A confirmed range extension for the south-eastern long-eared bat (Nyctophilus corbeni) into the central Victorian Murray corridor

Abstract

The threatened South-eastern Long-eared Bat (Nyctophilus corbeni, EPBC Act 1999 Vulnerable) is an insectivorous microbat that is dependent on tree hollows for roosting. Although it is sparsely distributed throughout the Murray-Darling Basin, its contemporary Victorian distribution was believed to be limited to a small population in semi-arid mallee habitats in the state's North-West. That was until a lactating female was captured in the floodplain forest in Gunbower National Park, along the Murray River in north-central Victoria, in late 2021. In light of this new record, in an ecological setting not typically occupied by the species, we sought to (a) confirm the presence of an established population of N. corbeni at Gunbower; and (b) if present, characterize the day roosts being used. Over eight nights (73 trapnights), we captured 172 microbats, including five N. corbeni. Traps set with acoustic lures (the Autobat MK2, or a generic bat chirper) appeared to capture more bats per trapnight than those set without lures. Four individual N. corbeni were successfully radiotracked to their roosts, which were a mix of small-diameter (19.5–36 cm DBH), typically multi-stemmed, live, dying and dead Black Box (Eucalyptus largiflorens) and Grey Box (Eucalyptus microcarpa) trees. While day roosts do not appear to be limiting for this species in this location, further research is needed to understand what trees are being used as maternity roosts (which may be more specialized), how far up- and down-stream along the Murray River this new population extends, and whether it is geographically and/or genetically connected to populations in the Victorian mallee or in New South Wales.