1912] Bryant: Relation of Birds to a Grasslwppcr Outbreak 15 

 Western Me.vdowlark 



Average no. of Total 

 Number Aniaml ^'egetahle grasshoppers per cent 



birds Date food food per bird grassiloppers 



10 July 11, 22, 1011 99.0 1.0 7 83.1 



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



BicoLORED Red-wing 

 6 June 22; July 6, 1911 83.5 16.5 2 37.0 



4 July 13-16, 1912 96.0 4.0 9 81.2 



ileadowlarks took very nearly the same percentage (99, 99.2) 

 of animal food each year, showing that at this time of year the 

 bird is almost wholly insectivorous. The availability of grass- 

 hoppers as a diet appears to have influenced the birds taken in 

 1912, for they averaged sixteen grasshoppers apiece as against 

 seven taken by birds collected in 1911. A greater difference in 

 kind of food is to be noted in the case of the red-winged black- 

 birds. The number of grasshoppers taken per bird is compara- 

 tively smaller than in the meadowlark. as is also the percentage 

 of food made up of these insects. 



As the numbers of grasshoppers in 1911, compared to the 

 numbers in 1912, is not definitely known, it is impossible to 

 state whether these birds changed their food habits in response 

 to the extreme availability of the insect in 1912. It is also im- 

 possible to state whether the numbers taken in 1912 were in 

 direct proportion to the numbers taken in 1911 or whether they 

 failed to respond to the change in insect population. The fact 

 remains, however, that meadowlarks and red-winged blackbirds, 

 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 beetles 

 and weed seeds, thus causing an increased percentage of grass- 

 hoppers to be taken as food. The direction of the change in 

 food habits was, however, coincident with that in food supply. 



A considerable percentage of the food of insectivorous birds 

 each year is made up of grasshoppers. This shows that grass- 

 hoppers are taken as food when they are in small numbers as 

 well as when they are extremely abundant. Even though it be 

 found that the proportion which this particular kind of food 



