Article by Clancy Hall, conservation biologist
As springtime marks the birthing season for most of our flying foxes, it is also the time of year when many of our microbat species give birth.
In October and November, female eastern forest bats form maternity roosts with over 50 other pregnant mothers, and often give birth to twins. To accommodate such large numbers, and to create the right humidicrib-style settings, these bats require the large hollows provided by big old eucalypt trees.
With all their pups nestled together in a nursery, the mums are free to escape in the cool of the night for a quick feed on moths, mosquitoes, flies and wasps. Remarkably, when the females return, they can pick their own babies out from all the other pups! Males of the species prefer to roost alone, often under a layer of loose tree bark.
The species’ latin name Vespadelus pumilus means little wasp-like (bat), no doubt referring to its diminutive 4-5g body size and tendency to whizz by at high speed after insects.
Even for experts, the species is difficult to distinguish from other small microbats without a bat detector (i.e. a sound recording device which converts bat vocalisations into a frequency audible to humans). For those with a discerning eye, females may be distinguished by their comparatively short, domed head and darker skin on the face and wing, and the males by examining the size and shape of more personal appendages!
Eastern forest bats prefer moist conditions and are common in rainforest gullies and neighbouring wet sclerophyll habitat. Although the species is not threatened, females are especially vulnerable to the loss of large natural hollows through land clearing. If you require the removal of one or more old trees, please consider the time of year, as it may be home to a colony of bat mums and their tiny pups.