Reproductive ecology of Commerson's leaf-nosed bats Hipposideros commersoni (Chiroptera: Hipposideridae) in South-Central Africa: interactions between seasonality and large body size; and implications for conservation
The annual cycle and reproductive ecology of a large population of Commerson's leaf-nosed bats, Hipposideros commersoni, was studied in central Zimbabwe. The influence of the extremely large body size of this microchiropteran, interrelating with a seasonal, tropical environment, was the central theme of this study. Adaptive responses to seasonal environmental changes differed between reproducing adults of the sexes. Reproductive females dispersed twice during the annual cycle, while in contrast adult males reduced activity during the cool, dry season. A polygynous mating system was characterised by breeding males defending demarcated territories within the daylight roost. Synchronized parturitions within maternity roosts (in late October) created a hot, humid microclimate which facilitated rapid post-natal development of neonates. The large body size of H. commersoni is suggested to have evolved in response to different selective agents, including: availability of large, hard shelled arthropods as prey; energetic constraints; and availability of fat reserves to ‘ride out’ inclement periods when food is limiting. Sexual selection may be the ultimate cause of a large body size. The conservation of H. commersoni is discussed given the history and pressures for guano exploitation of their breeding caves and the keystone role of these large bats in transferring nutrients and energy into the cavernicolous ecosystems where they roost and breed.