Abstract # 101:

Scheduled for Friday, June 22, 2007 01:30 PM-01:45 PM: Session 11 (North Main Hall C/D)

Costs of Providing Infant Care in Wild Golden Lion Tamarins at Poço das Antas Biological Reserve, Brazil

J. M. Siani and J. M. Dietz
University of Maryland, Department of Biology, Program in Behavior, Ecology, Evolution and Systematics, College Park, MD 20742, USA
     Body mass and activity budgets may reflect energetic demands of infant care and can indicate patterns of individual investment in reproduction. We investigated the cost of infant carrying on body mass and activity budgets for 26 individuals in six groups of wild golden lion tamarins (Leontopithecus rosalia) from 2004 through 2006. Body masses were collected weekly during infant dependency without captures, and at semiannual captures. We collected behavior data using focal sampling and collected infant carrying data continuously. We analyzed data using ANOVAs corrected for multiple comparisons [a=0.01]. When infants were present in groups, time spent foraging for fruit decreased and traveling and social activities increased. Individuals carrying infants decreased overall foraging time (i.e. for fruit and animal prey) and increased time spent stationary, a shift that may conserve energy and increase predator detection. Only reproductive females decreased time spent traveling when carrying infants. These females contributed the greatest proportion of infant carrying during the first 4 weeks of infancy and overall. Adult males and non-reproductive females contributed equally to infant carrying throughout infant dependency yet carried more frequently when traveling. Although changes occurred in activity budgets, all adults maintained a stable body mass throughout infant dependency. This suggests that caregivers have the ability to compensate for energetic costs of providing infant care or that the physical costs may be minimal due to the shared responsibility of infant care within the group.