and high adult female mortality. Lactation stress associated 

 with rearing fawns to weaning age may be severe (Short et al. 

 1969, Clutton-Brock et al . 1982), even during relatively good 

 forage years. Females that have recruited fawns to early 

 winter do not accumulate as much body fat as females that did 

 not have fawns or lost them early. Successfully rearing fawns 

 for 2 successive years or more probably requires drawing on 

 body reserves in addition to the nutrition supplied by current 

 forage . 



The cumulative effect of several years of successful fawn 

 recruitment is relatively poor body condition for the female. 

 The "average" decline in fawn production and recruitment rates 

 that we observed after 6 years of age and increase in female 

 mortality between ages 6 and 7 probably reflected this 

 cumulative reproductive stress. Obviously, not every female 

 on the area died between ages 6 and 7 or did not rear a fawn 

 at age 7. Based on the evidence obtained, however, those 

 females which had successfully reared the most fawns prior to 

 6 years of age were in poorest condition and thus most 

 vulnerable to either death or poor recruitment of fawns 

 thereafter. 



The exact age of the female may not be the most critical 

 factor, but rather her reproductive history. On "average", 

 6-year-old females are most vulnerable, but a 5-year-old 

 female that has recruited fawns for 4 successive years is 

 probably more vulnerable than a 6-year-old female that has 

 only recruited 2 fawns in 5 years. 



Prevailing environmental conditions, especially during 

 summer and autumn may be important in these relationships. If 

 a dry summer and/or autumn occurs after 2 to 3 years of above 

 average fawn recruitment for the population, females that rear 

 a fawn to weaning, or close to weaning, during the dry year 

 are often in very poor condition. They may be in too poor of 

 condition to breed or to breed at maximal rates such that 

 initial fawn production declines, as was the case during 

 1983-84 and 1984-85. Additionally, many females may be in 

 such poor condition that they die over-winter. Thus, because 

 of declining female condition resulting from cumulative 

 reproductive stress, a series of years of high fawn 

 recruitment carries within it the seeds of its own 

 destruction. 



Similarly, the older and dominant breeding males, which 

 are most active during the autumn breeding season, are in 

 poorest condition entering winter and are the males most 

 likely to die over-winter (Gavin et al . 1984). Their deaths 

 occur because of excessive energy expenditure immediately 

 prior to winter, not because of intraspecif ic competition for 



312 



