26 increments of coverage by sagebrush-grassland 

 5 increments of coverage by sagebrush-grassland 



5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 



% of Block Covered by Sagebrush-grassland Habitat 



25% 



26-50 % 



51-75% 



76-100% 



Figure 9.2 



Use of sagebrush grassland type by mule deer 

 in relation to amount of that type per 28.5 ha 

 block. 



types in which mule deer were observed during aerial surveys 

 from July 1978 through April 1980, and block analysis of all 

 aerial observations during 1976-1984 (Table 9.4). 



All 3 methods showed similar use of the pine-juniper 

 types, but use of Douglas fir- juniper types was higher and use 

 of sagebrush-grassland was lower based on direct aerial 

 observations and aerial observations submitted to block 

 analysis than determined by observations along vehicle routes. 

 All 3 methods also indicated that use of sagebrush-grassland 

 was highest and use of Douglas fir-juniper types was lowest 

 during spring. However, both direct aerial observations and 

 the block analysis indicated the highest seasonal use of 

 Douglas fir-juniper types occurred in winter when use as 

 determined by vehicle routes was lowest. Observability 

 differences between timbered and open habitats for vehicle 

 routes and aerial observations must have been important, but 

 some of this difference might have been influenced by winter 

 severity. Approximately 54% of all mule deer observed from 

 the air during the severe 1978-79 winter were in Douglas fir- 

 juniper types compared to only 26% during the relatively mild 

 1979-80 winter. All winters during 1960-1964 were mild and 



250 



