Bare-rumped sheathtail bat
Common name: bare-rumped sheathtail bat
Scientific name: Saccolaimus saccolaimus nudicluniatus
Legislative name: Saccolaimus saccolaimus
Family: Emballonuridae (sheathtail bats)
Conservation status: This species is listed as Endangered in Queensland (Nature Conservation Act 1992) and is Critically Endangered nationally (Environment Protection and Biodiversity Conservation Act 1999). It is ranked as a high priority under the Department of Environment and Heritage Protection Back on Track species prioritisation framework.
This large sheathtailed bat gets its common name from the lack of fur on the lower part of its back beyond the hips. The dorsal fur is dense and silky and is coloured red brown to dark brown or black with small white patches. It has sparse fur on its face, forearms, inner surface of ears, upper surface of tail membrane, and wing membranes between the forearm and the legs. It does not possess the wing pouch that several other sheathtail bats have, but it does have a throat pouch, which is well developed in males and rudimentary in females (Churchill 1998; Menkhorst and Knight 2001). Northern Territory individuals seem to be slightly larger, darker (almost black) on the dorsal fur compared to the Queensland specimens (Troughton 1925; McKean et al. 1981; Hall 1995).
Habitat and distribution
The bare-rumped sheathtail bat occurs primarily in tropical eucalypt woodland and possibly rainforest in the coastal lowlands of north-eastern Queensland and the Top End of the Northern Territory. It prefers open woodlands, particularly poplar gum woodland, and tall open forest. In Northern Territory, it occurs in Darwin woollybutt forest. The small number of confirmed roosts located in Australia has been in tree hollows. Most roosts are located in poplar gum Eucalyptus platyphylla hollows at 10-15 m in height with a roost entrance 6-7 m above the ground. A few roosts are found in caves and mines.
The sheathtail bat occurs in two distinct populations, one in coastal Queensland from around Townsville to near Coen, and another in the top end of the Northern Territory. It also occurs in New Guinea.
Life history and behaviour
The life history and ecology of this species are poorly known both within Australia and elsewhere within the bat’s range. All information is based on anecdotal observations.
The colony size usually ranges from 3 – 40 bats. In roosts this species crawls away rapidly when disturbed rather than taking flight. It is a fast and highly maneuverable flier. Nocturnally active, it begins foraging in the early evening. It takes flight by dropping for about three metres to gain speed before opening its wings. Bare-rumped sheathtail bats are insectivorous although the type of insects taken has not been documented it is likely to forage primarily for aerial insects over the woodland/forest canopy but may fly lower when foraging over open situations (Bonaccorso 1998; Churchill 1998; Woinarski & Milne 2002).
The exact periods of mating and giving birth are unknown (Hall 1995). Observations of its reproduction have found females pregnant or with a single young in mid December. Breeding appears to be slightly later in the Northern Territory with pregnant females recorded between January and March (McKean et al. 1981; Churchill 1998).
The threats impacting the survival of this species are not yet well understood. However, known and likely threats include:
- Loss of habitat - parts of its range has been subjected to extensive habitat clearance for agriculture and urban development.
- Timber collection and targeted tree removal - timber collection and the targeted removal of hollow-bearing and dead trees along road reserves, in parks and other urban situations may result in the destruction of some roosts.
- Competition for hollows - in some areas this species may be adversely impacted by feral birds such as the common myna Acridotheres tristis, native birds that have benefited as a result of urban/agricultural environments (e.g. rainbow lorikeet Trichoglossus haematodus and the sulphur-crested cockatoo Cacatua galerita) and introduced insects (e.g. feral bees).
A national recovery plan for bare-rumped sheathtail bat has been developed and recommends the following management actions:
- Conduct intensive surveys at known localities to determine the distributional limits of the Northern Territory and Queensland populations.
- Carry out ecological research to determine habitat requirements, roost and maternity site selection, threatening processes and whether populations of this species are viable.
- Protect suitable and potential habitat in conservation reserves, such as coastal areas of the Wet Tropics bioregion.
- Increase the protection of known roosts both on and outside reserved lands.
Churchill, S 1998, Australian Bats, Reed New Holland, Sydney.
Duncan, A, Baker, GB and Montgomery, N (Eds.) 1999, The Action Plan for Australian Bats, Environment Australia, Canberra.
Hall, LS 1995, Bare-rumped Sheathtail bat Saccolaimus saccolaimus, pp. 469–70, in Strahan, R (ed), The Mammals of Australia, Reed Books, Chatswood, NSW.
Menkhorst, P and Knight, F 2001, A Field Guide to the Mammals of Australia, Oxford University Press, Melbourne.
McKean, JL, Friend, G and Hertog, AL 1981, Occurrence of the sheath-tailed bat Taphozous saccolaimus in the Northern Territory, Northern Territory Naturalist 4, 20.
Schulz, M and Thomson, B 2007, National recovery plan for the bare-rumped sheathtail bat Saccolaimus saccolaimus nudicluniatus. Report to Department of the Environment and Water Resources, Canberra, Queensland Parks and Wildlife Service, Brisbane.
Troughton, E Le G 1925, A revision of the genera Taphozous and Saccolaimus (Chiroptera) in Australia and New Guinea, including a new species, and a note on two Malayan forms, Records of the Australian Museum 14, 313–41.