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ALWAYS IN SEASON/ MIKE JACOBS: Great northern hawk arrives in the valley

Illustration by Mike Jacobs1 / 2
Mike Jacobs2 / 2

A lot of good things can be said about the rough-legged hawk, and it's not hard to get started.

The rough-legged hawk is conspicuous and easily identified, yet it is enigmatic and even exotic.

It is a large bird, so it can be conspicuous. Its flight is unlike any other large hawk species. It perches in the open, often in an isolated tree or on a utility pole or a rock pile. It is relatively slow to take flight, which observers can exploit for close looks at the bird.

That's the conspicuous part.

The rough-legged hawk displays a variety of plumage patterns that is unusual among hawks, but the range of colors is limited to black, white, tones of gray and some dark browns. That makes it enigmatic.

Yet it displays marks that are consistent and reliable aids to identification. These are best seen in flight; resting birds can be confused with other hawks, and even eagles, but practice and familiarity lessens the risk.

The exotic element is distribution. The rough-legged hawk is an Arctic bird. It nests on the tundra at the northern edge of North America and Eurasia, where small mammals, including lemmings, form the bulk of its diet.

The limited range of colors and the wide range of plumage patterns help the birds blend into the tundra.

Protective coloration is only one of the adaptations rough-legged hawks have developed for life on the tundra. Another is reflected in the name. Unlike most hawk species, rough-legged hawks have feathered legs for protection against the cold.

In winter, the hawks move south, showing up on dependably every year, though not always in large numbers. Their appearance in the Red River Valley coincides with the arrival of winter.

That can't be held against the rough-legged hawk; instead, the arrival of the hawk is a reason for keen anticipation. Despite its predictability, sightings of rough-legged hawks don't happen every day. Instead, the hawks are present here for only a short time, often less than a fortnight, but sometimes as much as a month or more. Quite often, they are present through December; counters often find them on the annual Christmas tallies.

The critical variable is food supply. Heavy snow makes hunting difficult, and rough-legged hawks move south to open areas without snow cover, sometimes getting as far south as coastal Texas.

The hawks move north again as the snow melts and prey becomes available.

This behavior is very like that of another tundra nester, the snowy owl.

Populations of both species vary with food supply in the Arctic. If the population of small mammals is sparse, predators such as the snowy owl and the rough-legged hawk might have trouble securing adequate food for their young. Good hunting makes for larger populations and more winter hawks and owls in the Red River Valley.

Grassy areas bordering the Red River Valley attract rough-legged hawks because they offer good hunting of species similar to those that occur in the Arctic. While the hawk nesting range is wide open country, like the valley, rough-legged hawks are cliff nesters.

In the valley, the hawks use whatever elevation they find, which explains their appearance on telephone poles and tree limbs. They're not loners; sometimes, several perch in the same tree.

A rough-legged hawk at rest can be distinguished by the size of its head, which is small in proportion to the body. Often the head is quite light, sometimes nearly entirely white, which can cause confusion with bald eagles. Eagles are larger, bulkier birds.

In flight, rough-legged hawks are distinctive. The small head is discernible, but the telling field mark is the white rump. The rump patch is a mark of the Northern harrier, as well, but harriers are smaller, trimmer birds.

Unlike other large hawks, rough-legged hawks are capable of hovering, and this behavior is a tactic fairly commonly used by hunting rough-legged hawks.

In flight, rough-legged hawks often show a dramatic contrast between black and white, with black in the elbows of the wings and on the belly. Some rough-legged hawks are almost entirely dark.

It would be exaggeration to say that rough-legged hawks are common in the Red River Valley, but they are a prominent part of the valley scene in the late fall. The birds don't spend as much time in the valley in spring; they're apparently in a hurry to reach the Arctic.

Rough-legged hawks often occur along County Road 33, the paved road that leads from Manvel to Gilby, N.D. I drive this road often and look forward to seeing the great northern hawk, which for me marks the passing of another season and the start of another year.