1914] Brijatit: Economic Status of the Wcsfcni Mnuhnrtark 487 



yet they are not immune from the attaelc of birds because of 

 such coloration. The fact that protective coloration is of maxi- 

 mum utility to the insect only when it is at rest, and of minimum 

 utility when it is moving or when it is out of its natural haliitat, 

 in a large measure explains the occurrence of these insects in 

 the food of birds. 



Cow-killers (Mutillidae) have been found in several instances. 

 These insects are usually considered as being warningly colored. 

 Were they as abundant as other insects the numbers taken by 

 western raeadowlarks would be insignificant. In that they are 

 not numerous, the fact tliat five stomachs contained them indi- 

 cates that their warning coloration did not protect them wholly 

 from attack. 



It may even be said that certain unpalatable insects are taken 

 as food simply because they are made conspicuous by movement, 

 thus setting up a chain of reflexes in the bird which result in 

 their being eaten. The reflexes set up by the stimulus of the 

 sight of food play an important part in determining the kind 

 and amount of food taken. A bird feeding on grasshoppers 

 would doubtless be more greatly influenced by the sight of another 

 grasshopper than by that of a small beetle or even a cricket the 

 same size as the grasshopper. The psychological process involved 

 in the feeding habit has been little studied. Its importance as 

 a factor suggests this as a fruitful source from which might come 

 illuminating evidence on the problem. 



Availability as a Factor in the Kind and Quantity of Food 

 Western meadowlarks collected in grain fields appear to take 

 as food practically every kind of insect and other arthropod to be 

 found in grain fields. Small size does not govern the kind of 

 food, for one bird was found to have eaten aphids. Nor, on the 

 other hand, does large size preclude attack, for pinicate beetles 

 {Eleodes sp.) are eaten. Insects with stings, such as ants, bees, 

 and wasps, insects with noxious secretions, such as stink-bugs, 

 and even hairy caterpillars are regularly taken as food. The 

 respective quantity of each kind taken appears to parallel their 

 abundance and accessibility. The term avaitabilitij denotes the 



