Ran across a large dark hawk yesterday. It has the shape of a buteo, underwing pattern resembled that of a Rough-legged Hawk. I've never seen a dark one, although Sibley's states 40% of the Eastern birds are dark. I'm leaning toward Rough-legged Hawk.
I agree, an adult dark-phase Rough-legged. The whitish tail wih a dark subterminal works for this, as does the white patch at the base of the primaries. The one other give-away is the whitish area at the base of the bill, a characteristic that does not show up on adult dark-phase Ferruginous (see attached head close up photo) or Swainson's Hawk. And adult dark-phase Red-tailed Hawks have a red tail... I am still looking for my first sighting of one of these dark-phase RLHA here out west.
Greg
Over here, Rough-legged Buzzards are 100% light, don't think the dark phase has ever been recorded here.
Resin
