INTRODUCTION 3 



selected individuals. Many reptiles were captured by hand, although some 

 of the swifter ones could be obtained only by shooting. 



But the taking of specimens was only one of several lines of activity. 

 The morning of each day was usually spent away from camp observing 

 and making notes upon the various species to be seen — their local distri- 

 bution, forage habits, nesting behavior, and all the other observable features 

 connected with their life histories. Each member of the party carried a 

 notebook (journal) in which the observations of each day were recorded. 

 Notes on the behavior of individual animals were written down usually 

 while observation was in progress, to insure the entry of details with 

 accuracy. When nests, burrows, or other 'workings' were examined, the 

 measurements and diagrams were entered directly in the journal. Censuses 

 were gathered as they were taken, the individuals pencil-checked one by one 

 according to the method described fully elsewhere (p. 22). Photographs 

 were taken of 'associations,' workings, tracks, and nests, and these mater- 

 ially supplemented the written data. 



Limitation of Time 



It became necessary, as in all such undertakings as this, arbitrarily to 

 fix upon a date beyond which no further matter would be incorporated 

 into this report. This date was set as December 31, 1920. Even though 

 important new facts have been reported from the Yosemite region by 

 competent observers since that date, we have forborne inclusion thereof. 

 Inevitably, such additions will continue to be made so long as people with 

 an interest in natural history visit the Yosemite region. The natural 

 history resources will never become exhausted ; and that is one fascinating 

 feature of this field of inquiry. Our efforts, then, have been to assemble 

 all the available information concerning the vertebrate animals of the 

 Yosemite region up to and including December, 1920. 



