Sex differences in the consequences of maternal loss in a long-lived mammal, the red deer (Cervus elaphus)

In several primates, the presence of mothers affects the growth, survival and reproduction of their offspring, but similar effects have not yet been demonstrated in ungulates. Here, we investigate the effects of the mother's presence in a population of red deer (Cervus elaphus) on the Isle of Rum, Scotland, which is the subject of a long-term, individual-based study. We compared measures of performance including antler growth in young males and age at first reproduction in females and survival of deer with mothers still alive against those that have lost their mothers (orphans). We show that orphaning both before and after weaning increases the risk of a natural death for both sexes. For males, no maternal benefit was detectable past 24 months of age while, for females, post-weaning benefits continued throughout life. Orphaning resulted in compromised male physical condition as measured by a reduced probability of growing antlers by 16 months of age while no evidence for compromised reproduction was found in females. These results support assertions that post-weaning maternal associations affect the development and survival of offspring.