Late pregnancy glucocorticoid levels predict responsiveness in wild baboon mothers (Papio cynocephalus)

Maternal care is the most significant measure of successful adaptation among female mammals. Understanding the predictors of individual differences in offspring care is a major objective of mammalian reproductive biology. Recent studies suggest that differences in caregiving motivation may be associated with variation in glucocorticoid (GC) hormones in new mothers. Despite these intriguing reports, questions remain about the stability of this association during a period of rapid change in both behaviour and physiology, about whether this relationship is dependent on other nonhormonal variables and about the generality of this pattern across species and in wild populations. Glucocorticoids modulate animals' responses to ongoing stressors and may also prepare animals for predictable future challenges. We evaluated evidence for both actions of GCs on maternal responsiveness towards infant cries during the first 2 months of infancy in 34 wild baboon mother-infant dyads in Amboseli, Kenya. We found that stable individual differences in faecal GCs during late pregnancy predicted stable individual differences in maternal responsiveness after birth, even after controlling for maternal rank and parity, and infant sex and distress rate. This study is among the first to provide evidence of preparative actions of GCs in wild animals and to show stability of behavioural and hormonal traits during a period of rapid changes in both hormones and behaviour. Because elevations in GCs during late pregnancy are probably primarily of fetal rather than maternal origin, our results raise the intriguing possibility that parent-offspring conflict may underlie the preparative actions of GCs on maternal responsiveness to infant distress. © 2008 The Association for the Study of Animal Behaviour.

Duke Scholars

Author Susan C. Alberts Biology