Survey guidelines for Australia’s threatened non-flying mammals

Mahogany glider

Petaurus gracilis

States and territories: Queensland

Regions: North-eastern Queensland: distributed in a narrow and fragmented band generally below 120 m above sea level between Crystal Creek south of the Herbert River and the Hull River near Tully, covering an area of approximately 720 km² (QPWS 2001; Jackson 2008).

Habitat: Open woodland on Quaternary alluviums and low granite rises that supports species of bloodwoods (for example, Corymbia clarksoniana, C. intermedia or C. tessellaris), eucalypts (for example, E. platyphylla or E. tereticornis), melaleucas (for example, Melaleuca dealbata, M. viridiflora or M. leucodendra), and acacia species; often with a grass tree Xanthorrhoea johnsonii understorey (QPWS 2001).

Habit: Arboreal.

Avg. body weight: 407 g (males); 365 g (females) (Jackson 2008).

Activity pattern: Nocturnal.

Diet: Omnivorous, nectar, pollen, plant exudates, honeydew and arthropods. (Jackson 2008).

Breeding: Primarily give birth to one or two young between April and November; with a second litter raised in high quality habitat if the first litter is lost (Jackson 2008).

Description

The mahogany glider was first described in 1883 but was known only from a few specimens collected between 1886 and 1974 (Jackson & Claridge 1999). Over that time the species status was unclear and was often referred to as a squirrel glider, Petaurus norfolcensis because of its similarity in appearance. However, in 1986 three skins in the Queensland Museum were positively identified as P. gracilis, and in 1989 the species was recorded in the wild (Jackson 2008). Since then, the species has been found to have a fragmented and restricted distribution along the southern lowlands of the wet tropics region (Jackson & Claridge 1999).

Mahogany gliders are found in an open woodland habitat comprised of bloodwoods, eucalypts, melaleucas and acacias (Van Dyck 1993). The species is highly mobile and depends on continuous forest and woodland cover to range freely (Van Dyck 1995). The availability of suitable habitat has been reduced by approximately 80 per cent through land clearing practices, which is considered the primary threat to the species’ survival (Jackson 2008).

The species is elusive and virtually silent (Van Dyck 1995) and therefore, unlike other glider species, cannot be detected by calls. Individuals nest in eucalypt hollows, with up to ten nests being used at any one time by the same individual or socially monogamous pair (Jackson 2008).

Management measures are outlined in the species’ recovery plan (Parsons & Latch 2007), along with an evaluation of the previous recovery plan and threats currently facing the mahogany glider.

Survey methods

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

• 
  daytime searches for potential den sites in hollow-bearing trees (description of the survey technique and recommended effort is outlined in Section 3.1)
  
• 
  daytime searches for signs of activity (description of the survey technique and recommended effort is outlined in Section 3.2), such as gashes or scratches made in upper branches of bloodwoods and large-fruited red mahoganies, chunks of grass tree Xanthorrhoea johnsoni flower stalks lying on the ground, or scats on the ground below trees, particular those considered potential den sites
  
• 
  stagwatching surveys at potential den sites (description of the survey technique and recommended effort is outlined in Section 3.3.4)
  
• 
  spotlighting surveys along transects, tracks or roads, depending on the nature of the site according to the method outlined in Section 3.3.3, however, additional surveys from a vehicle may also be made
  
• 
  an arboreal cage trapping program conducted according to the method outlined in Section 3.3.9 may be required if the species is not detected through the aforementioned surveys, or to distinguish the species from other sympatric glider species, for example, by morphological characteristics or DNA analysis from a tissue sample (note that appropriate licences are likely to be required from Queensland government authorities).
  

A possible alternative survey method may be the use of hair sampling devices. However, at this stage this method cannot be considered as a standard because the species is not included among those species known to be distinguishable from hair samples (see Table 2, Section 3.3.7). Identification of the species from guard hairs may be possible in the future on the advice of appropriate experts in this field.

Similar species in range

The mahogany glider is sympatric with the sugar glider P. breviceps. The sugar glider is separated by its small size (that is, half the length of the mahogany glider), distinctive white underbody, a longer, pointed muzzle, and a distinctive call. Mahogany and squirrel gliders are geographically isolated, with the closest known populations being approximately 25 kilometres apart (Jackson & Claridge 1999). The mahogany glider can be distinguished from the squirrel glider by its larger size, the presence of brown and honey tones and the longer, less bushy tail which is narrow at its base. The fluffy glider, Petaurus australis subsp., can readily be separated as it is larger, has a predominantly pale yellow underside, frequently utters a diagnostic call and produces diagnostic feeding marks in the trunks and boughs of trees. Due to the difficulty in separating the mahogany glider from squirrel and sugar gliders, all identifications should be confirmed by experienced field staff.

References

Isaac, J. L., Parsons M. and Goodman, B. A. 2008. How hot do nest boxes get in the tropics? A study of nest boxes for the endangered mahogany glider. Wildlife Research 35: 441-445.

Jackson, S.M. 2000a. Habitat relationships of the mahogany glider, Petaurus gracilis and the sugar glider Petaurus breviceps. Wildlife Research 27: 39-48.
Jackson, S.M. 2000b. Population dynamics and life history of the mahogany glider, Petaurus gracilis, and the sugar glider, Petaurus breviceps, in north Queensland. Wildlife Research 27: 21-37.
Jackson, S.M. 2008. Mahogany Glider Petaurus gracilis. In ‘The Mammals of Australia’ (Ed. S. Van Dyck and R. Strahan) pp. 233-234 (Reed New Holland: Sydney).
Jackson, S.M. and Claridge, A. 1999. Climatic modelling of the distribution of the mahogany glider (Petaurus gracilis), and the squirrel glider (P. norfolcensis). Australian Journal of Zoology 47: 47-57.
Parsons, M. and Latch, P. 2007. Recovery plan for the mahogany glider Petaurus gracilis. Report to Department of the Environment, Water, Heritage and the Arts, Canberra. Environmental Protection Agency, Brisbane.
QPWS 2001. Mahogany Glider recovery plan, 2000-2004. Report to Environment Australia, Canberra. Queensland Parks and Wildlife Service, Brisbane.
Van Dyck, S. 1993. The taxonomy and distribution of Petaurus gracilis (Marsupialia: Petauridae), with notes on its ecology and conservation status. Memoirs of the Queensland Museum 33: 77-122.
Van Dyck, S. 1995. Mahogany Glider (Petaurus gracilis). In ‘The Mammals of Australia’ (Ed. R. Strahan) pp. 232-233 (Reed Books: Sydney).