ALWAYS IN SEASON/ MIKE JACOBS: Owls attract attention in winter
Yes, this is another column about owls, making two in a row. The snowy owl was last week's subject; this week's bird is the great horned owl. These are the continent's largest owls, but apart from size, they don't have very much in common.
The snowy owl is a bird of open country; the great horned owl seeks cover.
The snowy owl has a limited range and shows up in our area irregularly and unpredictably.
By contrast, the great horned owl is a wide-ranging bird, occurring almost everywhere in North America south of the tree line. Great horned owls also occur in South America, and they resemble Eurasian eagle owls so closely that some scientists consider them a single species.
There's a dispute about whether snowy owls and great horned owls are closely related; for centuries, snowy owls have been regarded as monotypic; that is, the only species in a genus (rather like being a kid without cousins). Genetic testing has shown closer affinities, however, and the birds may be related after all (rather like finding a branch of the family that was previously unknown).
Snowy owls occur in Eurasia as well as North America; great horned owls occur only in the Americas, and they are the only one of the so-called "eagle owls" found in the Western Hemisphere — unless the snowy owl also counts as a member of the family.
Great horned owls are adapted to a wide variety of habitats, including forests and deserts as well as city parks and neighborhoods. Snowy owls nest on the Arctic tundra; outside of nesting season, they occur in open country.
Snowy owls hunt by day as well as by night — mostly by day in our area. Snowy owls hunt on the wing. Great horned owls are active at night, and they are perch-and-pounce hunters that drop on their prey from concealed perches.
Snowy owls are wanderers; great horned owls are strongly territorial, and many pairs occupy the same territory throughout the year and from season to season.
Snowy owls are seen more often than heard; with great horned owls, the opposite is true.
Snowy owls are regarded as a sign of winter and severe weather. The hooting of horned owls is a certain sign of spring. It's part of their courtship.
Courtship among great horned owls begins in mid-February; pairs call back and forth, alternating low-pitched hooting noises that are easily heard and unmistakable. This is a synchronized territorial advertisement, a call and response called "duetting" that strengthens the pair bond.
Nesting in our area begins in early March; eggs may hatch by April Fools' Day. Thus, great horned owls aren't troubled by a cold spring; their feathers provide insulation for eggs, protecting them even in subzero temperatures. Snowy owls, on the other hand, head north as the light grows stronger. They find nesting places on the ground north of the tree line.
In general, snowy owls are most numerous here in spring and fall; great horned owls may be most numerous in winter—because some great horned owls move down from the north, perhaps in response to food shortages or difficult hunting conditions.
Some of these northern great horned owls can be quite light, almost as light as snowy owls. The telling difference is location and behavior. A big owl seen among trees, including city neighborhoods, is most likely a great horned owl. In open country, a big owl is more likely to be a snowy owl.
Great horned owls have "horns," which snowy owls lack. These are really tufts of feathers that help direct sound to the birds' ears, one of the adaptations that help make great horned owls extraordinary hunters. Others are keen eyesight, noiseless flight and gripping power in the feet and talons.
These contrasting owls are two of as many as a dozen species of owls that might be encountered in our area. The Grand Forks County checklist includes nine owl species, five of which nest here; the state checklist has 11 species, seven of them nesting, and the Minnesota state list has a dozen species, 10 of them nesting.
Owls in winter are more likely to cause a stir among birders, partly because they are easier to see, partly because their behavior changes in ways that humans tend to notice, and partly because the owl family is just plain full of surprises.
The great horned owl fits all of these categories, and so it is a fitting choice to be bird of the week.