INTRODUCTION xv 



often wretchedly incorrect in mounted birds. The traditional 

 demand for color plates will be less insistent when other diag- 

 nostic factors than color are given the importance which should 

 be assigned to them. 



Relative abundance of birds is obviously a fluctuating quantity. 

 The Red-bellied Hawk, formerly plentiful in willow timber of 

 southern California, now, with the cutting of willows and killing 

 of hawks, is almost extinct. Changes produced by the develop- 

 ment of the country ' increase in population and in number of 

 hunters, and extension of agricultural areas have in many cases 

 greatly altered relative numbers of individuals. The draining of 

 lakes has wiped out whole colonies of birds, while, on the other 

 hand, construction of reservoirs in the interior has led to rapid 

 local increase in the bird population. 



It is hoped that the student will regard the identification of a 

 bird as but the first introduction which will lead to a growing 

 intimacy. There is keener pleasure as well as greater scientific 

 value in knowing a few birds well than in habitually striving for 

 long lists and seeking rarities and doubtful records. 



