Wikipedia says that the Rough-legged Buzzard (Buteo lagopus) is called the Rough-legged Hawk in North America:
It is between 50 and 60 centimetres long with a 130 cm wingspan. Its breeding range is northernmost Europe, Asia, and North America, but it migrates further south in winter..
It breeds on cliffs, slopes or in trees, laying about four eggs, but more in good lemming years. It hunts over open land, eating small mammals and carrion. This species, along with the Osprey, is one of the few large birds of prey to hover regularly.
There’s more information and pictures on All About Birds.