Abstract # 205:

Scheduled for Monday, August 28, 2017 02:00 PM-02:15 PM: (National Ballroom Salon B) Oral Presentation


CHANGES IN ASSOCIATION OF AGING WILD MALE CHIMPANZEES (PAN TROGLODYTES SCHWEINFURTHII) OF THE KANYAWARA COMMUNITY, KIBALE NATIONAL PARK, UGANDA

L. Hagberg1, M. Emery Thompson2, M. Muller2, E. Otali4, R. Wrangham1 and Z. Machanda3
1Harvard University, Department of Human Evolutionary Biology, 11 Divinity Avenue, Cambridge, MA 02138, USA, 2University of New Mexico, 3Tufts University, 4Kibale Chimpanzee Project
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     In chimpanzees, males cooperate more frequently and form stronger bonds than females. These bonds are important in gaining and maintaining dominance rank, which is important for reproductive success. While male rank peaks around 30 for adult male chimpanzees, not much is known about how male affiliation changes with age. We predict that male association will decrease with age as social bonds become less important given the reduction in rank. Using 21 years of data on the Kanyawara community, we analyzed spatial and temporal association of male chimpanzees in one year periods to calculate a combined association index (CAI) and determine the number of preferred social partners (PSP) for each male in each year. Age had no effect on average CAI (p = 0.271) nor on number of PSPs (p = 0.592) when controlling for rank. However, there was an interaction between age and rank (p < 0.001) such that low ranking prime age (15-35) males have low association compared to high ranking prime age males, while past prime age (35+) males have the same association regardless of rank. Interestingly, older males had higher CAI with partners closer to their age (p < 0.001), suggesting that older males form stronger bonds with age-matched partners, regardless of their rank. These results suggest that male social bonds are important for older males for reasons independent of rank acquisition.