226 BULLETIN 50, UNITED STATES NATIONAL MUSEUM 



BUTEO REGAUS (Gray) 



Ferruginous Rough-legged Hawk 



Adult (sexes alike). — Light phase: Feathers of forehead, crown, 

 nape, and sides of throat with fuscous shaft streaks edged with orange- 

 cinnamon, laterally and basally white producing a distinctly streaked 

 brown and white appearance; in some specimens very little orange- 

 cinnam^on is present on these feathers; scapulars, interscapulars, back, 

 rump, and lesser and median upper wing coverts bright orange- 

 cinnamon to ferruginous, the feathers with very large and conspicu- 

 ous fuscous or fuscous-black centers, these centers largest on the upper 

 back, smallest on the median upper wing coverts; (these dark areas 

 generally smaller in females than in males) ; greater upper wing coverts 

 deep mouse gray becoming browner internally; secondaries and inner 

 primaries deep mouse gray with a silvery bloom on the outer webs, 

 becoming paler, browner and whiter, on the inner webs, the second- 

 aries barred with dusky, the inner primaries less distinctly so; the 

 outer primaries largely immaculate white on the inner webs; broadly 

 tipped with deep neutral gray and with the outer webs deep neutral 

 gray with a silvery bloom; upper tail coverts bright orange-cinnamon 

 to ferruginous barred with fuscous, and white basally; rectrices vari- 

 able, whitish to light neutral gray more or less washed with dull 

 ferruginous and flecked and mottled with ferruginous and deep neutral 

 gray; occasionally the outer rectrices with a small subterminal fuscous 

 shaft spot; sides of face like top of head; chin, throat, and breast white, 

 the breast feathers with cinnamon shaft streaks; abdomen, sides, and 

 flanks white with wavy cross bars of ferruginous and fuscous; thighs 

 deep ferruginous barred with fuscous; under tail coverts white; axillars 

 and under wing coverts mixed white and deep ferruginous; iris clear 

 light yellow; cere, edges of commissure, and feet bright yellow, bill 

 very dark bluish horn; mouth purplish flesh color; livid bluish along 

 edges. 



Adult (sexes alike). — Melanistic phase: Very different from light 

 phase; entire head and body, upper and under wing, and tail coverts 

 deep clove brown to dark sepia, some of the feathers, especially on 

 the throat, breast, sides, and interscapulars edged with cinnamon; 

 remiges as in light phase except that the deep mouse gray is replaced 

 by deep clove brown; tail as in light phase but with the outer webs of 

 the rectrices heavily washed with deep clove brown; soft parts as in 

 light phase. 



Adult (sexes alike). — Rufous phass: Like the melanistic phase, 

 but more reddish; the clove brown replaced by chocolate. 



Immature (sexes alike). — Light phase: Similar to adult but with 

 the entire underparts practically immaculate white; occasional fus- 

 cous subterminal spots on the sides and very small paler ones on the 



