FACTORS IN BIRD MORTALITY 



sides in early July when the thistles flourish, are the "thorns 

 in the flesh" — however innocent — of our little dickcissel. I 

 followed a mower in a twenty acre field of clover at the edge of 

 the village one May day and picked up no less than twelve nests 

 with eggs scattered on the ground. 



The prairie horned lark (Octocoris praticola) is another vic- 

 tim of the agriculturist. The first nests of the season are 

 placed in closely cropped pasture land in late March and earlv 

 April. The young 



family is therefore 

 awing before stock 

 is turned into the 

 field. On account 

 of its early nesting 

 date probably 95 

 per cent of these 

 first broods are 

 successfully reared. 

 But woe to the 

 second nests of the 

 season which are 

 placed by the hills 

 of growing corn 

 about the first 

 w e e k in June. 

 Then comes the 

 farmer with h i s 

 plow, and thous- 



sands upon thous- first nest op hoened lark 



ailds OI horned Second nests at hills of corn are nearly all destroyed 



larks' nests are covered up forever. With the third attempt at 

 nesting comes the second plowing and the tragedy is repeated 

 each season with scant hopes of this bird every learning from 

 experience. 



The chipping sparrow will soon become extinct, with the 

 elements as chief factor, unless it learns to build upon stronger 

 foundations. Few of these little unattached homes of hair and 

 grasses can weather a summer wind storm. 



When all the factors of bird mortality and the forces that 

 work against their increase are considered, it is wonderful that 

 we are blessed with any bird life at all. 



