Search

Wild chimpanzees routinely share high-value resources such as meat obtained through hunting and fruit procured from raiding crops. Although it is predicted that the proximate mechanisms for sharing behaviour are the result of reciprocity, interchange and mutualism, examinations of these factors in captivity have not mirrored the degree to which they are found in the wild. The goal of the current study was to investigate how a group of seven captive chimpanzees responded when a highly desirable and monopolizable resource diminished over the course of eight months. To do this we measured the amount of time that was spent sharing food at an artificial termite mound as well as the relationship between dyads that spent time sharing. Our results contradicted our predictions that rates of aggression would increase and the number of individuals fishing at the termite mound would decrease when resources diminished, as we observed no difference in either variable over time. We did, though, find an increase in the amount of sharing as the number of baited holes decreased. We also found a correlation between the strength of dyadic relationships outside of the study and the amount of time that individuals spent sharing with each other. [ABSTRACT FROM AUTHOR]

Understanding the rates and causes of mortality in wild chimpanzee populations has important implications for a variety of fields, including wildlife conservation and human evolution. Because chimpanzees are long-lived, accurate mortality data requires very long-term studies. Here, we analyze 47 years of data on the Kasekela community in Gombe National Park. Community size fluctuated between 38 and 60, containing 60 individuals in 2006. From records on 220 chimpanzees and 130 deaths, we found that the most important cause of mortality in the Kasekela community was illness (58% of deaths with known cause), followed by intraspecific aggression (20% of deaths with known cause). Previous studies at other sites also found that illness was the primary cause of mortality and that some epidemic disease could be traced to humans. As at other study sites, most deaths due to illness occurred during epidemics, and the most common category of disease was respiratory. Intraspecific lethal aggression occurred within the community, including the killing of infants by both males and females, and among adult males during the course of dominance-related aggression. Aggression between communities resulted in the deaths of at least five adult males and two adult females in the Kasekela and Kahama communities. The frequency of intercommunity violence appears to vary considerably among sites and over time. Intercommunity lethal aggression involving the Kasekela community was observed most frequently during two periods. Other less common causes of death included injury, loss of mother, maternal disability, and poaching. Am. J. Primatol. 70:766–777, 2008. © 2008 Wiley-Liss, Inc. [ABSTRACT FROM AUTHOR]