Microclimatic conditions in maternity caves of the bent-wing bat, Miniopterus schreibersii: an attempted restoration of a former maternity site.

Abstract

A 2-year study of Bat and Robertson caves in south-eastern South Australia provided information on the microclimatic conditions in a maternity cave of the bat Miniopterus schreibersii. The study also monitored changes in the temperature and humidity conditions in what is believed to be a former maternity site, Robertson Cave, following restoration of the damaged dome. The maternity cave, Bat Cave, was characterised by mild hypoxic and hypercapnic conditions, high relative humidity, and temperatures in the roosting area of around 30°C. Accumulated guano deposits had some areas of heat generation, but the bats themselves appeared to be the primary modifiers of their own microenvironment. To support this finding, the recapping of Robertson Cave resulted in high humidities and a narrow range of temperature fluctuations; however, the temperature never reached the levels seen in Bat Cave. Our conclusion that the heat production of the bats themselves is the prime factor affecting microclimatic conditions necessary for breeding may relate to the observation that few maternity sites serve large and widespread populations of this species.