BASAL RATES OF METABOLISM OF NECTARIVOROUS BATS (PHYLLOSTOIMIDAE) FROM A SEMIARID THORN FOREST IN VENEZUELA

The phyllostomid bats Choeroniscus godmani, Glossophaga longirostris, and Leptonycteris curasoae maintained normothermia throughout 1.5- to 3.0-h experiments at ambient temperatures of 12-29 degrees C. Above lower-critical temperatures, C. godmani and L. curasoae had basal rates of metabolism close to expected values for mammals of their body mass, but G. longirostris had a basal rate 120% of that expected. Thermal conductance for C. godmani was near the expected mass-specific value for mammals, whereas values for G. longirostris and L. curasoae were higher than expected. Poorly ventilated caves acting as heat traps were selected by L. curasoae as maternity roosts. Population size in such roosts may approach 10,000 bats, and metabolic heat production of the colony elevates air temperatures within such caves to 33-34 degrees C. Colonies of G. longirostris and C. godmani often number <20 individuals in caves, mines, or buildings with air temperatures of 26-28 degrees C. Our results support the hypothesis that ecological factors, such as roost microclimate and diet, influence rates of metabolism in phyllostomid bats.