Positional behaviour and patterns of support utilization in chimpanzees

Abstract

Understanding the complex interplay between chimpanzee locomotion, feeding patterns, and both arboreal and terrestrial substrate utilization in their natural context is vital since chimpanzee populations and their habitats face unprecedented threats. This knowledge is essential for developing effective conservation strategies in both national parks and semi-wild ecosystems. Chapter 2 of this dissertation examines the support usage patterns used by habituated wild Eastern chimpanzees (Pan troglodytes schweinfurthii) during posture and locomotion. This study reveals that as chimpanzees age, they increasingly rely on medium to large supports and frequently employ two or three supports simultaneously for stability. In contrast, juveniles and infants utilize four or more supports more frequently than their older counterparts, with juveniles displaying heightened arboreal tendencies, using branches, lianas, trunks, and saplings more frequently. Furthermore, the dissertation investigates the influence of support characteristics on positional behavior, revealing common patterns across age-sex groups. Adult-like support utilization and locomotor competence emerge during adolescence but differ due to individual variation and body size. The impact of habitat structure and support availability on support use underscores the significance of comprehending locomotor behavior in arboreal primates. In Chapter 3, the study delves into how chimpanzees interact with their natural environment during locomotion and posture across different behavioral contexts. It emphasizes the essential role of understanding how positional behavior relates to support use in making informed decisions for the conservation of our critically endangered closest living relatives. Examining wild Eastern chimpanzees in a pristine natural forest environment, the research highlights the effect of support size on positional behavior. Notably, differences in locomotor and posture modes are observed on supports of varying diameters, suggesting that support size restricts the chimpanzees' positional repertoire. For example, quadrupedal locomotion is more frequent on large diameter supports. Multinomial logistic regression analyses suggest that support characteristics (type and diameter), age, sex, rank, and their combined effects significantly predict posture and navigation within the canopy. Suspension and vertical movement are linked to small support diameters, with little correlation observed on large supports. In conclusion, this dissertation underscores the critical relationship between chimpanzee locomotion, feeding, and arboreal substrate use. It emphasizes the significance of age, sex, and environmental factors in shaping these behaviors and highlights the implications for habitat management and conservation efforts for this endangered species. By gaining a deeper understanding of these complex interactions, we can develop more effective conservation strategies for both national parks and semi-wild ecosystems where chimpanzee populations and their habitats are under unprecedented threats.