Survey guidelines for Australia’s threatened non-flying mammals

Southern brown bandicoot (Nyuts Archipelago)

Isoodon obesulus nauticus

States and territories: South Australia.

Regions: East Franklin, West Franklin and Saint Francis Islands, South Australia

Habitat: Heath and coastal scrub.

Habit: Ground-dwelling.

Avg. body weight: 850 g males and 700 g females (Braithwaite 1995).

Activity pattern: Nocturnal.

Diet: Unknown, but probably invertebrates, tubers and fungi.

Breeding: Unknown.

Description

The Nyuts Archipelago southern brown bandicoot I. o. nauticus has a range restricted to the Franklin Islands in the Great Australian Bight, Nyuts Archipelago and Saint Francis Islands off the coast, near Ceduna, South Australia. Subfossil evidence of the species has also been recorded on two other islands off the coast of South Australia (Flinders Island and Revesby Island) (Paull 1995). The relationship between this subspecies and other southern brown bandicoot subspecies is unresolved (see Pope et al. 2001). The subspecies and their distributions have been described in the previous species profile for the mainland subspecies of southern brown bandicoot, Isoodon obesulus.

Copley and colleagues (1990) estimated the population size of the Nyuts Archipelago southern brown bandicoot on the Franklin Island to be approximately 1000 and relatively stable. The Franklin Island populations as well as those on Saint Francis Island are protected by the inclusion of the islands in conservation parks.

Survey methods

Surveys to detect the presence of the Nyuts Archipelago southern brown bandicoot within its known range should focus on detecting signs of foraging and tracks, rather than expending effort trapping or conducting hair sampling surveys. Given that the species’ highly restricted range does not overlap with other bandicoot species, then the application of direct detection methods is not considered necessary to confirm the species’ identity. Therefore, the following survey techniques are recommended to detect the presence of the Nyuts Archipelago southern brown bandicoot in areas up to 5 hectares in size:

• 
  daytime searches for potentially suitable habitat resources. A description of habitat preferences for this sub-species is not available and so all habitats should be searched (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 and mammal nests and dens in areas where the species distribution may be in question (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 (description of the survey technique is outlined in section 3.3.6) using one camera per hectare. Autumn is preferred, but can be year round if validated with supporting evidence. A minimum of two surveys, each of 14 day duration, should be conducted, timed at least one month apart and at least one undertaken following significant rainfall
  
• 
  community liaison to detect the location of additional populations of the species.
  

Similar species in range

There are no other species of bandicoot that occur within the known range of the Nyuts Archipelago southern brown bandicoot. However, the species is similar in appearance to the mainland subspecies.

References

Braithwaite, R.W. 1995. southern brown bandicoot Isoodon obesulus. In ‘The Mammals of Australia’. (Ed. R. Strahan) pp.176-177. (Reed Books: Sydney).

Copley, P., Read, V., Robinson, A. and Watts, C. 1990. Preliminary studies of the Nuyts Archipelago bandicoot (Isoodon obesulus nauticus) on the Franklin Islands, South Australia. In ‘Bandicoots and Bilbies’. (Eds. J. Seebeck, P. Brown, R. Wallis, and C. Kemper). pp. 345-56. (Surrey Beatty and Sons: Sydney).
Paull D. 1995. The distribution of the southern brown bandicoot (Isoodon obesulus obesulus) in South Australia. Wildlife Research 22: 585-600.
Paul, D. 2008. southern brown bandicoot Isoodon obesulus. In ‘The Mammals of Australia’. (Eds. S. Van Dyck and R. Strahan) pp. 180-182 (Reed New Holland: Sydney).
Pope, L., D. Storch, M. Adams, C. Moritz 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.

Southern marsupial mole, yitjarritjarri, itjaritjari

Notoryctes typhlops

Distribution: Distributed across much of Australia’s sandy desert country in Western Australia, Northern Territory and South Australia.

Habitat: Sand desert country, most often recorded on sand dunes with various acacias and other shrubs, sometimes in association with spinifex (Benshemesh 2004). They can also occur in sandy plains and possibly river flats, especially where aeolian dunes also occur. Most locations are those with deep loose soil (Benshemesh 2004).

Habit: Mostly underground, about 20–60 cm below the ground surface, moving about by digging back-filled tunnels in search of prey (Benshemesh 2008).

Avg. body weight: Poorly known. Weight range from a limited sample was 40–70 g (Benshemesh 2008).

Activity pattern: Unknown daily activity pattern, as the species spends virtually all of its time underground. Occasional individuals come to the surface, such as after heavy rain or during cold weather (Benshemesh 2008). It is thought that such individuals may be under stress.

Diet: Poorly known. Limited data suggests it is largely insectivorous, with ant larvae, sawfly larvae, beetles, beetle larvae and cossid moth larvae recorded eaten by captive and wild specimens (Benshemesh & Johnson 2003). It has also been recorded eating geckoes, spiders and centipedes in captivity (Benshemesh 2008).

Breeding: Very little known. Records available indicate that one or two young are born and raised to independence in the pouch (Langford & Pavey 2002). Nothing is known about how individuals find each other, mate and raise young whilst underground.

Description

The southern marsupial mole, although widespread across the sandy deserts of Australia, remains an enigma. ‘Blind with shovels for hands and a subterranean lifestyle, marsupial moles have mystified scientists for over a hundred years and inspired a rich Aboriginal mythology’ (Benshemesh 2008). It is so poorly known that the endangered listing is a precautionary measure as their status is described as ‘unknown, but probably common’ (Benshemesh 2008).

Given the similarity in appearance between southern and northern marsupial moles (see ‘similar species’ below) and the lack of reported information about the species’ biology, discerning the ranges of the two marsupial mole species is difficult. Recent work suggests that the edges of the distributions of the two species exists somewhere in the Tanami Desert, with the southern marsupial mole occurring in the east and the northern marsupial mole N. caurinus in the western Tanami, but it remains uncertain whether these forms are sympatric (Benshemesh 2004).

Marsupial moles have specialised adaptations that have evolved in response to the species' burrowing lifestyle (Langford & Pavey, 2002). Their eyes are vestigial and hidden under the skin, their ears are reduced to a simple opening beneath the fur on either side of the head, and their conical shaped noses are covered with a tough, horny shield to protect against the sand. To burrow through the sand, the third and fourth digits of the forefoot are enlarged and possess large shovel-like claws for digging. They have a short, hard and leathery tail that is marked by distinct rings, ending in a horny ‘knob’. The colouration of the fur can vary from near white through pinkish to rich golden red.

Survey methods

The most efficient method of surveying for marsupial moles is to count the number of tunnels underground (Benshemesh 2005). A summary of the technique is provided below (note that the surveyor should consult J Benshemesh for advice prior to conducting any surveys):

• 
  survey trenches should be dug approximately 80 centimetres deep, 120 centimetres long and 40 centimetres wide
  
• 
  the trench should be dug with caution, and the use of mechanical equipment should be avoided
  
• 
  digging should cease if marsupial moles are observed
  
• 
  trenches should be allowed to dry for between three to five days (few tunnels will be apparent until the soil is adequately dry)
  
• 
  the tunnels will appear as circular or oval shapes, usually larger than 25 millimetres (but depending on the angle made with the trench wall)
  
• 
  trenches should be dug at three levels on the dune: near the crest, mid slope, and at the base of the dune, positioned less than 1 kilometre apart
  
• 
  in suitable habitat, two to six tunnels are usually found per square metre of vertical trench face.
  

Valuable information can also be obtained recording tracks, and photographs should be taken for confirmation by an expert, particularly in areas of uncertainty between the known ranges of the two species (Benshemesh 2004).

Other techniques that could be employed in areas up to 5 hectares in size, but are less reliable and efficient, include:

• 
  daytime searches for potentially suitable habitat resources, such as sandy soil in the central desert regions (description of the survey technique and recommended effort is outlined in Section 3.1)
  
• 
  early morning (that is, before the sun is too high, making tracks hard to discern, and before a breeze disturbs track definition) searches for signs of activity, particularly for tracks (photographs should be taken for confirmation by an expert) or individuals that may be observed on the surface following rain or during cold weather (description of the survey technique and recommended effort is outlined in Section 3.2). Any person undertaking track searches needs to have experience at tracking and identifying small mammal track signs in arid desert country, and
  
• 
  collection of predator scats, owl casts or remains, targeting predatory bird and mammal nests and dens (description of the survey technique and effort is outlined in Section 3.2.3). Marsupial moles can be identified to genus from hair samples (see Table 2, Section 3.3.7), or to species if genetic techniques are used.
  

Similar species in range

The taxonomy of the Notoryctes is unclear, with a suggestion that there may be one or more currently undescribed species. Currently two species of marsupial moles are recognised: the southern marsupial mole Notoryctes typhlops and the northern marsupial mole Notoryctes caurinus. The two species are thought to have an overlap in distribution; however, this has not currently been demonstrated. Although the two species can be separated genetically, they are difficult to separate morphologically. Characters used include the slightly smaller size, the narrower and shorter snout, the lack of anterior molars and the remaining cheek teeth are smaller and simpler in structure in the northern marsupial mole (Benshemesh 2008; Benshemesh & Aplin 2008). In addition, the tracks have been reported to be distinct between the two species (Benshemesh & Aplin 2008). Langford and Pavey (2002), in their description of the southern marsupial mole, refer to ‘morphometric and dental studies’ as the basis for the separation of the southern marsupial mole from the Great Sandy and Gibson Deserts from the northern species. Since distinguishing the species in the field may not be possible, identification is likely to require a tissue or hair sample, provided that the appropriate permission and licensing has been granted by the relevant state or territory government organisation.

References

Benshemesh, J. 2004. Recovery Plan for Marsupial Moles Notoryctes typhlops and N. caurinus. 2005 – 2010. Northern Territory Department of Infrastructure, Planning and Environment, Alice Springs.
Benshemesh, J. 2005. Manual for Marsupial Mole survey and Monitoring by Trenches, Version 1.0. Report to Anangu-Pitjantjatjara Land Management and the Department of Heritage and Environment (SA).
Benshemesh, J. 2008. Itjaritjari Notoryctes typhlops. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 412 – 413. (Reed New Holland: Sydney).
Benshemesh, J. (2009). NT DIPE, Alice Springs. Personal communication regarding Survey methods for the Southern Marsupial Mole
Benshemesh, J. and Aplin, K.P. 2008. Kakarratull Notoryctes caurinus. In ‘The Mammals of Australia’ (Eds. S. Van Dyck and R. Strahan) pp. 410 – 412 (Reed New Holland: Sydney).
Benshemesh, J. and Johnson, K. 2003. Biology and conservation of marsupial moles (Notoryctes). In ‘Predators with Pouches: the Biology of Carnivorous Marsupials’ (Eds. M. Jones, C.R. Dickman and M. Archer) pp. 464 – 474. (CSIRO Publishing: Melbourne).
Langford, D. and Pavey, C. 2002. Threatened species of the Northern Territory - Southern Marsupial Mole Notoryctes typhlops. Available from: www.nt.gov.au/nreta/wildlife/animals/threatened/pdf/mammals/southern_marsupial_mole_vu.pdf. Accessed 2010-03-22 T11:45:45.
Paltridge, R. 2002. The diets of cats, foxes and dingoes in relation to prey availability in the Tanami Desert, Northern Territory. Wildlife Research 29: 389 – 403.