THERMOREGULATION, ENERGY-METABOLISM, AND TORPOR IN BLOSSOM-BATS, SYCONYCTERIS-AUSTRALIS (MEGACHIROPTERA)

Since little information is available on torpor in bats of the suborde r Megachiroptera, we investigated whether the small(18 g) blossom-bat Syconycteris australis displays torpor in the laboratory. Bats entered daily torpor when food and water were withheld for one night and the air temperature (T-a) was below about 26 degrees C. Torpor began short ly after lights went on in the morning and lasted for a maximum of 12 hours. During torpor at T-a 18 degrees C, metabolic rates fell to a mi nimum of about 15% of that in resting individuals at the same T-a, and to about 40% of the basal metabolic rate. The body temperature (T-b) during torpor was metabolically defended at or above about T-b 18 degr ees C. Individuals that did not enter torpor in the morning reduced th eir T-b from about 34.5 degrees C, observed in resting individuals tha t had been fed during the previous night, to values between 30.2 and 3 2.8 degrees C, and the resting metabolic rate fell by about 25%. The a bility to undergo short periods of torpor may explain why the distribu tion range of S. australis extends much further south than that of oth er small Australian megachiropteran bats.