By Mark Simpson
The Spotted-tailed Quoll is the largest marsupial carnivore currently living on the mainland of Australia. Once widely distributed throughout the continent, it has seen a 50 to 90% reduction in
range since European settlement, with the current population being estimated at between 5,500 and 10,000. Both males and females have large home ranges of up to 1750 hectares and this, coupled with widespread distribution and cryptic habits, have made the species notoriously difficult to observe in the wild. Demonstrating how elusive the Spotted-tailed Quoll can be, a study¹ conducted in 1993 only captured four individuals from 4133 trap nights (Watt 1993).
Because of the associated difficulty, the first field based research into quoll populations didn’t get off the ground until the early 1990s when, in partnership with the Queensland State Government, Dr A. Watt prepared the ‘Conservation status and draft management plan for Dasyurus maculatus and D. hallucatus in southern Queensland’ ¹. Since then, research into the Spotted-tailed Quoll has slowly increased but there are still significant gaps in scientific knowledge. In 2002 Stephanie Meyer-Gleaves of Griffith University, started collecting data for her PhD thesis² on the ecology and conservation of quolls with the aim of further adding to the bank of scientific knowledge.
Meyer-Gleaves (2008)² began by surveying ten sites in southern Queensland and four in New South Wales between 2002 and 2006. The aim was to identify a viable population so that a long term study could be undertaken. After much research it was decided that the principal study site was to be Cullendore, a semi-rural location consisting of two adjacent private properties: one a working cattle farm, the other a tourism resort known as ‘Cherrabah’.
The Cherrabah property, which makes up the bulk of the Cullendore study site, is approximately 2120 ha in size and has been operating as a private tourist resort for the past 30 years. The landscape of the property that has enabled the Quoll population to survive and flourish has remained largely undisturbed over the last three decades.
In order to ascertain the Cullendore population’s size and demographics, Meyer-Gleaves undertook lengthy field based research involving the live trapping of individual quolls. In addition to the collection of a wide variety of biological data it was also hoped that a dietary analysis of prey species could occur. To achieve this Meyer-Gleaves primarily used live trapping, supplemented with hair traps and soil plots.
The live traps were baited with chicken wings and checked sequentially each day from dawn. Once trapped, each quoll’s biological information was recorded and some individuals were microchipped for future identification. Dietary information was collected by analysing scats left during the trapping process. The results conclusively showed that the three most common vertebrate prey species were Common Brushtail Possums, followed closely by Swamp Wallabies and then Eastern Grey Kangaroos. In total, mammals accounted for 63% of the quoll diet, indicating that they are an opportunistic and highly carnivorous species.
Predicting the Survival of the Cullendore Population
In 2006 the Cherrabah property was slated for potential development, involving a proposed large hotel and villa complex that would include a skirmish park, golf course, airport runway, historical museum and a small wildlife zoo. An area of 820 ha of the site was enclosed by an electric fence, with a broad strip of habitat being clear-felled to enable the fence’s construction. This fenced-off section represents one third of the habitat available to the quoll population with Meyer-Gleaves’ research indicating up to 20% of the quolls may have been immediately affected by the erection of the electric fence.
Using the data collected from her field studies, Meyer-Gleaves undertook a population viability analysis (PVA) to predict the survival of the Cullendore Spotted-tailed Quoll population. Using this
method it was aimed to determine the risk of extinction to the population due to disturbances associated with the proposed development.
The PVA model identified that any increase in mortality among juveniles or adult females would greatly decrease the chances of the Cullendore population’s survival. Meyer-Gleaves concluded that if mortality increased by as little as 15% then extinction was likely to occur in approximately 10 years. She stated that ‘the likelihood that the Cullendore population will become extinct in the near future must be taken seriously. These PVA models should, therefore, be used to assist managers and decision makers when evaluating the various options for the management and development of the Cherrabah property and consequently the fate of the Cullendore quoll population. Any action undertaken on the property, be it disturbance activities, the construction of physical barriers, the alteration of habitat, the removal of prey species, or a lack of introduced predator control, will influence the survival of individual quolls and thus the survival of the entire population’ (Meyer-Gleaves 2008, p. 147).
The NSW and Queensland Spotted-tailed Quoll populations identified by Meyer-Gleaves (2008) appear to have the highest density of individuals currently remaining on the Australian mainland, with the Cullendore population representing the only known thriving community of the species in southern Queensland.
The demographic and biological characteristics of the Spotted-tailed Quoll make isolated populations extremely vulnerable to even small increases in mortality. It is therefore imperative to the long-term survival of quoll populations in southern Queensland and throughout Australia that large tracts of habitat are preserved and that connectivity in the form of wildlife corridors are created. It is unlikely that parks or reserves alone can ensure the survival of the species; safe havens located on private lands are vital.
The long term future of the Cullendore Spotted-tailed Quoll population looks to be uncertain at best. If the proposed development of Cherrabah gets the green light it could prove disastrous. The extinction of the population is highly possible within only a small number of years if habitat disturbance occurs unchecked and conservation efforts are either nonexistent or unsuccessful. In concluding Meyer-Gleaves (2008) states ‘an increased effort to encourage the Cherrabah owners to manage the property for the benefit of the resident quoll population needs to be undertaken if this population is to survive in the long-term.’
¹ Watt, A. (1993). Conservation status and draft management plan for Dasyurus maculatus and D. hallucatus in southern Queensland. Report to Department of Environment and Heritage Queensland.
² Meyer-Gleaves, S. (2008). Ecology and Conservation of the Spotted-tailed Quoll (Dasyurus maculatus maculatus) in Southern Queensland. PhD thesis, Griffith University.
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