Male-Female Association Patterns Among Free-ranging Chimpanzees (Pan troglodytes schweinfurthii)

Although male-female relationships can offer a number of advantages such as protection or social support, they are poorly studied among primates compared to same-sex relationships. We used 12 yr of data from the Kanyawara chimpanzee community to compare three independent measures of association (party association, 5m association, and grooming) among all adult dyads. Party association exhibited by male-female dyads was of intermediate strength between strong male-male and weak female-female association. Male-female dyads were less likely to be within 5m of one another and to groom as male-male dyads, but equally likely to be within 5m and more likely to groom as female-female dyads. Variation in male-female association strength was not related to male rank but was affected by female ranging patterns and female reproductive states. Females with core areas in the center of the home range were more likely to be in parties with males but did not show higher spatial proximity or grooming indices compared to females ranging in the periphery. Party association and 5m indices were higher for dyads of males and estrous females compared to those with anestrous females. These results indicate that male-female dyads are likely to associate with one another more often than female-female dyads because of overlapping ranging patterns and short-term changes in female reproductive state. We conclude that male and female chimpanzees do not exhibit proximity and grooming patterns indicative of strong affiliative bonds. This study also highlights the importance of using multiple independent measures of bond strength in studies of primate social dynamics.