Seasonal differences in foraging dynamics, habitat use and home range size of Wahlberg’s epauletted fruit bat in an urban environment

Abstract

Urbanization through the process of habitat loss and fragmentation affects  ecosystems. Many species are no longer able to survive in these urban areas; however, there are some that have been able to persist and even thrive in these habitats. One such species is Wahlberg’s epauletted fruit bat (Epomophorus wahlbergi). Little is known about its existence in urban areas. Consequently we studied their seasonal variation in home range size, movements and foraging dynamics in the urban environment of Pietermaritzburg, South Africa. In a pilot study in summer, adult fruit bats (n = 8) were caught, fitted with radio-transmitters, and their movements followed for 12 nights and days. Although their movements varied considerably, no bats left the urban environment. Some of the larger distances covered in a single night were 2 and 5 km. In winter, an additional ten adult fruit bats were caught and fitted with radio-transmitters. Movements were followed for three weeks during winter and spring respectively. Winter home range size was greater than spring home range size. During winter the bats fed mostly on syringa fruits (Melia azedarach), an alien invasive, while their diet in spring was more varied and included species of indigenous and exotic fruits. The reduced variety of fruit eaten in winter may be explained by a reduction in fruiting plant  species, and thus a reliance on a few species to meet their dietary requirements. The bats would have a role in seed dispersal but therein lies the problem of them also dispersing invasive plants. Further research is needed to assess the role played by exotic and alien plant species in the continued success of urban wildlife, in particular fruit bats. The seasonal variation in home range size gives insight into the urban movements of Wahlberg’s epauletted fruit bats. The use of exotic and invasive plants by these bats is also significant.

Key words: Chiroptera, fruit bat, urban environment, home range, roost sites, seasonal differences, movement.