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Each winter, tens of thousands of bald eagles descend on the lower Fraser Valley—a migratory group that biologists say forms the world's largest aggregation of eagles.
The spectacle is in full swing along the Harrison River, where returning salmon attract eagles from Alaska and the Yukon.
From November to February, the shores around Harrison Mills become a seasonal feeding ground for the birds as northern lakes and rivers freeze, says longtime bald eagle researcher David Hancock.
“Most of them are breeders from the north who come here to escape northern winters,” said Hancock, founder of the Hancock Wildlife Foundation, which specializes in raptor conservation efforts.
“When the lakes and rivers in the Yukon, Alaska and northern British Columbia freeze, their fish go under the ice. So they head south.”
Thousands of eagles flocked to the Fraser Valley. During their annual migration, the birds gather in the Harrison Mills area to feast on salmon. Our Banit Breich went to see this seasonal spectacle.
He estimates between 35,000 and 50,000 birds move through the region each winter.
With salmon runs now at their peak, experts say conditions are ideal.
“We're in the midst of a big salmon run, and of course the eagles are back,” said ornithologist Rob Butler, director emeritus of the Pacific Wildlife Trust. “If there is a good salmon run, the eagles will stay on those rivers for a long time.”
During the months when there aren't enough salmon in the river, the birds head to the Salish Sea coast and hunt ducks for the rest of the winter, Butler said.
“So the ducks, of course, are hoping for a big salmon run,” he added.
The Harrison River is one of the most productive salmon streams in Canada, and that's a big reason migration is concentrated here rather than elsewhere in the province, Butler said.
“Wonderful comeback”
Both experts say the annual gathering is also a testament to how much the bald eagle population has recovered since its population collapsed in the mid-20th century.
When Hancock first surveyed in the 1950s and '60s, he counted just three breeding pairs in the Fraser Valley. Today, he says, there are about 700 pairs and it's a “wonderful comeback.”
According to Butler, the collapse was linked to the widespread use of the pesticide DDT, which thinned eggshells and devastated populations throughout North America.
“Then the numbers started to rebound because people stopped hunting them and stopped poisoning them.”
Eagles support thriving ecosystems and tourism
Eagles also help maintain balance in the Harrison River ecosystem by eating salmon carcasses and naturally limiting fish and duck populations.
“They are sort of the conductors of the great choreography that we see here,” Butler said.
He says their presence also draws crowds, as the Harrison Eagle Festival has become a favorite destination for bird watchers and photographers.
“It was incredible,” said visitor Dan Woudstra, who boarded a jet boat on an eagle watching tour along the Harrison River.
“I don't think I've seen eagles like this anywhere else. It's truly magical to see a creature like this in its element, doing its thing.”
Experts say the eagles will remain there until February and then return north.
