Thousands of bald eagles descend on B.C.’s Fraser Valley for winter migration

Every winter, tens of thousands of bald eagles descend on the lower Fraser Valley — a migration biologists say forms the world’s largest congregation of eagles.

The spectacle is well underway along the Harrison River where returning salmon are drawing in eagles from as far as Alaska and Yukon.

From November through February, the banks 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 these are northern breeders who come down here to escape the northern winters,” said Hancock, the founder of Hancock Wildlife Foundation, which specializes in raptor conservation efforts. 

“When lakes and rivers freeze in Yukon, Alaska and northern B.C., their fish go under the ice. So they come south.” 

WATCH | World’s largest bald eagle congregation begins:

World’s largest bald eagle congregation descends on Harrison Mills

Thousands of eagles have flocked to the Fraser Valley. The annual migration sees the birds gather in the Harrison Mills area to feast on salmon. Our Baneet Braich went to witness the seasonal spectacle.

He estimates 35,000 to 50,000 birds move through the region each winter.

With the salmon run now peaking, experts say conditions are ideal.

“We’re right in the middle of the big salmon run and, of course, the eagles are back,” said ornithologist Rob Butler, honorary director of the Pacific Wildlife Foundation. “If it’s a good salmon run, then the eagles will stay for a long time on those rivers.”

During months when the river doesn’t have enough salmon, Butler says, the birds head to the coast, along the shorelines of the Salish Sea and hunt for ducks the rest of the winter.

“So the ducks, of course, hope that there’s going to be a big salmon run for them,” he added.

The Harrison River is one of Canada’s most productive salmon waterways, a key reason the migration concentrates here rather than elsewhere in the province, Butler said.

‘A remarkable comeback’

Both experts say the annual congregation is also evidence of how far bald eagles have rebounded since populations dwindled in the mid-20th century.

When Hancock first conducted surveys in the 1950s and 60s, he counted just three breeding pairs across the Fraser Valley. Today, he says there are about 700 pairs, a “remarkable comeback.”

The collapse was tied to widespread use of the pesticide DDT, which thinned eggshells and devastated populations across North America, according to Butler.

“Then the numbers started to come back because people stopped hunting them and stopped poisoning them.”

Eagles keep ecosystems and tourism thriving

Eagles also help maintain balance in the Harrison River ecosystem by scavenging salmon carcasses and naturally limiting fish and duck populations. 

“They’re kind of the conductors of the grand choreography that we see around here,” Butler said.

He says their presence also draws crowds with the Harrison Eagle Festival having become a staple for birdwatchers and photographers.

“It was incredible,” said visitor Dan Woodstra, who hopped on a jet boat as part of the eagle viewing tour along the Harrison River.

“I don’t think I’ve seen eagles like that anywhere else. Magical, really, to see such a creature in its element doing its thing.”

Experts say the eagles will remain until February before heading back north.