1912] Briiaitt : Eclat ion of Birds to a Grasshopper Outbreak 7 



Blackbirds, kingbirds, shrikes, and nieadowlarks appeared to 

 be feeding almost wholly upon grasshoppers, and so must be 

 considered among the most efficient destroyers of these insects. 

 Kingbirds, and shrikes, better known as butcherbirds, were con- 

 stantly seen to catch a grasshopper, carry it to the telephone 

 wires, beat it to pieces, and eat it. The work of these birds 

 and also of blackbirds and orioles was so evident that several 

 ranchers reported these birds as being beneficial in the destruc- 

 tion of grasshoppers. 



Although observation in the field furnishes evidence as to 

 the kinds of birds feeding on grasshoppers, and somewhat as 

 to the quantity consumed, yet stomach examination must be de- 

 pended upon for a verification of the observations made and for 

 dependable evidence as to the numbers of insects taken. Since 

 the mandibles of grasshoppers pass through the alimentary tract 

 undigested, and since they can also be found in the faeces, the 

 number of grasshoppers eaten by a bird is easily determined by 

 counting these hard parts found in the stomach. Some experi- 

 ments with nestling birds, made by me in the spring of 1912, 

 showed the time of digestion in young meadowlarks to be between 

 two and four hours. Young birds were starved for several hours, 

 and then fed on grasshoppers, beetles, etc. After certain periods 

 of time the birds were killed and their stomachs examined. After 

 two hours most of the soft parts of the grasshoppers were di- 

 gested, and at the end of four hours, nothing but a few hard 

 parts remained in the stomach. It was found that it took 

 longer to digest grain. The number of insects found in the 

 stomachs of the smaller birds, at least, represents, therefore, the 

 number eaten by the bird within four hours of the time the bird 

 was killed. Experiments by other investigators have .shown the 

 time of digestion in birds as large as the crow to be a))out the 

 same as that determined by me for the meadowlark. At this 

 rate, the number of grasshoppers destroyed in a day must be 

 at least three times as great as the number found in the 

 stomach. 



Only a few birds of each, species were examined, but even 

 these small numbers should give a fairly accurate idea of the 

 extent to which birds in the infested areas were feeding on 



