DESERT BLACK-THROATED SPARROW 997 



of Black-throated Sparrows. * * * Next I noticed that the down of 

 nestlings of this species exhibited a similar whitish appearance, 

 and this aroused the idea that both these peculiarities might be 

 responses to some single item in the environment of the bird." Both 

 nest hning and down of this sparrow fall into the hghtest of the 

 categories estabhshed to study this relationship in 15 species of 

 desert buds. J. M. Linsdale concludes birds that nest in exposed 

 situations in hot regions "have pale or paUid nestling plumages and 

 nest Hnings which reflect and counteract the harmful effects of sun 

 rays." 



Plumages. — J. M. Linsdale (1936b) states that "Down on the young 

 birds was white, shghtly grayish, and very buffy". J. A. Allen (in 

 Scott, 1887) describes the juvenal birds thus: "The young in first 

 plumage have the feathers of the breast and flanks narrowly streaked 

 \di\\ dusky, the streaks being most distinct on the breast. The 

 general color of the lower parts differs little from that of the adult." 

 The head and cheek patch are gray to grayish-brown, and there is a 

 prominent supercihary stripe. William Brewster (1882a) adds "back 

 faded brown with shaft-stripes of a darker shade on most of the 

 feathers; wing-coverts and outer webs of inner secondaries, reddish- 

 buff." The outer secondaries are dark, edged with buff'; the pri- 

 maries are dark broAvn. The tail is like that of the adult. Black 

 may begin to appear on the throats of the young birds as early as 

 July, but most of the molt into the adult plumage occurs in the fall. 



In the adult the throat patch and lores are black, and the cheek 

 patch is black shading to gray posteriorly. The white superciliary 

 stripes nearly meet over the bill. A white malar stripe does not 

 quite reach the bill, but is continuous with the white breast. Flanks 

 are gray, tinged with, buff in some specimens. The fore part of the 

 crown is gray, this blending into grayish-brown on the hind crown, 

 neck and back. The upper tail coverts are gray. The \^dng feathers 

 are dark, the secondaries Hned with buff. The tail feathers are 

 black; there is a white stripe on the outer edge of the lateral rectrix, 

 which is white-tipped. There is a trace of white at the tips of the 

 second and sometimes other rectrices, but this is quickly worn off. 

 The coloration of the sexes is ahke. 



Food. — Joe T. Marshall, Jr., writes me that he obtained seeds and 

 "rocks" from the stomach of a specimen taken in Arizona in the fall. 

 Seeds and gravel were similarly found in a bird taken in New Mexico 

 in November. A specimen taken in Janaury in northern Sonora 

 had been eating small seeds. Marshall considers that the species 

 probably eats seeds in the winter and insects during the nesting 

 period. I have often seen adults carrying insect matter toward their 



