Not waiting for the death knell. A pilot study to examine supplementation and survivorship in a declining population of Tasmanian eastern quoll (Dasyurus viverrinus) (original) (raw)
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The spotted-tailed quoll (Dasyurus maculatus) is an endangered marsupial carnivore endemic to eastern Australia. A paucity of information on the dynamics of wild populations has hindered conservation of the species. The population dynamics of spotted-tailed quolls were investigated in an area of unusually high abundance in north-eastern New South Wales, where density is conservatively estimated at 0.3 km-2. Sixty individual quolls were captured on 331 occasions over 22 months. Apparent survival, timing and rate of reproduction, and morphometric data were compared with those of quolls from other areas. Population models were employed to investigate patterns in the behaviour and apparent survival of quolls in the study area. The high abundance of D. maculatus identifies the study area as vital to the conservation of quolls on mainland Australia, and to the future study of the species.
Continuing decline of the eastern quoll in Tasmania
2022
Like many other Australian mammals, the eastern quoll (Dasyurus viverrinus) was widespread on the Australian mainland but went extinct there during the 20th century. The species remained abundant in Tasmania until a rapid decline occurred from 2001 to 2003, coinciding with a period of unsuitable weather. We provide an updated analysis of eastern quoll population trends in Tasmania by analysing a Tasmania-wide time series of annual spotlight counts (1985-2019). Eastern quolls were widespread and abundant in Tasmania until the early 2000s. A distinct change occurred in the early 2000s in the east and northeast, which led to severe population reductions. However, we present new evidence of an earlier decline in the north (mid-1990s) and a more recent decline around 2009 in the south. Range-wide declines have continued unabated during the last decade, resulting in a ∼67% decline (since the late 1990s) in the area with high quoll abundance. Although the timing of the major decline in the...
Journal of Wildlife Diseases, 2020
We evaluated the health of 31 (eight males, 23 females) founder eastern quolls ( Dasyurus viverrinus), translocated to a fenced reserve in the Australian Capital Territory between February 2016 and July 2017. Quolls were wild caught in Tasmania (16 animals) or captive bred at Mount Rothwell Biodiversity Interpretation Centre, Victoria (15 animals). Quolls were assessed for the presence of selected potential pathogens ( Toxoplasma gondii, herpesviruses, Salmonella serovars, hemoprotozoa, and ectoparasites). We assessed the relationships among sex, provenance (captive or free ranging), Toxoplasma gondii or herpesvirus infection, weight, and hematologic and biochemical variables. Six of 21 quolls (29%) tested were seropositive for antibodies to Toxoplasma gondii. Seropositive quolls weighed significantly more and had significantly lower potassium levels, anion gaps, and urea and triglyceride levels than seronegative quolls had. Eighteen of 31 (58%) combined conjunctival-pharyngeal-cloa...
Australian Mammalogy, 2020
While fenced reserves provide sanctuary for many threatened prey species, few projects have reintroduced native threatened predators, despite their potential role in regulating prey, addressing prey naivety, trophic regulation, and predator conservation. We aimed to investigate a set of issues unique to predator reintroduction into fenced reserves: how to contain predators that are naturally wide roaming, how to estimate carrying capacity, and will native predators impact resident threatened species? We conducted a trial reintroduction of four western quolls (Dasyurus geoffroii) (two males, two females) into a fenced reserve where four threatened prey species had been reintroduced and feral cats and foxes excluded. We monitored quoll survival, diet, movement and reproduction. Nocturnal foraging ranges measured over a fortnight were 3-17 km 2 , favouring burrows in dune habitat for shelter. Dietary analysis indicated a preference for reintroduced bettongs and western barred bandicoots, and resident hopping mice. Successful breeding was recorded but the two male quolls eventually escaped the reserve by climbing over the external fence and did not return. Results suggest that quoll reintroductions to fenced reserves will require fence designs that enable quolls to climb back into the reserve, threat management outside the reserve, and close monitoring of prey species.
This paper explores the question of why the endangered Spotted-tailed Quoll Dasyurus maculatus remains abundant in parts of north-eastern New South Wales, while populations in many other areas have declined or disappeared. Based on a two-year field study of a high-density population, we discuss a number of possible explanations for this pattern. These include high availability of prey (in particular, arboreal mammals), quality and spatial extent of habitat, low density of competitors, and relatively small home range sizes of females compared to those in other areas. We emphasise the importance of maintaining high densities of hollow-bearing trees, which probably help to support prey populations. Managers should also seek to maintain an abundance of fallen timber, which provides shelter and movement pathways for quolls. We hypothesise that the low density of foxes in our study area, along with the large expanse of relatively undisturbed habitat, most likely explains the high abundance of D. maculatus. However, experiments are required. Fox removal experiments should be conducted as a matter of highest priority, and should seek to measure the response of quolls to the removal of foxes at least at the individual level and preferably also at the population level.
Australian Mammalogy, 2014
The eastern quoll (Dasyurus viverrinus), while still relatively abundant in Tasmania, is now threatened by the recently introduced European red fox (Vulpes vulpes). Due to a lack of demographic information on eastern quolls, molecular data become a crucial surrogate to inform the management of the species. The aim of this study was to acquire baseline genetic data for use in current and future conservation strategies. Genetic variation, at seven microsatellite loci, was lower in Tasmanian eastern quolls than in quoll species from the Australian mainland. Within Tasmania, genetic variation was greater in central than peripheral populations, with the lowest levels detected on Bruny Island. Significant genetic population structure, consistent with regional differentiation, appears related to geographic distance among populations. Levels of gene flow appeared moderate, with genetic admixture greatest among central populations. Therefore, eastern quolls from genetically diverse central Tasmanian populations will become an important source for conservation initiatives if widespread declines begin to occur. Ongoing genetic monitoring of existing populations will allow conservation strategies to be adaptive. However, in order for translocations to be successful, managers must not only consider the genetic composition of founding individuals, but also habitat-specific adaptations, disease and threatening processes at translocation sites.
Declining populations in one of the last refuges for threatened mammal species in northern Australia
Austral Ecology, 2018
Australia has contributed a disproportionate number of the world's mammal extinctions over the past 200 years, with the greatest loss of species occurring through the continent's southern and central arid regions. Many taxonomically and ecologically similar species are now undergoing widespread decline across the northern Australian mainland, possibly driven by predation by feral cats and changed fire regimes. Here, we report marked recent declines of native mammal species in one of Australia's few remaining areas that support an intact mammal assemblage, Melville Island, the largest island off the northern Australian coast. We have previously reported a marked decline on Melville Island of the threatened brush‐tailed rabbit‐rat (Conilurus penicillatus) over the period 2000–2015, linked to predation by feral cats. We now report a 62% reduction in small mammal trap‐success and a 36% reduction in site‐level species richness over this period. There was a decrease in trap‐su...
Australian Zoologist, 2011
This paper explores the question of why the endangered Spotted-tailed Quoll Dasyurus maculatus remains abundant in parts of north-eastern New South Wales, while populations in many other areas have declined or disappeared. Based on a two-year field study of a high-density population, we discuss a number of possible explanations for this pattern. These include high availability of prey (in particular, arboreal mammals), quality and spatial extent of habitat, low density of competitors, and relatively small home range sizes of females compared to those in other areas.
Animal Conservation, 2004
Island populations are an interesting dichotomy in conservation biology. On the one hand, they can be a refuge for species where mainland populations have been decimated by loss of habitat and predation by exotic predators. On the other hand, island populations usually have reduced genetic diversity and are more susceptible to extinction through genetic and demographic processes. Genetic variation and morphological characters were measured for island and mainland populations of Parantechinus apicalis, small dasyurid marsupials, restricted to southwest Australia. Genetic variation at seven microsatellite loci revealed low levels of heterozygosity (H e = 0.20 − 0.44) and high levels of inbreeding (F e = 0.40 − 0.72) in island populations compared with the mainland population (H e = 0.73). A nested clade analysis revealed that allopatric fragmentation was probably responsible for the association between geographical location and control region haplotypes, which is consistent with the isolation of populations on islands and indicative of two main populations of P. apicalis representing separate conservation units for management. While these results are typical of many island populations, they have important implications in terms of the conservation of threatened species in Australia and around the world, where island populations are a common source of founders for captive breeding and translocation to mainland sites.