Traveling on 99 just north of the border, Tricia and I saw a huge congregation of eagles just North of the Ladner Trunk road and easy of the highway. There were no less than 300 birds congregated throughout the woodlot. Does anyone know what the attraction is?
Veronica and Whatcom birders,
The attraction for Bald Eagles around Boundary Bay is ducks-- of which about 50,000 winter at Boundary Bay each year.
As most of us know, the preferred food of Bald Eagles is fish-- especially dead fish (which are easier to catch!) Salmon runs attract hundreds of Bald Eagles, or in some cases even thousands, to places like the Squamish River and lower Harrison River in BC, the Chilkat River in Alaska, and to a lesser extent, the Nooksack and Skagit Rivers in Washington. However, this food source is available for only a short time each year (mostly November through January).
After the salmon carcasses have all disappeared or been washed away by the high waters of winter storms, Bald Eagles in the Vancouver area concentrate in the Fraser Delta and especially near Boundary Bay. The peak numbers of eagles around Boundary Bay are from February through April. With 50,000 ducks in the area, there are a small number dying of various causes every day, as well as some which may be sick or weak and are easy for eagles to catch. Eagles in fact are quite capable predators, and not infrequently will catch and kill perfectly healthy ducks, gulls, or other large birds. However, with ducks as with fish, they prefer to feed on those that are already dead, injured, or sick, which is why there are so many eagles around Boundary Bay.
The number of eagles around Boundary Bay never fails to impress birders visiting from other parts of North America. However, it hasn’t always been so; in the 1960s, when eagle numbers were very low because of DDT poisoning, you would have had to work hard to find 20 or 30 eagles in the area. Fortunately, their numbers now seem to have rebounded to equal the pre-DDT numbers.
Wayne C. Weber
Chirp,
I would add that there is a landfill dump in Delta that is an attraction to Bald Eagles, especially young birds.
See this excerpt from a newspaper article in 2011.
Starving bald eagles, desperate to find food after a failed southern B.C. chum salmon run, are gathering in record numbers at the Vancouver landfill, says eagle expert David Hancock.
The wildlife biologist earlier this month counted nearly 1,400 eagles -triple the usual number at this time of year -at one time at the landfill, located in Delta.
"The chum salmon didn't come in and with no other major concentration of food they are gathering everywhere and many are starving," said Hancock.
He said a world record was set in mid-December when 7,200 eagles were spotted on the Chehalis River, which flows into the Harrison River. Hancock said that 10 days after the raptors finished feeding off salmon carcasses, only 345 eagles were spotted on the river.
"They had to go somewhere. They're incredibly mobile -can move 500 to 1,000 miles a day. They're forced to go where they can find food."
He said young eagles are essentially scavengers because it takes them two to three years to learn how to hunt. Many rely on dead salmon and swarming masses of herring.
"To catch a specific fish or duck, that comes later, and is a developed skill."
cheers,
Doug Brown
A naturalist once corrected me when I said eagles were scavengers, he said “No, they are just birds of opportunity”. JH
