Home » Plants & Animals » Birdwatching » The Snowy Owl - A Lesson in Adaptation

The Snowy Owl - A Lesson in Adaptation

© Terrie Murray

This week we're going to do something a bit different. Rather than looking at lots of different kinds of birds, we're going to look at one specific type of bird, because it has a lesson to teach us.

Just this last week the Oregon Birders' On-Line e-mail list reported that a snowy owl is being seen at the airport in Eugene, Oregon. Similarly, five years ago (November, 1996) I received a message from a bird watching friend of mine that a snowy owl had been sited in a different spot here in Oregon's Willamette Valley. We were all excited, because this is a very rare bird for Oregon. I'd lived here for 16 years, and couldn't remember hearing about snowy owls before. As the winter progressed, the sightings become more frequent. In one week in January, 1997 there were 34 snowy owls seen in one place in British Columbia, about 30 reported in Washington State, and at least 5 here in Oregon. As more and more of these owls began being seen, I wanted to learn more about this Arctic visitor.

There are 146 species of owls in the world. Of them all, the snowy owl is perhaps the most beautiful. The owl stands about 23 inches high. Younger birds and female birds have some black feathers, but fully-grown males are pure white. Snowy Owls are Arctic birds, and they breed and raise their young on the tundra in northern Canada and Alaska, far above the Arctic Circle. During the winter most snowy owls will leave the harsh Arctic weather and will travel south, though usually not much further south than central Canada.

Most owls are nocturnal, which means they are active and hunt at night. Snowy owls are diurnal birds. Diurnal means that they are active and hunt during the day. This makes a lot of sense, because during the northern summer the sun is up for 20 hours or more, so it was necessary for the snowy owl to adapt itself to learn to hunt during the daylight. However, because the sun is not up for very long during the northern winter, snowy owls have adapted so that they can hunt both during the day, when there is light, and during the night, when there is not.

Although they eat many different kinds of prey, by far the primary food of snowy owls is lemmings, a rodent about the size of a large mouse. It was formerly thought that snowy owls were seen south of their range only when the lemming population crashed in the Arctic. Now scientists have learned that the reason for the owl traveling so far south of their normal range may be more complicated than that, and may be more correctly attributed to an overall ratio of predators and prey in the entire snowy owl range, or even to a more specific loss of prey in a particular area, rather than to a population crash of one particular kind of prey in the entire snowy owl range.