The Collaborative International Dictionary of English v.0.48:

Roughleg \Rough"leg`\, n. (Zool.)
   Any one of several species of large hawks of the genus
   Archibuteo, having the legs feathered to the toes. Called
   also rough-legged hawk, and rough-legged buzzard.
   [1913 Webster]

   Note: The best known species is Archibuteo lagopus of
         Northern Europe, with its darker American variety
         (Sancti-johannis). The latter is often nearly or
         quite black. The ferruginous roughleg (Archibuteo
         ferrugineus) inhabits Western North America.
         [1913 Webster]