552 BULLETIN 203, UNITED STATES NATIONAL MUSEUM 



He says that those of the upper margin of this area are broadly 

 tipped with pearl-gi'ay, which becomes ashy with wear. "This gray 

 band, posteriorly on the crown, has its feathers tipped with Mars- 

 brown and the basal black gradually diminishes more posteriorly as 

 the extent of brown on each feather increases. There is a yellow tinge 

 in some of the feathers. The width of the band varies greatly. The 

 bright yellow chin is also acquired and young birds and old become 

 indistinguishable." 



The adult winter plumage is acquired "by a complete post-nuptial 

 moult in July and August. It differs from the first winter dress in 

 possessing a complete black 'mask', which includes the forehead, lores, 

 orbital ring and auriculars, only the forehead and the auriculars being 

 slightly veiled. The 'mask' has a distinct cinereous posterior border 

 veiled on the crown with Vandyke-brown. The yellow below is deeper 

 and the brown w\ash on the flanks darker in most cases." He reports 

 that 6 specimens out of 22 in this plumage show a few white feathers 

 in the orbital ring, usually confined to the lower eyelid, and 3 out of 23 

 spring males show the same peculiarity, which seems to be purely 

 individual and possibly peculiar to the younger birds. 



The adult nuptial plumage is "acquired by wear," although he thinks 

 there must be only a limited prenuptial molt, for he examined speci- 

 mens of this species taken eveiy month in the year, but found "only a 

 few young birds showing actual moult in February, March and April." 

 He adds that "the adult nuptial and winter plumages are so extremely 

 similar that wear alone might convert the latter into the former," 

 although even with the large series he examined positive conclusions 

 were not possible. 



In the female "the plumages and moults correspond to those of the 

 male. In juvenal plumage the sexes are alike. In first winter plum- 

 age the female is much browner, the yellow of the lower surface is 

 wholly replaced by buff, and there is no black about the head. The 

 first nuptial dress is assumed by a limited prenuptial moult (some- 

 times suppressed) illustrated by a specimen of February -itli. Later 

 plumages differ little, except in j^ellowness, from the first winter dress 

 and no black is ever assumed about the head." 



Albinistic plumages of the yellowthroat have been reported. 



Food. — In the case of the yellowthroat, as of ether birds which 

 usually inhabit places remote from agricultural areas, no studies 

 based on the stomach contents of a large and representative number 

 of individuals has been made. However, from various field observa- 

 tions and the few stomachs that have been examined we know the 

 yellowthroat is insectivorous in its food-eating habits. In its nesting 

 haunts it has been observed feeding on beetles, grubs, larvae and 

 adults of moths and butterflies, flies, ants, spiders, plant lice, and such 



