Temperature Regulation and Rate of Metabolism in Three Bornean Bats

Abstract

Data are presented on temperature regulation and rate of metabolism in three Bornean bats, Cynopterus brachyotis, Eonycteris spelaea , and Hipposideros galeritus . These species maintain core body temperature at 36.5, 34.0, and 31.9°C, respectively, a sequence also found in the level of basal rate of metabolism, namely 92, 73, and 55% of the values expected from mass, respectively. These data and those available in the literature demonstrate that much of the variation in basal rate among bats correlates with food habits, independent of phylogeny. Thus, Cynopterus , like other frugivorous species, has the highest basal rate reported here, and Hipposideros , an insectivorous species, has a low basal rate. The intermediate basal rate in Eonycteris may reflect a large mass (52 g) for a nectarivorous species. The variation in basal rate may be understood principally in terms of the phenology of foods used. Previous estimates for basal rate of metabolism and minimal thermal conductance of Neotropical bats have been readjusted for temperature and pressure.