Maternal rank is not correlated with cub survival in the spotted hyena, Crocuta crocuta

Reproductive success in female spotted hyenas, Crocuta crocuta, is positively correlated with social rank. High-ranking females are known to produce more offspring, but the effects of maternal rank on early cub survivorship have not been investigated. Cub mortality was examined over a 4-year period in one clan of wild-living spotted hyenas in Kenya. Data were obtained for 100 cubs in 63 litters produced by 27 adult females. Survivorship of cubs from birth through their first year was examined as a function of litter size, sex of cubs, and maternal rank. Overall, cub mortality was high (61%). Contrary to expectation, singleton cubs did not survive better than twins, and there was no difference in survivorship between female and male cubs. High-ranking mothers were not more successful at raising twins or daughters than were low-ranking mothers. There was no correlation between cub mortality and maternal rank. Peaks in cub mortality coincided with life stage events, including mean age of arrival at a communal den, and age at which cubs began visiting kills. Documented causes of mortality included intraclan infanticide, disease, orphaning, predation by lions, and a mechanism of filial infanticide that has not been previously described in this species: selective litter reduction by mothers via partial litter abandonment. No instances of facultative or obligate siblicide were detected. During this study, association between rank and number of cubs surviving to 1 year of age appeared to be due to differences in reproductive output and not differential survival of cubs within their first year.