Rough-legged hawks are abundant in the Red River Valley

Jim Brosseau, a doctor in Grand Forks, was driving to his hometown of Drayton, N.D., when he noticed something he hadn't seen before: "at least a dozen large birds either hovering overhead or sitting on the fence posts.

"They were not in flocks, but each was alone.

"They looked like hawks, and had black wings with striking white markings on them.

"I can't recall ever seeing such birds before, especially in such numbers.

"Do you know what they were?"

As a man of science, Brosseau provided rich details, even in a short message.

The birds were rough-legged hawks, I replied.

Rough-legged hawks are among the largest hawks that occur here, large enough to be confused with eagles.

This confusion is the greater because many rough-legged hawks have dark bodies and pale heads, rather like bald eagles.

Eagles, however, do not hover. Among large raptors, only rough-legged hawks can do that.

Brosseau noted significant field marks of the rough-legged hawk, as well. They are dark, overall, but with striking markings, including a bold pattern in the wings and a big white patch on the rump. These give the rough-legged hawk a distinctive mottled look, quite unlike any other bird that occurs here.

That said, rough-legged hawks display quite a range of plumage. Some -- perhaps a fourth -- are very dark.

Brosseau provided a couple of details about behavior, too.

Rough-legged hawks do seek perches that give them a view of the countryside -- fence posts and isolated trees, for example.

And they do form loose flocks, sticking within sight of each other but allowing enough space for each bird to hunt successfully.

Two other circumstances pointed to the same species.

First, the route from Grand Forks to Drayton crosses open, almost treeless grasslands. This is exactly the kind of habitat that rough-legged hawks prefer.

And second, rough-legged hawks have been abundant this November. One observer reported seeing more than 50 on a drive through rural Grand Forks County. Suezette and I regularly see two dozen or more on our 30-mile commute to work every morning.

The appearance of such large numbers of rough-legged hawks suggests a couple of things.

First, the birds had a successful nesting season.

This is not always the case for rough-legged hawks, which inhabit some of the harshest habitat on earth. They are northern birds. In fact, they are the only species of hawk that nests entirely within the Arctic Circle.

Food must have been plentiful there this summer. In years of abundance, each pair of rough-legged hawks might raise seven young or more. In years of scarcity, one or two would be the norm.

Second, there's plenty of food for the hawks here. As open-country hunters, rough-legged hawks need large populations of small mammals in order to survive. And they have to be able to see them in order to capture them.

For this reason, we may be nearing the end of the season for rough-legged hawks. Snow cover will limit their hunting success, and they'll move father south -- but only until they find open ground for hunting.

Often, this kind of ground occurs in highway rights-of-way, so it's not surprising that rough-legged hawks would be frequent along the interstate highway between Grand Forks and Drayton. The highway provides a kind of edge habitat where mammals can dart into the open and where hawks can seize them.

This is not without hazard for the mammals, of course, but also for the hawks. Many hawks are killed by cars.

Still, the rough-legged hawk is not a threatened species. Indeed, it may be among the world's more common hawks. Rough-legged hawks also occur in Europe and Asia.

Perhaps, part of the reason for their success is their preference for habitats that humans find unappealing -- the Arctic to raise their young and open, windswept grassy areas to spend the winter.

This year's abundance of rough-legged hawks does raise a question about another northern raptor. Snowy owls have been notably absent.

This is unusual.

Some years, snowy owls are abundant enough to earn the Grand Forks area a reputation as among the most dependable spots to see these birds south of the Canadian border.

But not this year.

I've yet to see a snowy owl this season. Nor have I had reports of any.

Jacobs is editor and publisher of the Herald.