30 BULLETIN 107, U. S. DEPARTMENT OF AGRICULTURE. 



eaten 25 or more weevils in one stage or another, and 3 had also eaten 

 a few pupae. 



Of the remaining items of animal food, caterpillars (5.59 per 

 cent), ground beetles (4.2), and Hemiptera (mainly the small cicada, 

 Platypedia putnami) (4.09) were most conspicuous. Weed seeds 

 again were prominent, amounting to 22.3 per cent, while grain 

 formed about 4^ per cent. 



Summary. — Though the individual vesper sparrow is unable to 

 consume as many of the insects in question as some of his larger and 

 more voracious neighbors, as Brewer's blackbird or the robin, its 

 economic relation to the weevil is nevertheless important. During 

 June and July it subsists on the pest to the extent of over half of 

 its food, while from a fifth to a third more is composed- of other 

 equally injurious insects, together with weed seeds. The grain eaten 

 is doubtless mainly waste. These birds, whose natural home is in 

 the dry sagebrush areas, probably are just beginning to discover 

 the food supply obtainable in alfalfa fields. As they become more 

 accustomed to visiting the alfalfa, we may expect them to render 

 still greater service in the suppression of the pest. 



WESTERN SAVANNAH SPARROW. 



(Passerculus sandivichensis alauclinus.) 



The western savannah sparrow is to the average person an incon- 

 spicuous individual in the bird life of Utah, even though fairly 

 abundant in many sections. It is frequently met in the Salt Lake 

 Valley, but is much more common in the valley of the Weber, where 

 in some fields it is the most abundant of the sparrows. 



In May, 1911, seven savannah sparrows were obtained. All but 

 one had fed on the weevil, and this pest composed 72.42 per cent 

 of the stomach contents. The larvae apparently were preferred, for, 

 although adult weevils were common, they occurred at an average 

 of only a little over one per bird, while the larval form was found 

 at the rate of 21 in every stomach. One had eaten no less than 61 

 of the green worms, the highest number recorded for the species. 



The remaining food, which, save a mere trace of rubbish, was en- 

 tirely animal in character, verifies the claim that this bird is one of 

 the most highly insectivorous of sparrows, and that " they take equal 

 rank in this regard with such notable insect destroyers as the cat- 

 bird, robin, and bluebird 'V The food other than weevil was de- 

 cidedly in the bird's favor as a large part was caterpillars, fly larvae, 

 plant lice, and some unidentified coleopterous larvae. 



1 Judd, S. D., The Relations of Sparrows to Agriculture, Bull. 15, Biol. Survey, U. S. 

 Dept. of Agr., 1901. 



