Vertebrate Fauna of the Pacific Coast 

 north, Lower Sonoran, Upper Sonoran, Transition, 

 Canadian, Hudsonian, Alpine-Arctic. The three zones 

 above Transition are often grouped together and 

 spoken of as Boreal, while the two Sonoran are 

 together designated as Austral. The Transition 

 zone, as its name implies, is an area of overlapping 

 and blending of the two main divisions. In a gen- 

 eral way all these zones or belts of animal and plant 

 life exhibit a general east and west trend; but in 

 California, because of the effect of the adjacent 

 ocean, and the great altitude and north and south 

 trend of the mountain ranges, the zones apparently 

 bear little relation to latitude (see life zone map of 

 California, PI. LXIII). 



The extremes of climate are so great within the 

 limits even of California that all six of the zones 

 named are represented within its confines. The 

 traveler who will seize the opportunity, and devote 

 a week or so to a side excursion, may best appre- 

 ciate the fact of the existence of these life zones by 

 journeying up over the crest of the high central or 

 southern Sierra Nevada, In much smaller limits 

 and briefer time the ascent of one of the high 

 mountains of southern California such as San 

 Jacinto Peak or San Gorgonio Peak will serve to 

 demonstrate the same situation. 



A section across the central Sierra Nevada in 

 the latitude of San Francisco will pass through the 

 Yosemite Park. In following the Yosemite Valley 

 Railroad out of Merced the sightseer for the first 

 hour traverses the floor of the San Joaquin Valley 

 toward the foothills. From the train along that 

 section of the route traversing the Merced River 

 bottom he will note Fremont cottonwoods, valley 

 oaks, and planted orchards of fig, olive and orange 

 trees, all indicative of the Lower Sonoran zone. A 

 day put in appropriately at a representative point 

 in this valley area will sliow the presence of mock- 

 ingbirds about the ranches, a peculiarly Californian 

 species of beaver along the river, and many other 

 exclusively warm-belt types of animal and plant life. 



A little above Merced Falls the railroad enters the 

 first foothills of the Sierra Nevada, and concur- 

 rently appear with remarkable abruptness an en- 

 tirely new set of trees and lesser plants accompanied 

 by as distinct a set of birds and mammals. The Upper 

 Sonoran zone has been entered and may be recog- 

 nized in distant view by the presence of the digger 

 pine, the blue oak, and by a host of bushy plants 

 which constitute the chaparral. Some birds which 

 may be seen throughout this zone are: California 

 jay, brown towhee, wren-tit, California thrasher, 



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