Senescence in breeding success of female Alpine chamois (Rupicapra rupicapra): the role of female quality and age

Although numerous studies have reported reproductive senescence in wild animal populations, we still know very little on inter-individual differences in rates of ageing and on the factors accounting for these dif- ferences. To investigate age-related variation in breeding success in a natural population of Alpine chamois (Rupi- capra rupicapra), we used 15 years of data obtained by monitoring individual ear-tagged females. Analyses at the population level confirmed the occurrence of a decline in female breeding success, which is most noticeable from 9 years of age onward. Using an age-reverse approach, we showed that senescence in female breeding success occurs at the same age, since only very old individuals (older than 16 years) showed a decline in breeding success in the years preceding death. Interestingly, we also found evidence that ‘success comes from success’, as females that gave birth in a given year were more likely to procreate again in the fol- lowing year. Moreover, results showed that discrepancies between successful and unsuccessful individuals tend to becomemorerelevantintheoldestageclasses.Therewas no evidence of a terminal allocation. These results empha- size the importance of age-dependent effects and individual quality in shaping reproductive senescence in a wild long- lived ungulate.