rough-legged hawk

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A large hawk (Buteo lagopus) that breeds in the Arctic and ranges into North America and northern Eurasia. It has whitish feathers covering the legs.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun large hawk of the northern hemisphere that feeds chiefly on small rodents and is beneficial to farmers