Sexual Differences in Chimpanzee Sociality

Scientists usually attribute sexual differences in sociality to sex-specific dispersal patterns and the availability of kin within the social group. In most primates, the dispersing sex, which has fewer kin around, is the less social sex. Chimpanzees fit well into the pattern, with highly social philopatric males and generally solitary dispersing females. However, researchers in West Africa have long suggested that female chimpanzees can be highly social. We investigated whether chimpanzees in the Taï Forest (Côte d’Ivoire) exhibit the expected sexual differences in 3 social parameters: dyadic association, party composition, and grooming interactions. Though we found a significant sexual difference in each of the 3 parameters, with males being more social than females, the actual values do not reveal striking differences between the sexes and do not support the notion of female chimpanzees as asocial: females had dyadic association indices comparable to mixed-sex dyads, spent ca. 82% of their time together with other adult chimpanzees, and had a comparable number of grooming partners. Further, female associations can be among the strongest bonds within the community, indicating that both sexes can have strongly favored association partners. The findings are in contrast to reports on East African chimpanzees, the females of which are mainly solitary and rarely interact with other females. Our results suggest that researchers cannot generally regard chimpanzee females as asocial and need to redefine models deriving patterns of sociality from dispersal patterns to integrate the possibility of high female sociality in male philopatric systems

International Union for Conservation of Nature (IUCN) Red List Assessment, Temminck's red colobus (Piliocolobus badius temminckii), 2020.

Piliocolobus badius temminckii populations are patchily distributed and most are small, isolated and in decline. The loss of 22% of the total habitat of this taxon combined with unsustainable levels of hunting and reports of extirpation at some locations have caused a decline suspected to exceed 50% of the population over the last 30 years (three generations for this taxon). The demand for natural resources has increased with the doubling of the human population in the four range countries since 1990. Bushmeat trade estimates strongly suggest unsustainable levels of exploitation that, if not controlled, could lead to further extirpations (Minhós, Wallace et al. 2013). Therefore, this subspecies is listed as Endangered under criterion A2bcd