Closely allied to the true Buzzards are the Rough-legged Buzzards (Archibuteo), which differ in having weaker bills and feet and with the tarsus densely feathered in front to the base of the toes. They are as large as, or slightly larger than, the largest Buteos, and although numbering only four species, are widely spread over both the Old and New Worlds. The American Rough-legged Hawk (A. lagopus sancti-johannis) is one of the largest ” as well as one of the most striking of American Hawks.” It is about twenty-four inches long, irregularly varied above with white, grayish, and dusky, and whitish below, spotted, chiefly on the breast, with dusky, but sometimes nearly uniform black. It is, says Fisher,”one of the most nocturnal of our Hawks,and may be seen in the fading twilight watching from some low perch, or beating,with measured, noiseless flight, over its hunting ground. It follows two very different methods in securing its food, one by sitting on some stub or low tree and watching the ground for the appearance of its prey, as the Red-tail does;the other by beating back and forth just above the tops of the grass or bushes,and dropping upon its victim, after the manner of the Marsh Hawk. Its food consists principally, if not almost exclusively, of the smaller rodents, and most prominent among these are the arvicoline mice and lemmings.” It is found throughout the whole of North America, but breeds mainly to the north of the United States, where Richardson speaks of it as hunting for its prey “by the subdued daylight which illuminates even the midnight hours in the high parallels.”
Its return from the north is forced rather by the advancing snow than by the cold, which it appears well able to withstand, and in spring it begins the return journey in February and early March. The nest is placed in trees or on ledges, and is made of small sticks and twigs, and lined with fine grass and feathers. From three to five eggs constitute a set, these being greenish white, which fades to a dull white, and very variously marked. In the western United States this is replaced by the Ferruginous Rough-leg or Squirrel Hawk (A. Ferrugineus), which is much larger and has a larger and stronger bill, and is much more rusty in coloration, with the under parts mostly pure white. This Hawk is preëminently a bird of the prairie, and is styled by Dr. Coues ” the handsomest of the North American Falconidoe.” It nests usually in trees, or where these are not available, on rocky ledges, building a rather bulky nest which is lined with weeds or grass. The ribs and smaller bones of the buffalo, where these existed on the plains, were sometimes used for the main part of the nest. The eggs three or four in number are similar to those of the last species.
The remaining species are the European Rough-leg (A. Lagopus) of the western portions of the Eastern Hemisphere, and the Himalayan Rough-leg (A. Strophiatus) of Nepal and Tibet.