Behaviour and ecology of the Northern lesser galago (Galago senegalensis)

Ellison, Grace (2022) Behaviour and ecology of the Northern lesser galago (Galago senegalensis). Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Galagids (family: Galagidae; suborder: Strepsirrhini) are small nocturnal primates distributed across sub-Saharan Africa. Knowledge on their behaviour and ecology is important for understanding our early primate ancestors, who were also most likely small and nocturnal. Data on the behaviour and ecology of many galagid species is lacking but urgently needed for their effective conservation in the face of anthropogenic threats. The Northern lesser galago (Galago senegalensis) is the most widely distributed of all the galagids, occupying a range of habitats, and is therefore a particularly suitable model species for the study of the behaviour and ecology of galagids. I researched Northern lesser galagos from January 2016 to January 2022. For my thesis I had the following aims: highlight taxonomic and geographic biases in the study of all galagids; investigate Northern lesser galago activity and social behaviour; determine factors that contribute to Northern lesser galago sleeping ecology; assess the response of Northern lesser galagos to systematic predation from Western chimpanzees (Pan troglodytes verus); and create a non-invasive method to retrieve DNA from wild galagids. I used a range of methods for data collection: systematic search of the literature, continuous behavioural observations, vegetation surveys, line transect surveys, and non-invasive sampling; and analysis: hypothesis testing, negative binomial regression, logistic regression, text mining, random forest classification analysis, distance sampling, density surface modelling, and DNA extraction and amplification. My systematic review in Chapter 2 revealed that, between 1971 and 2020, most research was on larger-bodied species and those with larger geographic ranges, and study sites were in cooler and more accessible areas. The behavioural study in Chapter 3 found that, at Kwakuchinja in Tanzania, Northern lesser galago behaviour varied across different periods of the night, with foraging being most prevalent in the evening (post-dusk). The use of both vocal and olfactory social communication, observations of complex social behaviours, and galagos at Kwakuchinja being in groups in the majority of observations, suggests that Northern lesser galagos may have a higher degree of sociality than previously thought. The study of Northern lesser galago sleeping ecology at Kwakuchinja in Chapter 4 revealed that sleeping sites allow galagids to remain hidden but able to escape easily from opportunistic predators, especially aerial predators, and remain cool when sleeping during the day. Chapter 5 found that, at Fongoli in Senegal, Northern lesser galagos sleep inside trees with several escape routes from chimpanzees, which systematically hunt them at their sleeping sites. When active, galagos at Fongoli avoid areas frequently used by chimpanzees. Finally, Chapter 6 describes a novel non-invasive technique that can be used to obtain samples from galagids for genetic analysis. This thesis contributes significantly to the understanding of Northern lesser galago behaviour and ecology, revealing how they respond to the different pressures acting on populations across their range. The knowledge on Northern lesser galago microhabitat requirements and activity will be invaluable in future behavioural research and for implementing effective conservation strategies. For the study of all galagids, the review acts as a guide to ensure that future research addresses the uneven representation of species and study sites. The novel non-invasive genetic sampling method presents a way to study the genetics of galagids and other nocturnal, arboreal or cryptic animals, with a plethora of applications.