Hancock here: A backgrounder on our Bald Eagles of the Fraser Valley
Vancouver has Two Distinct Bald Eagle Populations:
– November tells the tale –
Southern British Columbia, particularly our lower Fraser River Valley, has two very distinct populations of bald eagles. First, we have our very successful breeders who have 19 nests in the City of Vancouver, more than 80 nests in the City of Delta, 43 in Surrey , and I have identified over 480 nesting territories in the valley but expect there are well over 550 pairs nesting between Vancouver and Hope. For those of you living along the shoreline hosting a few big trees, visiting a city park or golf course with their wonderful cottonwoods and remnant conifers, or who drive the suburban farmland in Greater Vancouver and stare in amazement at eagle nests surrounded by houses and industry, you have seen our great natural treasure — remember this is all part of what makes Super Natural British Columbia – SUPER.
This local nesting phenomena is a wonderful increase from only 3 nesting pairs in the early 1960’s (my thesis years) when the local eagles had been defined as ‘vermin’ and regularly shot – particularly by Americans who got $2.00 for each pair of eagle legs. Eagles only became icons of good when Rachael Carson led the world in an educational campaign against pesticides and changed our attitude towards predators all at the same time. It took the eagles 20 years to believe we could be trusted neighbors.
Then we have the most observable population of eagles, our winter migrants: sometimes 10,000 can be seen on the Harrison River and after those salmon carcasses get washed away you can see them along Boundary Bay and at the Landfill or distributed throughout the Valley scrounging road kills and farm offal. Our Annual Fraser River Bald Eagle Festival on the Harrison is most people’s introduction to the world’s largest gathering of eagles. (www.FVBEF.org for Festival details) The Festival is coming up November 16 and 17 this year. It offers wonderful viewing sites free.
These northern migrants start to arrive here just after our breeders return from their northern migration but these northern residents are simply here because their northern breeding territories across northern BC, Alberta, Alaska and the taiga of northern Canada freezes up all winter totally depriving them of food. These northern eagles are basically scavengers, totally dependent upon our ice-free rivers to deliver them spawning salmon carcasses from November thru February. They do almost no hunting — this is their season to be lazy. Their northern rivers spawn their salmon as early as June and thru August but by November their rivers freeze up, covering up with ice any remaining carcasses. They depend upon our ice-free rivers and more recently on garbage dumps.
They forage our ice-free rivers until the carcasses are eaten out or washed out by heavy rains. Usually, by February through March these migrants start their northern return along the coastal flyway largely dependent upon the spawning herring but never missing a village garbage dump. Others fly up the Fraser River flyway timing their trip to the calving period of our huge interior cattle industry delivering up afterbirth and an occasional stillborn calf. By April we just have our breeders and a few sub-adults
But you asked: How do our breeders accomplish a northern migration and return in only two months? Good question. First, we know that some of our southern breeders go as far as the Alaskan SE coast and as far eastward as Great Slave Lake – because eagles carrying satellite trackers showed the way. Others may migrate fewer miles but to find the early northern spawning salmon you have to go north to about Bella Coola. But then you ask how do they actually fly that far — perhaps three to five thousand km return?
Interestingly eagles are not great flyers. They are lightweights in reality, preferring to soar and glide downhill. But that is why they have huge nearly 2 m long broad wings. As most local residents know we have a fairly steady air mass moving eastward in from the Pacific. That air mass hits a mountain chain, almost unbroken from California to Alaska, that forces the air up nearly two km. That rising air literally lifts the eagles up and they simply circle, gain more height, and then glide downhill. Eagles regularly go to 2km high and one eagle, not here thank you, hit an aircraft at over 8 km up. And this elevator works in both directions. Our breeders and offspring get a free downhill glide north to the early salmon runs at the end of their breeding season in July and then again back south to our ice-free rivers in fall. Our recent tracking’s show they readily cover 200 km a day so it is a wonderful downhill week to Alaska and another back.
David Hancock: (Cell: 604 761-1025 – for Press Interviews )
Director, Hancock Wildlife Foundation: (www.hancockwidlife.org for live-tracking eagles)
Fraser Valley Bald Eagle Festival: (www.fvbef.org for Festival events Nov.16-17)