Survey guidelines for Australia’s threatened non-flying mammals

Woylie, brush-tailed bettong

Bettongia penicillata ogilbyi

States and territories: Western Australia (excluding translocated populations).

Regions: Confined to three reserves and surrounding areas in the wheatbelt of Western Australia: Dryandra Forest, Tutanning Nature Reserve and Perup Forest. The former range of this subspecies is unclear but it was widespread south of the tropics, including the central Western Australian deserts and into the southern region of the Northern Territory, where it had disappeared by 1960 (Burbidge et al. 1988). The woylie has been established by translocation at a number of localities in Western Australia, South Australia and New South Wales (for example, Priddel & Wheeler 2004; Martin et al. 2006).

Habitat: The remaining locations for the woylie are all characterised by open forest and woodland with a tussock grass ground layer or understorey of woody scrub and the presence of thickets of the plant genus Gastrolobium (Papilionaceae), which contains monofluoroacetic acid (de Tores & Start 2008). Formerly the woylie occurred in a more diverse range of habitats, including arid Triodia grasslands. During the day the woylie shelters in a nest constructed of grass or shredded bark located in a shallow depression concealed under a bush, the foliage of a grass tree, Xanthorrhoea, fallen log or other cover (Christensen & Leftwich 1980).

Habit: Ground dwelling.

Avg. body weight: Males 980–1850 g; Females 750–1500 g (de Torres & Stuart 2008).

Activity pattern: Nocturnal.

Diet: Principally underground fungi (native truffles) supplemented by tubers, bulbs, grains, seeds, insects and resin exudates from Hakea (Proteaceae) species (de Tores & Start 2008). The woylie can store food in their cheek pouches for subsequent caching.

Breeding: Breed continuously under suitable conditions, giving birth to one (rarely two) young and producing up to three young per year (Christensen 1980; de Tores & Start 2008).

Description

‘Woylie’ is the indigenous Nyoongar name which refers to the ability of this species to carry nesting material with the tip of its prehensile tail. The woylie formerly occupied large areas of arid and semi-arid regions of southern Australia, comprising two subspecies: the woylie B. p. ogilbyi that is now confined to a small number of localities in far south-western Australia, and the brush-tailed bettong B. p. penicillata that formerly occurred in eastern Australia, but is now extinct (Burbidge et al. 1988). The boundaries of occurrence of these two subspecies are unclear and the subspecies status of former populations in central Australia is unknown. Reasons for the extinction of the eastern subspecies and the major contraction in range of the woylie are attributed to fox and feral cat predation (Burbidge et al. 1988; de Tores & Start 2008). Other factors include habitat destruction and alteration, including changes to fire regimes and impacts associated with domestic and feral herbivores (Start et al. 1995). Since 2001, woylie numbers in the last remaining localities have suffered declines of greater than 93 per cent in some populations. These recent declines have been attributed to an as-yet unknown disease predisposing individuals to predation by foxes and feral cats (Henstridge et al. 2008; Wayne 2009).

Survey methods

On the basis of previous surveys, the following survey techniques are recommended to detect the presence of the woylie in areas up to 5 hectares in size:

• 
  daytime searches for potentially suitable habitat resources such as open forest and woodland with tussock grass ground layer and thickets of Gastrolobium (description of the survey technique and recommended effort is provided in Section 3.1)
  
• 
  in areas of higher densities: cage trapping surveys using a mixture of peanut butter, rolled oats and sardines conducted according to the procedure adopted in the Woylie Conservation Research Project Operations Handbook. Due to an unknown disease being implicated in recent population declines, cage trapping requires a high standard of hygiene – for example, not moving traps between locations and ensuring traps are hygienically maintained (CALM 2005; Chapman et al. 2005). Additionally, capture in traps may result in the physical injury of trapped animals, capture myopathy, rejection of pouch young and the risk of predation through daytime release.
  

However, where the species is at low densities or confirmation of sightings is required, trapping may be an inefficient technique on its own so should be conducted in conjunction with a variety of other techniques, such as:

• 
  car-based spotlight surveys along fixed transects conducted according to the procedure adopted in the Woylie Conservation Research Project Operations Handbook
  
• 
  daytime searches for signs of activity, including diggings, tracks and nests (description of the survey technique and recommended effort is outlined in Section 3.2). However, caution is required to distinguish diggings and tracks from other sympatric mammal species and the location of nests should follow the technique of Christensen and Leftwich (1980)
  
• 
  searches for distinctive nest depressions immediately following fire before any significant rain or wind events (following Christensen & Leftwich 1980)
  
• 
  deployment of hair tubes, particularly in areas with low densities (description of the survey technique and recommended effort is provided in Section 3.3.7), provided that expertise to identify hair samples is available
  
• 
  use of camera traps accompanied with bait stations, baited with peanut butter, rolled oats and sardines (see Section 3.3.6)
  
• 
  scats are difficult to locate, but any scat searches should use molecular based methods to confirm the identity of the macropod species present (Alacs et al. 2003)
  
• 
  community liaison to search for additional locations, particularly on private land (description of the survey technique and recommended effort is provided in Section 3.2.1).
  

Similar species in range

The woylie in south-western Australia can be distinguished from other small macropods by the dark tail with the end half possessing a distinctive ridge-like or brush-like appearance. Additional characteristics separating the woylie from other small macropods in south-western Australia are: a) quokka Setonix brachyurus is larger in weight (up to 4.2 kilograms) and has a shorter tail lacking the crest of blackish fur on the end half; b) Gilbert’s potoroo Potorous gilberti is smaller, confined to dense heathland, is darker, possesses a longer, pointed muzzle, and the tail is noticeably shorter than the head-body length; and c) burrowing bettong Bettongia lesueur lives in burrows, lacks the tail crest and is yellow-grey rather than grey to greyish-brown on the dorsal surfaces.

References

Alacs, E., Alpers, D., de Tores, D.J., Dillon, M. and Spencer, P.B.S. 2003. Identifying the presence of Quokkas (Setonix brachyurus) and other macropods using cytochrome b analyses from faeces. Wildlife Research 30: 41-47.

Burbidge, A.A., Johnson, K.A., Fuller, P.J., and Southgate, R.I. 1988. Aboriginal knowledge of the mammals of the central deserts of Australia. Australian Wildlife Research 15: 9-39.
CALM 2001. Sand pads – using tracks to monitor fauna. Information Notes No. 10, Department of Conservation and Land Management, Perth.
CALM 2005. Department of Conservation and Land Management Animal Ethics standard operating procedures. Department of Conservation and Land Management, Perth.
Chapman, T., Sims, C. and Mawson, P. 2005. Minimising disease risk in wildlife management. Standard operating procedures for fauna translocation, monitoring and euthanasia in the field. Department of Conservation and Land Management, Perth.
Christensen, P. and Leftwich, T. 1980. Observations on the nest-building habitats of the Brush-tailed Rat-kangaroo or Woylie (Bettongia penicillata). Journal of the Royal Society of Western Australia 63: 33-38.
Christensen, P.E.S. 1980. The biology of Bettongia penicillata Gray, 1837, and Macropus eugenii (Desmarest, 1817) in relation to fire. Forests Department of Western Australia Bulletin No. 91. Forests Department, Perth.
de Tores, P.J. and Start, A.N. 2008. Woylie Bettongia penicillata Pp. 291-292. In Van Dyck, S. and Strahan, R. (Eds.) The Mammals of Australia. Third Edition. Reed New Holland, Sydney.
DEC 2008. Diagnosis of recent Woylie (Bettongia penicillata ogilbyi) declines in south-western Australia. Western Australian Department of Environment and Conservation.
Henstridge, J., Munday, A., Caccianiga, R. and Trafalski, S. 2008. Analysis of Upper Warren Woylie data. Produced by Strategic Information Consultants, Perth. www.daa.com.au/fileadmin/presentations/woylie_data_presentation.pdf. Accessed 1 August 2009.
Martin, S., Bull, S., and Peters, P. 2006. Reintroduction of the Brush-tailed Bettong (Bettongia penicillata ogilbyi) into Lincoln National Park. Department of Environment and Heritage, Adelaide.
Orell, P. 2004. Fauna monitoring and staff training: Western Shield review – February 2003. Conservation Science Western Australia 5: 51-95.
Pizzuto, T.A., Finlayson, G.R., Crowther, M.S. and Dickman, C.R. 2007. Microhabitat use by the Brush-tailed Bettong (Bettongia penicillata) and burrowing bettong (B. lesueur) in semiarid New South Wales: implications for reintroduction programs. Wildlife Research 34: 271-279.
Priddel, D. and Wheeler, R. 2004. An experimental translocation of Brush-tailed Bettongs (Bettongia penicillata) to western New South Wales. Wildlife Research 31: 421-432.
Start, T., Burbidge, A. and Armstrong, D. 1995. Woylie Recovery Plan. Second Edition. WA Wildlife Management Program No. 16, Dept of Conservation and Land Management, Perth.
Triggs, B. 1996. Tracks, scats and other traces: a field guide to Australian mammals. Oxford University Press, Melbourne.
Wayne, A. 2009. Woylie declines: what are the causes? Information Sheet 7/2009. Science Division, Dept of Environment and Conservation, Perth.