BIRDS IN RELATION TO THE ALFALFA WEEVIL. 



55 



To the number of weevils destroyed by the young we must add 

 those eaten by the adult birds during this time. As four nestlings 

 appear to be a fair average for a brood, there would be one-half as 

 many adults as young; and although the food of old birds was only 

 about 18 per cent weevils during May, June, and July, it amounts 

 to a considerable quantity in the period that they have young in the 

 nest to feed. 



While the writer does not wish to have too great emphasis placed 

 upon such somewhat theoretical deductions, at least they serve to 

 show, with a fair degree of certainty, what might be expected of such 

 a colony under favorable circumstances. 



ADULT ENGLISH SPARROWS. 



Careful observation shows that adult sparrows are frequent visitors 

 to alfalfa fields. Their visits are most often when there are young 

 to be fed, and at such times the parent birds consume much the same 

 kind of food as their progeny, especially the adult weevil. Fields 

 nearest barnyards, where these birds nest, are benefited most, but 

 numerous cases were observed where the adult birds were traveling 

 considerably over 100 yards to secure the desired food. "Wherever 

 these birds nested in large numbers a more or less regular stream of 

 adult sparrows was observed flying to and from the badly infested 

 portion of some near-by alfalfa field. 



In the two seasons' work 101 stomachs of adult English sparrows 

 were collected, 14 in April, 67 in May, 20 in July, and 3 in August. 



April. — But few adult English sparrows were found in alfalfa 

 fields this early in the season. Breeding and nest building were 

 occupying their time, and they were seldom seen far from farm 

 buildings, where they found ample food in horse droppings and 

 chicken feed. 



Weevils (adults in every case) occurred in 6 of the 14 stomachs 

 and amounted to a little over 1 per cent of the contents. As the 

 entire animal food amounted to but 2.57 per cent, the weevil formed 

 almost half of it. In every case save one, only a single insect was 

 taken, and in that instance two adult weevils composed 10 per cent 

 of the contents. 



The other animal food consisted entirely of dung beetles (Apho- 

 dius). Seeds of such plants as pigweed (Chenopodium) , amaranth 

 {Amaranthus retro flexus) , and filaree {Erodium cicutarium) made 

 up 3 per cent, while the remainder was grain, mostly wheat. 



As these birds were collected in April, 1912, when very inclement 

 weather prevailed, the food was confined almost entirely to that 

 secured about the barnyard. 



May. — The 63 birds taken in May indicate a beginning of the sea- 

 son's work on the alfalfa weevil. Forty-six had feed on the insect, 



