If further study of the effects of livestock grazing on 

 deer in this environment is desirable, it might require that 

 1 large study area (150-250 km 2 ) be established with no 

 livestock grazing in order to compare mule deer habits and 

 population trend in the absence of livestock grazing with data 

 from grazed systems . 



Because cattle may displace elk to some extent (Campbell 

 and Knowles 1978) and diets of mule deer and elk overlap more 

 closely than diets of mule deer and cattle (Mackie 1970), elk 

 may potentially compete with mule deer. However, increasing 

 numbers of elk in recent years did not keep the mule deer 

 population from increasing as well (Fig. 9.11). During 1960- 

 63, Mackie (1970) estimated by unduplicated counts from the 

 ground and air that a maximum of about 100 elk used the area. 

 Aerial counts during winter from 1963 to 1975 ranged from 5 to 

 136 elk, indicating little change in the elk population from 

 around 100 elk during the period 1960-1975. Numbers remained 

 relatively stable through 1979, after which the number of elk 

 on the study area increased steadily until an average of 306 

 elk used the area for the combined autumn, winter and spring 

 seasons by 1986 (Fig. 9.11). Average numbers for the 3 

 seasons were used to represent elk populations because many of 

 the highly mobile elk do not remain within our study area 

 yearlong. In recent years, the number of elk using the area 

 has increased from autumn through spring. During 1986-87, 169 

 elk were counted during autumn, 334 during winter, and 415 

 during spring. During 1976-83, when counts were also made 

 during summer, elk numbers on the area were generally higher 

 during summer than in any season except spring. 



The mule deer population reached 2 succeeding all time 

 peaks despite a 3-fold increase in elk numbers over 20 years. 

 More elk were on the area during spring 1987 than mule deer 

 during the low in spring 1976. To this point, increasing 

 numbers of elk have not resulted in declining mule deer 

 populations. We do not know, however, if the mule deer 

 population increase would have been greater if no elk were 

 present or if an increase in elk numbers beyond current levels 

 will affect mule deer populations. Given the reduced hunting 

 pressure on female mule deer and the broad environmental 

 fluctuations since the mid-1970s, we can determine no 

 significant impact on mule deer populations attributable 

 unequivocally to competition with cattle or elk. Certainly, 

 major changes and trends in mule deer numbers during 1960-1987 

 did not appear significantly affected by competition with 

 cattle or elk. 



273 



