^°^i9i4^ ] Bryant, Birds as Grasshopper Destroyers. 177 



other insect making up a larger percentage of food is the ever- 

 present beetle. 



The individual records of meadowlarks show that the numbers 

 of grasshoppers taken is very large as well as the percentage taken 

 as food. From fifteen to thirty average-sized grasshoppers are 

 usually consumed every four hours. Meadowlarks collected near 

 Stockton, San Joaquin County, March to April, 1911, averaged 

 nearly six grasshoppers apiece, thus showing a daily average of 

 over seventeen. The same birds averaged ten crickets per day. 

 Grain, weed seeds, and other insects made up the larger part of the 

 food. A young meadowlark was fed 28 small grasshoppers (half 

 an inch in length) at one meal. The capacity for the destruction 

 of grasshoppers is therefore very great. The extent to which this 

 capacity is used is dependent on the availability of the insect. 



Such is some of the evidence regarding the destruction of grass- 

 hoppers by birds in California. It allows of the conclusion that 

 birds are really a significant agent in the destruction of these pests. 

 It does not allow of the conclusion that they can be rehed upon to 

 limit their numbers below the point where damage can result, 

 Man demands too great a readjustment of natural conditions to 

 permit of complete dependence on the natural order of things. 

 But because artificial means of controlling insect pests must be 

 used, the value of a knowledge of the interrelations of organisms 

 is in no way lessened. 



In a study of this kind we can at best but discover the more 

 obvious relations between birds and insects. Occasionally we can 

 infer that certain interrelations exist which are not capable of being 

 demonstrated by direct evidence. For instance: The failure of 

 birds to check an insect outbreak after insects have appeared in 

 abnormal numbers is evident to all. The success in preventing 

 insects from becoming abnormally abundant is not apparent. 

 In fact no absolute proof of their good work in this connection is 

 obtainable. It must simply be inferred from data regarding the 

 food of birds and their relation to insects when they appear in 

 abnormal numbers, that the regulative influence exerted at times 

 when normal conditions exist is just as important if not more 

 important than their influence under abnormal conditions. It 

 seems safe to conclude that the regulative influence exerted by 

 birds keeps pace with the fluctuations of insect life. 



