Date: 2/5/19 11:59 am From: Gregory Hanisek via CTBirds <ctbirds...> Subject: [CT Birds] Rough-legged Hawk yes & no
For more than a month we've been experiencing a stubborn case of “Rough-leg fever” (or to keep it current maybe Buteo measles). Tucked in among some well-documented records of Rough-legged Hawks there have been some equally well-documented cases of Red-tailed Hawks being ID'd as Rough-legs. There's one thing we can all do to help get this under control. Don't use hovering flight as a way to identify a Buteo as a Rough-legged. IT DOESN'T WORK.
To be specific, it doesn't work all the time, which means when you see a hovering Buteo, you have to ask this question: Is this bird a Rough-legged Hawk or a Red-tailed Hawk? I think most birders know that RTs can hang in the wind, but some think the really slow, low, graceful hovering is an RL exclusive. In fact, while in general the two species have their own styles, some RTs can do anything an RL can do.
So employ one of the prime commandments of good birding – don't relay on a single field character. There's a less well-known behavior that birders tend to pick up as their skills are improving. It's something they might share with the less experienced – because RL is lighter, more graceful and smaller-footed that RT, it can easily perch on the tippy-top smallest branches of even a rather modest bush. If you point this out to some awe-struck friends just hope the bird doesn't take off and fly right over you. IT MIGHT BE AN RT. This is another behavior, common among RLs, but well within the RT repertoire. Frank Mantlik told me an RT present at Short Beach and Stratford Point earlier in Jan was very good at this – to the point where he'd had birders tell him they'd just see an RL.
So how to tackle an RL ID? First determine if the bird is a light or a dark morph. If you get to this point, the chances of crossing up RL vs RT are greatly reduced. If you jump on a hovering bird as an RL, with confidence but no other evidence, basic observational psychology comes into play. Instead of critical separating of species, you start to make what you're looking at fit into your preconception. There's probably a fancy psych term for this, but old-time birders called it “going down the rabbit hole.” In 60+ years of birding I've ended up smelling like Cottontail enough to learn some lessons.
Right now in CT we have a few RTs from farther N or W, and without getting into the thorny subject of subspecies it's worth noting that they don't look exactly like our local RTs. This could be enough to start a journey down the burrow.
I'm not going to go over differences in the 2 species in great detail. Careful study of a good field guide (you own a field guide, right?) should show what to look for once you dodge the hover pitfall. To me the best place to look first is the underside of the wings, followed by the tail, and underparts of the body. Then its details, details, details.