120 



THE AMEBIC AN NATURALIST 



[Vol. LI 



closely approximates the summer temperature at from 6,000 to 

 9,000 feet on Mount Shasta and above 7,000 feet on the Warner 

 Mountains. In these three areas, the air is cooler in summer 

 than in the interlying areas and thus better adapted to the finely 

 adjusted requirements of the Oregon jay. Summer tempera- 

 ture, between certain degrees, is one critical factor. 



Three more factors present themselves for consideration in 

 connection with the Oregon jay, those of humidity, rainfall and 

 cloudiness. Humboldt Bay lies in the most humid and continu- 

 ously rainy section of California. Mount Shasta and the War- 

 ner Mountains are relatively arid, the latter most notably so. 

 It would appear, therefore, that humidity, rainfall and cloudi- 

 ness had little or nothing to do with cutting off the range of this 

 bird, though one or other of these factors may have been respon- 

 sible for the very slightly darker tone of color which distin- 

 guishes the coast jays (subspecies Perisoreus ohscuriis ohscurus) 

 from those in the interior (P. o. griseus). But, however this 

 may be, it is clear that temperature must dominate greatly over 

 the three factors named in checking dissemination. 



In summary, we may therefore dispose of the following fac- 

 tors as having little or no effect on the distribution of the Oregon 

 jay as a species : the nature or quantity of its food supply, at- 

 mospheric density and pressure, cloudiness, rainfall, humidity 

 of the air or soil, and winter temperature. This eliminates all 

 but the two factors: shelter of a sort provided by the forest 

 habitat, and temperature of the summer season. 



The Case op the Cony 

 The cony or pika is a mammal represented in California by 

 four quite similar races {Ochotona taylori, 0. schisticeps schisti- 

 ceps, 0. s. muiri, and 0. s. alhaius) , which agree distributionally in 

 occupying a very restricted habitat along high mountain crests. 

 I know of no place in central California where conies range 

 below an altitude of about 8,000 feet, and they range upwards 

 to fully 12,000 feet in the vicinity of Mount Lyell. They thus 

 occupy an altitudinal belt between extremes 4,000 feet apart. 

 With regard to zones of vegetation conies live from considerably 

 below timberline to considerably above timberline. 

 observation shows that their existence is in no way correlated 

 with that of trees or shrubs of any sort. Like their relatives, 

 rabbits, they feed entirely on low vegetation, biennials 



Intended jmM 

 rrelatcd |^^H 

 ves, the J^^H 



