other recruitment and mortality had remained the same, the 

 population growth rate would have been r=0.466, approaching 

 the 0.509-0.516 growth rates observed for white-tailed deer on 

 The George Reserve over 6 and 7 year periods (McCullough 

 1983) . 



If all fawns born during 1979 were recruited and no 

 mortality of adults had occurred, the instantaneous growth 

 rate would have been r=0.602. However, because fawn 

 production during 1979 was the highest ever recorded and 

 natural mortality was very low, an instantaneous growth rate 

 of 0.466 might be about the maximum realistically expected. 

 The maximum potential growth rate could have been higher, 

 however, during an initial year with a different female age 

 structure than occurred during 1979. 



Because mule deer on this area, and most others, seldom 

 breed as fawns, potential growth rate of the population can be 

 influenced by female age structure (proportion of yearlings in 

 June population) . Few yearlings occurred in the population 

 during spring 1978 as compared to spring 1979. If fawn 

 production in 1978 had been equivalent to that of 1979 and no 

 adult or fawn mortality occurred, the instantaneous rate of 

 growth for the population would have been r=0.758. The 

 difference between maximum potential growth rates for 1978 

 (0.758) and 1979 (0.602) was a result of differing proportions 

 of nonproductive yearlings in the population. Because of the 

 increasing number of recruited fawns, a maximum potential 

 growth rate of 0.758 cannot be sustained, even without 

 mortality, unless substantial net emigration of yearlings 

 occurs. The large proportions of non-reproducing yearlings 

 reduce the maximum instantaneous growth rate to about r=0.500 

 (0.479-0.513) in subsequent years. These calculations 

 indicated that the spring-to-spring population growth rate 

 observed for 1979-80 (r=0.352) was near the maximum 

 sustainable, given hunting mortality of males. 



High instantaneous rates of growth were not sustained for 

 long periods during 1960-1987. An observed r=0.350 was 

 sustained for 2 years from spring 1978 through spring 1980. 

 Extended through spring 1981, the average instantaneous growth 

 rate was 0.292 and through the 5 years of population increase 

 ending in spring 1983, r=0.182. Some natural mortality of all 

 deer and hunting mortality of adult males occurred throughout 

 the 5-year period. Also, net emigration of yearling females 

 occurred during spring 1980 and 1981, a more severe winter 

 than average occurred during 1981-82, and hunting mortality of 

 females and fawns was added during the fourth and fifth years 

 of population growth. 



Average instantaneous growth rates of 0.159 occurred for 

 a 3-year period and 0.135 for a 4-year period during 1967- 



88 



