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Pseudocheirus occidentalis

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA MAMMALIA DIPROTODONTIA PSEUDOCHEIRIDAE

Scientific Name: Pseudocheirus occidentalis
Species Authority: (Thomas, 1888)
Common Name(s):
English Western Ringtail Possum, Western Ringtail, Ngwayir
Taxonomic Notes: Pseudocheirus occidentalis is often considered to be conspecific with P. peregrinus (e.g., Groves 2005). It is treated as a separate species here following the advice of the IUCN SSC Australian and Melanesian Non-volant Mammal Specialist Group.

Assessment Information [top]

Red List Category & Criteria: Vulnerable B1ab(ii,iii,v) ver 3.1
Year Published: 2008
Date Assessed: 2008-06-30
Assessor(s): Morris, K., Burbidge, A. & Friend, T.
Reviewer(s): Lamoreux, J. & Hilton-Taylor, C. (Global Mammal Assessment Team)
Justification:
Listed as Vulnerable because its extent of occurrence less than 20,000 km2, it has a severely fragmented distribution, and there is a continuing decline in the area of occupancy, the extent and quality of its habitat, and in the number of mature individuals.
History:
1996 Vulnerable (Baillie and Groombridge 1996)
1996 Vulnerable
1994 Vulnerable (Groombridge 1994)

Geographic Range [top]

Range Description: The Western Ringtail Possum has a restricted distribution in south-western Western Australia; it is found along the coast from south of Bunbury to Waychinicup National Park (near Albany) and in suitable habitat inland, most notably at Perup Nature Reserve and surrounding State forest near Manjimup (Maxwell et al. 1996; de Tores 2008). It was recently recorded in stands of Peppermint near the Harvey River and in Jarrah/Marri forest near Collie (north-east of Bunbury); however, the long term persistence of the species in these areas is not confirmed (de Tores et al. 2004). The Western Ringtail was formerly more widespread: in the 1970s it was known from Casuarina woodlands in the wheatbelt near Pingelly (south-east of Perth), and it is thought to have once occurred throughout much of south-western Western Australia (but not necessarily continuously distributed) (Maxwell et al. 1996; de Tores 2008).
Countries:
Native:
Australia (Western Australia)
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Common in suitable habitat (de Tores 2008). The highest densities of this species were recorded in Peppermint habitat near Busselton area; relatively high densities were found in Jarrah/Marri forest at Perup (de Tores 2008). However, populations in coastal habitat (the majority of its range) are thought to be declining due to habitat loss and fragmentation.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: The Western Ringtail Possum is associated with Peppermint (Agonis flexuosa). Along the coast, it is found in Peppermint forest and woodland and in Tuart (Eucalyptus gomphocephala) forest, typically with a Peppermint mid-story. Inland it is found in Jarrah (E. marginata), Wandoo (E. wandoo), and Marri (Corymbia calophylla) forest (de Tores 2008).

This species is nocturnal and arboreal. It is a folivore; its preferred food is Peppermint foliage, or if that is unavailable, myrtaceous species. Reproduction occurs year-round. The greatest number of young are born in late autumn and winter; the least number of young are born in late summer. Litter size ranges from 1 to 3 young, and is most commonly 1. At approximately 3 months age, the young emerge permanently from the pouch. Female young generally remain in the home range of their mothers, while male young disperse from their mother’s range when they are about 7 months old (at weight of 600 - 700 grams). The individual home range of this species varies in size, with larger sizes occurring in low density populations. This species has been recorded to live more than six years (de Tores 2008).

There is thought to be some degree of competition and/or habitat partitioning with the Common Brushtail where the two species co-occur, but the extent and effect of this competition is not clear. However, there is negligible competition for nesting sites, as the Western Ringtail makes dreys (built of vegetation), rather than using treeholes as does the Common Brushtail. The dreys are normally found in the mid- to upper- canopy, but can occur lower to ground (de Tores 2008).
Systems: Terrestrial

Threats [top]

Major Threat(s): Coastal populations of the Western Ringtail Possum are threatened by habitat loss and fragmentation associated with urban development (de Tores et al. 2004; de Tores 2008). Inland populations are threatened by habitat modification, and also timber harvesting. Predation by introduced foxes (Vulpes vulpes) is also a major threat to this species. In areas where fox populations are controlled, predation by python (Morelia spilota imbricate) and by introduced cats is a major threat. Populations also may be threatened by increasing fire intensities, and by burning operations associated with logging and clearing (de Tores et al. 2004; de Tores 2008).

Conservation Actions [top]

Conservation Actions: Many of the known inland Western Ringtail Possum populations in the inland Perup area occur in national forest, and are outside areas marked for logging. Some of these populations are the subject of a research project quantifying threats to the species (de Tores et al. 2004). The species is listed as Vulnerable by Australian government.

The Western Ringtail species has been the subject of translocation programs in an attempt to mitigate the effects of habitat loss (de Tores et al. 2004; de Tores 2008). In a recent review, de Tores et al. (2004) noted that success of translocated populations has not been demonstrated at any of the release sites, and that the primary release site (Leschenault Peninsula Conservation Park) has suffered a population decline. This review also found that effective monitoring of the response of the species to fox control programs is lacking outside of a few select translocations sites.

Recommended conservation measures include: implementation a monitoring program at sites selected to represent the range of habitats used by the Western Ringtail in order to assess possum population changes and responses to fox control and the impacts of other management practices; establishment of a effective monitoring program at translocation sites; identification of sites of high conservation value to the Western Ringtail; conservation of Western Ringtails in public lands managed by the Department of Environment and Conservation (Western Australia); minimizing impacts of land developments; education and liaison with towns with or near to Western Ringtail populations (de Tores et al. 2004).

Citation: Morris, K., Burbidge, A. & Friend, T. 2008. Pseudocheirus occidentalis. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 18 September 2014.
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