Each year about this time my wife, Sandy, and I have the opportunity to hear the nighttime duet hooting of a pair of great horned owls near our home on the edge of Lake Waconia.

Other observers can hear this, too. Pairs of these owls can be heard throughout much of Minnesota. The birds are setting up nesting territories and declaring boundaries. They are the earliest nesting birds in the state; egg-laying begins in late January. Although the female great horned owl is a bit larger than her mate, the male has a larger voice box and a deeper voice. The difference is evident when you listen to a pair converse.

The great horned owl has been called the “tiger of the air” because of its large size and ravenous feeding habits, but it also is a generous provider for its young.

The owl requires an enormous amount of food as all birds do. It has an extremely high metabolism and can process the equivalent of its own body weight in food each day. It also is a killer by nature. It takes all manner of prey, from insects, earthworms, fish and amphibians to birds and quite large mammals. As predators, there are fewer owls than the food they eat, which is necessary or they would eat themselves out of business.

The tiger comparison applies well to the owl’s way of hunting, for the sweep of its great wings in the silent air is as noiseless as the tread of a big cat’s padded feet on the soft earth. A horned owl glides as silently as a shadow through the forests and over the meadows. To an unwatchful cottontail rabbit or striped skunk that shadow means sudden death from powerful talons. Because of its great strength, the owl does not hesitate to attack much heavier birds and mammals, such as hawks, porcupines and the occasional domestic cat.

Banding is a tool used to determine the longevity of birds. The oldest great horned owl on record was at least 28 when it was found in 2005 in Ohio.

The owl is nearly 2 feet long, with a wingspan of 5 feet and a weigh between three to four pounds. It is the only large owl with ear tufts. Other identifiers are its brown streaks, white throat collar and yellow eyes.

Jim Gilbert’s Nature Notes are heard on WCCO Radio at 7:15 a.m. Sundays. He taught and worked as a naturalist for 50 years.