Bat Societies across Habitat Types: Insights from a Commonly Occurring Fruit Bat Cynopterus sphinx

Abstract

Bats constitute the second most speciose order of mammals and are known for their gregarious and flexible social structure. Urbanisation can lead to changes in the availability of, or access to, resources, such as roosting sites, food, and mates, and thus can potentially affect the social and mating systems. In this chapter, we summarise knowledge of the effects of urbanisation on the social structure of bats and highlight gaps in the literature. Further, we discuss the social structure and reproductive output of Cynopterus sphinx, a fruit bat ubiquitous across human-dominated habitats in South and Southeast Asia. We followed two C. sphinx colonies over multiple seasons to understand how urbanisation impacts the social systems of these colonies. We used direct observational and genetic data to compare the colony size, social subunit size, relatedness, and reproductive output of both colonies. On average, the rural colony was larger than the urban colony. The two colonies did not differ significantly with respect to social subunit size and relatedness, suggesting minimal impact of urbanisation on social structure. However, there was a significant difference in reproductive output, with the reproductive success of females from the rural colony being 1.7 times greater than that of the urban colony. Our results from a single rural and urban colony located nearly 500 km apart suggest that urbanisation may reduce fecundity and urban areas may act as ecological traps. Future studies with more extensive sampling are needed to identify the main drivers of female reproductive success and the cause of reduced female fecundity in urbanised habitats.