As one of North America’s largest, heaviest and most powerful owls, the snowy owl excites and delights all who encounter this far northern denizen. Part of the snowy owl’s mystique surely lies in its large size and nearly pure white plumage, but its relative scarcity and irregular occurrence in the U.S. also contribute to this owl’s “wow” factor.
Snowy owls live and breed on the far northern fringes of North America’s arctic tundra. Some winters, however, they migrate to the northern U.S. (and occasionally farther south). It has always been believed that the owls moved south during winter when prey is scarce in the north, but recent surveys show that some snowy owls migrate annually regardless of prey availability in the north. Weather and snow depth have also been looked at as possible reasons for the owls’ winter movement. But whatever the reason, most birders in the northern U.S. eagerly anticipate the arrival of these spectacular birds.
Snowy owls are easy to recognize. They are about the size of a great-horned owl, but are nearly entirely white with a variable amount of dusky brown barring over much of the body. This dark barring, which probably aids in camouflaging the owl, is both age- and sex-dependent. Young females show the most barring, while adult males show the least.
All snowy owls have rather small, narrow eyes with golden yellow irises. Like all owls, they have superior vision both during the day and at night; they also rely on their hearing to help them hunt. Flying silently enhances hearing.
Lemmings make up a large part of the snowy owl’s diet. In fact, one owl may eat more than 1,600 lemmings per year. However, if lemmings are scarce, snowy owls will also eat rabbits and birds such as ducks. Owls that migrate south of the breeding grounds where there are no lemmings subsist on a diet of whatever prey is locally abundant--other birds, rabbits, squirrels or mice.
Once you’ve located a snowy owl, you will probably be able to observe it all winter. Banding studies show that the owls demonstrate winter site fidelity and defend their feeding territories from other owls.
Snowy owls also aggressively defend their breeding territories from other owls and any other intruders as well. Perhaps this is why so little is known about the snowy owl’s courtship or nest selection. Nests are found on windswept hillocks or large boulders that allow a commanding view of the surrounding countryside. It is believed the female scrapes out a hollow using her claws and by turning her body around and around on the scrape. She adds no feathers or other material to the nest, so the eggs and young are totally dependent on her for warmth. She lays between three and eleven eggs at two- to four-day intervals—the number of eggs being dependent on the availability of prey. Incubation begins with laying the first egg and lasts approximately thirty-one days or until the last egg has hatched. During this time the male guards the nest and feeds the female, but does not participate in incubation.
Chicks are born helpless, although they are covered with down feathers—a condition known as semialtricial. But they grow quickly and are able to leave the nest after only fourteen days. The owl family may remain together, with the young being fed by both parents, for several months.
People have been observing snowy owls for eons. They are the oldest bird species recognizable in cave drawings by the Paleolithic people of Europe. Bones of snowy owls have been found in these caves as well, indicating that these people probably did more than merely observe these large owls.
Fortunately, today’s laws prohibit trophy hunting or adding owls to your menu. But observing them is always fun. Away from their breeding grounds, snowy owls may seem quite docile around humans, often sitting still and allowing fairly close observations.
Although snowy owls do the majority of their hunting just after dark, it’s not necessary to go out at night to observe them. Their daytime hours are often spent on conspicuous perches. Some of the best places to look for snowy owls are marshes, meadows, farm fields and coasts—anywhere they have a good view of the surrounding countryside. You may spot them perching on open ground, sitting on utility posts or perching on roofs.
So be on the lookout this winter. Perhaps you will be lucky enough to encounter an arctic visitor from the north.
Snowy Owl (Bubo scandiacus)
Length: 23 inches
Wingspan:52 inches
Weight:4 pounds
Adult male: Nearly entirely white with scarce, dark barring over back, belly and wings. Eyes yellow and elliptical.
Adult female: Similar to male with more dark barring on body.
Juvenile: Similar to adults, but very heavily barred with dusky brown over much of the body.
Voice:Song is a deep, repeated hoot or broo. Call is a high, drawn-out scream.
Behavior: Largely diurnal. Migrates to northern U.S. (sometimes farther south) in some winters. Flight is strong and steady, but not rapid. May appear quite docile away from the breeding ground.
Mating/Breeding: Mainly monogamous. Courtship includes an aerial display consisting of an undulating flight in front of the female followed by a ground display and presentation of food (usually lemming).
Nest: A bare scrape on a raised hummock of ground. No feathers or other lining material used.
Clutch: Usually 3 to 5 eggs when food is limited, 7 to ll eggs when food is plentiful. The white eggs are 2.2 inches long.
May forego nesting when prey is scarce.
Incubation: 32 to 34 days
Fledge: 32 to 34 days
Food:Lemmings and other rodents are primary food. Will also eat hares, birds and occasionally fish and other aquatic animals.
Habitat: Treeless arctic tundra.
Territory: Males establish territory on arctic breeding grounds. Usually widely spaced from other snowy owls.
Breeding Range: Alaska and the Canadian arctic.
Winter Range: Breeding range to southern Canada and northern U.S. (occasionally farther south).
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