Our off-season migrant
For a bird enthusiast, there are primarily three types of bird species to observe: year-round residents, seasonal residents, and migrants.
The first type is obvious: species that spend their entire lives in the same place, more or less. Resident species might move about a bit in search of food, like crossbills, and they might seasonally migrate in altitude—up the mountain in the summer, down the mountain in the winter, like the Townsend Solitaire—but, by-and-large, residents remain in the same area in which they were born.
The second type is our typical summer resident, such as the American Robin. They call this place home, if only for the breeding season, and fly elsewhere for the winter.
The third group is composed of the migrants, those species that regularly visit our area as they pass through on their way to somewhere else. For example, Tundra Swans visit our area as they head north to the Arctic for the summer and then again in the fall as they head back toward their wintering grounds. Migrants do not normally hang out here otherwise.
Now there are exceptions to the above, but our featured bird this month is one of the second types of species. Except in this case, this bird practices a reverse-migration pattern. Instead of visiting our area as a summer migrant, this bird does so as a winter migrant. That’s right: our region is this bird’s wintering area. Welcome to the wonderful world of the Rough-legged Hawk.
The Rough-legged Hawk is a big bird, similar in size to its cousin, the Red-tailed Hawk. And as its name implies—well, I guess it implies, it is rather a strange name—its legs are covered in feathers, much like the Golden Eagle. It is one of only three raptors in North America that has this feat (pun! Though it did require some loose grammar there), as most birds-of-prey lack leg feathers. This is probably an adaptation to their Arctic and high-latitude living.
Rough-legged Hawks might be difficult to identify in the field because they are not overly distinctive in coloration. They look like a typical, not-sure-what-specie-it-is hawk. And to add to the confusion there are two color-types, or morphs: a dark morph and a light morph. Even more, there are also intermediaries that range between the light and dark poles. And while the legs are feather covered, this might not be obvious when observed, even with binoculars. So how is a birder going to definitively identify a Rough-legged Hawk in the field? Easy: look at the bird’s wrists.
Wrists? Birds have wrists? Of course they do! Hey, even whales have wrists! But you need to understand this anatomical term within an avian context. In other words, a bird’s wrist is not exactly analogous to a mammal’s wrist, or yours, assuming you’re a mammal. A bird’s wrist is best observed when the critter is in flight. The wrist is the prominent bump on the leading edge of the extended wing. If you imagine the long, outward extending feathers at the end of a hawk’s wing as fingers, those “fingers” extend from the wrist. And this is important to know when identifying the Rough-legged Hawk. These birds have a noticeable large black “spot” (perhaps “smudge” might be a better term) on the wrist on the underside of the wing. And this field mark is true regardless of what color morph your subject bird is. Black-colored wrist spot = Rough-legged Hawk.
Rough-legged Hawks also have relatively small talons. This is probably a reflection of their preferred prey: little rodents. In the Arctic tundra the target rodents are lemmings; in our area it is voles. Though these birds are apt to take whatever comes their way, assuming they think they can manage it. So if you want to mark the Rough-legged Hawk on your life list, head for open areas. You might key in on any large raptors that appear to be hovering, as this hawk can hover for bit like an osprey. It is the only large hawk that typically does this.
Because this bird breeds in the Arctic on the tundra, it is a ground nester. Its range is also circumpolar, meaning its breeding range extends completely around the arctic: across North America, Asia, and Europe. Subsequently its wintering range extends along similar latitudes around the world. It is a relatively common bird, though only seasonally so. But its population numbers do wax and wane in sync with lemming populations, a pattern that is similar other prey/predator species relationships, such as lynx and hares.
Okay, so a lot of people will not bother to know anything more about the Rough-legged Hawk than “hey, there’s a big hawk over there.” What a pity. To me that’s the equivalent of saying, “Gosh, there a big ungulate over there.” Whatever. If only these birds could tell their stories. Keep that in mind when you’re out stalking our seasonal winter friend. Happy birding!