At night I hear them in the spruce trees outside my house: Great horned owls, hooting back and forth. Summer’s over, so all the other noisy night creatures – the crickets, the toads – are gone. It’s quiet; the hooting is the only non-human-generated sound out there, and it’s loud. I’ve never seen them, but I’m happy that these fascinating, powerful birds have chosen my trees to roost in. Because owls prefer to roost close to their food source, it means I live in an area with a diverse ecosystem, where nature is still healthy enough to support owls.
Horror movies make the hoot of an owl out to be scary, but unless you’re a mouse, there’s nothing to worry about. Owls do us a service. Since their diet is primarily rodents, owls benefit humans by helping to keep their populations in check. And over millions of years they have evolved into remarkably efficient predators.
With exceptions, owls are carnivorous birds; they hunt for prey. (A few of the smaller owls eat insects.) Most hunt at night. Some species wait on a branch and pounce when a potential meal comes into their orbit. Others, like barn owls, fly around actively searching for food. Depending on its size – the bigger the owl, the larger its prey – owls will eat mice, rats, voles, frogs, snakes, fish, rabbits, and squirrels. The biggest ones will even hunt other birds, including smaller owls, as well as raptors such as ospreys and peregrine falcons. They swallow their prey almost whole, and later regurgitate whatever is indigestible.
Owls look plump, but that’s because they have such fluffy, dense feathers. Their wing feathers aren’t stiff like that of most other birds, but are soft at the edges. This means the wind doesn’t whistle through the feathers when they fly. Their flights are almost silent. Their prey doesn’t hear them until it’s too late.
Owls have odd-looking faces as birds go, but they are a marvel of efficiency. Their heads are large relative to their bodies. In some species this is in order to accommodate asymmetrical ears, which increases their ability to hear from different directions. Their cupped faces help funnel sounds to the ears. Their hearing is so developed they almost don’t need to use their vision to hunt. They can detect and catch prey under snowpack or in complete darkness.
However, those large eyes do come in handy. They give owls exemplary night vision, up to 100 times better than a human’s. Where most birds have eyes on either side of their heads, owls’ eyes face front, like ours. Owls cannot move their eyes, but they compensate by being able to turn their heads 270 degrees. They have 14 bones in their neck to help them do it (we have a paltry seven).
There are 19 owl species in the U.S. They are found in every state, including Hawaii. The most common include the barn owl, screech owl, great horned owl, and barred owl. Most are not endangered, but like so many other animals, habitat destruction, climate change, and pesticides (in the owls’ case, from eating rodents that have ingested rat poison) have contributed to a decline in their populations.