326 University of California Publications in Zoology [ V L - 16 



be said also that the winds of the prairie area are probably less strong 

 than those of the sagebrush area. 



Climatological data from the Blue Mountains is very scanty and 

 consists only of records of precipitation at two stations on the lower 

 ridges. It is evident that the precipitation is very much higher on 

 these ridges than in the prairie area. The temperature of the area is 

 considerably lower than in the adjacent areas, but no definite records 

 could be obtained. There is a much greater snowfall in the mountains 

 than in the lower country and the snow lies on the mountains all winter 

 and often until late in the spring. 



INFLUENCE OF ARTIFICIAL CONDITIONS 



The animal habitats of southeastern Washington have been greatly 

 altered by the work of man. Farming is extensively carried on and in 

 the prairie area a very large percentage of the land is under cultiva- 

 tion. Irrigation is also practiced in the valleys of both the prairie and 

 sagebrush areas. All of the land not under direct cultivation has been 

 heavily grazed by cattle and stock. Part of the timber along the 

 streams has been cut down and much of the brush has been cleared 

 away. Houses have been built and shade trees planted in places 

 where formerly no trees grew. In the Blue Mountains there have 

 been many destructive forest fires and much timber has been cut. In 

 the region it is now difficult to find an area of any size which shows 

 the primitive conditions in completeness. 



These changes in the environment have caused great changes in the 

 abundance of the different species of vertebrates. Some species are 

 greatly reduced in numbers or have been exterminated in the region ; 

 others have held their own or have increased to some extent. The 

 species of the open fields have probably suffered most by the occupa- 

 tion of the region by man. Extensive hunting has operated to reduce 

 in number or exterminate some of the game animals. On the other 

 hand, a few game species have been intentionally introduced by man, 

 and a few obnoxious species have been unintentionally introduced. 



