Wednesday, February 3, 2010

Loitering, mostly.

In winter there are frequently Bald Eagles perched in the large cottonwoods next to the Vancouver Landfill. You can see them as you pass south of the dump along Highway 99 in Delta. I wondered what exactly drew them there. Was it the thousands of gulls that are drawn to the trash, or is it the trash itself?

It turns out people have studied this:

FORAGING ECOLOGY OF BALD EAGLES AT AN URBAN LANDFILL

It was determined that "Eagles fed primarily on human refuse (95%, n = 628), but food items taken from the landfill accounted for only 10 ± 3% of their daily energy needs. Subadults foraged at the landfill more often than adults, and most “refuse specialists” appeared to be subadults. Eagle time budgets consisted of mostly resting (91%), the remainder largely spent drinking (2.6%), scavenging (2.3%), and pirating (1.8%)."

So mostly, most are just hanging around, only occasionally snaring the odd tasty pork chop or sausage link. They may appreciate the relative warmth (of decomposition), the shelter of nearby conifers, and, who knows, the rumbling of big trucks? They are more likely to pirate a gull than eat one.

I now wonder if the majority look down their beaks at the "refuse specialists."

Reference:

KYLE H. ELLIOTT, JASON DUFFE, SANDI L. LEE, PIERRE MINEAU, JOHN E. ELLIOTT. 2006. FORAGING ECOLOGY OF BALD EAGLES AT AN URBAN LANDFILL. The Wilson Journal of Ornithology 118 (3), 380-390.

6 comments:

Sheila said...

Interesting, kinda gross, but interesting.

KaHolly said...

Certainly makes one wonder. As always, an interesting post.

Karen said...

Maybe the crow mobbing behavior is because the eagles are stealing their garbage?! Yuck. We are such a disgusting species. Who can blame the animals for lazing around and eating our leavings when we make them so prolific and available?

tully monster said...

My national bird hangs around dumps drinking, scavenging, and pirating. Not surprised in the least.

Kyna said...

What a crazy picture! I've seen tons of gulls, but never an eagle (let alone a gang of eagles) at the dump...O_O

Moonstone Gardens said...

I agree with tully monster. They are just like our politicians.
Cindee