xiv INTRODUCTION 



are treated briefly in an Appendix, while no mention is made of 

 accidental visitants or strays from distant habitats. Measure- 

 ments indicate average length of the various species, in many of 

 which there is considerable variation, especially between sexes. 



The student should be familiar with distributional lists of birds 

 of his locality, though the beginner finds the information in such 

 lists largely obscured by the abundance of citations and references 

 which are studiously avoided in the preparation of this book. All 

 such information essential for field work, in addition to original 

 observations, is assembled in " Birds of the Southwestern United 

 States," and great care has been given to further emphasize these 

 data by bold-face type, spacing, and arrangement of text. This 

 will greatly accelerate the progress of the student in field identifi- 

 cation, and in memorizing the following data: 



1. Status of bird: winter visitant; resident; etc. 



2. Approximate abundance when known: rare; common; local; 

 etc. 



3. Associational or Life-Zone distribution: willows; oaks; 

 desert; chaparral. 



4. Diagnostic characteristics or field marks. 



All descriptions are designed for field identification rather than 

 for minute study with skins. Special attention is called to birds 

 which it is practically impossible or very difficult to distinguish 

 satisfactorily in the field, indicating the species with which a 

 given bird may be confused. 



In the popular mind color and size have been the chief diagnostic 

 factors in the identification of birds. As a matter of fact, size is 

 largely relative and is difficult to determine. Color is deceptive, 

 dependent to a large extent upon the light, and is often in areas 

 which are more or less concealed. It is of the greatest importance 

 for the student to note the mannerisms of the bird ; to recognize 

 the family characteristics, as those of the Flycatchers; to look for 

 the shape of bills which will identify insect or seed -eating birds; 

 to associate a bird with its habitat; to make such observations as 

 that the Bush-Tits occur in flocks and the Kinglets singly. It is 

 believed that the pen drawings will serve their purpose in deline- 

 ating patterns and areas of color, in showing bills and the general 

 shape of birds, and in giving the characteristic attitudes which are 



