Catherine Hobaiter
ID: UNCST-2019-R001480
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Social structure and territory use in the chimpanzees of the Budongo Forest Reserve, Uganda
REFNo: NS56ES
East African chimpanzee society is characterised by a fission-fusion structure. The traditional view holds that all of the males within a chimpanzee community will range together and form close social bonds, whilst the females disperse, with less affiliation among non-kin (Wrangham, 1979; Goodall, 1968; Gibly and Wrangham, 2008). Much recent work focuses on understanding the nuances of, and variation within, chimpanzee social structure (see Aureli et al., 2008). We plan to investigate how population constraints, sex ratios, and territorial ranging interact with the chimpanzee communities’ social structures in the Budongo Forest. In particular we will explore how population characteristics and instability in the social structure might influence ranging decisions and social grouping over time.
In the Budongo forest there are two habituated communities of chimpanzees: Waibira with around 120 individuals, in which habituation started in 2011, and Sonso with around 65 individuals, in which habituation started in 1990. These two neighbouring groups present a unique opportunity to explore the impact of social and environmental factors on chimpanzee territorial behaviour.
Within the chimpanzee fission-fusion social system, members of a larger group form numerous subgroups that merge and split in response to social and ecological factors like food availability, predation pressure, and the presence of receptive females. While communities typically consist of 50-70 individuals with around 10-15 adult males, abnormally large communities exist in Ngogo (over 200 individuals) and Waibira (estimated 120 individuals), where over 30 adult males have been recorded. However, little is known about differences in social structure and associated consequences in these communities. One study has indicated clear subgrouping in the males of Ngogo, who range in two distinct ‘neighbourhoods’ rather than as a single unit (Mitani & Amsler, 2003). The result begs the question of whether this social structure is related to the unusual demographic size or is a consequence of other factors in Ngogo. Is there similar evidence of subgrouping amongst male chimpanzees in Waibira? If so, this may be an indication of the need to manage male-male social interactions when part of an abnormally large community. Indeed, Lehmann and Boesch (2004) reported that subgrouping patterns in chimpanzees of the Taï National Park in Côte d’Ivoire were dependent on total community size and number of males, with smaller communities exhibiting higher cohesiveness and a reduction in fluidity of the fission-fusion system.
In addition to the number of individual males influencing subgrouping within a community, the presence of individual differences may also impact the male social structure. For example alpha male chimpanzees are known to exhibit different dominance styles that may be more cooperative or agonistic during their tenure as alpha (Foster et al., 2009). Furthermore, the fate of usurped males after they lose their alphaship may be related to their dominance style (Uehara et al., 2004). Changes in the rank of individual male chimpanzees may also impact the social behaviour of their relatives. While other male chimpanzees, even when closely related, represent possible competitors, female relatives such as mothers, or sisters who remain resident in their natal community, may adjust their social behaviour depending on the rank of their sons and brothers.
One external environmental factor that may influence male chimpanzee subgrouping is the presence of human researchers. As we have long-term data available for the Waibira community we can compare the variation in territory use and in male subgrouping over the course of habituation, allowing us to explore the impact of habituation on chimpanzee behaviour.
In addition to variation in the number and personality of males within a community, the use of territory and male sub-grouping may be impacted by the behaviour of neighboring communities. Chimpanzee intercommunity disputes are agonistic, and may include lethal aggression, particularly where a single male or small party encounters a larger number of males from the other community. As such they represent a significant pressure on chimpanzee use of territory.
The number of males in a chimpanzee community influences how large the territory is, and when food availability is stable and abundant, it is thought that more energy is directed at territory utilisation and defense (Herbinger et al., 2001). Previous work from Kibale has also shown that on a given day, higher numbers of males in a party of chimpanzees will increase their tendency to patrol borders (Mitani and Watts, 2005). As periods of social uncertainty surrounding alpha changes can affect associative patterns and grooming behaviour, especially between males (see Koyama et al., 2017), it raises the question of how social instability impacts male territory usage. We will explore the almost 30-year data set of the Sonso chimpanzees in order to test whether or not the number of independent males, and/or the presence of individual males, impacts the size of the communities’ territory and their use of the areas within it. We will also investigate peripheral territory ranging in relation to alpha male transitions.
Understanding the social grouping and ranging patterns over time will shed light on the function and motivation of chimpanzee territoriality. Understanding the ways that population characteristics, social relationships, and territory usage interact has implications for both ecological theory and for conservation management.
Research Questions
1. Male subgrouping within communities (lead researcher Ms Bodden)
◠Is there evidence of subgrouping or ‘neighbourhoods’ among male chimpanzees in the Waibira community? If so, how does this structure affect cohesion and stability?
â— How does the Waibira community structure compare to that of the males in Sonso and how have subgroups changed over time?
â— What effect have alpha male transitions had on subgrouping structure in the Waibira males?
2. Male use of territory in the Sonso community (lead researcher Ms Shearer)
â— How does the number of independent males, and the leadership of individual alpha males influence the size and use of the Sonso territory?
◠What social factors predict Sonso chimpanzees’ peripheral territory usage across seasons? We will explore the number of independent males, the identity of the alpha male, and the proximity to alpha male transitions.
3. Female association and subgrouping patterns (lead researcher Mr Chapoy)
â— Do females who migrate from the same community preferentially associate with each other? We will explore the behaviour of the four confirmed immigrants from the Sonso community to the Waibira community.
â— Do female relatives of independent males vary their use of the territory with variation in their male relatives ranks? We will explore the physical and social centrality of females who are closely related to males who move into or out of the top three rank positions.
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UK |
2018-07-13 |
2021-07-13 |
Natural Sciences |
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Non-degree Award |
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Hilda Nakalema Sekabira
ID:
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Evaluating the Impact of Early Initiation of Antiretroviral Therapy (ART) on Patient Outcomes Among HIV-Infected Adolescents and Young Adults in Uganda
REFNo: HS218ES
BROAD AIM: The broad aim of this study is to assess the impact of early initiation of ART on patient outcomes, over time, among adolescents and young adults (AYA), 15 - 24 years of age, living with HIV, in high-volume health facilities in Uganda before and after the implementation of the 2013 WHO ART treatment guidelines.
SPECIFIC AIMS:
Aim 1: To assess the effect of early ART on adherence to medication among AYA 15 - 24 years, before and after the implementation of the 2013 WHO ART treatment guidelines.
Aim 2: To assess the effect of early ART on the rate of Opportunistic Infections (OI) episodes among AYA 15 - 24 years, before and after the implementation of the 2013 WHO ART treatment guidelines.
Aim 3: To compare survival and predictors of survival among AYA 15 - 24 years, before and after the implementation of the 2013 WHO ART treatment guidelines.
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Uganda |
2018-07-05 |
2021-07-05 |
Medical and Health Sciences |
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Degree Award |
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