THE VERTEBRATE FAUNA 

 OF THE PACIFIC COAST 



BY JOSEPH GRINNELL 



Director, Museum of Vertebrate Zoology, 

 University of California 



THE observant traveler has in one respect a 

 distinct advantage over the resident naturalist: 

 the traveler is enabled to secure first impres- 

 sions in rapid succession of the conspicuous pe- 

 culiarities of the various regions through which he 

 passes; in other words, even though his survey may 

 be extremely superficial, many facts having to do 

 with variation in faunal complexion from place to 

 place are borne in upon his senses as they certainly 

 never can be upon those of the sedentary naturalist. 



The vertebrate fauna of the Pacific Coast region 

 of North America shows wonderful variation often 

 within limited space. The tourist reaching the 

 Pacific Coast for the first time across any one of 

 the transcontinental routes from the East will be 

 astonished at the great and abrupt changes in evi- 

 dence in the flora as he emerges from the interior 

 desert tracts toward the seacpast. No less striking 

 are the abrupt transformations in faunal com- 

 plexion. 



Roughly speaking, there are two main inter- 

 secting division lines in faunal demarkation: the 

 one shows a general east and west trend, though 

 tortuously diverted along mountain ranges, and 

 divides the Pacific Coast area into a northern or 

 Boreal region and a southern or Austral region, 

 evidently having to do with temperature; then there 

 is a north and south dividing line which separates 

 the region into a Pacific Coast strip, of obviously 

 humid climatic conditions, and an interior, much 

 more extensive area, conspicuously arid. Corre- 

 lated with the quadrants thus roughly designated 

 are four major sets of animals, each one of which 

 possesses a greater or less proportion of peculiar 

 specific, generic, or even family types. 



The student of faunistics in the West is, how- 

 ever, soon impressed with the fact that there is really 

 no such simple situation as above indicated. The 

 broken topography, with lofty elevations, and the 

 long coast line extending from the latitude of Sitka, 

 far up in the belt of the prevailingly westerly winds, 

 to the horse latitudes of Lower California, consti- 

 tute some of the important factors which lead to 



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