A strong flier, the common sheath-tailed bat is an agile and active species (3), flying high up in open areas in search of food (11).
This species is an insectivore (3) (12) (13) and hunts its prey on the wing (9) (13). Beetles form the bulk of the common sheath-tailed bat’s diet, but other insects are also eaten. Hunting alone, a common sheath-tailed bat finds food by flying slowly in a straight line over the feeding grounds at night, following a grid pattern over bushes and water (9) and detecting insects in mid-air using echolocation (6). During a feeding session, the common sheath-tailed bat may periodically rest on rocks next to cracks and fissures, which it will squeeze into if it is disturbed (9).
Groups of common sheath-tailed bats at roost sites are relatively small, with many consisting of fewer than 20 individuals (14), usually hanging more than 50 centimetres away from each other (9). The common sheath-tailed bat is reported to regularly relocate its roosting site (14), and can be found clinging in a spider-like manner to walls and ceilings in a variety of caves, from small cracks to large limestone caverns (10).
The common sheath-tailed bat has one breeding season per year (3) (15) (16). In central Queensland, mating occurs between late August and early September (3) (14), with young being born in late November or early December (3) (5) (14). However, the timing of breeding varies depending on the location, and in other areas young are reported to be born as early as October (5) (16), or as late as April (3). Interestingly, only the right ovary of the female common sheath-tailed bat is functional (16).
The gestation period of the common sheath-tailed bat is thought to be about four months (3) (16), after which time the female gives birth to a single young which is born with fur and with open eyes (3) (5) (14). The young sheath-tailed bat becomes independent at about three to four weeks old, and is almost full-grown at three months of age (3) (14). Female common sheath-tailed bats first reproduce at 9 months of age, while males do not begin mating until they are 21 months old (3) (5) (14). Breeding colonies of the common sheath-tailed bat are usually relatively small, and even the largest colony rarely exceeds several hundred individuals (10).
In the winter months, the common sheath-tailed bat has been observed in a state of torpor, with its body processes slowed to a fraction of their normal rate. Torpid bats roost in cool, shallow caves or near the entrance of large caves where there is cold air movement. If temperatures are very low, the common sheath-tailed bat may roost in a sunny patch of the cave wall near to the entrance. Torpid bats are still active, and quickly retreat to inner parts of the cave if disturbed (10).