380 ROUGH-LEGGED FALCON. 



have beside me specimens in which the colour of the plumage is very dif- 

 ferent, some being quite light, others almost black ; and I feel pretty con- 

 fident that further researches i-especting this species will shew that my 

 opinion is not incorrect, when I say that the Rough-legged Falcon of 

 America and the F.alco niger of Wilson, are the same bird. 



I am of opinion that the reason for which the dark coloured indivi- 

 duals are of much rarer occurrence with us, than the lighter ones, is, that 

 the former being older and stronger birds, are much better able to bear 

 the inclemency of the weather in more northern regions. 



Falco lagopus, Gmel. Syst. Nat. vol. i. p. 260 — Lath. Ind. Ornith. voL i. p. 19 — 

 Ch. Bonaparte, Syiiops. of Birds of the United States, p. 32. 



BuTEO LAGOPUS, Sivains. and Richards. Fauna Bor. Amer. part ii. p. 52. 



KouGH-LEGGED Falcon, Falco lagopus, Wils. Amer. Ornith. vol. iv. p, 59. pi. 33. 

 Fig. 1 Nuttall, Manual, part i. p. 97. 



Middle-aged Male. Plate CLXVL 



Bill short, as broad as deep at the base, which is cerate, the sides con- 

 vex ; upper mandible with the dorsal outline straight and declinate at the 

 base, soon becoming convex, the tip trigonal, descending obhquely, 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 imder 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 ; aU 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 co- 

 vered 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 



