CAVE UTILIZATION BY NAMIBIAN BATS - POPULATION, MICROCLIMATE AND ROOST SELECTION

Ten caves in central Namibia were searched for cave bats during May an d June 1996. Up to seven species were found sharing a single cave. Dif ferent species of bats were found to select roost sites with significa ntly different microclimates, based on temperature and relative humidi ty. Bats were using these caves as over-wintering sites and were selec ting either cool microclimates in which to enter daily torpor or warm microclimates to enable them to remain active with minimal energy expe nditure. Hipposideros commersoni was observed to remain inactive at th e roost for days without entering torpor or leaving the cave to forage . This large bat appears to over-winter by relying on its considerable fat store at this southern limit of its distribution. Roost behaviour , colony size and roost location within the cave was examined for each of the nine bat species encountered.