30 



kj 20 



o 



(£ 

 tD 



Ul 

 < 

 kJ 

 < 10 



1 I 



JAN FEB 

 1977 



MAR 



APR 



MAY 



JUN 



JUL 



— I — 



AUG 



SEP 



OCT 



NOV 



DEC 



JAN 

 1978 



Figure 26. 



Monthly changes in average group sizes of mule deer, white-tailed 

 deer, and pronghorn antelope, January 1977-January 1978. 



remain similar to that during spring and summer. During the winter of 1977- 

 1978, concentrations of mule deer occurred in a hilly region between the North 

 Fork of McGuire Creek and Prairie Elk Creek, and in an area of coulees and bad- 

 lands south of Fort Peck Reservoir. Mule deer were not observed on the proposed 

 mining area after December 20, 1977, and winter groups observed in the vicinity 

 remained in rough breaks areas north and south of the proposed mining area. 



Mule deer density estimates were based on winter 1977-1978 aerial survey 

 data. These were the best data available, since snow cover of 95-100%, cold 

 temperatures, and clear skies contributed to good aerial visibility of mule 

 deer during this survey. Minimum population counts of 532 mule deer on the 

 reconnaissance area and 55 on the mine study area were obtained, giving minimum 

 density estimates of 0.10 mule deer/km2 (0.25/mi2) and 0.22 mule deer/km-^ (0.56/ 

 mi2) for the two areas, respectively. Scattered groups were observed in the 

 northern half of the reconnaissance area, giving a minimum density estimate of 

 0.03 mule deer/km^ (0.08/mi2) for this area; the southern half supported more 

 mule deer with a minimum density estimate of 0.16/km2 (0.42/mi ). 



103 



