S4 BULLETIN 107, U. S. DEPAHTMEHT OF AGRICULTURE. 



BREWER'S SPARROW. 



(Spizella breweri.) 



Brewer's sparrow, or the little sagebrush chippy, as it is sometimes 

 called, has, like several of its close relatives, learned within the past 

 four or five years that alfalfa fields afford an excellent supply of 

 animal food. In some localities during May and June there is little 

 to choose between the merits of this bird and the savannah sparrow 

 as weevil destroyers. . 



Brewer's sparrow does not become abundant until May, and in 

 this month 14 were obtained. Half of these were taken in the season 

 of 1911 when the weevil larva? were well advanced. These insects 

 composed 43.43 per cent of the food, and occurred in all but one of 

 the stomachs, averaging 2.2 adults and 6.9 larvae per bird. Twenty- 

 four larvse was the largest number present in any one stomach. 



The stomach of the bird which had not fed on the weevil was nine- 

 tenths full of plant lice, a food item which occurred in 7 of the 14 

 stomachs, and amounted to over 38 per cent of the food. In one case 

 these insects composed practically the entire contents (97 per cent). 

 Caterpillars were present in five stomachs, forming 7.7 per cent. 

 Spiders and miscellaneous beetles were estimated at about 3 per cent 

 each, and the remaining animal food was of small quantities under 

 several heads. The vegetable portion (1.1 per cent) was entirely 

 weed seeds. 



Each of the 15 Brewer's sparrows collected in June had fed on the 

 weevil. Three were nestlings, but their food differed but little from 

 that of adults. In only one instance did the weevil amount to less 

 than a fourth of the food, while in one it composed the entire stomach 

 contents, 25 larva? being present. Three others were examined in 

 which the weevil formed over 95 per cent of the food, these birds 

 having eaten 17 larvse, 19 larvae and 1 adult, and 28 larva?, respec- 

 tivety. The average of 0.4 adult and 15.3 larvee eaten by these birds 

 totaled nearly two-thirds (G4.6 per cent) of the food. 



Caterpillars superseded plant lice as the next most important food 

 during this month, forming 14.5 per cent of the stomach contents, 

 while the latter amounted to only about half that quantity. Spiders, 

 the only other important component of the animal food, were eaten 

 freely by four birds, giving a percentage of 6.13 for the month. 

 Merely a trace of weed seeds was present. 



In July 13 of the 17 Brewer's sparrows collected had fed on the 

 weevil, but a decrease in the bulk was noted, it composing 44.8 per 

 cent of the stomach contents as compared with 64.6 per cent for June. 

 There was a slight increase in the number of adults eaten (0.6) and 

 a corresponding decrease in the larva? (11.8). The highest number 

 of larva? recorded for an individual of this species is 45. These com- 



