48-61 cm (19-24") Fairly common. Breeds in far north, winters south in open country.
Large hawk. Tail and wings are longer than most buteos. Highly variable.
Light phase: more common light phase is dark brown above with a light head and underparts except for dark belly band and black at bend of wings; white tail with dark terminal band.
Dark phase: all dark except for base of tail and underside of flight feathers. Often hovers.
Song: thin whistle.