation site.
Brackendale - Squamish Bald Eagle Festival: The Squamish River and its several tributaries, just north of Vancouver, BC at Brackendale, reached its peak number of wintering eagles in 1994 of 3769 eagles along the 20 miles of its river system. This one time world record has long since been shattered by the eagles at Harrison Mills, BC. This coming January will mark the 27th annual Brackendale - Squamish Bald Eagle Festival, making this the longest running bald eagle festival in the world. I have been honored to be part of the counts and frequently lecture on the eagles at the Brackendale Art Gallery evening events. Due to the over-harvest of salmon and some local environmental poisoning catastrophes a few years ago the counts have declined substantially in recent years. This count is one of the most organized and takes about 60 counters to cover the 20 miles of river. See the Brackendale Bald Eagle Festival
Fraser Valley Bald Eagle Festival - at Harrison Mills BC: On December 18, 2010 a count of 7362 bald eagles in a two kilometer distance along the Harrison River, with an estimate of over 10,000 eagles in the 10 square kilometer wintering area, was a world record for any concentration of large predator. It certainly established the Harrison Mills, at the confluence of the Harrison - Chehalis Rivers, as home of the largest concentration of bald eagles ever witnessed anywhere. While usually 1000 to 1500 eagles are viewed during the 3rd weekend of November, the annual date of the Fraser Valley Bald Eagle Festival, the peak numbers of eagles are usually mid December when the northern rivers are frozen or the salmon carcasses are eaten out.
The count area for the Official Fraser Valley Bald Eagle count on the 3rd weekend of November incorporates 6 count locations from the western shore of Harrison Bay to the Tapadera Camp Grounds. The biggest counts of eagles are now found along the Harrison at the confluence of the Chehalis River -- a mere few hundred meters east of the Flats and only visible from a boat. These Chehalis Flats are where our Tower cams are located. The eagle numbers build through November, peak in December and wane through January and February. The milder Harrison Mills area, thanks to the purity of the Harrison - Chehalis watershed purity, remains the last great salmon buffet along the coast and has in recent years become the Bald Eagle Capital of the World. I am also a Director on the FVBEF committee and undertake these counts. See the Fraser Valley Bald Eagle Festival site.
Bald Eagle biologist.
(Review as of August 2012)