Rough-legged Falcon, Falco lagopus, Wils. Amer. Ornith. vol. iv. p. 59. pl. 33. Fig.1.—Nuttall, Manual, part i. p. 97.
Middle aged Male. Plate CLXVI.
Bill short, as broad as deep at the base, which is cerate, the sides convex; upper mandible with the dorsal outline straight and declinate at the base, soon becoming convex, the tip trigonal, descending obliquely, acute, the sharp margin undulated and perpendicular; lower mandible with the back convex, the edges sharp, arched, and inflected, the tip obliquely truncate. Nostrils large, subovate in the fore and under part of the cere. Head rather large, broad, neck of moderate length, body robust. Feet short, robust; tarsi roundish, feathered; toes short, and rather small, hind toe and inner strongest and nearly equal, the latter connected with the middle at the base by a short membrane, the outer smallest; all with four transverse scutella at the end, the rest of their upper parts covered with very small hexagonal scales; claws compressed, strong, curved, acute, flat beneath.
Plumage ordinary, soft beneath. Space between the bill and eye covered with bristly feathers, the bases of which are furnished with short barbs. Feathers of the head and neck lanceolate, of the back and breast broad and rounded, of the legs short and narrow, excepting the external tibial, which are long and rounded. Wings long, third quill longest, fourth almost equal, second shorter than fifth, first very short; first four abruptly cut out towards the end on the inner web; secondaries broad and rounded. Tail rather long, broad, rounded.
Bill dull bluish-grey, black at the end. Iris hazel, projecting part of the eye-brow greenish-blue, cere yellow. Toes yellow, claws black. Bases of the black bristles of the lore whitish. The head and neck are streaked with umber-brown and yellowish-white, the centre and tip of each feather being of the former colour. Back umber-brown, variegated with light reddish-brown and yellowish-white. Quills dark brown towards the end, the outer webs of the first six tinged with grey, the base of all white, that colour extending farther on the secondaries, of most of which, and of some of the primaries, the inner web is irregularly barred with brown. Upper tail-coverts white, irregularly barred with dark brown. Tail white at the base, brown and mottled towards the end, with a broad subterminal bar of brownish-black, the tips brownish-white. Middle and hind part of the thorax, with the sides blackish-brown. Breast yellowish-white, largely spotted and blotched with umber. Feathers of the legs paler yellowish-red, barred with dusky; abdomen yellowish-white, as are the under tail-coverts, which are marked with a small brown spot.
Length 22 inches, extent of wings 4 feet 1 inch; bill along the back 1⅜, along the edge 1 7⁄12; tarsus 2 11⁄12.
The Female agrees in colouring, but is considerably larger.
The old bird, which has a very different look as to colour, has been noticed or described under different names.
Black Hawk, Falco Niger, Wils. Amer. Ornith. vol. vi. p. 82. pl. 53. fig. 1.