Summary 



To summarize, then, many different factors influenced 

 and/or interacted to influence fawn production and recruitment 

 and adult mortality. Summer forage condition, especially 

 forage guality as determined by the availability of succulent 

 green vegetation during spring and summer, was extremely 

 important. Forage guantity was generally adeguate during all 

 seasons and only incidentally related to population 

 performance. Both forage guantity and guality appeared to be 

 controlled primarily by climatic variation and succession; 

 deer densities and grazing or browsing by deer had no 

 detectable effect. 



Climatic factors also determined the timing and length of 

 periods of both positive and negative energy balance. Weather 

 conditions, especially precipitation received during the 9 

 months prior to initiation of plant growth and temperature 

 during the growing season, determined total forage production 

 and length of time that forage plants remained succulent and 

 provided guality forage. During some years, heavy late summer 

 or early autumn rains result in an autumn "green-up, " 

 prolonging the period of positive energy balance. Weather 

 factors influencing variability of onset and end of winter and 

 severity of winter all affected the length and severity of the 

 period of negative energy balance. Forage conditions from 

 spring through autumn, together with current and past history 

 of lactation stress, established the condition of the female 

 entering winter. The consequence of the condition in which 

 deer enter winter during any particular year depends .on the 

 length and severity of the winter period. Length and severity 

 act together, but length acts primarily in determining how 

 long deer must use maintenance guality or poorer forage, 

 whereas severity determines the degree of energy deficit 

 relative to available forage and fat reserves. Possible 

 summer-winter energy balance combinations are as variable as 

 the weather. In one sense, net recruitment of deer to the 

 population is the result of a net annual positive energy 

 balance, and net deaths in the population are the result of a 

 net annual negative energy balance. 



Predation rates on mule deer by coyotes appeared to be 

 closely related to cycles in microtine rodent and lagomorph 

 populations, which served to buffer predation on deer during 

 periods of relative abundance. However, high prey populations 

 may also result in high coyote populations that persist for a 

 year or 2 after the "crash" of the small mammals. Within 

 those underlying cycles, the exact level of lows and highs in 

 alternate prey populations is probably set by forage/cover 

 conditions influenced by climatic variation. In addition, the 

 level of coyote predation during winter can be influenced by 

 variable snow and ice conditions that determine accessibility 



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