Don’t let windows be a pain for songbirds
Since the first of this month, a male bluebird has been attacking his image in a large living room windowpane facing our backyard.
Meanwhile, he plucks up mealworms we’ve put out and carries them to a female in the nest box. It’s mating time, which starts early for our bluebirds. The male will fiercely defend his breeding territory from an interloping male, which is what he sees in the mirrored image of himself in the window.
The bird is neither dumb nor lacks keen eyesight.
A songbird’s brain has an intellectual capacity comparable to the brain of a chimpanzee. For example, consider a songbird’s language consisting of complex songs and chirps that a bird learns from its parents and nearby adults just as we learn language during childhood.
Songbirds also have superior eyesight that allows them to see the ultraviolet spectrum that’s invisible to our eyes. Birds also perceive shades of the same color in sharper contrast than we can see.
But despite a great brain and superior vision, our male bluebird cannot see the difference between his reflection and a real bird.
Captive chimpanzees will at first see their mirrored image as another chimp. But after playing with the mirror for a few days, they’ll recognize their image.
By comparison, it takes humans roughly 18 months after birth to recognize their faces in a mirror.
Magpies are the only birds we know of that recognize themselves in a mirror. But their brains are larger and more highly developed than the brains of songbirds.
Songbirds cannot distinguish their mirrored image from anoth
er bird. Nor can they see reflections of trees and the sky in glass as anything but natural surroundings. They’ll slam into windows thinking they’re flying toward trees or into the air.
Millions of springtime migratory songbirds crash to their deaths against tall buildings with large, lighted glass panes reflecting a clear flight path in the sky. The Houston Audubon Society advocates “lights out” in buildings during migration.
Meanwhile, what to do about our male bluebird attacking his image in the window? Silhouette decals of hawks and falcons pasted on the window won’t work because shapes don’t fool birds.
We bought a clear window film with embedded vertical lines that broke up the mirror effect of glass. And the bluebird no longer sees his reflection as an intruding male.