grazed in spring and summer as livestock were turned onto 

 uplands from the bottoms came to receive little or no spring 

 grazing and only light to moderate use during summer and 

 autumn. Thus, the quantity and quality of available summer 

 forage probably increased progressively through time. 



The second major environmental change occurred as a 

 result of wildfire that burned approximately 315 ha of Douglas 

 fir habitat on the northwest portion of the study area in 

 1961. Because areas adjacent to the burn also had low 

 densities of deer during the 1960s, it is unlikely that 

 displacement of deer from burned to unburned habitat was 

 responsible for the average low deer densities in the area 

 through 1964. It seems more likely that regrowth of shrubs 

 and forbs improved forage conditions (Eichhorn and Watts 1984) 

 and led to more intensive deer use after the mid-to-late 

 1960s. Knowles (1975) also reported disproportionately high 

 deer use in the vicinity of burns in similar habitat on the 

 NCRCA. 



Other temporal changes or variations in spatial 

 distribution occurred in relation to seasonal movements, 

 winter severity, and trends in density of deer on the study 

 area. Overall, mule deer were observed in 792 (83%) of the 

 953 28.8-ha blocks during the 32 full-coverage aerial surveys 

 from 1976 through 1984. They occurred in 64%, 60%, 65%, and 

 53% of the blocks during summer, autumn, winter, and spring, 

 respectively. However, because individuals were less 

 observable and fewer total deer were seen during summer and 

 autumn than during winter and spring, these data were adjusted 

 based on the number of different blocks/deer observed. 

 Relative to the number observed per season, deer were most 

 widely dispersed among blocks during summer, followed by 

 autumn and winter-spring. This was also expected on the basis 

 of increasing group sizes that indicated increasing 

 aggregation from summer through spring. 



As deer numbers declined across the area during the early 

 1970s, a disproportionately large decline occurred in counts 

 within subdivisions along the southern fringes of the area 

 adjacent to the prairie. Similarly, population growth during 

 the late 1970s and early 1980s was marked by a 

 disproportionately greater increase in fringe areas, 

 especially in the southcentral and southwest. Regardless of 

 the manner of data collection, deer moved from areas of low 

 relief near the prairie to areas of steeper terrain near the 

 river during severe winters with deep snow cover. That 

 distributional change was also documented by movements of 

 marked and radio-collared deer during 1976-1984. 



More specific data on relationships between changes in 

 deer numbers and spatial distribution were obtained during the 



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