36 



Mule deer observations per hour of aerial survey (Table 2) 

 show December to have the greatest concentrations of the five 

 complete seasons. The fall, winter and spring 1980 seasons had 

 similar indices of relative abundance (Odum 1959) with a rancje 

 of only 3.0 deer observed per hour. This reflects the relatively 

 mild weather conditions prevalent during the 9 month period. 

 The increased number observed per hour in the 1981 summer season 

 over the I98O summer season, a 7^.^^ increase, may indicate a 

 rising trend in population numbers. General numbers observed 

 are lowest during the spring, before the fawns are born, and 

 summer, when the deer are still widely dispersed. Extreme 

 drought conditions alter normal distribution patterns and force 

 deer to concentrate near water. This occurred in May 1980 and 

 shows up as the highest indicies of relative abundance figure 

 observed in the Sweeney-Snyder study, 39.0 in May of 198O 

 (Table 2). As the drought continued, many deer left the study 

 area for the Rosebud Creek and Tongue River bottoms. The 

 result was the low Indicies observed for June and July of 198O, 

 the driest months of the study. 



Mule deer population structure was determined during August, 

 October and November. The I98O composite result shows 58.5 

 fawns per 100 does in the Sweeney-Snyder study area (Table 3). 

 The number of fawns per 100 does increased by 38 percent from 

 August 1980 to August 1981. These are good reproduction figures 

 and indicate a healthy mule deer herd (Swenson 1978). In spite 

 of several years of bucks only hunting, there were over twice as 

 many bucks as does in the Sweeney-Snyder study area during August 

 1981. Bucks comprised over 50^ of the population in November 198O 

 as well as August I98I. This may be explained by a different 

 distribution pattern for bucks and does during the driest months. 

 As more does migrate to the adjacent creek bottoms to have fawns, 

 a higher percentage of bucks occurs in the uplands of the Sweeney- 

 Snyder study area. The small percentage of fawns in the fall 

 population, 21.6^, may indicate some problems in the future. 

 Swenson (1978) estimated that mule deer in Region 7 could maintain 

 stability with 30-35 percent fawns in the postseason period. 



Distribution : Spring distribution is shown in Figure 35. Mule 

 deer were found over the entire unit in small groups, only three 

 observations being more than 8 head. A cluster of observations 

 occurred in the northeast corner of the study area in the Miller 

 and Cow Creek drainages. Another group was located on Hart Creek 

 in the southern portion of the study area. The central region 

 had many scattered observations. 



The summer distribution (Figure 36) pattern was even more scattered 

 and nearly 85% of the observations were of the 1-3 group size 

 category. An anomaly was observed in that most of the observations 

 occurred on the ridpces between drainage ways. The exceptions 

 were the lower portions of Cherry, Hen and Snyder Creeks. These 

 areas had available water while the other drainages were dry. 

 This lack of water is probably the limiting factor for wildlife 

 in the Sweenev-Snyder study area. 



