370 BULLETIN 5 0, UNITED STATES NATIONAL MUSEUM 



KEY TO THE RACES OF PARABUTEO UNICINCTUS 



a. Breast and abdomen uniform dark sooty brown; no white showing on tliese 

 areas. 

 h. Size smaller, wings averaging 330 mm. in males, 347 mm. in females 

 (southeastern United States, eastern Mexico, and Central America). 



P. u. harrisi, ad. (p. 370) 

 65. Size larger, wings averaging 342 mm. in males, 375 mm. in females (south- 

 western United States and northwestern Mexico). 



P. u. superior, ad. (p. 374) 

 aa. Breast and abdomen with at least a little whitish. 



h. Breast and abdomen dark sooty brown, very sparsely streaked with paler 

 (white or buffy) ; rectrices uniform fuscous-black, tipped with white. 



P. u. unicinctus, ad. (extralimital) '^ 

 65. Breast and abdomen with much whitish or buffy streaking; tail not as 

 above. 

 c. All the rectrices grayish brown, conspicuously narrowly banded with 



fuscous-black P. u. unicinctus, juv. (extraUmital) 



cc. The median rectrices, at least, not banded or very faintly so. 



d. Dark, the breast often almost uniformly dark (southwestern United 



States and northwestern Mexico P. u. superior, juv. (p. 374) 



dd. Paler, the breast buff}' streaked with dark (southeastern United States, 

 eastern Mexico, and Central America) P. u. harrisi, juv. (p. 371) 



PARABUTEO UNICINCTUS HARRISI (Audubon) 



Harris's Dusky Hawk 



Adult (sexes alike). — Entire head, nape, scapulars, interscapulars, 

 upper back, throat, breast, sides, and abdomen (but not the thighs 

 or under tail coverts) dark sooty brown to fuscous, usually blacker 

 on the scapulars and upper back than on the head or underparts; the 

 lower back and rump similar but tinged with dark chestnut; lesser 

 upper wing coverts rich chestnut; the median upper wing coverts 

 fuscous edged with chestnut; greater upper wing coverts dark fuscous ; 

 remiges dark fuscous becoming fuscous-black on the primaries; the 

 four outermost primaries with their inner webs emarginated, the fifth 

 slightly sinuated; the fourth primary the longest, then the fifth, the 

 third and sixth about equal, the second slightly longer than the seventh, 

 the first shorter than the ninth; upper tail coverts white, sometimes 

 with concealed fuscous bars or spots; rectrices basaUy white and 

 tipped with white; otherwise black, the lateral rectrices paling very 

 slightly to fuscous on the inner webs; under wing coverts and thighs 

 rich chestnut; under tail coverts pure white; iris hazel brown; cere, 

 lores, and orbit yellow; bill light bluish ash, dusky toward the tip; 

 feet orange-yellow; claws black. 



"^Falco unicinctus Temminck, Planches Col., hvr. 53, 1824, pi. 313 (vicinity 

 of Rio Grande, near Boa Vista, Brazil).— ^l si wr unicinchis Cuvier, Regne Anim., 

 i, 1829, 322. — Morphnus unicinctus Lesson, Man. d'Orn., i, 1820, 90. — Parabuteo 

 unicinctus unicinctus Swann, Monogr. Birds Prey, i, 1925, 162; Peters, Check- 

 Hst Birds of World, i, 1931, 240. 



