Science for Policy Research findings factsheet Project 1.1.4

Securing the threatened kowari in remote South Australia

In brief About the kowari and its habitat

The kowari, Dasyuroides byrnei, The kowari is a nocturnal predator Understanding the response of is a carnivorous dasyurid marsupial whose diet consists of invertebrates kowaris to rainfall has vital practical that occurs in arid Australia. and rodents. During the day this importance for their conservation. The species is currently listed species shelters in burrows dug into Large rainfalls following long droughts as Vulnerable on the IUCN Red sand mounds that occur infrequently lead to regional-scale population List. This research describes the across stony gibber environments, explosions of rodents and their kowari’s population dynamics in where temperatures often exceed predators such as owls and diurnal what is possibly one of its last 40°C in summer and fall below 5°C raptors. However, dasyurid mammals refuges, the Clifton Hills cattle in winter. It weighs up to 175 g (males) of the kowari’s size respond in a station in the Sturt Stony Desert or 140 g (females), which highlights its much less predictable fashion than of South Australia. Our results vulnerability: it lies within the critical rodents to these climatic events. suggest that if the trends we weight range (35–5500 g) that, for Also unlike rodents, it is not clear observed also occur elsewhere mammals, has been most susceptible whether dasyurids depend on dry- in the kowari’s total range, it to extinction in Australia. season refuges. Part of the reason would be eligible for listing on the population dynamics of dasyurids Kowari populations have declined the IUCN Red List as Endangered. may differ is that they are secondary across the central Australian deserts consumers, feeding largely on We make recommendations for and the species currently has a invertebrates which themselves urgent research to: very limited distribution. Only a few respond variably to drought-wet populations now remain, located • determine the exact nature cycles. Nonetheless, some studies in arid South Australia and western of the threats suggest that populations of dasyurid Queensland. In these central deserts • control predators and marsupials like the kowari do expand of Australia, the drought–wet cycles fence from cattle in response to heavy rainfall events are driven principally by the El because rodents also make up a • undertake captive breeding Niño Southern Oscillation, and are large part of their diet. programs in predator- particularly intense. proof reserves to act as insurance populations. Kowari on gibber. Photo: NathanBeerkens Our research We have determined the long- term population trends for two populations in the Sturt Stony Desert in arid South Australia, located on Clifton Hill Station. We tested whether the two populations have had similar or different (asynchronous) trajectories. Species with multiple populations with the same trajectories can be more susceptible to extinction than asynchronous species, because all populations will decline at once, leaving no opportunity for individuals Leadbeaters Possum (Gymnobelideus leadbeateri). to recolonise from adjacent Photo:D Harley CC BY-NC-ND 2.0 Flickr Shelter sites are scarce. Photo: Robert Brandle populations. Our team used long-term survey Key threats records (2000–2015) to investigate The kowari is at risk from the impacts little cover and shelter from raptors whether the kowari population of introduced predators such as cats and introduced predators, and a currently occurs in favourable and foxes. The risks are particularly reduction of burrowing opportunities habitat and took advantage of high for the kowari from predation may increase the risk of predation. improving climatic conditions over by feral cats. Further, grazing and The accumulated and interacting the period. We then assessed the trampling from stock can flatten sand effects of predation, grazing and extinction risk of the two Clifton mounds and degrade habitat for predicted range declines from climate Hill Station populations using breeding burrows. change may further amplify the risk of advances in population viability extinction for the kowari. analysis modelling techniques. Drought–wet cycles are predicted to intensify with climate change. This makes it vital to understand how Threats from grazing animals and the kowari maintains its populations introduced predators are also through climatic extremes and how anticipated to intensify. The open it might persist in the future. gibber habitat of the kowari provides

Kowari in Sturt Stony Desert. Photo: William La Marca Kowari in Sturt Stony Desert. Photo: William La Marca

Study methods Key findings The location and habitat of the study, Six habitat variables were scored: Regardless of climate conditions, the Sturt Stony Desert, possibly one the kowari populations in South • gibber pavement of the last refuges for the kowari in Australia declined over the period South Australia, had rainfall above • sand mound (discrete sand 2000–2015. This finding was in spite the median in 2000, 2003 and 2011, rises of sandy clay loam) of some evidence that both their body and below the median in most other • thin sand spread (no distinct condition and rate of reproduction years between 2000–2015. form and structure) increased after rain. The research team surveyed animals • sand dune (deep sands generally The region where we surveyed the using live-trapping techniques to more than one metre high) kowari featured favourable habitat. measure annual population size, This leads us to suggest that the reproductive activity and body • impermeable drainage studied populations are under stress condition. We compared the depression (bare or pavement from external pressures rather than average body condition of adults but with obvious algal cover threats arising from within the species each year, using data from 2000 to from temporary flooding – themselves. Livestock grazing and 2015, by comparing body mass to includes hard pans and introduced predators are believed to head length, omitting females with lake beds) be having the most negative effects. pouch young (as they can channel • cracking clay drainage The two populations of kowari resources into reproduction rather depression (includes temporary showed highly similar (synchronous) than bodily growth). swamps and gilgais, i.e., trajectories. Unfortunately, this We collected habitat data from 25 m small ephemeral lakes). suggests an increased risk of × 25 m plots at 200 trap locations Population viability analysis extinction due to the low opportunity in the two sites, which were located required the use of high-performance for recolonisation from adjacent 30 km apart. This distance ensured computing facilities at the University populations, as they will also be independence; and no marked of Sydney. We accounted for the declining. In fact, the results from animals moved between the sites. difficult nature of remote fieldwork the population viability analysis in arid Australia by allowing the suggest that, if similar trends occur population viability analysis to elsewhere, the species would be include years when fieldtrips eligible for listing on the IUCN Red List may have to be cancelled due as Endangered, with a 20% chance of to harsh weather conditions. extinction within the next 20 years. Recommendations We recommend urgent research to better understand the exact threats to the kowari populations in South Australia. Monitoring needs to continue and be expanded to encompass other populations within the current very limited range. There is enough evidence to call for control of introduced predators and fencing from cattle of known population centres to be undertaken Kowari food. Photo: Robert Brandle without delay. The population decline in the face of these threats indicates an urgent need for captive breeding programs to be established in predator-proof reserves to act as insurance populations.

Kowari’s distinctive dark tail tuft. Photo: Cat Lynch

Cited material Further Information Greenville, A.C., Brandle, R., Canty, P. Dr Aaron Greenville, The University of Sydney and Dickman, C.R. (2018). Dynamics, [email protected] habitat use and extinction risk of Robert Brandle, Department for Environment and Water, Government of South Australia, a carnivorous desert marsupial. [email protected] Journal of Zoology. Forthcoming: https://zslpublications.onlinelibrary. Prof. Chris Dickman, The University of Sydney wiley.com/doi/abs/10.1111/jzo.12605 [email protected]

This project is supported through funding from the Australian Government’s National Environmental Science Programme.