2 ANIMAL LIFE IN THE YOSEMITE 



April 26 until July 6. That same year, two brief trips were made into 

 Yosemite Valley, at the end of February and at the end of April. In 1919 

 work in the western part of the region was carried on from May 5 to 27 ; 

 and in 1920 work was in progress there from June 20 until August 11. 



Nine hundred and fifty-seven 'man-days' (one man in the field one 

 day) were put in. The field notes written occupy 2001 pages, and the 

 specimens secured by our regular field men number 4354. The photographs 

 obtained number 700. In addition, as indicated elsewhere, much valuable 

 information and many important specimens were secured from residents 

 in the Yosemite region. 



All the materials upon which, this report is based, including specimens, 

 maps, notebooks, and photographs, are now contained in the Museum of 

 Vertebrate Zoology of the University of California and are the property of 

 the State of California. 



Field Personnel 



Eight different persons participated at one time or another in the 

 field work of the Yosemite Survey; 248 days were put in by Joseph 

 Grinnell, 170 days by Tracy I. Storer, 111 days by Walter P. Taylor, 

 110 days by Joseph Dixon, 103 days by Charles L. Camp, 92 days by 

 Gordon F. Ferris, 91 days bj^ Charles D. Holliger, and 32 days by Donald 

 D. McLean. It should be understood that whatever degree of accuracy 

 and fullness the present report may possess rests upon the diligence, as 

 field collectors and observers, of each and every one of these persons. 



Field Methods 



The general plan of work was much the same at all the collecting 

 stations. It was of course essential, in the interests of truth and scientific 

 accuracy, that many specimens be obtained in order that correct identi- 

 fication of the species might be insured. Hence, each member of the party 

 kept out a line of mouse and rat traps for the capture of the various species 

 of small mammals. These were set in ' likely ' places : along stream banks 

 for shrews ; in runways of meadow mice ; about brush heaps or downed logs 

 for white-footed mice, and so on. Special traps were set for moles, for 

 pocket gophers, and for carnivorous species. These traps were baited the 

 last thing each evening and Avere visited early the next morning so as to 

 collect the animals caught before they might be harmed by sunshine or by 

 insects. Where chipmunks abounded, or ground dw^elling birds w^ere numer- 

 ous, traps were often visited during the day to recover such animals as were 

 caught ; or else the traps were purposely sprung in the morning and reset 

 again in the evening in order to avoid capturing mammals or birds not 

 needed for specimens. Birds were obtained, when necessary, by shooting 



