Drivers of range shifts in female wild eastern chimpanzees, Pan troglodytes schweinfurthii, following female death events

Highlights

• The strength of ties to females who died influenced ranging behaviour/resource access.
• Strong social ties to a female who died caused a shift away from that female's range.
• Females who lost maternal kin subsequently lost habitat quality.
• Females who lost strong nonkin associates subsequently improved habitat quality.

Abstract

Ranging behaviour is often linked to resource availability within a given habitat, and site fidelity to specific ranges is expected to improve foraging efficiency and thus impact fitness. Yet social animals must also navigate affiliative, in addition to competitive, dynamics of a shared environment. The ranging patterns of highly social species should thus reflect the compromise between both foraging and social needs, and range shifts may reveal important information about socioecology. Species with high fission–fusion dynamics present an interesting system to evaluate these factors since individuals often range alone to mitigate feeding competition but seek out social opportunities when advantageous. Here we assess the influence of habitat quality and social bonds on female range shifts after the death (i.e. removal) of other females in a population of eastern chimpanzees. We combine behavioural, ecological and geospatial data from 40 years, 29 death events and 45 female chimpanzees. We found significant differences in the patterning of range overlap following death events depending on the relationship of surviving females to the deceased. Females with strong social ties to a female prior to that female's death significantly decreased range overlap with the dead female's vacated range compared to females with weak associations to the dead female. Furthermore, females that lost maternal kin subsequently lost habitat quality whereas those who lost strong nonkin associates gained habitat quality. Our findings add to the body of work suggesting that female social bonds shape ranging decisions and highlight the complex balance females must strike between their social investments and ability to access high-quality resources.

Citation

Abigail R. McClain, Steffen Foerster, Joseph T. Feldblum, Kara K. Walker, Deus Mjungu, Anne E. Pusey, Carson M. Murray, Drivers of range shifts in female wild eastern chimpanzees, Pan troglodytes schweinfurthii, following female death events, Animal Behaviour, Volume 238, 2026, 123651, ISSN 0003-3472, https://doi.org/10.1016/j.anbehav.2026.123651.