This allopatry combined with differences in plumage (see appearance) and, apparently, certain measurements, has been the background for the split, but hard scientific data are presently lacking (AOU).

The rufous-thighed hawk resembles the sharp-shinned hawk, but upperparts are darker, streaking to underparts rufous or dusky, cheeks are typically with a clear rufous patch (occasionally lacking almost entirely) and iris is yellow (contra illustrations in some books).

The great majority of this hawk's prey are small birds, especially various songbirds such as sparrows, wood-warblers, finches, wrens, nuthatches, tits, icterids and thrushes.

Rarely, rufous-thighed hawks will also eat rodents, lizards, frogs, snakes, and large insects.

After hatching, the young are brooded for 16 to 23 days by the female, while the male defends the territory and catches prey.

The rufous-thighed hawk is fairly common (but easily overlooked due to their secretive behavior) and presently considered safe.