New Zealand Lesser Short-tailed Bat - Behaviour

Behaviour

Short-tailed bats are nocturnal, spending the day roosting in hollow trees. Many bats roost alone, using small cavities in the wood, but colonies of over a hundred individuals are not uncommon. Although they generally use natural cavities or crevices, they have also been reported to chew out burrows within the wood using their sharp incisor teeth. Such burrows consist of hollowed out chambers connected by narrow tunnels up to several metres in length. They typically spend only a few weeks at any given roosting site, before moving on, although individual roosts may be reused repeatedly over the course of several decades.

The bats emerge from their roosts 20 to 150 minutes after sunset, and forage for much of the night. Short-tailed bats spend only around 30% of their foraging time catching insects in the air, typically flying less than 2 m (6 ft 7 in) above the ground, and a further 40% feeding from plants. The remaining 30% is spent hunting on the forest floor, a higher proportion than any other species of bat. To assist with this unusual style of hunting, short-tailed bats are able to fold their wings inside a protective sheath formed from their membranes, and the wings have only a very limited propatagium, making them more flexible and mobile. Movement along the ground is also assisted by strong hind limbs and a robust pelvic girdle, and by the additional talons on their claws.

They hunt their prey using scent, passive hearing, and echolocation. Their main calls have a wide bandwidth and are multiharmonic, with a peak amplitude of 27 to 28 kHz. They also make shorter pulsed, frequency modulated calls. The bats enter torpor in cold weather and stay in their roosts for up to 10 days at a time before emerging to feed. They may also enter daily torpor when roosting alone. However, they are capable of remaining active even in subzero temperatures when necessary.