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Patterns in the modern decline of western Australia's vertebrate fauna: Causes and conservation implications


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The conservation status of terrestrial vertebrates occurring on the mainland of Western Australia was assessed. Extinctions and declines are virtually confined to non-flying mammals with mean adult body weights between 35 g and 4200 g. Variation in patterns of attrition within this critical weight range (CWR) can be explained almost entirely by a combination of regional patterns in rainfall and, to a lesser extent, species' habitat and dietary preferences. Similar patterns of mammal attrition were recognisable throughout the continent, except that the CWR was 35 to 5500 g.Environmental changes since European settlement have emulated an increase in aridity by reducing the environmental productivity available to vertebrates. These include the diversion of environmental resources to humans and introduced species, and a reduction in vegetative cover by exotic herbivores and changed fire regimes. Our analyses support the view that the reduction in available productivity has caused CWR mammals to suffer the greatest attrition because of their limited mobility, but relatively high daily metabolic requirements. The direct elimination of confined populations of mammals by exotic predators has exacerbated this attrition. We derive priorities for the conservation of Australian mammals.
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... When patch burning ceased, or was degraded, biological productivity was lost after about five years. Burbidge and McKenzie (1989) identified biological productivity loss as the primary cause of Critical Weight Range mammal extinctions in the arid and semi-arid zones. Menkhorst (2009) found loss of TO-LM plausible but rejected it because: a) 'it struggles to account for the rapidity of the mammal declines' as it would take some years to transform the fine-grain mosaic to coarse grain (awaiting senescence and bushfires); and b) there was scant evidence that Aboriginal people applied a patch-mosaic fire regime at a broad scale in this part of Australia. ...
... Furthermore, our subtraction argument also fits the progressive loss of mammal species across the continent over the following century (e.g. Burbidge & McKenzie 1989;Latz & Griffin 1978). If, as we contend, the cessation of TO-LM is the initial causal factor driving mammal extinctions, then a suite of expanded actions (hitherto ignored) for redress of the acknowledged continental declines of ecosystems becomes available. ...
... In analysing the twentieth-century attrition and extinction of species in WA (and across Australia) Burbidge and McKenzie (1989) attributed the loss of native fauna to the loss of available productivity, most pronounced in Critical Weight Range mammals that had relatively high metabolic requirements (c.f. reptiles) and lesser mobility (c.f. ...
The nineteenth century mass mammal extinctions in the semi-arid zone of the Murray‒Darling basin, southeastern Australia, are examined in the context of prior traditional land management. A model of grassland dynamics reveals a multi-trophic level productive pulse one to five years post-fire, followed by senescence and increasing flammability. Traditional Owner patch burning of grassland optimized human and mammalian food (including tubers, seeds and fungi) and decreased fire risk. Over at least 40 000 years, the persistence and abundance of fauna responded to this energetically closed self-reinforcing management. In 1830, depopulation (disease, massacres and displacement) effectively ended traditional management, an ecologically traumatic event that extinguished these productivity pulses. Associated mammal populations of c. 20 species collapsed, and all eco-engineering and mycophagous species, such as bilbies, bettongs and bandicoots, rapidly disappeared. Traditional land management increased productivity, habitat heterogeneity and reduced wildfire risk, underpinning mammal abundance. This has remained unrecognized by most mammalogists and land managers. Blaming extinctions predominantly on the additions by Europeans (introduction of ungulates, feral grazers and predators etc.), disastrous as they were, fails to acknowledge the initial cause of rarity, i.e. loss of productivity, habitat and niches when traditional management was subtracted from country. As ecosystems continue to degrade, understanding the primary cause is fundamental to improved management. Although too late for extinct species, respect for, and inclusion of, traditional land management knowledge provides a direction for future land management.
... Between the 1980s and the early 2000s, a body of evidence was generated on the impacts of foxes on native species in Australia (e.g. Burbidge and McKenzie 1989;Kinnear et al. 2002). The evidence indicated that foxes are omnivorous hunters that prey on small native mammals, birds, reptiles, amphibians and insects as well as eating fruits (Triggs et al. 1984). ...
... The evidence indicated that foxes are omnivorous hunters that prey on small native mammals, birds, reptiles, amphibians and insects as well as eating fruits (Triggs et al. 1984). Fox predation has been implicated as the main factor in the complete or regional extinction of a range of critical weight range (35-5,500 g) native mammals (Burbidge and McKenzie 1989;Short and Smith 1994), as well as small reptiles (Olsson et al. 2005;Stobo-Wilson et al. 2021) and ground-nesting birds (Dickman 1996). ...
... Anon, 2018), however, little research has been undertaken to confirm these hypothesized threats to the species or the level of impact. Parma wallabies fall within the critical weight range body mass of Australian fauna that has been decimated by introduced predators (Burbidge and McKenzie, 1989) and hence are clearly threatened by eutherian predators. While introduced red foxes are a threat (Catling and Burt, 1994), parma wallabies are also killed by dingoes (Robertshaw and Harden, 1986;Glen et al., 2006) and the young are likely killed by feral cats. ...
... The critical weight range refers to the body mass of mammals that have declined since European colonization of Australia due to the effects of introduced species(Burbidge and McKenzie, 1989). It originally ranged from 35 g to 5.5 kg, but may be larger than this.Imperiled: The Encyclopedia of Conservation ...
... nov. falls within, or close to a critical weight range of mammals prone to feral cat (Felis catus) and red fox (Vulpes vulpes) predation (35-5500 g) (Burbidge and McKenzie 1989;Woolley et al. 2019). Given the paucity of knowledge, it is unknown what the impact of cat predation is on the subspecies. ...
A population of white-footed dunnarts (Sminthopsis leucopus) occurs in the Wet Tropics bio-region of tropical north Queensland, Australia separated by about 1800 km from conspecifics in temperate New South Wales, Victoria and Tasmania. We conducted targeted surveys for S. leucopus in northeast Queensland and obtained new records, including the first reported capture of the species in Queensland in 18 years. We assessed the genetic and morphological divergence of the north Queensland population against New South Wales, Victorian and Tasmanian S. leucopus, in conjunction with distribution and habitat differences, to assess whether this isolate should be described as a distinct taxon. Sequencing of the mitochondrial Cytochrome b gene revealed genetic divergence estimates of 2.3-2.8% and 4.3-4.8% between the north Queensland population and S. l. ferruginifrons (Victoria) and S. l. leucopus (Tasmania) respectively. Based on genetic divergence, cranial morphology, differences in habitat, and geographical isolation , we describe the north Queensland population as a new subspecies of Sminthopsis leucopus. We suggest a conservation classification of Endangered given its small distribution, apparent low density, tropical upland location and potential threats, especially related to climate change.
... The eastern quoll ('murunguny' in the local Indigenous Ngunnawal language) is a small-to-medium (0.7e2 kg), critical weight range (Australian mammals between 35 and 5500 g which suffer the greatest attrition from predation by introduced predators, Burbidge & McKenzie, 1989), carnivorous marsupial (family Dasyuridae, Stannard & Old, 2013). As generalist predators, they hunt mammals, birds, reptiles, crustaceans and invertebrates, and will also scavenge on carcasses (Blackhall, 1980;Godsell, 1983). ...
Reintroductions involve the relocation of animals into their historical range following extinction or extirpation. In this context, individuals with certain personalities may be more successful than others. For example, proactive individuals may dominate by being bolder, exploratory and more willing to take risks in familiar, stable environments (i.e. the source environment). Reactive personalities, in contrast, may thrive in novel, unstable environments (i.e. the release site) by being vigilant and risk averse. In addition, an individual's ability to adjust its behaviours over time (plasticity, or responsiveness) can play a pivotal role in determining postrelease performance. There is uncertainty, however, surrounding which behavioural measures translate to reintroduction success. We conducted behavioural assays and postrelease monitoring for eastern quolls, Dasyurus viverrinus, to determine whether behavioural measures (e.g. latency to emerge, time spent vigilant) could predict postrelease survival and dispersal in a fenced sanctuary. Using the ‘behavioural reaction norm’ approach, we found that personality derived from time spent exposed or vigilant during the assays had significant associations with postrelease den sharing and home range, while plasticity derived from latency (i.e. time delay) to reach food had a significant association with mean distance between consecutive dens. We recommend that proactive and rigid founders be preferred for initial trial reintroductions, and that reactive and plastic founders be used to supplement the population in later translocations. Our study demonstrates that, by including novelty, innovative behavioural assays offer significant value as a conservation tool to provide the fastest pathway to reintroduction success.
... In the 220+ years since European colonisation of Australia, at least 33 species of native terrestrial mammal have been rendered extinct on the continent and its territories (Woinarski et al. 2014(Woinarski et al. , 2015(Woinarski et al. , 2019. Patterns of extinction on the continent are taxonomically uneven, with rodents and marsupials most affected, and a disproportionate number of extinct species falling within a critical weight range between 35 and 5500 g (Burbidge and McKenzie 1989;Woinarski et al. 2015). ...
Australia has suffered more modern mammal extinctions than any nation. Among the list of extinct species is the blue-grey mouse (Pseudomys glaucus), a rodent known from just three specimens (two from southern Queensland and one from northern New South Wales). We investigated circumstances of collection for the three specimens referred to this species to better illuminate optimal habitats and climatic conditions for continuing rediscovery efforts. No additional information could be found on two specimens from southern Queensland sent to the Natural History Museum, London. However, we recorded a first-hand account of how the northern New South Wales specimen was collected and have established that the collection year was 1956. We also obtained a copy of correspondence from Ellis Le G. Troughton thanking the collector for the contribution. The northern New South Wales specimen was from a pastoral property formerly dominated by woodland vegetation communities on alluvial soils. It was captured during a mouse plague following consecutive seasons of above average rainfall. Pseudomys glaucus is likely already extinct, but our results help better direct any future survey efforts. Surveys should be targeted in woodland communities on alluvial floodplains in the Darling Riverine Plains bioregion, following periods of above average rainfall conducive to the irruption of rodent populations.
... desertification, erosion) and many native wildlife species (e.g. declines and extinctions) in the 1800s and 1900s (Burbidge and McKenzie, 1989;Idriess, 2001;McKenzie et al., 2007;Woinarski et al., 2015). Many threatened species presently exist within the region where these cluster fences are being erected, including small mammals, ground-dwelling birds, and reptiles (Smith et al., 2020b). ...
Increased demand for livestock products is exacerbating conflict with predators in many parts of the world, fuelling an increase in predation management practices in many grazing systems. In Australia, exclusion fences are being erected across broad areas to facilitate the sustained eradication of dingoes, an apex predator, prompting concern for possible cascading effects on extant wildlife populations. We experimentally assessed population trends of mammals, reptiles and ground-dwelling birds inside and outside of two large, fenced areas over a five-year period subsequent to the erection of the fences and the removal of dingoes. Wildlife population abundances inside the fences were always higher or the same as outside the fences, and all wildlife species exhibited similar population trends within each treatment over time. The only exception to this was kangaroo populations, which fluctuated widely inside fenced areas but remained relatively low and stable outside fenced areas. Kangaroos exhibited negative relationships with dingoes, although unmeasured variables limited our ability to quantify specific causes for kangaroo population trends. Vegetation trends were virtually identical between treatments, indicating that wildlife population trends are closely linked to vegetation conditions and not predator abundances. These applied, experimental results demonstrate that top-predator removal does not routinely cause trophic cascades (including mesopredator releases) in Australian rangeland ecosystems. We therefore encourage exploration of opportunities for targeted threatened species recovery in predator-free areas on land used for livestock production.
Carnivores have key ecological roles in structuring and regulating ecosystems through their impacts on prey populations. When apex‐ and meso‐predators co‐occur in ecosystems, there is the potential for complex interspecific interactions and trophic dynamics that can affect the composition and functioning of ecological communities. Investigating the diet of sympatric carnivores can allow us to better understand their ecological roles (e.g. potential suppression of herbivores) or impacts (e.g. predation of threatened species). Australia's alpine region provides an ideal system in which to explore spatial and temporal variation in predator and prey interactions, using the dingo (Canis dingo) and invasive red fox (Vulpes vulpes) diet. We examined the diet of dingoes and foxes across three different mountains and seasons in Victoria's alpine region, using macroscopic scat analysis. There was little diet overlap between the two carnivores, with foxes having a broader diet than dingoes. Dingoes primarily consumed larger mammal species, including invasive sambar deer (Cervus unicolor, 44%), and the native common wombat (Vombatus ursinus, 34%), whereas foxes typically consumed smaller mammals, including the native bush rat (Rattus fuscipes, 55%), and the invasive European rabbit (Oryctolagus cuniculus, 15%). Dingoes consumed more than thirty times the volume of large invasive mammals (predominantly sambar deer) than did foxes. Foxes consumed close to 15 times as many critical weight range individuals per scat than dingoes. Only one threatened critical weight range mammal species was identified within scats, the broad‐toothed rat (Mastacomys fuscus), found within five fox scats. Our results suggest that the introduction of novel prey may alter predator–predator interactions by causing a reduction in the dietary overlap. Therefore, in the context of integrated wildlife management and biodiversity conservation, any control of novel, invasive prey populations needs to consider possible flow on effects to apex‐ and meso‐predator diets and potential secondary impacts on native prey.
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Millions of native animals around the world are rescued and rehabilitated each year by wildlife rehabilitators. Triage and rehabilitation protocols need to be robust and evidence-based, with outcomes consistently recorded, to promote animal welfare and better understand predictors of wildlife survival. We conducted a global systematic review and meta-analysis of 112 articles that reported survival rates of native mammals and birds during rehabilitation and after release to determine intrinsic and extrinsic factors associated with their survival. We assessed survival during rehabilitation and in the short- and long-term post-release, with the hypothesis that survival will vary as a function of species body size, diel activity pattern, trophic level and study location (region of the world). We aimed to determine the direction of effect of these factors on survival to assist in decision-making during triage and rehabilitation. Results showed that mammals and birds were equally likely to survive all stages of rehabilitation, and survival rates varied between locations. Birds in North America had the poorest survival rates post-release, particularly long-term, as did diurnal and carnivorous birds in the short-term post-release. Anthropogenic factors such as motor vehicle collisions and domestic or feral animal attack contributed to morbidity and post-release mortality in 45% (168 of 369) of instances. The reasons for rescue and associated severity of diagnosis were commonly reported to affect the likelihood of survival to release, but factors affecting survival were often species-specific, including bodyweight, age, and characteristics of the release location. Therefore, evidence-based, species-specific, and context-specific protocols need to be developed to ensure wildlife survival is maximised during rehabilitation and post-release. Such protocols are critical for enabling rapid, efficient rescue programs for wildlife following natural disasters and extreme weather events which are escalating globally, in part due to climate change.
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This report provides an overview of the impact of feral cats Felis catus on native fauna of the Pacific region, with particular reference to Australia and its island territories. In Australia, cats take a wide variety of native species of mammals, birds and reptiles, but show evident preference for young rabbits or small marsupials where these are available. Reptiles are taken primarily in arid habitats, while birds often feature predominantly in the diet of cats on islands. Despite their catholic diet, population-level impacts of feral cats on native fauna have been poorly documented. There is considerable potential for competition to occur between cats and carnivorous species such as quolls and raptors, but no critical evidence has yet been adduced. There is also potential for amensal impacts to occur, either via transmission of the pseudophyllidean tapeworm Spirometra erinacei or of the protozoan parasite Toxoplasma gondii, but evidence for deleterious effects in free-living animals is not compelling. Direct predatory impacts have been inferred from anecdotal and historical evidence, more strongly from failed attempts to reintroduce native species to their former ranges, and most critically from the decimation of island faunas and responses of prey species following experimental removal of cats or reduction of cat numbers. Attributes of the biology of feral cats and their prey species derived from the literature review were used to develop a rank-scoring system to assess the susceptibility of native species to cat predation. Species listed federally as endangered or vulnerable were designated as being at zero, low or high risk of impact from cats according to their attribute scores, and their distributions mapped from primary sources and actual locality data. Based on the number of threatened species they contain, localities and regions within Australia were placed in order of priority for future research to clarify the precise impacts of feral cats. Although difficult and expensive to carry out, controlled and replicated field removal experiments are recommended to elucidate cat impacts in all mainland areas. Removal of cats should take place also on offshore islands and island territories, but only if pilot studies show that this will not release populations of alternative predator species such as introduced rats. If release appears likely, cats should be removed only as a component of an integrated control program that targets all relevant predators.
At least 16 species of Australian mammals have become extinct over the past 200 years. Without islands, however, this figure would be even worse as nine species that were formerly widespread on mainland Australia were or are restricted to land-bridge islands. In addition, 13 species and subspecies of endangered and vulnerable mainland mammals that still occur on the mainland have island populations, reducing their chance of extinction. In all, 43 islands protect 29 taxa of Australian threatened mammals. Since European settlement some island mammal populations have become extinct, while many new populations, of both Australian and exotic mammals, have been established. The extinction of island native mammal populations is significantly correlated with the introduction of exotic mammals. Management of islands needs to concentrate on four areas: quarantine, monitoring (of both native mammals and possible introduction of exotics), eradication of exotics and translocations of native species. Prevention of introduction and establishment of further exotics to important islands through quarantine procedures is vital, especially for islands with permanent or temporary human habitation. Eradication or control of existing exotics is required for many islands and eradication of further introductions, as soon after detection as possible, should be a high priority action for nature conservation agencies. Past exotic mammal eradications and needs for the future are discussed. Translocations of island mammal populations to the mainland should take place only where the species is extinct on the mainland. Translocation to islands, where translocation to or on the mainland is not feasible, is an important conservation technique. Islands with exotics can be of value for re-introduction of locally extinct mammals or introductions (marooning) of threatened species that are at risk from feral predators on the mainland once the exotics have been eliminated.