Flight Lines: Rodents beware, rough-legged hawks in area
Mid-winter on the northern Great Plains is a time of trial and forbearance for its scattered inhabitants, both human and animal. Frequent storms, such as last weekend's whoppers, continually test our collective backbones. At times such as these, it helps to consider the early pioneers who endured the same conditions with considerably fewer amenities. I can't even get my arms around the thought of a frozen dirt floor, for instance. Not to mention having to dig a path to the outhouse (thank God for Sears and Roebuck).
While we sit in the relative comfort of heated homes, though, the critters make a stoic go of it outside. Those which hibernate - their numbers are very few - are lucky. The rest must engage in a day-to-day struggle to produce enough heat to survive. In other words, they must eat. A lot.
One such organism well-adapted to take on such a challenge is the rough-legged hawk (Buteo lagopus). It's a circumpolar raptor which nests from the treeline north into the arctic, feeding mainly on lemmings during the breeding season. Only during winter months do these rodent hunters descend to lower latitudes where we get to view them.
Describing a "roughleg" is not an easy exercise. To steal a phrase from the snack food industry, the bird comes in a variety pack. Very few birds are considered polymorphic, meaning exhibiting varied plumages. Most are raptors. Of those, all are open country hunters. There exists no satisfactory explanation for the phenomenon.
With roughlegs, everything from all-dark birds to very light ones can be encountered. Expert Brian Wheeler says, "All ages and sexes exhibit extraordinary variation within each morph."
A typical light-morph female (the majority of wintering birds found on the northern Great Plains are females) shows starkly contrasting dark and light feathers. The bird's white wings and tail display dark trailing edge borders in flight. Large black bull's eyes can be seen on each wing's "wrists," in addition to a bold, black belly band.
It's nearly the same size as a red-tailed hawk but for a hunter-killer, roughlegs appear almost dainty. In addition to small feet and a petite bill, its head is smoothly rounded and seems to lack the ferocious expression of most raptors. Like a Volkswagon Beetle among Humvees.
For those with an eye for etymology, the Latin species name, lagopus, will surely ring a bell. The word can be translated as "hare-foot," meaning the legs of the rough-legged hawk are feathered all the way to the toes; a trait which likely serves the bird well in the arctic.
It might be that the bird's habits are more discernable than its appearance though. It's one of the few raptors capable of hovering - holding in the air while seeking prey on the ground below. Some say this adaptation stems from living in the treeless tundra. Roughlegs also have a curious habit of perching on the highest and tiniest of branches atop the only tree around; surely those small feet help in this regard.
Rough-legged hawks might be a rodent's worst nightmare. Since we have no lemmings here, wintering birds shift their prey base to include other small furbearers. A 1942 study conducted in Michigan and cited in Hawks, Owls, and Wildlife (Craighead and Craighead) confirms this, "The diet of the rough-legged hawks...was 98 percent mice, rats, and shrews."
Quite a few rough-legged hawks were spotted in the area earlier this fall and a couple even hung around long enough to be recorded during the local Christmas Bird Count. But the recent blizzards may have forced their relocation. Why? Wheeler writes, "Deep snow, which conceals prey, may force rough-legged hawks to vacate certain areas in winter."
The birds display strong site fidelity to wintering areas and are known to return year after year to the same location. We may very well see these birds again next year. Less snow would certainly help. But then we couldn't boast of our hardiness in the face of winter stress; stress our forbearers withstood with a quiet and dignified resolve.