Looking for owls? Follow your crows

Owls have a hold on our imaginations, and many of us are disappointed that they're so tough to observe in the wild. But here's a tip for improving your chances: Let other birds alert you to owls.

It's true — if you want to see a great horned, screech, barred, long-eared or saw-whet owl, be on alert if you hear birds making a commotion — this often means they've spotted an owl in their territory. Many kinds of birds, from chickadees to red-winged blackbirds to white-breasted nuthatches and even cardinals and goldfinches, scold and flutter around owls to try to drive them away, a behavior called mobbing.

"All small birds seem to dislike birds larger than themselves, and it's common to find smaller, more nimble birds dive-bombing and harassing larger ones," says Kevin McGowan, a project manager at the Cornell Lab of Ornithology. Even if they can't drive off the larger bird, "they can at least advertise its presence" to warn other birds.

Crows, especially, yell and fly at a perched owl (usually hidden from view), sometimes for hours on end. Such mobbing activity often serves to recruit other birds to join in the fight against a common foe.

"Owls are such frequent targets of mobbing — and so hard to see otherwise — that listening for mobbing calls is a good way to find owls during the day," says McGowan.

The first saw-whet owl I ever spotted was pointed out by nuthatches and chickadees circling and "dee-ing" around a slump of twigs and leaves in an evergreen. The owl was invisible but the birds' behavior clearly indicated a predator was on the scene. And sure enough, after several noisy minutes, the little owl turned its head and its large yellow eyes gave it away.

Why are songbirds so intolerant of owls? Most birds work the day shift and sleep at night. They know that night-hunting owls can easily grab a sleeping bird.

One of the most difficult owls to spot is the aptly named long-eared owl, a handsome bird that often perches next to tree trunks and blends in with the bark. I recently found a long-eared after listening to chickadees making agitated calls in a regional park's woods. It took a while to find the cause, but suddenly a branch of a deciduous tree formed itself into a lean long-eared owl. I watched it briefly, then backed out of the woods.

Birds seem to mob most intensely when they're on breeding territories and especially when they have vulnerable young in the nest. Although they sound furious, they seldom cause injury. But very aggressive birds, such as kingbirds, blackbirds and crows, may actually strike the source of their anxiety.

Is this something that all birds know by instinct or is mobbing a learned behavior?

Like almost all bird behaviors, it's a mix of learned and hard-wired activity, says McGowan. "Species have been selected to pay attention to the calls of other birds, but I imagine they learn about individual predators in their individual areas, and they certainly learn about where these predators hide."

Bird columnist Jim Williams, who took the stunning photos that accompany this column, is a willing student of mobbing behavior.

For all of you owl fanciers out there, this is often the formula for success.