252 NORTHERN YELLOW-THROAT 



under the genus Geothlypis. The black 'mask' of the males is an unmistakable 

 mark and while this is lacking in the female she possesses enough of the Yellow- 

 throat individuality of manner to be easily recognized in life. 



The form here described under the name brachidactyla includes also the 

 race lately known as Geothlypis trichas trichas from Maryland and southward in 

 the Piedmont region. Birds from this region average smaller and have less 

 yellow on the abdomen than northern examples but as I have elsewhere said 

 (The Auk, Jan. 1907) they do not seem to me to deserve recognition by name, 

 and, furthermore, the name trichas is not applicable to them, but to the race here- 

 tofore known as Geothlypis trichas ignota. Length (skin), 4.50; wing, 2.20; 

 tail, 2.05 ; bill, .42. 



Adult d, Spring. — A broad, black 'mask' across the forehead and on the 

 sides of the head bordered posteriorly by bluish gray; upperparts olive-green 

 with a grayish or a brownish tinge strongest on the hindhead; wings and tail, 

 externally, olive-green without white patches or bars, bend of wing yellow, 

 outer vane of outer primary whitish; throat and breast yellow, belly whitish 

 generally more or less tinged with yellow, sides brownish, under tail-coverts 

 yellow. 



Adult 3, Fall. — Similar to adult <$ in Spring but browner above and on 

 sides, forehead and auriculars more or less tipped with grayish, the gray of 

 forehead and crown tipped with brown. 



Young d 1 , Fall. — With a general resemblance to the adult ? in Fall but 

 with more or less black basally, grayish tipped feathers in the auriculars and 

 below the eye, and, in some specimens, a few in the forehead; lores dusky 

 yellowish. The adult plumage is acquired by partial molt the following Spring. 



Adult 2, Spring. — No black 'mask'; above olive-green washed with grayish 

 or with brownish, brightest on the forehead where sometimes distinctly reddish 

 brown; rump and upper tail-coverts greener; tail and wings, externally, olive- 

 green without white patches or bars, bend of the wing yellow, outer vane of 

 outer primary whitish, eye-ring whitish ; throat and upper breast yellow or yel- 

 lowish in varying amount, belly whitish more or less buffy, sides brownish, 

 under tail-coverts yellowish. 



Adult ?, Fall. — Similar to adult $ in Spring but, browner above, on sides 

 and on belly; throat and upper breast yellower, the yellow washed with buffy. 



Young $, Fall. — Upperparts uniform brownish olive-green; throat faintly 

 tinged with yellow or buffy without yellow; belly whitish washed with buff 

 or yellowish ; sides brownish. Like adult $ in Fall but forehead not noticeably 

 browner than back, throat and upper breast much paler. 



Nestling. — Above olive-brown, browner in some specimens, greener in others 

 wing-coverts tipped with cinnamon; below dusky yellowish olive, belly and 

 under tail-coverts yellower and without dusky wash. 



General Distribution. — Eastern North America. 

 Summer Range. — Eastern North America west to the Great 

 Plains region, north from the northern part of the Austroriparian 

 fauna to Manitoba and southern Labrador. 



