Abstract # 13386 Event # 66:

Scheduled for Thursday, August 22, 2019 04:15 PM-04:30 PM: (Room 325) Oral Presentation


E. E. Kane1, T. Susanto2,3 and C. D. Knott1,3
1Boston University, Department of Anthropology, 232 Bay State Road, Boston, MA 02215, USA, 2Universitas Nasional Department of Biology, Jakarta, Indonesia, 3Gunung Palung Orangutan Conservation Project
     When female chimpanzees, orangutans, and callitrichids share challenging-to-process resources with their offspring, they improve access to foods and calories which would otherwise be unavailable. Adult chimpanzees share foods rarely, but when they do, sharing valuable resources solidifies inter-individual bonds (e.g., when building coalitions or eliciting copulations). While maternal-offspring food sharing has been studied in wild orangutans, the context in which adult orangutans share food and feed in proximity is poorly known. We use 27 years of research on orangutans in West Kalimantan, Indonesia, to examine this behavior. Food sharing and tolerance were observed during 2,131 follows between 1994-2019. Mother-infant food sharing occurred in 78%, female-female sharing in 22%, male-female sharing in 32%, and male-male in just 1%. Adult females shared foods at different rates with adult males than with offspring (Chi-square=49.27, p<0.01, N=589 events). Eighty-one percent of mother-offspring food sharing/tolerance was fruit, compared to only 71% of male-female food sharing/tolerance. Durio, Lithocarpus, and Willughbeia (hard-to-process fruits) were most frequently shared by mothers. Twenty-three percent of male-female food sharing/tolerance occurred while eating termites; only 3% of mother-infant sharing did. Only two of 350 mouth-to-mouth or hand-to-mouth transfers involved adult males and females. Mothers increase their offspring’s access to challenging resources. Food sharing/tolerance among adult males and females is not limited to valuable resources, but may indicate strong social tolerance or affiliation in generally solitary adults.