Monitoring bent-wing bats at Bat Cleft in Central Queensland

Abstract

Undertaking accurate counts is an important part of managing cave-dwelling bats species such as the little bent-wing bat (Miniopterus australis) population at Mt Etna. A thermal camera and automated counting system were trialled to see if the technology would work at Mt Etna with the goal of producing accurate counts of bats. Although the heat radiating from the rock meant that the background at Mt Etna was not perfect, the automated system was able to recognise and count the bats as they emerged. The number of bats emerging from the cave varied from 82 677 in 2017/18 through to 139 783 in 2018/19. These estimates are within the range of those made in the 1960 to 1980s, which suggests that the population is stable, but we are unsure of the accuracy of these previous counts. These results demonstrate that it is possible to obtain accurate counts of reasonably large bat populations such as Bat Cleft and the methodology may have application for other gregarious and nocturnal species whose numbers can be difficult to count at night.