The crossbill is a shining example of a bird with a bill that’s especially adapted to how the species lives and feeds. The tips of a crossbill’s beak literally cross, in a bizarre and dramatic overbite. Quick, get this bird some braces! No: the misalignment allows these avians to expertly snip cones from trees and, holding them in one claw, lever the scales open to expose the seeds. They then use their tongues to pull out the seeds.
What’s up with the bills?
Although plenty of birds have evolved bills to help them feed—the brown creeper, with its tweezers; the hummingbird, with its nectar-sucking syringe—a crossbill’s mouthpiece is particularly useful. A lot of bird food sources run low in the winter, but not for Mr. Crisscross. Conifer trees have plenty of cones all season long—no matter how frigid or snowy the weather. And since most birds don’t have the beaks (or the skills) to feed off cones…well, all the more for the red crossbill!
What do they look like?
Only the male red crossbill is actually red; females are yellow. They tend to forage in flocks, moving from one tree to another in a flurry of colour and noise. Crossbills can be as small as black-capped chickadees or as large as brown-headed cowbirds. There’s so much variation because North America has roughly ten different “types” of the species. (Experts, for the most part, don’t consider them subspecies.) Their beaks all vary slightly depending on the specific cones that they eat. Eastern Canada’s most common crossbill, for example, prefers pine and white spruce.
Why are crossbills noisy?
A red crossbill pair breeds in late summer, but, if the cone supply is plentiful, Mom and Dad will produce another two broods—even nesting and incubating eggs in the winter. Red crossbills will happily nest close to one another in areas thick with cones. As a species, they’re very social and generally good at sharing; ornithologists suspect that they call to one another while foraging to convey info about the quality of cones and seeds that they’re finding. This allows the flock to forage more efficiently—and that’s good for the species in general.