Record Number of Bald Eagles at Chehalis.
Thursday, December 02 2010 @ 06:13 PM EST
Contributed by: Pat B
Hancock here -- Nov. 27, 2010
Cold weather and few salmon up the North and along the central BC coast has driven record numbers of eagles South to the Chehalis - Harrison River Complex.
With the Harrison River so low in water we had to put the Fraser River Safari Jet Boat into the water at Kilby on the Harrison. The Fraser River itself was so low that for half a kilometer the deepest channel was only 1 1/2 inches of water - not even adequate for this incredible jet craft. The day started cool and foggy. We could not even see the nearby pylons but we knew from the drive over the Harrison River Bridge minutes earlier that it was sunny upstream .
We cautiously went off up the deep channel of the Harrison, passing what I suspected were 1000 plus eagle in Harrison Bay to our West. This was probably about right as the Bay was clear on the return and many trumpeter swan dotted the shoreline and easily 500 eagles were still on the flats and in the surrounding trees. Hundreds of additional eagles dotted the neighboring hills.
North of the bridge the fog disappeared and there before us was the largest concentration of bald eagles likely ever witnessed by humans in the last few centuries. The Chehalis Flats, the alluvial outflow from millennia of floods carrying gravel down the Chehalis River, was totally dotted with feeding and resting eagles. Some of the prominent larger trees, favored perching sites, contained over 40 birds per tree -- the eagles looked likes bunches of grapes ready for the picking.
This year for the first time, I became aware that the gravel outflow extended across the Harrison River and up against the eastern hillside, yielding a further 100 to 500 meter wide water inundated flats that extended over a kilometer. These shallows were literally alive with splashes of spawning salmon, digging their nesting redds, the frantic dives of gulls trying to get free floating eggs, and eagles coming and going everywhere.
This was a new spawning area to me. And I estimated that over 3000 to 3500 bald eagles were on the gravel feasting or arguing, or in the surrounding trees digesting dinner and waiting for the next feast.
The regular southward outflow from the Chehalis and its surroundings, the prime area we usually cover for the total count, had another 1500 eagles. Now we are at 4500 to 5000 eagles just in the Chehalis Flats. On top of this were another 500 - 1000 eagles from south of the Harrison Bridge, on the Harrison Bay flats and surrounding trees.
What a wondrous biological site: 5000 to 6000 of North Americas greatest predator and all in such a small concentrated area. This collection of eagles is probably the largest gathering of predators in the world. But why this record?
Actually the answer is not really good. Normally the entire coast of BC at this time of year supports about 50 to 100,000 bald eagles -- from the Alaskan border South. Generally each river tributary supports a few salmon runs and the spawned out carcasses feed the eagles during the winter. At least the fish are available until the local winter freeze up takes place. That freeze up forces the eagles Southward. A nice coincidence is that as we progress Southward down the continent, the salmon runs spawn later, enabling eagles to feast on their favorite food for over 6 months of the year.
This year much of the BC coast simply did not have a good return to the rivers of the spawning salmon. Something happened to these fish during their ocean migration. One exception was the much publicized Adams River sockeye run which was the largest in known history. But one river does not feed all our eagles. It looks like we are going to have a record mortality of eagles this winter.
On the cheerier side, we here can see the world's largest gathering of eagles along the Harrison - Chehalis Rivers for a few more weeks. The timing is yet undetermined. Two factors will determine how many and how long this massive population of eagles remains compacted on this small area. First, how long before the carcasses are eaten. Surely this group of eagles must be consuming 5000 pounds of salmon daily. Then there are gulls, crows and waterfowl feasting. Second, and related to the first, is how long before we get heavy rain and the floods wash the salmon carcasses into the deep water and downstream and into the waiting gullets of the several thousands of sturgeon waiting to suck them up. And sturgeon are great at waiting -- they have been in the worlds oceans for over 300 million years -- attesting to the success of their patience.
When the spawned out salmon carcasses are all gone the eagles will disperse.. Some will search other rivers, others will pursue finding road kills and man's garbage but most will disperse to the outer coast to search for washed up carcasses or take to robbing other predators and other breeding eagles who are already on their nesting territories. The next big coastal bonanza will be the herring and oolachin spawn in March and April -- a long time between meals.
If you get a chance to come to the Harrison - Chehalis Rivers this season, do it soon. The bell is ringing. Jo-anne and Rob, who own Fraser River Safari Tours have asked me again to lead another river tour this Sunday -- Dec. 5 -- 1100 at Kilby.
Call Jo 604 302-9579 for a reservation on this cosponsored event: FRFT and the HWF.
From Kilby the tour is both shorter and cheaper -- but something you will remember for ever.