Red-tailed sunset

By day, Kojonup Reserve – which is located about three hours south of Perth on Goreng Noongar Country – is alive with nature’s music: the jaunty yet melancholic calls of the Western Gerygone (Gerygone fusca) or the zip-crack sounds of a Rufous Whistler (Pachycephala rufiventris). But as dusk falls, another creature takes centre stage: the Red-tailed Phascogale (Phascogale calura).

Emerging from a nestbox, the phascogale springs into life, descending the tree in swift, jittery glides. It is semi-arboreal – as comfortable scaling trees as it is sweeping the forest floor. It leads a kinetic, fast-paced life, always on the lookout for small insects like beetles and spiders, sometimes even reptiles and small birds.

Its long nose is reminiscent of a bandicoot, and its large ears recall those of an adult quoll. But its defining feature is the red around the base of its tail. The tail, which can be longer than its body, swishes back and forth as it moves, providing a metronomic rhythm – both restless and precise.

Like other dasyurids – a family of small, carnivorous marsupials native to Australia – the Red-tailed Phascogale punches above its weight, in this case, around 40 grams.

Kenngoor, to use the Noongar name for the marsupial, once existed across half the continent – from Western Australia to Alice Springs – with populations flourishing in the semi-arid woodland of South Australia, Victoria and New South Wales. Now, the species is restricted to a few fragmented parts of the Western Australian Wheatbelt, less than 1% of its original range. It’s listed as vulnerable under the EPBC Act, ‘near threatened’ according to the IUCN.

In 2010, a population was translocated to Kojonup, a small area of bush off the Albany Highway, and one of an expanding number of Bush Heritage-managed individuals were released at first with another ten added a year later. The 392-hectare reserve, which was purchased by Bush Heritage in 1996, was chosen because it offered ‘Goldilocks’ conditions.

The chalky white trunks of the Eucalyptus wandoo contrast with the watercolour haze of the Rock Sheoaks (Allocasuarina huegeliana). Insects flourish. Hollows abound. And most remarkably, thanks to ongoing management, the reserve is largely free of cats, foxes and dogs.

Genevieve has just come back from this year’s monitoring. While population numbers of Red-tailed Phascogales appear to be down, this could be attributed to the time of year. “My hypothesis is it’s a reflection of the season,” says Genevieve, “rather than anything to do with the population.”

Usually, the monitoring trips take place in May, just before the breeding season when numbers peak. The field trip in 2024, however, had been particularly cold, and there was concern that the ‘Elliotts’ – an industry term for the aluminium boxes baited with a mixture of oats, peanut butter and sardines – can become ‘cold boxes’ when the temperature drops at dusk. The decision was made to try April instead.

The results show the importance of annual monitoring. The translocation to Kojonup has so far been a success story, but ongoing success is a fragile, long-term pursuit. “Small, isolated populations like these,” says Genevieve, “are at risk of stochastic events.” Any change in conditions, whether climate-, food- or predator-related, can sound a death knell for the population.

One positive is that genetic testing was undertaken on the Kojonup population in 2022, and the results showed genetic diversity levels comparable with wild populations.

Rhiannon de Visser, a zoologist based in Perth, conducted this genetic research as part of her Honours thesis. She says it should be seen as a good result considering it was a translocation with a small number of animals. Inbreeding can occur in small populations, and the species’ most famous trait – its semelparity, where males die at the end of their first breeding season – can threaten diversity during bad years if breeding rates are low.

“The collaboration between Bush Heritage Australia, Australian Wildlife Conservancy, Department of Biodiversity, Conservation and Attractions and the University of Western Australia was integral to the project’s success,” says Rhiannon. “If we didn’t have all of those organisations onboard, working together, it probably wouldn’t have been feasible.”

But Rhiannon and Genevieve both note the dangers of complacency. Research is also required into habitat use, seasonal behaviours, food preferences and movement ecology. For the latter, an interesting aside is whether the Kojonup individuals engage with wild populations nearby. Not only would this research strengthen the species’ chances of survival at Kojonup – it could also inform reintroduction programmes elsewhere.

“We’re really proud of what we’ve achieved and how we’re helping to safeguard the species, but you can never be comfortable that it will stay this way,” says Genevieve. “Ideally, there’d be more research projects on this species and that just comes down to funding and interest from university students like Rhiannon.” •

We gratefully acknowledge Peter and Maxine Wilshaw for their support of Rhiannon’s research at Kojonup Reserve.