The bufflehead’s size is the result of an unlikely relationship in the northern forest.
Full disclosure: I am writing a fascinating article about buffleheads not just because they are fascinating. I really, really want to share pictures of these adorable ducks. I can’t get enough of them. Where I live, buffleheads are one of the birds of winter. They bob and dive on the bay all day long, and their buoyancy is contagious: it lifts my spirits too.
Bufflehead’s size: handy and adorable
It was in researching these remarkable little creatures that I discovered that the qualities that make them adorable—that tiny size and huge head—are adaptations to give them an edge in nesting season.
It’s not easy being tiny when you’re a duck. Predators are many (in this bird’s case, great horned owls, bald eagles, peregrine falcons, and other fearsome raptors) and competition is keen. Buffleheads are closely related to goldeneyes and mergansers, and these much-larger relatives can really give them a run for their money in competing for the nutritious insect larvae and crustaceans that make up their diet.
But here’s where they have an edge, these wee bathtub-toy birds: come nesting season, their relatively-huge relatives have more trouble finding real estate.
Contracting out the construction work
Think about it: these ducks are cavity nesters. They need the safety from predators that a hole in a tree provides (unlike, say, mallards who nest on shore and risk unpleasant visits from mink and otters). But a duck is never going to be able to build its apartment for itself. Imagine that rounded duck bill trying to hammer a hole in a tree. Imagine those webbed feed trying to hang onto the truck while it works. Nope, not gonna happen.
So they need to find cavities made by other birds—almost always woodpeckers. And the bufflehead has come to rely on one of the most abundant and industrious woodpeckers of the boreal forest: the northern flicker.
Flickers don’t mess around. I have seen them destroy, er, adapt a bluebird box to their own needs within a couple of hours. Near my sister’s home in Calgary, flickers have pounded a hole in the exterior wall of a church (Plaster? Stucco? Child’s play for a flicker) and have made it their home for a few years now.
But a flicker’s nest hole isn’t huge; it’s just as big as it needs to be for a single flicker to squeeze in and out. And that’s probably why buffleheads have never evolved to be bigger than they are: since time immemorial, they have been flicker nest hole specialists. Where flickers live (or lived the previous year), there live buffleheads.
And to compensate for their teeny dimensions, buffleheads are able to put on an impressive show by fluffing up the feathers of their head to huge proportions. Buffalo-heads indeed; look at that noggin! Take that, goldeneyes and other territory-encroachers.
The gales of November (and December, and January)
I wish I could watch these tough little birds in action on their nesting territory, but I don’t seem to get up to the boreal forest much anymore. My time to watch them is in winter, when the birds that nest west of the Rockies head to our coast. Most of the more easterly birds make their way to the Great Lakes, which doesn’t really sound like a fair exchange. It’s chilly there.
Buffleheads have a tough time in winter, and when things start to ice up they need to find open water. A bufflehead in winter has an average of 11 days’ worth of body fat stored up; by March on the Great Lakes they’ve got about four days left. That’s not a great margin for error—but it’s a price they pay for that tiny size and the payoff it brings in the beautiful boreal forest in nesting season.
Let me brighten your Friday.
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