Red-tailed Phascogales

Phascogales are dasyurid marsupials, related to antechinus, mulgara and quolls. There are three species of phascogale, the larger, approximately 230g, brush-tailed and northern brush-tailed phascogales (Phascogale tapoatafa and P. pirata) and the small, 40g red-tailed phascogale (P. calura), also known as the wambenger (Van Dyck and Strahan 2008).

The brush-tailed phascogale species are distributed around the forested margins of the Australian mainland, whereas, the red-tailed phascogale had a historical distribution throughout the western and central desert regions of the continent (Van Dyck and Strahan 2008). However, since European settlement, the range of the red-tailed phascogale has declined dramatically, and they are now restricted to isolated patches of sheoak (Allocasurina) and Wandoo (Eucalyptus wandoo) forest in a small area of the wheatbelt in south-west Western Australia. As a consequence of this decline, their limited geographical range and their small overall population size of less than 10,000 individuals, red-tailed phascogales are listed by the IUCN as near threatened (Friend 2008).

Red-tailed phascogales forage both on the ground and in trees, generally in association with stands of sheoak. They feed on a wide range of invertebrates, particularly cockroaches and beetles, but will also consume small birds and mammals, such as feral house mice (Mus musculus). They favour dense vegetation in climax communities (Kitchener 1981), but they also occur in roadside remnants, oil mallee plantations and small remnants and paddock trees in broadacre farming environments. How they adapt their behaviour, physiology and ecology to survive in these highly modified environments is poorly understood but is of great interest for the future conservation of the species.

Red-tailed phascogales nest in tree hollows, and like other small dasyurid marsupials, use daily torpor to conserve energy. Torpor is a controlled decrease in body temperature that reduces the metabolic rate and also the requirement for metabolic heat production. At an ambient temperature of 18°C, phascogales allow their body temperature to drop to as low as 23°C. Torpid phascogales assume a typical curled posture and are generally unresponsive. However, they can generate their own metabolic heat to re-warm to a normal body temperature of 34°C in a few minutes (Pusey et al. 2013).

Image of a torpid Red-tailed Phascogale

The reproductive biology of the red-tailed phascogale is particularly interesting, as the males only live to breed during one season, surviving for only 11.5 months. The breeding season is highly synchronous, with all mating occurring during three weeks in July, after which time all males in the population die as a result of an increase in stress hormones which lead to gastro-intestinal ulceration and ultimately haemorrhage. This post-mating male die-off is characteristic of other dasyurid marsupials, most notably various species of antechinus. Females survive after mating to raise the young, and can reproduce for up to three years. As many as 13 young are born in early August; up to eight of these are raised in the pouch. Females have eight nipples and young remained attached to the nipple for about 45 days, so excess young don’t survive. Females may store sperm from multiple males until ovulation, so a single litter of pouch young can have multiple fathers (Bradley 1997).

A female antechinus with pouch young.

The post-European decline of red-tailed phascogales was presumably a consequence of clearing for agriculture, resulting in habitat loss and fragmentation, combined with predation by introduced predators and a fire regime characterised by more frequent burning which reduced cover and impacted on the availability of nesting hollows in senescent vegetation (Friend 2008). The current range of the red-tailed phascogale is characterised by the presence of Gastrolobium and Oxylobium understory vegetation which naturally contains the toxin monosodium fluoroacetate or 1080 poison, for which native fauna in the region has developed a resistance, but is lethal to domestic animals and introduced predators such as cats and foxes. This may have contributed to a refuge in this region for the red-tailed phascogale and other native species (Van Dyck and Strahan 2008).

Conservation of the red-tailed phascogale will involve maintenance and monitoring of existing populations, some of which are already in protected areas, continued fire management and studying the impacts of changing predation pressure on phascogale populations. Understanding how phascogales respond to habitat modification and predator control programmes is important for the establishment of new secure populations (Kitchener 1981; Friend 2008).

Thanks to Dr Christine Cooper for providing this post. Dr Cooper is a research and teaching academic with expertise in environmental physiology. Her particular interests are in the energetic, thermal and hygric physiology of birds and mammals. Research knowledge gathered by Dr Cooper and her students will provide additional information necessary to protect these threatened marsupials.

References

Bradley, A.J. (1997) Reproduction and life history in the red-tailed phascogale, Phascogale calura (Marsupialia: dasyuridae): the adaptive-stress senescence hypothesis. Journal of Zoology, London 241: 739-755

Friend, T. 2008. Phascogale calura. The IUCN Red List of Threatened Species 2008: e.T16888A6544803.

Pusey, H., Cooper, C.E., and Withers, P.C. (2013) Metabolic, hygric and ventilatory physiology of the red-tailed phascogale (Phascogale calura: Marsupialia, Dasyuridae): Adaptations to aridity or arboreality? Mammalian Biology 397-405

Kitchener, D.J. (1981) Breeding, diet and habitat preference of Phascogale claura (Gould 1844) (Marsupialia: Dasyuridae) in the southern wheatbelt, Western Australia. Records of the Western Australian Museum 9: 173-186.

Van Dyck, S. and Strahan, R. (2008) The Mammals of Australia, Reed New Holland, Sydney.

Photo credit: All photos provided by Dr Christine Cooper. Top and bottom – Red-tailed Phascogales