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 Commerso n's leaf-nosed bats, Hipposideros commersoni, was studied in central Zimbab we. The influence of the extremely large body size of this microchiropteran , interrelating with a seasonal, tropical environment, was the central them e of this study. Adaptive responses to seasonal environmental changes diffe red between reproducing adults of the sexes. Reproductive females dispersed twice during the annual cycle, while in contrast adult males reduced activ ity during the cool, dry season. A polygynous mating system was characteris ed by breeding males defending demarcated territories within the daylight r oost. Synchronized parturitions within maternity roosts (in late October) c reated a hot, humid microclimate which facilitated rapid post-natal develop ment 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 avai lability of fat reserves to 'ride out' inclement periods when food is limit ing. Sexual selection may be the ultimate cause of a large body size. The c onservation of H. commersoni is discussed given the history and pressures f or guano exploitation of their breeding caves and the keystone role of thes e large bats in transferring nutrients and energy into the cavernicolous ec osystems where they roost and breed.