Vertebrate Fauna of the Pacific Coast 

 cony find their permanent abode. They, with other 

 similarly restricted species, characterize the Alpine- 

 Arctic zone. 



In so brief a portrayal it is practically impos- 

 sible to carry to the reader a satisfactory idea of 

 the facts of zonation as they really are. The trav- 

 eler who goes out to see and learn will quickly 

 secure vivid realization of this order of distribu- 

 tional behavior. 



Now, if one extends his acquaintance to other 

 areas of California he will rarely be at a loss to 

 diagnose any locality as to zone; but minor differ- 

 ences will present themselves, and these will come 

 to link themselves in his mind with differences in 

 humidity, just as the life zones do with temperature. 

 Thus, while wren-tits and brown towhees and wrens 

 and thrashers are to be found in the Upper Sonoran 

 zone of both the Yosemite section and the San Fran- 

 cisco Bay region, the subspecies represented in the 

 two areas are in these cases more or less distinct. 

 Some very different species, too, are severally char- 

 acteristic of the humid divisions of the different 

 zones. These subdivisions of life zones are called, 

 in a restricted sense, faunal areas, some, of weaker 

 peculiarities, subfaunas. 



Then there are still other divisions — associations. 

 In each zone and in each fauna one finds certain 

 types of vegetation and surroundings repeated; for 

 example, stream side, marsh, meadow, brush belt, 

 and forest, with minor variations. In each of these 

 is likely to be found a peculiar set of birds and 

 mammals, adapted to the narrow range of condi- 

 tions imposed. Thus, as will be readily understood, 

 is it possible to designate the range of a bird or a 

 squirrel or even a reptile or amphibian with fair 

 accuracy. For example, the black-footed gray squir- 

 rel belongs to the forest association, to the Santa 

 Cruz subfaunal division of the humid coast belt, to 

 the Transition life zone. 



The fascination attending this study of the geog- 

 raphy of animals lies not alone in the exhilaration 

 of exploring and search for rare specimens through 

 interesting regions, but in the infinite bearing such 

 findings have upon the problems of the origin and 

 behavior of species through both space and time. 



Of the many minor subdivisions of the western 

 United States the most distinctive is that to which 

 the term Californian Fauna may be closely re- 

 stricted. There is apparently no counterpart or 

 analogue on the Atlantic side of the continent. It 

 is an aggregation of animals occupying the vast 

 extent of lower mountain and foothill country of 



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