298 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



The first nuptial plumage is acquired by a partial prenuptial molt, 

 "which involves chiefly the head, chin and throat and not the rest of 

 the plumage. The black chin is assumed by the male and the forehead 

 becomes yellower by moult, wear removing the edgings everywhere so 

 that the streakings below and the throat become jet-black. Young and 

 old become practically indistinguishable, except that the wings and tail 

 of the young bird will average browner and more worn with the 

 edgings duller." In the female, "the first nuptial plumage differs 

 very little from the first winter, wear bringing out the streaking, 

 while a few feathers are assumed by moult on the chin." 



A complete postnuptial molt occurs in July, producing the adult 

 winter plumage, in which the male "differs somewhat from the first 

 winter, the black of the throat extending uninterruptedly to the apex 

 of the chin, further down on the throat, and in broader stripes on 

 the sides ; the wings and tail are blacker and the edgings grayer, espe- 

 cially on the tertiaries ; the concealed black of the back more extensive. 

 The veiling is conspicuous on the throat." The adult winter female is 

 much like the first winter male, "and may have considerable black on 

 the throat, and even the chin." 



The adult nuptial plumage is acquired mainly by wear, with only 

 slight indications of molt, as in the young bird. Dr. Dwight says of 

 the female : "The adult nuptial plumage is, in extreme examples, hardly 

 distinguishable from the male, but usually the black is much re- 

 stricted and the chin yellow, merely spotted with black." 



Food. — ^We have only scattering reports on the food of the black- 

 throated green warbler. S. A. Forbes (1883) examined the stomach 

 of one taken in an orchard infested with canker-worms in Illinois, 

 and found it to contain 70 percent of these destructive caterpillars, 

 15 percent beetles, 5 percent Hemiptera, and the remaining 10 per- 

 cent Hymenoptera, gnats, coleopterous larvae and mites. Five 

 stomachs of Nebraska birds, collected by Professor Aughey (1878), 

 contained an average of 23 locusts and 21 other insects. Of twelve 

 specimens examined by F. H. King (1883) in Wisconsin, "one had 

 eaten a moth; three, seven caterpillars; one, two diptera; one, six 

 larvae — probably caterpillars; three, eleven beetles; and one, a 

 heteroptera." 



Knight (1908) from Maine writes: "The food consists almost en- 

 tirely of insects, including beetles, flies, moths, spiders, grubs, larvae 

 and in general the sorts of insects found on the limbs and foliage of 

 the various evergreen trees and especially on the pines. Only rarely 

 do they take their prey in the air, preferring to diligently seek it out 

 among the branches and foliage." 



Probably all the items mentioned in the food of the young are also 

 eaten by the adults. Forbush (1929) adds to the list leaf rollers, leaf- 



