For the Birds Radio Program: Snowy Owls
The bird second only to the Adelie Penguin in the thermal conductance of its feathers is a fairly diurnal owl.
This winter is shaping up to be a good one for seeing Snowy Owls. These magnificent raptors of the far north “invade” the northern states, and sometimes even farther south, in a fairly regular cycle that corresponds with population cycles of their favorite food, lemmings. Although Snowy Owls specialize on these hamster-sized rodents, they are opportunistic and skillful at taking anything from small songbird nestlings to medium-sized geese. They seem to have extraordinary vision and hearing based on their ability to locate and catch prey, including lemmings that are hidden entirely by turf and snow.
Snowy Owls living in wetlands take a great many ducks, and many that come down to the United States in winter gravitate to shorelines where they feed mostly on ducks. When I lived in Madison, Wisconsin, a Snowy Owl spent most days of one winter sitting atop a telephone overlooking an open patch of water on Lake Monona, where large numbers of ducks congregated. A few times when I stopped by to see him, he was feasting on a duck at the edge of the ice. But those Snowy Owls wintering in agricultural areas or grasslands can survive entirely on mammals, from tiny mice to large snowshoe hares.
Snowy Owls, the heaviest owls of North America, are exquisitely adapted for arctic life. Their large size permits them to grow a thicker layer of feathers than most birds, and their thermal conductance, equivalent to that of arctic foxes, is second only to that of Adelie Penguins among all birds. Their insulation is so extraordinary that an individual’s temperature virtually never fluctuates more than one degree over any 24-hour period.
They are the most diurnal of our owls, a necessary condition for birds to raise their young in the “land of the midnight sun,” but are also adept at hunting at night. When they retreat south to our area, they hunt early in the morning and late in the afternoon rather than at midday, when they’re most likely to attract the attention of ravens, crows, and other mobbing birds. Once I watched a Peregrine Falcon dive-bombing a Snowy Owl on the ice in the Lake Superior harbor in Duluth. The owl stayed down, ducking its head repeatedly as the falcon kept attacking. Had it taken off, the falcon could have done serious damage. As it was, by the time the falcon moved on to other things, the owl was almost lying flat on the ground, but after the coast was clear he sat upright again.
Harry Potter’s owl Hedwig is probably the most famous Snowy Owl in the world. The owl character in the book is a female, but the birds used to portray her in the film are males. Male Snowy Owls are significantly smaller than females—an actor playing a young wizard can carry a male much easier than a female on his arm—and the plumage on adult males grows whiter and whiter each year, making mature males a most attractive cinematic choice against the black fabric of a wizard’s cloak.
In earlier times, people apparently looked at Snowy Owls with a more culinary intent, based on remains in cave deposits. The outline of a pair of Snowy Owls and their young was etched into a cave wall in France, the oldest known example of an identifiable bird represented in prehistoric cave art. It’s hard to know whether this represents some of the first wildlife art or the first illustrated dinner menu.
Snowy Owls may become fairly common this winter. Some of these birds arrive emaciated and end up starving, and most of them have never seen highways and other manmade hazards in their lives. It’s a good idea to have the number of your nearest wildlife rehabilitator handy before you come upon a situation where you need it, though a great many of these birds successfully return to the Arctic come spring. But already this fall I’ve heard of at least one case where one dropped down a chimney into a boiler room. This is a surprisingly common occurrence. These hardy birds spend much of their lives in the Arctic Circle, but apparently have never taken the opportunity to learn about the function of chimneys from Santa Claus.