Infant Survival Among Free-Living Bonnet Macaques (Macaca radiata) in South India

AbstractFemale reproductive success depends to a large extent on infants’ ability to survive to maturity. While most studies of female reproductive success have focused on the effects of individuals’ sociodemographic factors (e.g., age/parity, dominance rank) on offspring survival among wild primates living in less disturbed habitats, little research has focused on offspring survival in urban or periurban animals. Here we investigated sociodemographic and anthropogenic determinants of infant survival (up to 1 yr of age) in free-ranging bonnet macaques (Macaca radiata) living in a periurban environment in Southern India. We conducted the study from November 2016 to May 2018, on two groups of bonnet macaques at the Thenmala tourist site in the state of Kerala. Fifty infants were born across two birth seasons. Of these infants, 29.2% died or disappeared in 2017 and 26.9% died or disappeared in 2018. We found that infant survival was strongly influenced by the mother’s parity: infants of experienced mothers had a better chance of survival than those of first-time mothers. We also found that male infants were more likely to die than female infants. However, we found no effects of mothers’ dominance rank, or of frequency of mothers’ interactions with humans and time spent foraging on anthropogenic food, on infant survival. Our results, consistent with findings from other wild primate species, show that even in challenging human-impacted environments, experienced bonnet macaque mothers have greater success than inexperienced ones.