1914] Bryant: Ecoxaniic Status of flic Western Mcadoirlark 480 



unimportant in another place. Abundance even more than the 

 kind of an insect appears to govern its injurionsness. Hence 

 the direct value of the destruction of certain insects by birds is 

 difficult to estimate. 



The solution of the problem lies in a determination of the 

 comparative abundance of insects. The censuses of birds taken 

 by Forbes (1901) in Illinois have been of incalculable value to 

 ornithologists and everyone regrets the lack of others of the same 

 type. The entomologist has left this quantitative phase almost 

 wholly untouched. Consequently the economic ornithologist, in 

 attempting to determine the good accomplished by birds in de- 

 stroying insects, has no evidence on which he can depend as to 

 the comparative numbers of the insects upon which they feed. 

 The difficulty of obtaining any exact idea of the numbers of a 

 species of insect in the field is very great, but the importance 

 and value of the information will certainly repay effort made 

 in this direction. Economic ornithologists must necessarily await 

 data of this kind before they will be able to point out conclusively 

 the importance to be attached to the destruction of insects by 

 birds. 



In years past we have been wont to judge the value of a bird 

 entirely on its food. The present tendency to regard the food 

 habit as only one of the things to be considered in judging its 

 value is an advance worthy of note. The esthetic value is fast 

 coming to be appreciated by every one. It must certainly be 

 given an important place in any adequate estimate of a bird's 

 value. 



In a broad sense food preference furnishes evidence as to the 

 value of a bird. For instance, a bird that eats insects can be 

 considered of more value to the agriculturi,st than one that sub- 

 sists entirely on vegetable food. To particularize and say that 

 a bird prefers a certain kind of insect is to tread on dangerous 

 ground, for birds appear to be governed more largely by the 

 abundance of an insect than by its taste. The opportunity 

 afforded a bird for obtaining an insect appears to be a stronger 

 factor than memory of a bad taste. Consequently the old idea 

 of food preference must be modified to meet the modern idea of 

 availability as a factor in the kind and quantity of food. 



