type is of less importance than the function it provides. 

 Effective management, even on a specific area, needs to be 

 based on the why of use, not just the fact of use. 



At some point in time, for some purpose, mule deer used 

 all vegetation types on our area. The importance of some 

 types or sites to the long-term health of the mule deer 

 population was evident in some cases only after long-term 

 monitoring. Assenting to the "sacrifice" of some of those 

 areas based on limited data could have detrimental effects on 

 the population over the long-term. 



Mule deer on our study area appeared to strongly prefer 

 Douglas fir habitat types yearlong. However, Douglas fir 

 habitat was absent from the eastern portion of our study area 

 and further east in Montana. Obviously, mule deer in those 

 areas somehow survive and even thrive in the absence of 

 Douglas fir. Similarly, mule deer on our study area seem to 

 survive without the rocky outcrops prevalent on many Ponderosa 

 Pine winter ranges in western Montana. Thus, deer prefer 

 certain areas or types at certain times for what they provide 

 rather than what they are. On our study area, Douglas fir 

 types are relatively moist types within a drought-prone 

 environment. Where available, they provide hiding cover and 

 succulent forage during summer and autumn and thermal cover, 

 lower snow depths, and softer snow during winter. All of 

 these contribute toward the attainment of a positive energy 

 balance on an annual basis. 



As noted earlier, mule deer live well on many areas 

 without Douglas fir types. Something(s) else obviously 

 substitutes for the Douglas fir types and fulfills its 

 function in maintaining a positive energy balance for deer. 

 A common substitution factor in much of central and eastern 

 Montana is agricultural forage. Many crops, such as alfalfa, 

 remain succulent longer than natural forages. Others, such as 

 barley, corn, or sugar beets provide higher energy forage than 

 naturally available. These forages are also more dependable 

 than natural forages. Enough may be available for deer even 

 when drought results in an economic crop failure for the 

 farmer or rancher. Thus, these high quality, high energy 

 agricultural crops can often substitute for a lesser degree of 

 thermal cover, for example. In most "natural" situations, 

 there is an interaction between forage and cover in the energy 

 balance equation. That is, adequate thermal cover during 

 winter can help ameliorate the lack of quality forage because 

 it helps reduce energy use. Similarly, availability of high 

 quality agricultural forage may ameliorate the absence of 

 adequate thermal cover. 



The importance to deer populations of small, seldom used 

 areas or types and areas that often received use for a very 



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