Along the Harrison River in B.C.B次元官网网址檚 Fraser Valley, thousands of eagles are gathering to gorge on salmon that have reached the spawning ground.

David Hancock, a biologist who has been studying eagles for about 65 years, says the worldB次元官网网址檚 largest congregation of bald eagles happens on the river in the little community of Harrison Mills, about 100 kilometres east of Vancouver.

B次元官网网址淟ast Saturday morning I did a survey off the river and there were just over 7,000 eagles in the area,B次元官网网址� he said in a recent interview. B次元官网网址淭his is the most weB次元官网网址檝e ever had in November.B次元官网网址�

About 35,000 eagles gather in the lower Fraser Valley between November and February, and some days about 2,000 to 3,000 raptors move in, Hancock said.

B次元官网网址淚tB次元官网网址檚 the biggest single accumulating area because the Harrison River is the single most productive river,B次元官网网址� said Hancock. B次元官网网址淚tB次元官网网址檚 the only river in Canada called a salmon stronghold river.B次元官网网址�

The Harrison River is a tributary of the Fraser River and runs about 18 kilometres in length.

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As rivers in Yukon, Alaska and northern British Columbia ice up food supplies freeze too, which forces the eagles south.

B次元官网网址淥ur salmon are just beginning to die so the table is set down here,B次元官网网址� said Hancock.

But there are other factors that contribute to the number of eagles that descend on the area.

B次元官网网址淪ometimes the north doesnB次元官网网址檛 freeze up and the eagles donB次元官网网址檛 need to come,B次元官网网址� he added. B次元官网网址淪ome years we donB次元官网网址檛 get as many salmon so the table isnB次元官网网址檛 as generously set.B次元官网网址�

The eagles remain in the area until February although a few thousand may fly further south into Washington, Oregon and California as winter deepens.

Hancock said this year, the Harrison River does not have enough salmon.

B次元官网网址淭his was not a good year for spawning,B次元官网网址� he said.

When the salmon carcasses are gone, he said the eagles feed on spawned herring and oolachin, a smelt.

In about four years the area might not see as many eagles because overharvesting means there wonB次元官网网址檛 be as many salmon carcasses for them to feed on, he said.

Hancock said in the last two decades researchers have learned about the connection between the huge trees in forests in the area and spawned salmon. The carcasses of spawned salmon give nutrition to the soil, he added, which helps trees grow.

B次元官网网址淲ithout those salmon there are no big forests,B次元官网网址� Hancock said. B次元官网网址淭hatB次元官网网址檚 the lesson we learned in the last 20 years of ecology.B次元官网网址�

The Canadian Press

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