88 BULLETIN 86, UNITED STATES NATIONAL MUSEUM. 



Juvenal plumage. — In this plumage both sexes are decidedly 

 lighter and more closely and evenly mottled than in the adult, par- 

 ticularly above. In the male the upper parts are also more uniform, 

 with more ochraceous or gray and less black ; the tail and wing-quills 

 are broadly tipped with buff; the light bars of the tail are more 

 deeply buff ; the white throat-patch is more buffy ; the lower surface 

 duller, more ochraceous, more uniform, less distinctly and less 

 broadly barred. The subterminal bar on the tail is white, about as 

 in the adult. 



The Juvenal female differs from the adult female much as above 

 detailed for the male, but somewhat less so. She is similar to the 

 ]uvenal male, but has the light spot on the primaries smaller and 

 more deeply buff or ochraceous buff, instead of white or slightly 

 buffy ; the light throat-patch more deeply buff, never whitish ; and she 

 lacks the subterminal white bar on the tail. 



Very young birds, both male and female, before they are full 

 grown, are above very pale buff, finely and sparingly spotted with 

 black, and vermiculated with silvery gray ; and below, pale buff, with 

 narrow widely spaced bars of dusky or blackish. 



Nestling plumage. — Upper surface fawn color, clouded or ob- 

 scurely mottled with mars brown ; lower parts fawn color, unmarked, 

 but paling on the median portion of breast and abdomen. 



Seasonal variation. — Of normal seasonal plumage variation not 

 due to molt there is little or none ; what there is consists in the occa- 

 sional browning of the dark areas and the slight reduction of the 

 light markings from abrasion of the feathers. 



Molt. — From the fugitive natal plumage the young bird molts 

 directly into the juvenal plumage, growing the while, so that at least 

 by the time, often before, it has attained full size of body and wings, 

 the juvenal plumage is complete. Then by a practically continu- 

 ous molt, usually in September, it again changes its contour feathers, 

 but retains the remiges and rectrices. The combination plumage 

 of the first autumn is worn apparently until the following summer, 

 when the regular sequence of adult molt is begun. 



The adult of this species molts but once a year, usually between the 

 last of July and the middle of September, most individuals chiefly 

 in August, during which period all of the feathers, including 

 remiges and rectrices, undergo a. renewal. Subsequently, from Janu- 

 ary to July, the plumage becomes increasingly worn each month. 

 Some birds are considerably worn even by January, but, like Chor- 

 deiles virginianus, they rarely, if ever, become badly tattered. 



Individual variation. — ^In all the races of this species there is great 

 individual variation in both size and color. Such differences of size 

 appear in the tables of detailed measurements ; those of color are at 



