The way animals use space is a fundamental aspect of animal spatial ecology. Gaining insight into animal spatial utilisation facilitates a deeper understanding of their social structure and ranging patterns (Willems and Hill, 2009) and has important implications for species interactions and conservation efforts (Pearce et al., 2013). Factors such as resource distribution, predation risk and the potential for encountering hostile neighbours (Willems and Hill, 2009) contribute to the creation of a “landscape of fear” (LoF), resulting in variations in spatial distribution and behavioural patterns. In primates, peripheral areas within their home range that are likely to present encounters with neighbouring groups are generally underutilised, suggesting individuals perceive these areas to be risky (Wrangham, 2007). The ability to assess environmental risks is crucial for primates in determining the safest and most suitable locations for survival (Willems and Hill, 2009). In chimpanzees (Pan troglodytes schweinfurthii), where the likelihood of lethal and aggressive intergroup encounters is significant, the risks associated with these peripheral regions of the home range are heightened (Wilson et al., 2007) and have vital effects on behaviour and ecology. Yet, despite more than 400 combined years of study, there has only been a single study of LoF in chimpanzees and any other ape for that matter.

The influence of intergroup threat on spatial range use in primates has rarely been studied empirically (Benadi et al., 2008) and never in chimpanzees. Most research on chimpanzees focuses on forest-dwelling populations, leaving a significant gap in our understanding of chimpanzees across the ecological spectrum, including in savannah-woodland environments that characterise their distribution at the periphery (Senegal and western Tanzania) of their distribution. The Issa Valley, one of the driest, most open, and most seasonal habitats inhabited by chimpanzees (Drummond-Clarke et al., 2022) provides a unique opportunity to study ranging behaviour in response to spatial variation in risk. Savanna-mosaic environments like Issa are characterised by lower forest cover and higher ecological heterogeneity compared to forests (van Leeuwen et al., 2020). Issa is home to several large terrestrial predator species with observed encounters with chimpanzees. This, along with the habitat and the presence of neighbouring communities, makes it an ideal location for studying home range dynamics. Chimpanzees living in these landscapes have shown that they show variation in sociality as a result of the ‘extreme’ environment compared to their forest-dwelling counterparts (Moore, 1996). Understanding how chimpanzees navigate such risks is essential for uncovering behavioural adaptations that may differ from those observed in forested environments (Kalan et al., 2020), increasing our understanding of home range use in territorial species in highly heterogeneous habitats. Furthermore, savanna-mosaic habitats are thought to resemble early hominin environments, offering insights into the pressures that shaped hominin space use behaviour. By examining how chimpanzees at Issa respond to spatial variations in risk, this study aims to enhance our understanding of the species’ behavioural diversity and offers insight into adaptations that may have been critical during human evolution.

The aim of this study is to investigate whether spatial variation in perceived risk within a savannah-mosaic habitat influences chimpanzee behaviour.