466 Field Museum of Natural History — Zoology, Vol. IX. 



America (Argentine Republic). Breeds nearly throughout its North 

 American range. 



Adult male: Three outer primaries, notched; upper plumage, 

 dark brown, mixed with rufous brown and buff; primaries, dark 



Adult. 



Swainson's Hawk. 



Immature. 



brown, without bars; throat, white; a large rufous brown patch on 

 the breast; belly, buff white or whitish, marked with dusky and ru- 

 fous brown; tail, grayish brown, with indistinct dark bands. 



Adult female : Similar, but has the under marking darker and the 

 breast about the same color as the back. 



Melanistic plumage, male and female: Very dark or blackish; 

 specimens of this species are often taken in which the whole plumage 

 is sooty brown; usually the under tail shows pale rufous or whitish 

 markings, but specimens are common representing innumerable 

 different phases of plumage between the light and dark forms. 



