10 University of California Publications in Zoology [Vol. 11 



Class A represents birds taking an average of over 50 grass- 

 hoppers per day; class B, 25-50; class C, 10-25; and class D, 

 fewer than 10 grasshoppers. 



The comparative numbers of the different species of birds 

 were calculated by averaging the two censuses taken in the in- 

 fested area, and using the average per square mile as a multi- 

 plier. Although the table is probably far from accurate, yet it 

 gives some idea of the comparative destruction afforded by the 

 different species, and so its use here seems justified. It will be 

 noted that such birds as the red-winged blackbird and the 

 meadowlark, birds of small capacity, far outrank in destructive- 

 ness birds with larger individual capacity, because of their 

 greater numbers. The total destruction caused by the bird popu- 

 lation known to feed on grasshoppers must be 120.500 per square 

 mile per day at the minimum. 



In the cultivated districts western meadowlarks were very 

 abundant. It was estimated that they averaged from two to the 

 acre in some places, to ten or more in more favorable localities. 

 In alkali pasture land far from water, they did not average more 

 than one or two to the square mile. The stomachs examined 

 showed an average of sixteen grasshoppers per stomach, and 

 one bird had eaten at least twenty-five. On the average, a 

 meadowlark must have consumed at least fifty grasshoppers a 

 day. That means that theoretically a single bird, if it were 

 possible, would clean up about three square yards of the worst 

 infested areas a day, and nearly five square yards in the least 

 infested areas where damage was not serious. 



If the infested areas averaged four meadowlarks to the acre, 

 it would take these four birds 406 days to destroy every grass- 

 hopper on that acre, assuming no increase in the number of 

 insects. At this rate it can be seen that meadowlarks are un- 

 able, and even the whole present bird population, wholly to pre- 

 vent or control such an outbreak, even though the number of 

 insects consumed is very large. And yet the numbers destroyed 

 meant a diminution of the infestation and therefore a diminution 

 of the damage done. 



The bicolored red-wing was the bird most abundant. Large 

 flocks of from one to four hundred individuals were often seen 



