Data from: Alloparenting is associated with reduced maternal lactation effort and faster weaning in wild chimpanzees

Alloparenting, when individuals other than the mother assist with infant
care, can vary between and within populations and has potential fitness
costs and benefits for individuals involved. We investigated the effects
of alloparenting on the speed with which infants were weaned, a potential
component of maternal fitness because of how it can affect inter-birth
intervals, in wild chimpanzees (Pan troglodytes schweinfurthii) at Ngogo,
Uganda. We also provide, to our knowledge, the first description of
alloparenting in this population and present a novel measure of the
contribution of milk to infant diets through faecal stable nitrogen
isotopes (δ15N). Using 42 mother–infant pairs, we tested associations of
two alloparenting dimensions, natal attraction (interest in infants) and
infant handling (holding, carrying), to the proportion of time mothers
spent feeding and to maternal lactation effort (mean nursing rates and
mother–infant δ15N differences). Neither natal attraction nor infant
handling was significantly associated with feeding time. Infant handling
was inversely associated with both measures of lactation effort, although
natal attraction showed no association. Alloparenting may benefit mothers
by enabling females to invest in their next offspring sooner through
accelerated weaning. Our findings emphasize the significance of
alloparenting as a flexible component of female reproductive strategies in
some species.