Snowy Owl at Damon Point, WA
Twice a decade or so, we in the Pacific Northwest are graced by the presence of majestic Snowy Owls in the winter. People are seeing them now in many places in Washington State and all across the north-central United States and southern Canada http://www.spokesman.com/blogs/outdoors/2011/nov/28/snowy-owls-making-scene-across-country/. Clearly, a Snowy irruption is underway!
Irruptions are irregular migratory movements that depend upon such factors as food availability and/or a change in seasons. In the case of Snowy Owls, they have a lot to do with availability of their primary food source: Lemmings. Snowy Owls leave their Arctic tundra breeding grounds when the cyclical supply of food (Lemmings) is low. They will also sometimes leave after a big Lemming year, when there is a resultant bumper crop of young owls needing food and territory. Finally, extreme winter weather can drive owls southward.
Lemmings are small mouse-like rodents that remain active all year long; they do not hibernate. Lemmings eat shrubs, herbs and sedges in summer and Willow Buds, leaves, twigs and bark during the winter months. The notion that Lemmings commit mass suicide is a myth. They do, however, run as a group and will enter bodies of water to swim to another land mass.
Snowy Owls are one of the few resident bird species of the extreme northern Arctic tundra. The others are Gyrfalcon, Willow and Rock Ptarmigan and Common Raven. Even though there are relatively few bird species up there, predators still exist. Snowy Owls vigorously defend their nesting territories from wolves and Arctic Foxes. Other Arctic breeding birds like Snow Geese, Brant and Common Eiders will sometimes nest near Snowy Owls to discourage attacks from Arctic Foxes.
Snowy owls perch in open areas waiting for prey, which in these parts would often be Voles, other small rodents, Ducks or Coots. Their white color makes them conspicuous in our blue-green-gray winter color palette. In their Arctic home, however, white provides the perfect camouflage against the snow.
If you want to see a Snowy Owl, check your local birding sightings, which around here is Tweeters.com or nationally at E-bird.org. Or join me on a daytime Snowy Owling adventure. Look for the owls calmly sitting atop trees, power poles, driftwood, snags, small hills, or any perch that provides a view of open country. We are so accustomed to seeing garbage around, that we sometimes fail to investigate large white items in the countryside, like discarded plastic gallon jugs. Check these out with binoculars; they might just be Snowy Owls instead.
Sources: Arctic Studies Center; Cornell Lab of Ornithology Handbook of Bird Biology; Birds of Washington State by Brian H. Bell and Gregory Kennedy; Borealforest.org; Ornithology by Frank Gill; Sibley Guide to Bird Life and Behaviour by David Allen Sibley
