Care should be taken in interpretation of the tables and figures 

 presented herein as they represent only fifteen months observations 

 The winter period was exceptionally mild and the remainder of 

 the months were marked by below normal precipitation in most 

 instances. 



Otter Creek 



Mule Deer 



Population characteristics : During the study 831 mule deer were 

 observed in the Otter Creek study area (Table 1). Average 

 group size ranged from 2.4 during the summer months (1979) to 

 6.9 during winter. April 1980 had the highest individual 

 monthly average as mule deer remained in herds prior to spring 

 green-up. Deer were most scattered in May and June of 1980. 

 Dusek (1978) reported group size variation from 2.0 in summer 

 to 5.6 in winter in the Bull Mountains near Roundup. 



The indices of relative abundance (Odum 1959) have been used 

 to determine population trends in southeastern Montana (Martin 

 1980). Mule deer observations per hour of aerial survey (Table 

 2) show the highest numbers during fall when an average 31.1 

 deer were observed. November was the best month for observation 

 as 55.0 mule deer were observed per hour of flight. This 

 coincides with the time of year that deer should be most 

 numerous. February was the second most productive month, 40.4 

 deer observed per hour, reflecting the deer's need to feed more 

 as the effects of winter are being manifested. The fewest 

 deer were seen in May of 1980. This unusually low number, 2.8 

 per hour, is at least partially due to windy conditions during 

 the flight. Low numbers per hour should be expected in spring 

 and summer as the fawns have either not been born or are not 

 traveling with the adults. Martin (1980) reported a range of 

 6.1 mule deer observations per hour in summer to 25.3 in fall 

 m the Sarpy Creek area. 



Mule deer population structure was determined during September 

 and October (Table 3). During these months fawns are traveling 

 with the adults and are still small enough to be easily 

 Identified. Bucks are also easily classified. While there has 

 been some natural mortality among the young deer and some loss 

 ot adults to poaching and other factors, the population is at 

 Its yearly peak during this season. As can be seen production 

 was extremely good this year with 118.6 fawns per 100 does 

 observed in October prior to the hunting season. Considering 

 the extremely hard winters the last two years, 1977-78 and 1978- 

 79, it seems that this herd came through in excellent condition. 

 They apparently are considerably below the carrying capacity of 

 this range They also appear to be on an increasing trend as 

 Swenson (1978) reported that mule deer need only a 40 percent 



^rLi''''''i ^? rr^'" stable. The October flight revealed nearly 

 50 percent of the population to be fawns. 



11 



