Variations in care for cottontop tamarin, Saguinus oedipus, infants as a function of parental experience and group size

We examined the effects of parental experience and group size on infant care and development. Ten cottontop tamarin families were followed across three consecutive births of offspring to examine differences in survival, quality of care, developmental maturation and physical development for infants in two experimental conditions: (1) in large groups with previous parenting experience and (2) in small groups with little or no parenting experience. Although we found no differences in infant mortality, parents treated infants differently between conditions. However, when we examined the cumulative care provided by parents and sibling helpers together across experimental conditions, there were no differences in the rates of retrieval or rejection of infants. Overall levels of infant transport and food transfers were similar between conditions, with fathers and sibling helpers contributing the bulk of care. Fathers in small groups carried infants and transferred food with infants much more than helpers but, as group size increased, helpers augmented this role. Infant development varied with the experience of the family both between conditions and within a family. The results indicate that infants receive similar levels of care regardless of group size and parenting experience, although the individual contributions of family members change with both factors. Parental experience with previous infants had effects on early infant development, but only for the first sets of infants. (C) 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.