Protectors of crops and symbols of wisdom for millennia, owls have been around far longer than humans. Owls have left behind a fossil record 66 million years long, one of the longest of all groups of living birds. Owls belong to two families: Tytonidae and Strigidae. Some scientists believe owls of the Strigidae family may even descend from small dinosaurs.

The owl's many mysterious calls, glowing eyes, unusual shapes, and stealthy flight abilities can be fascinating or alarming. At the bottom of these intriguing trademarks is effective evolution; nearly every aspect of an owl's form contributes to its ability to capture prey.

The owl's large, reflective eyes are huge in proportion to its body and are designed to give it the best night vision of any animal. The soft feathers surrounding the eyes funnel sounds into highly sensitive ears, enabling an owl to hear prey hidden beneath snow or underground. A great gray owl can hear a beetle running through grass a hundred feet away or a mouse squeaking half a mile away.

An owl has 14 vertebrae in its neck, twice as many as most birds, allowing it to turn its head 180° to the right or left to quickly track sounds of potential prey. The softness and structure of owl feathers muffle the sound of flight so that the owl can approach prey without being detected. Once positioned over its prey, an owl easily grasps it with powerful toes, each of which ends in a long, sharp, curved talon. The owl's strong, broad wings are huge in relation to its body, giving it the power to easily carry prey back to the roost.

Courtship and Family Bonding

Owls have lengthy and involved courtship rituals, especially great horned owls. Courtship begins with the male sending out a call to announce his territory and chosen nesting site. A female soon arrives to inspect the situation; if she approves, she returns to her roost and answers his call. They hoot back and forth from their separate roosts for a few nights. Then the female roosts a bit closer and they continue hooting to one another for several weeks, eventually hooting in duet. When the female alights in the male's tree, they begin purring, gurgling, ruffling feathers, and preening one another. The male soon offers the female a freshly caught small mammal, which advances the courtship dance dramatically. The two owls begin hopping from branch to branch, lifting and overlapping wings.

Mated owl pairs often stay together for many years, sometimes using the same nest for over 20 years. They frequently settle in tree cavities or the remains of other birds' nests instead of creating their own nests, but they are extremely devoted to their offspring. The female does most, if not all, of the incubating while the male brings food and fiercely defends both her and the nest against intruders of any size. Attacks upon intruders become more aggressive once the owlets have hatched. Both parents share in defending and teaching the owlets until they are independent.

Where to Look for Owls

Owls can be found on every continent except Antarctica and in nearly all types of habitat, but their solitary and nocturnal habits, as well as the effectiveness of their camouflage, often make them difficult to spot. Twenty-one of the over 140 known species of owls live in North America. Though most owls prefer to live far from humans, barn owls and screech owls often live near humans because rats and mice are plentiful wherever people live.

Owls choose roosting spots that are well hidden and protected from the weather. Owl territories vary with the size of the species, the number of offspring typically borne, and the availability of food in the area. A great horned owl may need up to a thousand acres for its territory, while a great gray owl may need only a few hundred square feet.

A telltale sign that owls are living nearby is the pellet, a by-product of their digestion. Owls tend to eat their prey whole and have difficulty digesting hair, feathers, and bones, so they spit up these materials in the form of a pellet. The pellet's shape and contents can indicate the species of owl as well as its prey.

How to Listen for Owls

The name "owl" comes from the Old English word "ule," which means "to howl." A large and freely used vocabulary makes this a particularly fitting name. The patterns of short and long hoots enable owls to locate and communicate with one another. Some owls are heard only rarely, while others are constantly vocal. Calls heard in autumn are probably those of males establishing hunting territories; calls heard in late winter or early spring are likely to be those of courting pairs. The males' voices tend to be lower and to carry farther than the females' do.

Threats

Adult owls have few enemies other than humans. Many owls found dead are victims of deliberate or accidental human actions. Typical causes of death are being shot, trapped, hit by cars, and electrocuted on power lines. Alteration of habitat and the effects of insecticides on the food chain also threaten the survival of owls. In fact, the most common cause of death for owls and the main threat for owlets is starvation; up to fifty percent of owlets fail to survive while learning to hunt for their food. The main predators of owlets are crows or squirrels.

What We Can Do

We can help owls by preserving natural habitat and protecting it from degradation. Replacing chemical pest control with organic methods will foster a healthier ecosystem and a safer food supply. Preserving old, hollow trees and building nesting boxes for owls in protected places will also help ensure that these important and impressive creatures continue to live among us for the millennia to come.

Owling

Learning to recognize different owl calls will help you find and identify owls in your area. A good way to get started is to go into the field with an experienced owler. Most woodland owls call at dawn and dusk, so set out two or three hours before sunrise or two hours after sunset.

• Sound. If you play pre-recorded owl calls to elicit responses from owls in the vicinity, do so sparingly—and never during mating season. Indiscriminate use of recorded owl calls has been known to bring the breeding cycle of some owls to a halt. A less problematic approach to drawing owls out into the open is to emit hisses, cheeps, and squeals that are suggestive of a prey animal in distress.
• Light. Photographers' flashguns can damage owls' eyes, thus diminishing their ability to hunt. Use them in moderation, if at all. It is useful to bring a flashlight for better viewing at key moments, but try to minimize your use of it, so you don't interfere with the owls or spoil your own night vision. Let common sense and caution guide you. If you suspect that a particular owl-finding strategy may have a harmful effect, choose not to use it.