1212 U.S. NATIONAL MUSEUM BULLETIN 237 paet 2 



but one of the 14 stomachs, averaging 2.2 adult and 6.9 larval weevils 

 per bird. One bird which had not fed on the weevil was nine-tenths 

 fuU of plant lice, a food item which occurred in 7 of the 14 stomachs 

 and amounted to over 38 percent of the average diet. "Caterpillars 

 were present in five stomachs, forming 7.7 percent. Spiders and 

 miscellaneous beetles were estimated at about 3 percent each, and the 

 remaining animal food was of small quantities under several heads. 

 The vegetable portion (1.1 percent) was entirely weed seeds." In 

 June the sparrows' diet was 64.6 percent weevils and 14.5 percent 

 caterpillars, with again only a trace of plant material. In July weevils 

 composed 44.8 percent of the birds' diet, one individual ha\'ing con- 

 sumed 45 weevils' larvae, but in this month plant material, mainly 

 weed seeds, amounted to about 20 percent of the diet. These indica- 

 tions of a seasonal shift In dietary composition are borne out in a 

 further analysis by Martin, Zim, and Nelson (1951) : in the fall months 

 53 percent of the food was plant material, and in winter, 90 percent. 



Kalmbach also examined the stomach content of three nestlings 

 during June and found that their diet differed little from that of the 

 adults. Other observers have seen only insects being fed to young 

 birds at or near the nest. For instance, Grinnell, Dixon, and Linsdale 

 (1930) noted an adult at Lassen Peak, Calif., carrying large insects to 

 a recently fledged young bird. Isolated observations do not alter the 

 pattern. A single specimen collected among Russian thistles at Flux, 

 Utah, in September 1934, by G. F. Knowlton (1937b) contained 5 

 adult and 21 nymphal beet leafhoppers, 13 seeds, and numerous plant 

 and insect fragments. Stomach analyses of three specimens obtained 

 in summer in northern California (H. C. Bryant, 1911) disclosed that, 

 despite insect abundance, these individuals had fed primarily on weed 

 seeds augmented by a few small beetles. 



J. Grinnell (1914b) notes that birds wintering in the Colorado Valley 

 preferred to feed among the bushes on the desert and only visited the 

 river for water. 



Behavior. — Although Brewer's sparrow is the characteristic bird of 

 sagebrush country, its drab coloration and generally shy manner 

 do not attract much attention. Most observations, which all speak 

 well of the sociability of this small sparrow, have been made on migra- 

 tory flocks, to which attention is dra^vn by group size and vocaliza- 

 tion. Brewer's sparrows have been observed wintering in Texas in 

 the company of white-crowned, black-throated, vesper, and Savannah 

 sparrows (Van Tyne, 1936). A. C. Twomey (1942) records migrating 

 flocks regularly of from 50 to 100 individuals in the Uinta Basin, Utah. 



J. Grinnell (1923b), who considered breweri to be the most abundant 

 sparrow in Death Valley, Calif., records his observations on a transient 

 flock as foUows: "These sparrows showed a great weakness for bathing. 



