290 THE NORTH AMERICAN GRASSLAND 



sonii [Bach.] ) evidently occurred in great numbers, which were fur- 

 ther increased by the destruction of carnivores, especially the coyote, 

 for in 1893 a drive at Fresno resulted in the destruction of 20,000 

 rabbits (Palmer, 1897:51). With a single county as an exception out 

 of a total of ten, all drives were in counties originally containing large 

 areas of climax grassland (see Grinnell, 1933) . 



The California and Fisher ground squirrels {Otospermophilus gram- 

 murus Say, subspecies beecheyi and fisher i) constitute one of the most 

 characteristic species of this grassland, which extends also into other 

 grass-covered areas in the foothills and mountain parks (Grinnell and 

 Dixon, 1918). The seeds of grasses and forbs were probably the chief 

 original foods, and grasses are very largely used in lining nests. ^ The 

 enemies of the abundant animals within this prairie include the rattle- 

 snake {Crotalus confliientus oreganus [Holbr.]), the gopher or bull- 

 snake {PitKophis catcnifer varieties), the red-tailed and red-bellied 

 hawks, the badger, and the coyote. The pocket gopher {Thomomys 

 bottae [E. & G.] in several subspecies) extends throughout the great 

 valley, but is most abundant in the San Joaquin. Kangaroo rats 

 {Dipodomjjs ni'tratoides [Mer.]) are common along the flanks of the 

 upper San Joaquin valley, and the pocket mouse (Perognathus cali- 

 fornicus [Mer.]) is present in the same region (cf. Van Denburg, 

 1922). 



PALOUSE PRAIRIE 



Nature and Extent. This association is characteristic of the great 

 agricultural region of the Palouse, where it occurs in its most typical 

 form. As such, it is found in southeastern Washington, northeastern 

 Oregon, and adjacent Idaho, but its major dominants extend much 

 more widely to reach western Montana and northern Utah. They also 

 form the grassland of northern California and of part of southern 

 Oregon, but yield to chaparral and forest in the region about Mount 

 Shasta, so that there is little or no direct contact between this and the 

 California prairie proper. Owing to the mountain barriers in the east, 

 the transition to mixed prairie is generally rather abrupt, though some- 

 what obscured by the presence of Stipa comata and Agropyrum smithi 

 in both (Fig. 70). 



Climate. Owing largely to the climatic barrier fashioned by the 

 Cascade Range, the Palouse is a region of hot summers and winter 

 snows. Its most distinctive feature is the fact that the bulk of the 



1 This animal is notorious because of its taste for intr. duced agricultural 

 plants and fruits, which it will climb to get, and also because of carrying bu- 

 bonic plague. 



