Notes on the Plumage of North American Birds 331 



and female of this species, that of the latter being considerably duller, with, the 

 upper parts, especially the crown, washed with bronze or brownish. 



The nestling plumage is much like that of the Tree Swallow and conse- 

 quently is quite unlike that of the adult. From the young Tree Swallow the 

 young Violet-green may be known chiefly by a patch of white on the flanks and 

 by the less abrupt definition of the white of the underparts from the brownish 

 of the upper parts on the sides of the head and neck. But these differences are 

 not sufficiently pronounced to distinguish the two in life. 



A specimen taken in New Mexico, October 11, is undergoing a complete 

 molt which apparently would have brought it into the plumage of the adult 

 in winter. This differs from that of the adult in summer (as does that of the 

 Tree Swallow) in having the tertials tipped with white, a marking which dis- 

 appears with wear. 



Tree Swallow (Iridoprocne bicolor, Figs. 4, 5). — There is practically no 

 sexual difference in color in the Tree Swallow, but the nestling plumage (Fig. 5) 

 is strikingly unlike that of the adult. The upperparts and tail are dull sooty 

 grayish brown, usually without a trace of the iridescent bluish green so con- 

 spicuous in the adult; the wings are of much the same color but show greenish 

 reflections ; the underparts are slightly duller, less silky white than in the adult. 



The birds begin their migration in this plumage, but, as Dwight has shown, 

 between the latter part of August and October a complete molt occurs in which 

 the young bird assumes the plumage of its parents. 



There is no spring molt, and the summer plumage differs from that of winter 

 only in the absence of whitish tips to the tertials. 



Rough-winged Swallow {Stelgidopteryx serripennis, Fig. 6). — There is no 

 sexual difference in color in this species, but the young in juvenal plumage 

 differ from their parents in being washed with rusty, this color being clearer 

 on the wing-coverts and margins to the inner wing-feathers and pronounced on 

 the throat and breast, which are almost cinnamon. 



i'The post-juvenal molt doubtless occurs, as Dwight remarks, after the birds 

 leave us and are traveling to their winter homes in Central America. It brings 

 the bird into the plumage of the adult, which exhibits no seasonal variations. 



The adult Rough-wing somewhat resembles a young Tree Swallow in 

 general coloration but is duskier below, especially on the breast. 



Bank Swallow (Riparia riparia, Fig. 7). — The Bank Swallow is found in 

 both the New World and the Old. The sexes are alike, and there is 

 but Httle variation with age. The nestling plumage differs from that of the 

 adult in being slightly tipped with brownish or grayish above, in having the 

 throat more or less spotted with dusky and the tail squarer. 



This plumage is worn until after the bird leaves us for its winter quarters 

 in the tropics, and is replaced, before the birds' return to us, by one resembling 

 that of the adult. The adults also molt after leaving us, and the slight differ- 

 ences between winter and summer plumage are doubtless due to wear. 



