Infant handling and mortality in yellow baboons (Papio cynocephalus): evidence for female reproductive competition?

Abstract

This study examines negative and positive infant handling behavior in 24 free-ranging yellow baboon infants (Papio cynocephalus) studied over a 5-year period in Mikumi National Park, Tanzania. We test predictions of the female reproductive competition hypothesis to explain patterns of infant handling behavior by adult females (excluding the infant’s mother) in relation to observed cases of infant mortality by age 3 months (25% of infants in this study). Results show that: (1) low-ranking infants received more negative infant handling than high-ranking infants; conversely high-ranking infants received more positive infant handling; (2) female kin engaged in higher levels of positive infant handling than did non-kin, whereas non-kin showed higher levels of negative infant handling; (3) rates of negative infant handling varied by season, with high levels at the onset of the rainy season; and (4) high level of negative infant handling was a significant predictor of infant mortality by age 3 months (infant rank and sex did not predict survival). We discuss how the occurrence and interpretation of infant handling behavior in the literature has likely been confused by different definitions of this behavior, as well as differences in the socio-ecological context in which this behavior occurs.