204 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I50 



BUTEO PLATYPTERUS PLATYPTERUS (Vieillot): Broad- winged Hawk; 



Gavilan de Paso 



Sparvius platypterus Vieillot, Table Encycl. Meth., Orn., vol. 3, 1823, p. 1273. 

 (Philadelphia, Pennsylvania.) 



A medium-sized, heavy-bodied hawk; adult with side of head, 

 f oreneck and upper breast cinnamon-brown ; immature white under- 

 neath streaked with grayish brown. 



Description. — Length 340 to 410 mm. Adult, above grayish brown 

 to dull black, the feathers edged lightly with grayish white to 

 cinnamon-buff ; forehead and lores white ; crown feathers edged 

 lightly with dull white ; nape with concealed feather base white ; pri- 

 maries and secondaries tipped lightly with dull white; upper tail 

 coverts and lateral rump feathers tipped and barred broadly with 

 white; tail blackish brown to black, with two broad bars of grayish 

 white, a grayish brown band near the end and white tip; side of 

 head below eye blackish, edged with light gray, becoming browner 

 over the ear region, and continuing thus down the side of the neck ; 

 throat white to huffy white streaked with dull black ; under tail coverts 

 white to buff, immaculate or lightly marked with light brown; rest of 

 lower surface, including the feathered part of legs, banded 

 irregularly with broad marks of wood brown, edged somewhat with 

 dull gray and white ; under wing coverts buffy white, marked lightly 

 with light brown, with the longer, outermost feathers tipped and 

 barred lightly with grayish and brownish black ; under wing feathers 

 white, becoming gray and finally black at tips of primaries; under 

 surface of secondaries barred with dark gray and wood brown. 

 Some individuals are whiter below and blacker above, and some 

 browner above and below, with others in intermediate stage between 

 these two styles. 



Immature, blackish brown above, with the partly concealed feather 

 bases white so that this lighter color appears abundantly in spots and 

 streaks ; below white to buffy white, streaked lightly to heavily with 

 brownish black ; under wing surface whiter than in the adult. 



Rarely an individual shows a dark phase that is almost black, so 

 that it resembles the short-tailed hawk, but may be told by the smaller 

 feet, with the middle toe without the claw shorter than the bare 

 portion of the tarsus in front. 



Measurements (from Friedmann, U. S. Nat. Mus. Bull. 50, pt. 10, 

 1950, p. 309).— Males, wing 244-277 (262.8), tail 148.0-173.5 (159), 

 culmen from cere 17-20 (18.2), tarsus 57.5-65.5 (62.3) mm. 



Females, wing 265-296 (282.8), tail 155-185 (171), culmen from 

 cere 17.1-20.5 (19.3), tarsus, 59-66.4 (62.8) mm. 



