PREFACE 



The national parks of America render as their most important seiTice a full 

 free opportunity to all who will to find in them a complete recreation, physical, 

 mental, esthetic. In performing this service the animal life existing within their 

 borders constitutes a valuable asset. For the best recreative forces in nature are 

 those which ser\'e most quickly to call into play latent or seldom used faculties 

 of mind and body whose exercise tends to restore to normal balance the human 

 mechanism that has been disturbed by special or artificial conditions of living. 

 Foremost among these forces are the living things that move and utter sounds, 

 exhibit color and changing form, and by these qualities readily attract and fix 

 our interest. To seek acquaintance with those primal objects of interest is to 

 know the joy of vigorous muscular activity; better still, it is to realize the pos- 

 session of the generally neglected senses of far-seeing and far-hearing, and to 

 invite an esthetic appeal of the highest type and an intellectual stimulus of infinite 

 resource. 



Of the thousands who each year visit the Yosemite Valley and its environs, 

 a certain proportion are already interested in natural history; and anyone who 

 leaves the region without gathering some definite knowledge of its natural history 

 has failed to get adequate gain from his opportunities. The geology, topography, 

 and botany of the Yosemite have been studied with some care; and there are 

 instructive and stimulating manuals available dealing with these subjects. But 

 heretofore only a few brief accounts have appeared in print concerning the bird 

 life of the region, and practically nothing has been made available regarding its 

 mammals, reptiles, and amphibians. It was in an effort to supply this deficiency 

 that a survey of the vertebrate natural history of the Yosemite region was under- 

 taken by the California Museum of Vertebrate Zoology. The present volume deals 

 with the results of that survey. 



The principal objects in view in undertaking the survey were: To find out 

 what species of mammals, birds, reptiles, and amphibians exist, or have within 

 modern times existed, in the circumscribed area selected for study; to learn as 

 much as possible concerning the local distribution of each of these species, and 

 to map out the general life areas within the region; to learn as much as time 

 permitted of the food relations, the breeding habits, and the behavior, individually, 

 of each of the species; and finally to put all this information on permanent record, 

 in a form accessible to, and generally assimilable by, the public, both lay an<l 

 scientific. 



In attempting the achievement of this last aim the authors have brought 

 together their materials with every precaution to insure accuracy of fact and 

 correctness of inference. No sacrifice of precision has been made consciously with 

 the end merely of affording 'attractive reading.' At the same time, technical 

 terms, where the same ideas could be expressed in words familiar to every reader 

 of fair education, have been avoided. Ideally, we have tried to present our science, 

 perfectly good science, in straightforward, readable form. 



Joseph Grinnell. 

 Tracy Irwix Storer. 

 Berkeley, July 6, 1922. 



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