BIRDS IN RELATION TO THE ALFALFA WEEVIL. 43 



sections. Being a resident all the year, in early spring it could be 

 found searching diligently over the branches and trunks of cotton- 

 woods or flitting through dense thickets of hawthorn or willows. 

 In such environment it is quite possible for the chickadee to come in 

 contact with hibernating weevils. 



Six birds were collected in April, and the weevil was present in 

 the stomachs of three. Two of these contained 2 adults apiece, 

 while the third had 3, and this food amounted to about 3 per cent 

 of the stomach contents. 



Much of the food of these small birds was very finely divided 

 and in some cases unidentifiable. In three of the six stomachs, how- 

 ever, large numbers of plant lice were detected. Small lepidopterous 

 cocoons also were found. 



Even though the amount of food consumed by one of these birds 

 is small, there is reason to believe that the chickadees secure many 

 of those adults which make their winter quarters in crevices in the 

 bark of trees. 



WESTERN ROBIN. 



{Planesticus migratorius propinquus.) 



The western robin is a resident of parts of the Salt Lake Valley 

 the year round, but in the more exposed situations and in the higher 

 valleys surrounding Salt Lake it is a migrant and summer breeder. 

 In the lower valley it becomes very abundant in April and early May, 

 while a month or two later, though still common, it is most fre- 

 quently found in the shade of orchards or in truck-crop areas, where 

 the more thoroughly watered ground assures it a constant supply of 

 one of its favorite foods — earthworms. In the valley of the Weber 

 the robin was an abundant breeder and a frequent visitor to the in- 

 fested alfalfa fields. 



Forty-five birds were collected in April, but four stomachs, being 

 nearly empty, were not used in the computation. Three of the four 

 stomachs discarded, however, showed traces of the weevil. Of the 

 others, 28 contained the insects, adults in every case, which com- 

 prised a little over 14 per cent of the food. This material gave an 

 average of 5.63 adult weevils per bird. The best individual work 

 done by any robin in this month is credited to a male, which had cap- 

 tured no less than 56 of these insects. Another had eaten upward 

 of 20 1 . 



Caterpillars, many of which were cutworms, were taken with 

 almost as great avidity as the weevil, occurring in 27 stomachs, but 

 the larger size of these insects resulted in a much higher percentage, 

 23.24. One stomach contained at least 90 young caterpillars. Click 

 beetles (Elateridae) and their larvae, wireworms, were found in 18 

 stomachs and amounted to 11.10 per cent of the contents. One bird 



