44 



NORTH AMERICAN FAUNA 69 



Measurements in millimeters of 11 male specimens collected 

 during the breeding season on the Coastal Plain are as follows: 

 Wing,3 67.5-72.5 (70.2) ; tail, 46.5-52.0 (49.1) ; exposed culmen, 

 15.0-16.5 (15.3) ; tarsus, 17.0-19.0 (17.8) ; middle toe, 12.5-14.0 



(13.2) . Measurements in millimeters of 10 female specimens col- 

 lected during the breeding season on the Coastal Plains, are: 

 Wing, 66.0-72.0 (69.0) ; tail, 46.5-52.0 (49.4) ; exposed culmen, 

 14.8-16.0 (15.3) ; tarsus, 17.5-19.0 (18.2) ; middle toe, 13.0-14.0 



(13.3) . 



DISTINGUISHING CHARACTERS 



Sexes of the Swainson's Warbler are alike. Upperparts, includ- 

 ing wings, are brown, except the crown which is reddish brown ; 

 underparts are yellowish-white and unstreaked. There is no white 

 in wings or tail. The bill is large, thick at the base, and sharply 

 pointed. 



Similar species, — The Worm-eating Warbler has black stripes 

 on its crown. The Ovenbird is streaked below. Immature Con- 

 necticut Warblers (Oporomis agilis) and Mourning Warblers 

 (Oporomis Philadelphia) in fall plumage have eye rings. 



ADULT PLUMAGE 



The crown of the Swainson's Warbler varies from almost cin- 

 namon to chocolate brown, with a barely distinct buffy median 

 stripe from the base of the culmen through the forehead. There is 

 a white or pale yellowish supercilliary (eye) stripe, a dusky spot 

 in front of the eye, and a brownish postocular streak. The sides 

 of the head are otherwise pale buffy brownish. Back, scapulars, 

 rump, upper tail coverts, tail, and wing coverts are olive brown 

 or olive-grayish brown. Tertials are warmer brown (toward 

 mummy or prouts brown) ; secondaries and primaries are dusky, 

 edged with brown. (The closed wing appears browner than the 

 back). Underparts are yellowish white to nearly plain white 

 (possibly geographic variation), shaded with olive or olive- 

 grayish on the sides. Adults in autumn are indistinguishable from 

 breeding birds. 



The bill is brownish, except the undersurface of the lower 

 mandible, which is flesh colored. The iris is brown. Legs and feet 

 are of a pale (pinkish) flesh color. The culmen is slightly curved, 

 narrowed, and elevated between the nostrils. The foregoing de- 

 scription of plumage and soft parts is partly from R. Ridgway 

 (1902 p. 436-437). 



3 Wing measurements are for the chord, from bend wing to tip of longest primary. 



