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production In November was probably an artifact of the small 

 sample size. 



Spring distribution is shown in Figure 108. Mule deer In the 

 northern half of the study area tended to be fairly scattered, 

 while deer in the southern half were concentrated into two small 

 areas. The large deer herd (>16 deer) located Just west of the 

 study area in 198O was still on winter range on the West Decker 

 Mine. 



During summer most mule deer groups had less than 4 deer (Figure 

 109). The observations were scattered throughout the study area 

 except for three areas of high concentrations. Deer herds with 

 9-15 deer were seen in all three of these concentration areas. 

 The middle concentration area on the southern end of the 

 reservoir had very high concentrations of deer. This area had 

 extensive willow thickets in which deer were extremely difficult 

 to observe. Yet in the August 198I flighty 34 mule deer were 

 observed in an area of about 1 square mile in the center of 

 this concentration area. 



During fall mule deer observations in the northern part of 

 the study area decreased (Figure 110). Mule deer in the 

 southern part of the study area were gathered in larger herds 

 and concentrated into two small areas. As water levels in 

 the Tongue River Reservoir fall, mud flats are exposed and 

 willow thickets dry out at the upper end of the reservoir. The 

 ground becomes covered with tender, leafy weeds such as Rumex 

 spo. Mule deer move into this area as this food supply becomes 

 available. They reach the highest concentrations in fall, and 

 remain there until late fall (depending on snow cover). 



During winter mule deer were scattered throughout the northern 

 part of the study area and concentrated into three groups in the 

 southern part (Figure 111). The dashed lines show the three 

 winter ranges in the area outlined by Phillips (1978). Two of 

 the groups of sightings coincide with the winter range. The 

 lack of snow cover during the winter probably made it unnecessary 

 for mule deer to retreat to their usual winter ranges. It is 

 important to note that none of the three winter ranges were 

 entirely covered by my surveys. Incomplete coverage of a winter 

 range can easily lead to misinterpretation of its extent and 

 Importance. 



Vegetation Use - The majority of deer observed were in grasslands 

 during both spring seasons (Table l4l). Xeric grassland was 

 more heavily used in 1980 and sagebrush in 198I. In summer and 

 fall of 1980 the majority of deer were in riparian habitat. In 

 contrast, more deer were seen in grasslands, than in riparian 

 habitat in the summer of 198I. The summer of I98O had a drought, 

 so only riparian zones had green vegetation in late summer and 

 fall. Scattered rains occurred throughout the summer of 198I, 

 so uplands remained green through much of the summer, making 

 grasslands more attractive to mule deer. 



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