Survey guidelines for Australia’s threatened non-flying mammals

Gilbert's potoroo

Potorous gilbertii

States and territories: Western Australia.

Regions: Two Peoples Bay Reserve (near Albany), Western Australia.

Habitat: Dense coastal heath habitat (Johnston 2008).

Habit: Ground-dwelling (nest in ferns or wire-grass).

Avg. body weight: 875 g (Menkhorst & Knight 2001).

Activity pattern: Nocturnal.

Diet: Mycophagous (primarily subterranean sporocarps but some epigeous fungi also eaten), and some invertebrates and fruits.

Breeding: Unknown.

Description

Gilbert’s potoroo was believed extinct until it was rediscovered in very dense heathland at Two Peoples Bay in 1994 (Johnston 2008). The species has been separated from other Potorous species on the basis of genetic studies, which have shown that it is as different from the eastern long-nosed potoroo Potorous tridactylus and the long-footed potoroo Potorous longipes as they are from each other (Sinclair & Westerman 1997). Gilbert’s potoroo is similar in appearance to the long-nosed potoroo, although more rufous in colour (Menkhorst & Knight 2001). This species is a specialist mycophagist and over 90 per cent of its faecal matter comprises fungal material (Nguyen et al. 2005).

Survey methods

DEC (2009) use hair-arch surveys to search for new populations. In a hair-arch survey, flexible plastic sheets are bent into an arc and held in shape by bent fence wire then placed in animal runways. Hair arches are sometimes baited with universal bait to encourage animal visitation. Hair is collected with double-sided sticky tape attached to the inside of the arch. The DEC (2009) reports that hair collection is labour intensive, although this method is less invasive than live trapping. Baited camera traps may be useful for locating unknown populations, and universal baits with added truffle or pistachio oil have been used successfully on this species (T. Friend pers. comm.).

The survey techniques recommended to detect the presence of Gilbert’s potoroo in areas up to 5 hectares in size are the same as those recommended for the long-nosed potoroo, which are as follows:

• 
  daytime searches for potentially suitable habitat resources, such as areas with a dense understorey (description of the survey technique and recommended effort is outlined in Section 3.1)
  
• 
  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)
  
• 
  collection of predator scats, owl casts or remains, targeting predatory bird and mammal nests and dens (description of the survey technique and recommended effort is outlined in Section 3.2)
  
• 
  soil plot surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.2
  
• 
  baited camera traps using universal bait (peanut butter and rolled oats) with truffle, pistachio or walnut oil (description of the survey technique and recommended effort is outlined in section 3.3.6)
  
• 
  community liaison to identify new populations and increase awareness of this species may be of use.
  

It is recommended that one or more forms of direct detection surveys, such as spotlight surveys (Section 3.3.3), cage trapping surveys (3.3.10) or hair sampling surveys (3.3.7) should be conducted in association with the indirect survey techniques outlined above. Given the conservation status of this species, minimising handling and capture stress should be a priority. Therefore, non-trap methods of detecting this species (for example, camera traps and hair funnels) should be used wherever possible.

Similar species in range

Gilbert’s potoroo is sympatric with the southern brown bandicoot Isoodon obesulus. The tracks made by bandicoots are distinguishable from those of Gilbert’s potoroo by the presence of three rather than five digits on the forepaws, and bandicoot diggings have a distinctive conical shape. The woylie Bettongia pencillata also occurs in south-western Western Australia, although it is not known to be sympatric with the Gilbert’s potoroo in its limited range.

References

DEC 2009. Gilbert’s potoroo research activities, Western Australian Department of Environment and Conservation. Available from: www.dec.wa.gov.au/content/view/2979/1481/1/1/. Accessed 24-03-2010.

Friend, T. (2009). Vic. DSE Arthur Rylah Institute for Environmental Research. Personal communication regarding the Gilbert’s potoroo.
Johnston, P.G.2008. Long-nosed Potoroo Potorous tridactylus. In Mammals of Australia. (Eds. S. Van Dyck and R. Strahan) pp. 301-302 (Reed New Holland: Sydney).
Menkhorst, P. and Knight, F. 2001. A field Guide to the Mammals of Australia. (Oxford University Press: Australia).
Nguyen, V.P., Needham, A.D. and Friend J.A. 2005. A quantitative dietary study of the ‘critically endangered’ Gilbert’s potoroo Potorous gilbertii. Australian Mammalogy 27:1-6
Sinclair, E.A. and Westerman, M. 1997. Phylogenetic relationships within the genus Potorous (Marsupialia: Potoroidae) based on allozyme electrophoresis and sequence analysis of the cytochrome b gene. Journal of Mammalian Evolution 4: 147-161.

Golden bandicoot

Isoodon auratus auratus

States and territories: Western Australia and Northern Territory.

Regions: Northern Kimberley region and Augustus Island, Western Australia, and Marchinbar Island, Northern Territory (McKenzie et al. 2008).

Habitat: Hummock grass on sandstone and deciduous vine thickets (McKenzie et al. 2008).

Habit: Ground-dwelling.

Avg. body weight: 310 g (McKenzie et al. 2008).

Activity pattern: Nocturnal.

Diet: Omnivore: insects and tubers (McKenzie et al. 2008).

Breeding: Breeds throughout the year, with peaks in breeding activity at the height of the wet season (December to January) and the dry season (August) (McKenzie et al. 2008).

Description

The golden bandicoot had a former distribution that covered much of mainland Australia (McKenzie et al. 2008). Today, the species range is greatly restricted, with three subspecies occurring as follows:

• 
  I. a. auratus on Marchinbar Island (Northern Territory), the northern Kimberley (mainland Western Australia) and Augustus Island (Western Australia)
  
• 
  I. a. barrowensis on Barrow Island and Middle Island off the Pilbara coast (Western Australia) (Woinarski 2001), and
  
• 
  I. a. arnhemensis, previously recorded in Arnhem Land (McKenzie et al. 2008), but which has not been recorded from definite observations on the Northern Territory mainland in recent years despite large-scale biodiversity surveys (Woinarski 2001).
  

The taxonomy of these subspecies is currently under review and relationships between this species and the southern brown bandicoot I. obesulus are being explored (Pope et al. 2001).

Southgate and colleagues (1996) found that on Marchinbar Island the species had a preference for low heath or shrubland vegetation types that are found on sand or sandstone. From an analysis of 23 scats, the species’ diet comprised mainly invertebrates but also some plant matter (Southgate et al. 1996). Golden bandicoots dig conical foraging pits (Triggs 1998) and shelter during the day in rudimentary nests and shallow scrapes under vegetation or rocks (Southgate et al. 1996).

Threatening processes to the golden bandicoot are unknown, but anecdotal evidence suggests that predation by cats may be a factor (Southgate et al. 1996). Cats do not occur on Marchinbar Island and Barrow Island where populations are present; however, a population of golden bandicoots on Hermite Island became extinct when cats were introduced (McKenzie at al. 2008). Dogs are present on Marchinbar Island and golden bandicoot hair has been recovered from dog scat samples (Southgate et al. 1996). Changes to fire regimes are also believed to be driving the population trends of tropical mammals like the golden bandicoot.

Survey methods

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

• 
  daytime searches for potentially suitable habitat, such as heath and open woodland habitats on sandy or sandstone substrates (description of the survey technique and recommended effort is outlined in Section 3.1)
  
• 
  daytime searches for signs of activity, including tracks, scats, nests and conical foraging holes (description of the survey technique and recommended effort is outlined in Section 3.2)
  
• 
  collection of predator scats, owl casts or remains, targeting predatory bird/mammal nests/dens (description of the survey technique and recommended effort is outlined in Section 3.2)
  

• 
  soil plot surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.2
  

• 
  spotlight surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.3
  
• 
  baited camera traps using universal bait (description of the survey technique and recommended effort is outlined in section 3.3.6).
  

Southgate and colleagues (1996) reported that female bandicoots rejected pouch young after handling. Given that established non-invasive techniques like camera trapping are available, these options should be fully explored before using more invasive techniques. If animals are to be caught, high-sugar bait (containing honey or golden syrup) should be used in traps (see Southgate et al. 1996).

Hair sampling device surveys are not recommended because Southgate and colleagues (1996) did not successfully detect the golden bandicoot on Marchinbar Island with this technique. The geographic distribution of this species and its subspecies is still not well known and this should be considered when undertaking field surveys.

Similar species in range

The golden bandicoot is similar in appearance to the northern brown bandicoot Isoodon macrourus, which occurs throughout much of northern Australia. The two species can be distinguished easily by the larger size and duller colouration of the northern brown bandicoot.

References

McKenzie, N.L., Morris, K.D. and Dickman, C.R. 2008. Golden Bandicoot, Isoodon auratus. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 178-180 (Reed New Holland: Sydney).

NT DIPE 2002. Summary of fauna survey methods. Department of Infrastructure, Planning and Environment Biodiversity Unit, Northern Territory.
Pope, L., Storch, D., Adams, M., Moritz, C. and Gordon, G. 2001. A phylogeny for the genus Isoodon and a range extension for I. obesulus peninsulae based on mtDNA control region and morphology. Australian Journal of Zoology 49: 411-434.
Southgate, R., Palmer, C., Adams, M., Masters, P., Triggs, B. and Woinarski, J. 1996. Population and habitat characteristics of the Golden Bandicoot (Isoodon auratus) on Marchinbar Island, Northern Territory. Wildlife Research 23: 647-664.
Triggs, B. 1998. Tracks, Scats and other Traces: A Field Guide to Australian Mammals. (Oxford University Press: Melbourne).
Woinarski, J.C.Z., Palmer, C., Fisher, A., Southgate, R., Masters, P. and Brennan, K. 1999. Distributional patterning of mammals on the Wessel and English Company Islands, Arnhem Land, Northern Territory, Australia. Australian Journal of Zoology. 47: 87-111.
Woinarski, J. 2001. Golden Bandicoot Isoodon auratus. Threatened Species Information Sheet. Ed. J. Woinarski, Department Biodiversity section, Natural Systems, Department of Infrastructure Planning and Environment, Northern Territory.