Proximate factors of migration in Miniopterus natalensis (A. Smith 1833) in north-eastern South Africa

Abstract

Migration is one of the key evolutionary adaptations allowing animals to survive in a landscape with seasonally changing and geographically separated resources. Understanding the various underlying processes governing migration in species is crucial to the conservation of many migratory species. This is especially true for migratory bat species in South Africa, for which limited information is available and no conservation action plans are in place. In this thesis, I focus on investigating the different factors affecting migration in the cave-dwelling, insectivorous Natal long-fingered bat Miniopterus to ultimately better understand the process of migration, including the internal motivation to move, the physical ability to move, the timing of the movement and the external factors affecting movement. The populations of bats used for this study were located in a maternity cave in Thabazimbi, in Limpopo Province and an unconfirmed stopover cave in the Hennops River Valley, Gauteng Province, South Africa. Using long-term, historically collected data as well as data collected during this study, I investigated which climatic factors likely initiated migration, arrival and departure times at the maternity site and factors affecting nightly activity patterns (Chapters 2 and 3), the physiological needs of females during the maternity period and whether this species prepares for migration away from the site through fattening (Chapters 4 and 5), whether the sexes exhibit morphological differences in their ability to move (Chapter 6) and whether differential movement is detectable between the sexes using isotopic signatures (Chapter 7). Lastly, I summarised current known important roost localities for M. natalensis, assessed their current protection status and modelled likely migration paths between ecologically important roost sites (Chapter 8). My research provided novel information on the migratory processes of M. natalensis and will be useful for informing future conservation action plans for this and other cave dwelling bat species in South Africa.