Thesis (Ph.D.) - University of St Andrews, March 2009.

No description available.

The behaviour of 48 chimpanzees (Pan troglodytes verus) was studied over 27 months in Liberia, West Africa. The chimpanzees were first studied while they were housed in groups in enclosures in a medical research institute, and then after their release onto a 9.7 ha offshore island. When the chimpanzees were observed in captivity, data on social behaviour were collected with the use of check sheets and ad libitum notes. Data were collected on aggression, social grooming, social play, sexual behaviour, and individual spacing. After release onto the island, data on both social and subsistence behaviour were collected with the use of ad libitum notes. Both changes in social behaviour and in the development of subsistence behaviour were observed following release of the chimpanzees onto the island. Rates of aggression decreased following release, whereas rates of social grooming increased. Rates of social play decreased overall, but this was due to a decrease in social play by adults. Stereotyped or abnormal behaviour shown by some subjects declined. Subsistence behaviours which were observed following release were foraging for naturally occurring foods (leaves, fruits, seeds, and nuts), ant-eating, and tool-use for nut-cracking. Some subjects were also seen building sleeping-nests in trees. The chimpanzees also split into subgroups (including consortships) which showed similar trends in size and composition to those observed in wild populations of chimpanzees. Some techniques found to be useful during the release process are discussed, and the study is compared to previous primate release projects.

No description available.

The concept of culture has recently been used to explain behavioural variation and trans-generational continuity of behaviour in non-human animals and in chimpanzees in particular. However, few studies in the wild have systematically investigated how the environment and behavioural adaptation might influence behavioural diversity. In this context, one habituated community of wild chimpanzees (Pan troglodytes verus) at Bossou, Guinea, and two neighbouring non-habituated communities in the Nimba Mountains region of Guinea and Cote d'Ivoire were the subject of a detailed study of behavioural variation at the intra- and inter-community level. An ecologically-based approach was adopted to investigate variation in nest building, in the use of the oil-palm tree (Elaeis guineensis), in ant-dipping and in tool-choice and -manufacturing. A significant influence of environmental variables on nesting parameters emerged explaining much of the variation observed between the three sites. However, some differences that arose are more likely to reflect differences in social structure and organisation. The comparative study of the utilisation of the oil-palm tree failed to reveal proximate environmental parameters that might explain significant observed variations in use. These findings raise interesting and important questions pertaining to diffusion of behaviour between neighbouring chimpanzee communities. Dipping for driver ants, Dorylus spp., is often cited as one of the best examples of culture in chimpanzees. A detailed analysis of this behaviour at Bossou suggests that risk exposure affects frequency of performance in the developing chimpanzee and reveals a strong influence of prey characteristics, including aggressiveness and/or gregariousness , on tool length and technique employed. Variations in tool-choice and tool-manufacturing within and between three tool-use behaviours at Bossoui nvolving the use of a stick or a stalk were found to be significantly associated with the nature of the task and its predictability, emphasising the importance of environmental affordance and constraints on these processes. In addition, efficiency in behaviour across another set of three tool-use behaviours was explored focusing chiefly on age-class differences. An analysis of individual and community-level patterns of laterality in hand-use between these three tool-use behaviours is also provided. The data supply some evidence to support the selective advantages of lateralization in hand-use with respect to behavioural efficiency. The findings also suggest that haptic tasks have played an important evolutionary role in driving population-level handedness, and reveal that although complex tool-uses exhibited high levels of lateralization, these failed to show task specialisation across individuals. Finally, this thesis presents a comprehensive review analysis of individual and community-wide variation across a range of behaviours observed in chimpanzees and identifies paths and hypotheses that warrant further exploration and testing with the aim to gain further insight into cultural processes in nonhuman animals.

Thesis (Ph.D.(Zoology)) -- University of Pretoria, 2009. / Includes bibliographical references.

No description available.

Since no previous unifying theoretical framework existed for viewing the different instances of chimpanzee predatory aggression (i.e., predatory behavior, cannibalism, infanticide, and warfare), the author developed a model for predatory aggression which differentiated the proximate and ultimate causes of predatory aggression, showed how these proximate and ultimate causes are correlated, showed how the ultimate function of any instance of predatory aggression is the solution of an ecological problem (thus contributing to the gene copying success of an individual and his kin), and showed how predatory aggression is likely to appear when any of a variety of combinations of proximal environmental factors causes the benefits of predatory aggression to exceed its costs.The model also helped suggest how developing inter-community and intra-community selection pressures initially made it advantageous for predatory aggression to be used on conspecifics, and how multiple selection pressures brought about the merging of intra-specific and inter-specific aggressive components in chimpanzee killing behavior.Essential to the creation of this model was a theoretical discussion of killing behavior, a survey of chimpanzee behavior and social structure, a survey of the incidence of chimpanzee killing behavior, and a summary of the various hypotheses for the cause and functions of predatory aggression.The author sees this model as an advance over previous explanations of chimpanzees predatory aggression because the model explains the ultimate as well as proximate causes of predatory aggression, it shows how the ultimate function of predatory aggression is to solve ecological problems and contribute to the gene-copying success of an individual and his kin, and it indicates how predatory aggression can link with other types of aggressive behavior patterns depending upon the immediate conditions of the environment.The importance of the preceding study lies in its ability to provide a model for the evolution of conspecific killing in protohominids.

Thesis (Ph. D.)--University of Nevada, Reno, 2007. / "August, 2007." Includes bibliographical references (leaves 97-107). Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2008]. 1 microfilm reel ; 35 mm. Online version available on the World Wide Web.

The increasing rate of human population growth has expanded the human-primate interface, with more conversion of natural primate habitat to agricultural land. Elevated levels of crop-raiding by primates are a by-product of natural resources becoming less available, and the nutritional riches of agricultural production becoming increasingly known to the primates. It was the aim of this thesis to focus on the Bossou chimpanzees’ (Pan troglodytes verus) perspective of their habitat in the Republic of Guinea, West Africa, the risks and opportunities presented by a human-dominated landscape, and to detail their day-to-day coexistence with humans. I combined a variety of data collection techniques, from focal, scan and ad libitum behavioural sampling of the chimpanzees’ daily activities, to broad ecological and habitat surveys. The chimpanzees rely on cultivated foods, and thus are forced to respond to humans. However, significant variation in the importance of various cultivars in the chimpanzees’ diet exists; certain cultivars are mostly fallback foods, while others are preferred food items and taken according to their availability in orchards and fields. The usage patterns of wild and cultivated foods by the chimpanzees of Bossou are thus inextricably connected. Whilst engaged in crop-raiding the chimpanzees exhibit several behavioural adaptations, namely a decrease in vocalisation levels, and increases in the transportation of food and specific vigilance behaviour. Adult males and adult male-only parties crop-raid more than other age- and sex-classes/compositions, and are more likely to take risks by raiding in exposed environments with increased risk of human confrontation. The use of human cultivars also affects the socio-sexual behaviour of the chimpanzees: chimpanzees appear to share the fruits of their risky labours (crop-raiding) as a food-for-sex strategy, which allow adult males to advertise prowess and enhance affiliative relationships with reproductively valuable females (Hockings et al., in prep). In addition, behavioural adaptations to other anthropogenic high-risk situations such as road-crossing were found, with the chimpanzees exhibiting impressive levels of socio-spatial flexibility and cooperation (Hockings et al., 2006). The chimpanzees’ level of anxiety (as measured by rough self-directed scratching) increases when dealing with some of the challenges posed by their physical and social environment. The chimpanzees of Bossou have been forced to adapt ecologically and behaviourally to the various costs and benefits of living in a human-dominated environment.