WHITE-THROATED SPARROW 1375 



permanent and do not change from one nuptial plumage to the next. 



Adult white-throats undergo a complete postnuptial molt. The 

 data from banded birds in Algonquin Park suggest that a few birds 

 begin molting in late July, but the majority start in early August. 

 Most adult birds undergo their postnuptial molt at the same time 

 the young go through their postjuvenal molt. As the adult molt is 

 more extensive than that of the immature birds, it extends over a 

 longer period. 



The winter plumage of adult birds differs little from the nuptial 

 plumage except in the head pattern. Some birds retain the white- 

 striped coloration into the winter plumage, but most white-striped 

 individuals tend to have the median crown stripe and posterior super- 

 ciliary line tinged with buff. The plumage in other regions is not 

 changed appreciably. The tan-striped birds show no apparent change 

 in plumages. 



Comparisons of plumages of the white-throated sparrow with those 

 of other related species of Zonotrichia give some insight into the 

 nature of the color polymorphism of the white-throat (Lowther, MS.). 

 Within each of the white-crowned, golden-crowned, and Harris' 

 sparrow groups, the first winter plumages are uniformly colored and 

 characterized by the presence of brown and tan (or gray and tan) 

 and the absence of black and white (or gray) in the head pattern. 

 This is unlike the first winter plumage of the white-throat, which has 

 black as well as tan and brown in the head pattern. Adults of species 

 of Zonotrichia other than the white-throat, and including races of the 

 South American Z. capensis, are typified by a black and white or 

 black and gray head pattern similar to that of the white-striped type 

 of the white-throated sparrow. 



Thus the white-striped color type of the white-throat represents the 

 typical adult nuptial plumage of the species, and the tan-striped type 

 represents the first winter plumage. The coloration of the plumage 

 is unusual for the genus in that it combines the black of the adult with 

 the brown and tan of the typical first winter plumage. The tan- 

 striped adult plumage is, therefore, a retention of the first winter 

 plumage through subsequent molts. 



Food. — White-throated sparrows feed on both plant and animal 

 matter. Sylvester Judd (1901) examined the contents of 217 stom- 

 achs collected during every month except June. From these he 

 reported: 



The food for the year, as a whole * * * consists of 19 percent animal matter 

 and 81 percent vegetable matter. Of the vegetable food, 3 percent is grain, 50 

 percent weed seed, and the remainder chiefly wild fruit * * *. 



Some grass seed is consumed, particularly seeds of such troublesome species 

 as pigeon-grass, crab-grass and other panicums, and Johnson grass. This ele- 

 ment forms about 5 percent of the total food and is taken chiefly during Septem- 



