1914 J Bryant, Birds as Grasshopper Destroyers. 173 



relatively normal numbers and when they were in abnormal num- 

 bers. A glance at the following table will show the percentages of 

 the different kinds of food taken and the average number of grass- 

 hoppers taken per bird. 



COMPARATIVE DESTRUCTION OF GRASSHOPPERS IN TWO 

 SUCCESSIVE YEARS. 



Western Meadowlark. 



Per cent Per cent Average number Total 

 Number of animal vegetable grasshoppers per cent 



birds Date food food per bird grasshoppers. 



10 July 11, 22, 1911 99.0 1.0 7 83.1 



5 July 15, 17, 1912 99.2 .8 16 96.2 



BicoLORED Red-wing. 



6 June22; July6, 1911 83.5 16.5 2 37.0 

 4 July 13, 16, 1912 96.0 4.0 9 81.2 



Meadowlarks took very nearly the same percentage of animal 

 food each year, showing that at this time of year the bird is almost 

 wholly insectivorous. The availability of grasshoppers as a diet 

 appears to have influenced the birds taken in 1912 for they averaged 

 sixteen grasshoppers apiece as against seven taken by the birds 

 collected in 1911. A greater difference in kind of food is to be 

 noted in the Bicolored Red-wing. 



As the number of grasshoppers in 1911 compared to the number 

 in 1912 is not definitely known, it is impossible to say whether 

 these birds changed their food habits in direct proportion to the 

 number of grasshoppers or whether they were taken in an unequal 

 proportion due to the extreme availability of the insects in 1912. 

 The fact remains, however, that Meadowlarks and Bicolored Red- 

 wings, and probably all other insectivorous birds, not only took 

 greater numbers of grasshoppers when they were abnormally 

 abundant, but also forsook certain usual articles of diet such as 

 weed seeds and beetles, thus causing an increased percentage of 

 grasshoppers to be taken as food. 



One of the most interesting things which came out in the investi- 

 gation at Los Banos was the evidence that at least one of the 



