Survey guidelines for Australia’s threatened non-flying mammals

Northern bettong

Bettongia tropica

States and territories: Queensland.

Regions: Restricted to four locations:

• 
  Lamb Range east of Mareeba
  
• 
  Mount Windsor Tableland west of Mossman
  
• 
  Carbine Tableland
  
• 
  Coane Range near Paluma.
  

Habitat: Wet and mesic sclerophyll forests with a grassy ground-cover (Vernes et al. 2001) located on metamorphic and granitic soil substrates (Laurance 1997).

Habit: Ground-dwelling.

Avg. body weight: 1200 g (Winter & Johnson 1995).

Activity pattern: Nocturnal.

Diet: Primarily mycophagous, preferring the underground fruiting bodies of mycorrhizal fungi (Vernes et al. 2001). Grasses are important when fungi are unavailable (Abell et al. 2006).

Breeding: Breeding occurs throughout the year with one young produced per breeding event (Winter & Johnson 1995).

Description

The northern bettong is a small potoroid mammal restricted to fire-prone sclerophyll forests and woodland on the western edge of the wet tropics region of north-eastern Queensland (Winter & Johnson 1995; Vernes & Pope 2001). The taxonomic species status of the northern bettong is subject to debate, with some authorities considering it to be a subspecies of the brush-tailed bettong Bettongia penicillata tropica (Winter & Johnson 1995).

The northern bettong is estimated to have disappeared from over 90 per cent of its former range (Maxwell et al. 1996) and its occurrence is now within a restricted and fragmented range (Winter & Johnson 1995). Northern bettongs are solitary and nocturnal, sheltering during the day in a grass nest built under a tussock or a grass tree (Winter & Johnson 1995). Individuals have several nests within close proximity to each other and like other potoroids they have a relatively large home range area (59 hectares) with high rates of nightly movement (Vernes & Pope 2001).

In one study, truffles (underground fungi) comprised 23–67 per cent of the northern bettong's diet (Johnson & McIlwee 1997). Fire is thought to mediate truffle abundance in sclerophyll forests (Taylor 1992), and is likely to impact the northern bettong as well. Vernes and Pope (2001) investigated the effects of fire on a population of the northern bettong and found that a moderate-intensity fire did not significantly affect the home range size, location or rates of nightly movements of radio-tracked northern bettongs. These results suggest that the bettong’s behaviour was not disrupted by the moderately low-intensity fire, which may indicate that the species is adapted to frequent fires. Abell and colleagues (2006) found that northern bettongs used grasses as an alternative food source when seasonality of rainfall reduced the availability of fungi and that previous studies on this species’ dietary habits probably underestimated the importance of food resources other than fungi.

Survey methods

The following survey techniques are recommended to detect the presence of the northern bettong in areas up to 5 hectares in size:

• 
  daytime searches for potentially suitable habitat resources, such as areas with wet and mesic sclerophyll forests and a grassy ground-cover (description of the survey technique and recommended effort is outlined in Section 3.1)
  
• 
  daytime searches for signs of activity, including diggings, tracks, scats and nests (description of the survey technique and recommended effort is outlined in Section 3.2). However, because the rufous bettong may be sympatric in some areas with the northern bettong Bettongia tropica, direct detection survey techniques are required to distinguish between the species
  
• 
  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 are considered appropriate to determine if bettongs occur on the subject site. However, direct detection techniques are required to distinguish between the species
  
• 
  camera traps baited with universal bait and added almond, walnut or truffle oil (see potoroo profiles for further information) are likely to prove useful for positively identifying and minimising impact on animals and are also cost-effective (description of the survey technique and recommended effort is outlined in section 3.3.6).
  

One or more of the following survey techniques is required to distinguish between the northern and rufous bettongs where signs of activity have been detected:

• 
  possibly spotlight surveys conducted according to the description of the technique and the recommended effort provided in Section 3.3.3, if the habitat understorey is open enough to allow for an effective beam of light to search with
  
• 
  cage trapping surveys with universal bait and added almond, walnut or truffle oil (see potoroo profiles for further information) conducted according to the description of the technique and the recommended effort outlined in Section 3.3.10
  
• 
  hair collection (northern bettongs are identifiable from hair samples) (see Table 2, Section 3.3.7)
  
• 
  baited camera traps using universal bait (description of the survey technique and recommended effort is outlined in section 3.3.6).
  

Similar species in range

Northern bettongs appear to overlap in range with rufous bettong, but the latter occurs in drier habitat (Winter & Johnson 1995). The two species are distinguished by the smaller size of the northern bettong and the red colour of the rufous bettong's fur.

References

Abell, S.E., Gadek P.A., Pearce, C.A. and Congdon, B.C. 2006. Seasonal resource availability and use by a tropical mycophagous marsupial. Biological Conservation 132(4): 533-540.

Laurance, W.F. 1997. A distributional survey and habitat model for the endangered northern bettong Bettongia tropica in tropical Queensland. Biological Conservation 82: 47-60.
Johnson, C.N. and McIlwee, A.P. 1997. Ecology of the northern bettong, Bettongia tropica, a tropical mycophagist. Wildlife Research 24: 549-559.
Maxwell, S., Burbidge, A.A. and Morris, K. 1996. The 1996 Action Plan of Australian Marsupials and Monotremes. Environment Australia, Canberra.
Taylor, R.J. 1992. Fire, mycorrhizal fungi and management of mycophagous marsupials. Australian Journal of Ecology 17: 227-228.
Vernes, K. and Pope, L.C. 2001. Stability of nest range, home range and movement of the northern bettong (Bettongia tropica) following moderate-intensity fire in a tropical woodland, north-eastern Queensland. Wildlife Research 28: 141-150.
Vernes, K. and Pope L.C. 2006. Capture success and population density of the Northern Bettong Bettongia tropica in north-eastern Queensland. Australian Mammalogy 28: 87-92
Vernes, K., Castellano, M. and Johnson, C. 2001. Effects of fire on the diversity of hypogeous fungi consumed by a tropical mycophagous marsupial. Journal of Animal Ecology 70: 945-954.
Winter, J.W. and Johnson, P. M. 2008. Northern Bettong Bettongia tropica. In ‘The Mammals of Australia’. (Eds. S. Van Dyck and R. Strahan) pp. 294-295 (Reed New Holland: Sydney).