492 University of California Publications in Zoology [Vol. 11 



worms, caterpillars, wireworms, stink-bugs, and ants, insects most 

 of which are injurious to crops. The vegetable matter is made 

 up of grain and seeds. Grain as food reaches a maximum in 

 November, December, and January, insects in the spring and 

 summer months, and weed seeds in September and October. An 

 average stomach of a western meadowlark contains two and 

 three-fourths cubic centimeters of food. The kind and quantity 

 of food varies with the time of year and locality. 



A study of the relation of birds to insects has shown that 

 birds are important regulators of the numbers of insects for at 

 least two reasons : ( 1 ) the maximum consumption of insects comes 

 during the nesting season of birds, a time when the numbers of 

 insects are at a maximum; (2) birds change their food habits 

 and feed on the insect most available, thereby becoming important 

 balancers during insect outbreaks when insects appear in ab- 

 normal numbers. 



The verdict of ranchers throughout the state obtained by a 

 circular letter has shown that there is a wide difference of opinion 

 as to the extent of damage caused by the western meadowlark. 

 A majorit}^ maintain that this bird does not damage crops and 

 is. therefore, not a nuisance. 



A comparison of the injuries caused by the western meadow- 

 lark with the benefits it confers shows that it does more good 

 than harm, and so merits protection as an insectivorous non-game 

 bird. Crops may be largely protected by drilling grain deeply 

 or by furnishing the birds sufficient food by heavier sowing. 



The examination of so large a number of birds of one species 

 has furnished some interesting side-lights on the investigation. 

 Evidence on such biological problems as parasitism, malforma- 

 tion, albinism, natural death rate, etc., has been made available. 



Protective adaptations of insects do not render them immune 

 from the attack of birds. This investigation has demonstrated 

 the following facts bearing on the relation of birds to insects 

 with protective adaptations : 



1. Protective adaptations of arthropods such as stings, nox- 

 ious secretions, hairs, etc., have been overemphasized as factors 

 protecting the owners from the attack of birds. 



2. The "availability" of an in.sect or arthropod, when this 

 term is made to include the totality of factors governing the 



