for growth of fawns and recovery of females prior to winter 

 are, on average, most advantageous (Klein 1985). Short-term 

 variation in the weather is much more unpredictable. One 

 winter may be much longer and more severe than another and one 

 summer-autumn period may be much more arid than another. 

 These short-term differences in weather can result in great 

 annual differences in the rate of accumulation and use of fat 

 reserves . 



We believe that much of the difference in potential 

 density of deer between areas is established by the stable, 

 predictable properties of the environment such as topography, 

 soil fertility, general climate-weather pattern, and major 

 habitat types and their structure. Whether the deer 

 population is at the potential level or somewhere below that 

 density depends on annual variations in weather and other 

 factors that influence the amount of effective habitat. 



Discussion 



It is apparent that there is an interaction between the 

 habitat, its use by deer, and the population dynamics of the 

 deer. Not all habitat is equal in providing for the needs of 

 deer. During favorable periods, deer can successfully utilize 

 sub-optimal and marginal habitats by adopting specialized 

 habitat use and movements strategies, such as autumn-winter 

 migration, that enable them to fill their needs. During 

 extreme environmental conditions, even normally optimal 

 habitat on this area may temporarily fall short of supplying 

 the needs of deer. Deer utilizing sub-optimal habitat may not 

 be able to successfully use compensating strategies at all 

 during those periods. When environmental conditions 

 deteriorate to such an extent that compensating strategies of 

 habitat use are not adequate, fawn production and survival and 

 even adult survival declines; first in marginal habitats and 

 later in sub-optimal and optimal habitats if unfavorable 

 conditions persist very long. The behavior of mule deer on 

 this area, centering on parturition territoriality and a 

 matrilineal social structure, along with the length of 

 favorable environmental conditions establishes the relative 

 proportions of deer inhabiting areas that are optimal or less 

 than optimal for reproduction and survival. 



An area in the same general location as our study area, 

 that had less topographic relief, providing less vegetational 

 and phenological diversity, and the drainages oriented in 

 different directions (i.e., with more east- and west-facing 

 slopes and fewer south- and north-facing slopes) would 

 probably average a lower density of mule deer over time. 

 There would be fewer permanent home range sites that would 

 give deer visual isolation during fawn rearing and also allow 

 them to compensate for severe winters or drought. 



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