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Snow Birds

Winter 2007-2008 Newsletter

Before winter winds begin to howl, many folks head south or southwest: “snowbirds” seeking warmth. But the real snowbirds are of the avian variety.

Triggered by food shortages farther north, some species must head southward to survive winter. This is not called migration, but invasions or irruptions. Periodic crashes of rodent populations (owls) or poor conifer cone crops bearing few seeds (crossbills, pine siskins, redpolls and others) cause some birds to wander great distances.

The magnificent snowy owl (Nyctea scandiaca) primarily depends on lemmings in the Arctic, and about every four years, lemming populations crash. These large white to grayish-white, heavily built owls travel widely in winter and occasionally have been seen in Jo Daviess County. Look for them on power poles, on a hay bale in fields or along a shoreline. Their diet consists of rodents, birds, rabbits, squirrels, and they will wade into water to catch fish. The great gray owl and northern hawk owl are two other rarities from the North.

Our more familiar winter visitors are the dark-eyed junco (Junco hyemalis hyemalis) and the American tree sparrow (Spizella arborea), and we can count on them every year about late September or early October. Juncos are dark gray with white underparts while the American tree sparrow has a brown, partially streaked upper body and clear breast with a brown “button” spot. Bird feeders, especially those with small seeds, attract both these little sprites and they forage primarily on the seed dropped on the ground. Thickets and weed patches provide shelter and food. Gravel roadsides lure them when fields and hedgerows are snow-covered. Unfortunately, road salt ingested with the grit needed for digestion may contribute to declining numbers.

Sometimes a junco will have different plumage, a black “hood”, and pinkish sides. These are crosses with the subspecies “Oregon junco,” a very pretty bird indeed.

Enjoy these hardy inhabitants of far northern climes as they brighten our winter landscape. By late March or early April, they’ll head north once again.

—Grace Storch