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Hybridisation between wild and domestic canids is a global conservation and management issue. In Australia, dingoes are a distinct lineage of wild-living canid with a controversial domestication status. They are mainland Australia’s apex terrestrial predator. There is ongoing concern that the identity of dingoes has been threatened from breeding with domestic dogs, and that feral dogs have established populations in rural Australia. We collate the results of microsatellite DNA testing from 5039 wild canids to explore patterns of domestic dog ancestry in dingoes and observations of feral domestic dogs across the continent. Only 31 feral dogs were detected, challenging the perception that feral dogs are widespread in Australia. First generation dingo × dog hybrids were similarly rare, with only 27 individuals identified. Spatial patterns of genetic ancestry across Australia identified that dingo populations in northern, western and central Australia were largely free from domestic dog introgression. Our findings challenge the perception that dingoes are virtually extinct in the wild and that feral dogs are common. A shift in terminology from wild dog to dingo would better reflect the identity of these wild canids and allow more nuanced debate about the balance between conservation and management of dingoes in Australia.

Public opposition has shaped management of wild animals in Australia, but public interest in dingo control has been minimal. We hypothesised that this is due to lack of awareness of dingo management practices, in part because using the term “wild dogs” to describe management renders “dingoes” invisible, framing the issue as one of control of introduced pests rather than control of an iconic Australian animal. We distributed an online questionnaire survey to the Australian public (N = 811) to measure how the public perceived dingoes and their management, how these views compared with other animals managed as pests in Australia, and whether the term “wild dogs” has shaped views and knowledge of dingo management. Most respondents (84.6%) considered dingoes to be native to Australia and there was low approval of lethal control methods, except when justification was provided (e.g., to protect livestock or endangered native species). Only 19.1% were aware that “wild dog” management included dingoes, and attitudes towards “wild dogs” were more negative than those towards dingoes. If public awareness about dingo management increases, pressure from the public may result and shape future management actions, including restricting the use of lethal control practices like poison baiting on public lands. As such, public attitudes should be incorporated into decision-making, and appropriate communication strategies need to be employed to prevent backlash.

The impact of hybridisation between dingoes and domestic dogs, and the subsequent introgression of domestic dog genes into dingo populations, remains a topic of significant impact. It has been claimed, but with little evidence or logical argumentation, that dingoes with significant dog introgression have different effects on agriculture and ecosystems than dingoes with no dog introgression. Introgression is a natural process in evolution, occurring in many species, although this is sometimes human assisted. Canid species in particular show high levels of introgression, due to their genetic and phylogenetic similarities, and human persecution creates scenarios encouraging hybridisation. Dingoes are no exception and demonstrate high levels of introgression of domestic dog genes, particularly in the temperate areas of south-eastern Australia. The available evidence shows that this introgression has minimal effects on the functional morphology of the dingo skull. There is also some preliminary evidence that introgression has not had a major impact on dingo reproductive biology. Studies on the impacts of dingoes on arid, tropical and temperate ecosystems, where levels of introgression vary greatly, all show consistent positive impacts of dingoes, regardless of the amount of domestic dog genes within the dingo population, on these ecosystems. Hence, hybridisation and resultant introgression from domestic dog genes appear to have little effect on aspects of the functional morphology or ecological role of the dingo. Accordingly, introgression does not diminish the conservation status of the dingo.

Hybridisation resulting from human-driven shifts in species ranges is a global conservation concern. In Australia, hybridisation between dingoes (Canis dingo) and domestic dogs (Canis familiaris) has been identified as an extinction threat to the dingo, and is thought to be particularly widespread in south-eastern Australia. Here, we investigated the extent of hybridisation between dingoes and dogs in a sample of 783 wild-caught canids from eastern New South Wales, using an established 23-microsatellite test. We then mapped the distribution of these samples and identified three areas that are geographic hotspots of high dingo genetic ancestry using geospatial analysis. Between 9 and 23% of the wild canids that we sampled were classified as only having or likely to have only dingo ancestry. Only 0.6% of the wild canids we sampled were classified as having no dingo ancestry. Introgression from domestic dogs into the southeastern dingo gene pool has been extensive, with 76–88% of sampled dingoes carrying some dog ancestry. Spatial analyses revealed several geographic hotspots of high dingo genetic ancestry within north-eastern New South Wales (NSW) where there was a higher than expected prevalence of dingoes with no domestic dog ancestry. A key finding of our study is the observation of several regions where dingoes were largely free of admixture from dogs. There is an ongoing need for evidence-based strategies to reduce human-driven hybridisation by identifying and maintaining natural barriers to reproduction or limiting opportunities for wild-domesticate hybridisation. Globally, legislators and land managers may need to consider less restrictive species definitions to conserve endangered or ecologically significant taxa.

Chlamydiosis, caused by Chlamydia pecorum, is regarded as an important threat to koala populations. Across the koala's geographical range, disease severity associated with C. pecorum infection varies, with pathogen diversity and strain pathogenicity being likely important factors. To examine C. pecorum diversity on a sub-population level a Multi-Locus Sequence Typing (MLST) scheme, containing the housekeeping genes; gatA, oppA_3, hflX, gidA, enoA, hemN and fumC, was used to type strains from two sub-populations of koalas from the Liverpool Plains, NSW, Australia, with different disease expressions. Typing of samples from 2015 to 2017, revealed a significant association between sequence type ST 69 and clinical disease and a significant difference in sequence type frequencies between sub-populations. Sequence type ST 69 has previously been identified in both subclinical and clinically diseased koalas indicating that these markers alone are not illustrative of pathogenicity. However, recent emergence of this sequence type in a naïve population may explain the differing disease expressions. Sequence types ST 73 and ST 69 have been described in koalas across a broad geographic range, indicating multiple introduction events and/or a limited veracity of the MLST loci to explore fine scale epidemiological investigations, particularly those examining the interface between pathogenic strain and disease outcome.

Cryptococcosis, caused by environmental fungi in the Cryptococcus neoformans and Cryptococcus gattii species complexes, affects a variety of hosts, including koalas (Phascolarctos cinereus). Cryptococcal antigenemia and nasal colonization are well characterized in captive koalas, but free-ranging populations have not been studied systematically. Free-ranging koalas (181) from the Liverpool Plains region of New South Wales, Australia, were tested for cryptococcal antigenemia (lateral flow immunoassay) and nasal colonization (bird seed agar culture). Results were related to environmental and individual koala characteristics. Eucalypt trees (14) were also randomly tested for the presence of Cryptococcus spp. by bird seed agar culture. In sum, 5.5% (10/181) and 6.6% (12/181) of koalas were positive for antigenemia and nasal colonization, respectively, on at least one occasion. And 64.3% (9/14) of eucalypts were culture-positive for Cryptococcus spp. URA5 restriction fragment length polymorphism analysis identified most isolates as C. gattii VGI, while C. neoformans VNI was only found in one koala and one tree. Colonized koalas were significantly more likely to test positive for antigenemia. No associations between antigenemia or colonization, and external environmental characteristics (the relative abundance of Eucalyptus camaldulensis and season), or individual koala characteristics (body condition, sex, and age), could be established, suggesting that antigenemia and colonization are random outcomes of host-pathogen-environment interactions. The relationship between positive antigenemia status and a relatively high abundance of E. camaldulensis requires further investigation. This study characterizes cryptococcosis in a free-ranging koala population, expands the ecological niche of the C. gattii/C. neoformans species complexes and highlights free-ranging koalas as important sentinels for this disease.

Taxonomy plays an important role in defining biodiversity and shaping conservation efforts. However, the biological species concept is a human construct and organisms that do not abide by ...

Shortly after the enactment of restrictions aimed at limiting the spread of COVID-19, various local government and public health authorities around the world reported an increased sighting of rats. Such reports have yet to be empirically validated. Here we combined data from multi-catch rodent stations (providing data on rodent captures), rodent bait stations (providing data on rodent activity) and residents’ complaints to explore the effects of a six week lockdown period on rodent populations within the City of Sydney, Australia. The sampling interval encompassed October 2019 to July 2020 with lockdown defined as the interval from April 1st to May 15th, 2020. Rodent captures and activity (visits to bait stations) were stable prior to lockdown. Captures showed a rapid increase and then decline during the lockdown, while rodent visits to bait stations declined throughout this period. There were no changes in the frequency of complaints during lockdown relative to before and after lockdown. There was a non-directional change in the geographical distribution of indices of rodent abundance suggesting that rodents redistributed in response to resource scarcity. We hypothesize that lockdown measures initially resulted in increased rodent captures due to sudden shortage of human-derived food resources. Rodent visits to bait stations might not show this pattern due to the nature of the binary data collected, namely the presence or absence of a visit. Relocation of bait stations driven by pest management goals may also have affected the detection of any directional spatial effect. We conclude that the onset of COVID-19 may have disrupted commensal rodent populations, with possible implications for the future management of these ubiquitous urban indicator species.

Habitat fragmentation changes landscape patterns and can disrupt many important ecological processes. Movement allows individuals to find resource patches to maintain their fitness and habitat fragmentation can disrupt this process. We explored the ecological impact of habitat fragmentation on movement and space use of a specialist folivore, the koala Phascolarctos cinereus. We GPS tracked koala movements within a fragmented agricultural landscape. We calculated the total distance moved across four months and the number of core patches by each koala. We used four metrics (proximity, functional connectivity, clumpiness, perimeter-to-area fractal dimension) to quantify landscape fragmentation within koala home ranges and determine its effects on movement and space use. Functional connectivity had the greatest effect on individual movement and space use. Decreasing connectivity led to longer and more direct movements by koalas and more core patches within an individual home range. Our study provides insight into the effects of habitat fragmentation on animal movement and space use, which can be used by wildlife managers to plan and manage landscapes more effectively.We conclude that restoring or protecting resource patches to promote greater functional connectivity will reduce the costs associated with the isolation of resource patches for species occupying fragmented landscapes. By providing a quantitative relationship between habitat connectivity and movement and space use costs, our results enable managers to set restoration targets, by identifying the most effective way to provide the functional connectivity minimizing the negative impact on focal species.

Recent studies suggest that apex predators play a pivotal role in maintaining healthy, balanced ecosystems. However, a criticism of studies investigating the ecological role of apex predators is that understanding does not come from manipulative experiments. Here, we use a before-after-control-impact-paired design to test predictions generated from trophic cascade theory (TCT) and mesopredator release hypothesis (MRH) by experimentally introducing dingoes into a 37-km2 paddock and measuring the resultant effects on mammal assemblages. To increase precision of parameter estimates generated by our experiment, we used a Bayesian framework which included prior information recorded from a mensurative study located in a comparable ecosystem that contrasted indices of mammal abundance where dingoes were common and rare. Results of the mensurative study were consistent with TCT and MRH. When using an uninformative prior, results of the experiment showed that dingo addition only had a negative effect on kangaroo activity. Use of an informative prior reduced uncertainty of the posterior mean parameter estimates from the experiment and suggested that red foxes were affected negatively and small mammals and rabbits were affected positively by dingo introduction. However, the prior had a strong influence on the posterior mean effect sizes for small mammals, rabbits and foxes. Opposite polarity of uninformed and prior parameter estimates for rabbits suggests that the prior was incompatible with the uninformed estimates from the manipulative experiment. Our study shows how use of logical informative priors can help to overcome statistical issues associated with low-replication in large-scale experiments, but the strong influence of the prior means that our findings were driven largely by the mensurative study.

Arboreal folivores are particularly vulnerable to the impacts of extreme climate change-driven heatwaves and droughts as they rely on leaf moisture to maintain hydration. During these increasingly frequent and intense weather events, leaf water content may not be enough to meet their moisture requirements, potentially leading to large-scale mortality due to dehydration. Water supplementation could be critical for the conservation of these animals. We tested artificial water stations for a threatened arboreal folivore, the koala (Phascolarctos cinereus), as a potential mitigation measure during hot and dry weather in New South Wales, Australia. We provided ground and tree drinkers to koalas and investigated changes in use with season, environmental conditions and foliar moisture. Our study provides first evidence of the regular use of free water by koalas. Koalas used supplemented water extensively throughout the year, even during cooler months. Time spent drinking varied with season and depended on days since last rain and temperature. The more days without rain, the more time koalas spent drinking. When temperature was high, visits to water stations were more frequent, indicating that in hot weather koalas need regular access to free water. Our results suggest that future changes in rainfall regimes and temperature in Australia have the potential to critically affect koala populations. Our conclusions can be applied to many other arboreal folivorous mammals worldwide which rely on leaves for their nutritional and water requirements. Artificial water stations may facilitate the resilience of vulnerable arboreal folivores during heat and drought events and may help mitigate the effects of climate change.

Australia’s native wild dog, the dingo (Canis dingo), is threatened by hybridization with feral or domestic dogs. In this study we provide the first comprehensive three dimensional geometric morphometric evaluation of cranial shape for dingoes, dogs and their hybrids. We introduce a novel framework to assess whether modularity facilitates, or constrains, cranial shape change in hybridization. Our results show that hybrid and pure dingo morphology overlaps greatly, meaning that hybrids cannot be reliably distinguished from dingoes on the basis of cranial metrics. We find that dingo morphology is resistant, with observed hybrids exhibiting morphology closer to the dingo than to the parent group dog. We also find that that hybridization with dog breeds does not push the dingo cranial morphology towards the wolf phenotype. Disparity and integration analyses on the ten recovered modules provided empirical support for modularity facilitating shape change over short evolutionary time scales. However, our results show that this is may not be the case in hybridization events, which were not influenced by module integration or disparity levels. We conclude that although hybridization events may introduce breed dog DNA to the dingo population, the native cranial morphology, and therefore likely the feeding eco-niche, of the dingo population is resistant to change. Our results have implications for conservation and management of dingoes and, more broadly, for the influence of integration patterns over ecological time scales in relation to selection pressure.

In the absence of top-down regulation by predators, herbivore populations irrupt. In irrupting populations of large herbivores deaths are frequent and availability of carrion from carcasses is high, potentially subsidising facultative scavengers such as crows and ravens. Increases in facultative scavengers could amplify perceived and real predation risk for small prey. We provisioned large-herbivore carcasses over 2 weeks at three sites (400 ha/site) in the Australian arid zone and monitored detection rates of facultative scavenger birds and low-nesting small passerines at these sites and at three control sites of the same size. We found that provisioning large herbivore carcasses rapidly increased local abundances of scavenging corvids Corvus coronoides and C. bennetti by 50% and decreased relative detection rates of a predation-sensitive small passerine, white-winged fairywren Malurus leucopterus by 50%. White-winged fairywren detection rates were inversely correlated with corvid abundances. Our study indicates that increases in carrion availability associated with herbivore irruptions subsidise facultative scavengers, and thus may indirectly affect co-occurring prey species.

Justification for lethal control in conservation is often presumed to be shaped by human attitudes toward different species and whether these species are regarded as native or introduced to a particular system. Conservation researchers and practitioners attitudes often differ in this regard, so different conservation frameworks have evolved such as traditional compositionalist conservation, ‘new’ functionalist conservation, and compassionate conservation. Yet, there is limited research on how the public perceives and values native versus introduced species and thus how public perceptions align with these different and somewhat conflicting definitions of conservation. We conducted an online public survey (N = 811) in Australia to explore how perceptions of species are related to each other and to the approval of lethal control. We focused on native kangaroos, the long-established dingo, and more recently introduced red foxes and wild horses. Perceptions of species' ‘nativeness’ varied and did not always align with policy definitions or reality, with 18.4% and 17.9% considering horses and foxes, respectively, to be native to Australia. The perception that a species was not native and was a pest were linked, and correlated positively with approval for lethal control. The results reveal the conflicting perceptions of conservation among conservationists, the public, and policy definitions. This highlights the difficulty of developing a set of agreed upon conservation goals which would help promote conservation practices supported by stakeholder values.

Aim Apex predators often exert strong, top-down effects on ecosystems, and their removal can result in the dramatic reorganization of ecosystems owing to herbivores and smaller predators becoming the dominant trophic-regulating species. However, field studies designed to understand the influence that apex predators have on ecosystems are hampered by the large spatial and temporal scales required. Here, we use pre-existing datasets to test predictions on the direct and indirect effects of apex predators on mammals and vegetation generated from trophic cascade theory and the mesopredator release hypothesis. Location Forests of south-eastern Australia. Methods We applied quantile regression to published data collected at 44 sites during the 1980s and 1990s. We investigated inter-relationships between abundance indices of an apex predator, the dingo (Canis dingo), introduced mesopredators, herbivores, ground-dwelling medium-sized mammals and small mammals, and inter-relationships between habitat complexity and abundances of dingoes and macropods. Quantile regression is well suited for investigating limiting factors of response variables, especially when the observations are made at large temporal and spatial scales. Results In accordance with trophic cascade theory, dingo abundance was negatively associated with macropod abundance and macropod abundance was negatively associated with habitat complexity; however, dingo abundance was not correlated with habitat complexity. Similarly, in accordance with the mesopredator release hypothesis, dingo abundance was correlated negatively with red fox abundance and red fox abundance was negatively associated with the abundance of ground-dwelling medium-sized mammals, but, dingo abundance was not correlated with the abundance of medium-sized ground-dwelling mammals. Main conclusions Our results suggest that the direct suppressive effects of the dingo on macropods and foxes occur simultaneously, but that their indirect effects on lower trophic levels are comparatively weak. Our study provides evidence that the effects of apex predators on other species can be exerted across large spatial scales and become manifest on species at multiple trophic levels.

There is global interest in restoring populations of apex predators, both to conserve them and to harness their ecological services. In Australia, reintroduction of dingoes (Canis dingo) has been proposed to help restore degraded rangelands. This proposal is based on theories and the results of studies suggesting that dingoes can suppress populations of prey (especially medium- and large-sized herbivores) and invasive predators such as red foxes (Vulpes vulpes) and feral cats (Felis catus) that prey on threatened native species. However, the idea of dingo reintroduction has met opposition, especially from scientists who query the dingo's positive effects for some species or in some environments. Here, we ask ‘what is a feasible experimental design for assessing the role of dingoes in ecological restoration?’ We outline and propose a dingo reintroduction experiment—one that draws upon the existing dingo-proof fence—and identify an area suitable for this (Sturt National Park, western New South Wales). Although challenging, this initiative would test whether dingoes can help restore Australia's rangeland biodiversity, and potentially provide proof-of-concept for apex predator reintroductions globally.

The diets of predators and their selection of prey often shape prey community dynamics. Understanding how different predators select their prey could enable ecologists to predict their impact on specific prey populations. Here, we investigate the diets of the feral cat (Felis catus), red fox (Vulpes vulpes), and dingo (Canis dingo) in the Simpson Desert of central Australia, over a 1-year period between 2011 and 2012, and compare the selectivity of these predators for small mammalian prey. We found that cats showed the greatest consumption of small mammals, whereas dingoes consumed larger prey, thus indicating preferences for different prey sizes. High occurrence of small mammals in the diets of all predators probably reflected high abundances of small mammals in the environment; rodents declined after an irruption, but were still abundant at the time of sampling. The cat exercised greatest selectivity for small mammal species, whereas the dingo did not positively select for any species. Positive...

Detection and avoidance of predator cues can be costly, so it is important for prey to balance the benefits of gaining food against the costs of avoiding predators. Balancing these factors becomes more complicated when prey are threatened by more than one type of predator. Hence, the ability to recognize species-specific predator odours and prioritize behaviours according to the level of risk is essential for survival.We investigated how rock rats, Zyzomys spp. modify their foraging behaviour and giving-up density (GUD) in the presence of an apex predator, the dingo Canis dingo, a mesopredator, the northern quoll Dasyurus hallucatus, a herbivore, the rock wallaby Petrogale brachyotis as a pungency control and water as a procedural control. Both dingoes and quolls consume rock rats, but because quolls can enter small crevices inhabited by rock rats, they pose a greater threat to rock rats than dingoes. Rock rats demonstrated a stronger avoidance to quoll odour than dingo odour, and no avoidance of the pungency control (rock wallaby) and the procedural control (water). GUD values declined significantly over the duration of the study, but did not differ between odour treatments. Our results support the hypothesis that prey vary behaviour according to perceived predator threat, and show stronger responses to potentially more dangerous predators.

As both companion animals and opportunistic predators, dogs (Canis lupus spp.) have had a long and complex relationship with humans. In Australia, the dingo (C. l. dingo) was introduced 4,000 years ago and, other than humans, is now the continent's top mammalian predator. Domestic dogs (C. l. familiaris) were introduced by Europeans more recently and they interbreed with dingoes. This hybridization has caused growing concern about the roles that domestic dogs and dingoes play in shaping ecosystem processes. There is also considerable debate about whether anthropogenic environmental changes can alter the ecological roles of dingoes. We used scat analysis to test whether the dingo, as the longer-established predator, occupies a different dietary niche from that of free-roaming domestic dogs, irrespective of human influence. Our results demonstrate considerable dietary overlap between dingoes and domestic dogs in areas where humans provide supplementary food, providing evidence against our hypothesis. However, the consumption by dingoes of a greater diversity of prey, in association with historical differences in the interactions between dingoes and humans, suggests a partial separation of their dietary niche from that of domestic dogs. We conclude that anthropogenic changes in resource availability could prevent dingoes from fulfilling their trophic regulatory or pre-European roles. Effective management of human-provided food is therefore required urgently to minimize the potential for subsidized populations of dingoes and domestic dogs to negatively affect co-occurring prey.

A sound understanding of the taxonomy of threatened species is essential for setting conservation priorities and the development of management strategies. Hybridization is a threat to species conservation because it compromises the integrity of unique evolutionary lineages and can impair the ability of conservation managers to identify threatened taxa and achieve conservation targets. Australia’s largest land predator, the dingo Canis dingo, is a controversial taxon that is threatened by hybridization. Since their arrival

Studies of environmental history provide an important lens through which to analyse our contemporary thinking and practices. Here we consider historic management of the conflict caused by dingo predation on livestock. We present unpublished findings of a comprehensive national survey of graziers’ attitudes, knowledge and interactions with dingoes that was conducted by Professor N.W.G. Macintosh in the 1950s. By analysing the 137 responses from this survey, we sought to determine the factors that shaped graziers’ attitudes and management decisions. The four most popular management methods employed to protect livestock from dingoes were trapping (80%), ground-baiting (68%), fencing (44%), and shooting (34%). Whether a respondent had sheep or not was the strongest determinant of which management methods were used, with sheep graziers less likely to use ground-baiting and shooting and more likely to use trapping and fencing. While some patterns among responses were evident, the study reveals the complex nature of graziers’ experiences with dingoes and suggests that, given the lack of scientific evidence available to them at the time of Macintosh’s survey, their decisions, observations, and attitudes were influenced by contextual factors. We use this analysis to consider how history has shaped contemporary dingo management. While the economic, social and environmental context has changed since Macintosh’s survey over 60 years ago, some historical attitudes and practices surrounding dingoes have endured and attacks on livestock by dingoes continue to be regarded as a major threat to graziers.

Livestock producers and governments have managed predators to protect livestock for millennia. But in recent decades attitudes towards predators and their management have shifted from solely killing towards coexistence and even conservation. In Australia, a continent-wide survey of graziers conducted in the 1950s provides an opportunity to consider how attitudes and practices surrounding dingo management have changed over the last 60 years. We created a survey that repeated questions and themes from the 1950s study and sent this to 75 of the properties where the original survey had been completed. We received 23 complete or semicomplete responses. Ground-baiting and shooting continue to form a major focus of management on the focal properties, while fewer respondents used trapping and fencing in the current survey than in the 1950s. Ten properties had adopted either or both of two lethal methods (aerial baiting and hiring professional doggers) since the 1950s survey. Unlike the 1950s survey, three respondents used non-lethal methods only (animal husbandry or livestock guardian animals) and indicated that they support maintaining dingoes in the landscape. This change, albeit small, may suggest that attitudes towards dingoes by graziers have diversified from solely lethal control. We discuss these trends and consider the future of dingo management in Australia. In accordance with changing attitudes among some producers, we suggest that governments must now consider the diversity of approaches to managing livestock in the presence of dingoes and offer more training and support for those methods that are proven effective.

The abundance of shrubs has increased throughout Earth's arid lands. This 'shrub encroachment' has been linked to livestock grazing, fire-suppression and elevated atmospheric CO2 concentrations facilitating shrub recruitment. Apex predators initiate trophic cascades which can influence the abundance of many species across multiple trophic levels within ecosystems. Extirpation of apex predators is linked inextricably to pastoralism, but has not been considered as a factor contributing to shrub encroachment. Here, we ask if trophic cascades triggered by the extirpation of Australia's largest terrestrial predator, the dingo (Canis dingo), could be a driver of shrub encroachment in the Strzelecki Desert, Australia. We use aerial photographs spanning a 51-year period to compare shrub cover between areas where dingoes are historically rare and common. We then quantify contemporary patterns of shrub, shrub seedling and mammal abundances, and use structural equation modelling to compare competing trophic cascade hypotheses to explain how dingoes could influence shrub recruitment. Finally, we track the fate of seedlings of an encroaching shrub, hopbush (Dodonaea viscosa angustissima), during a period optimal for seedling recruitment, and quantify removal rates of hopbush seeds by rodents from enriched seed patches. Shrub cover was 26-48% greater in areas where dingoes were rare than common. Our structural equation modelling supported the hypothesis that dingo removal facilitates shrub encroachment by triggering a four level trophic cascade. According to this model, increased mesopredator abundance in the absence of dingoes results in suppressed abundance of consumers of shrub seeds and seedlings, rodents and rabbits respectively. In turn, suppressed abundances of rodents and rabbits in the absence of dingoes relaxed a recruitment bottleneck for shrubs. The results of our SEM were supported by results showing that rates of hopbush seedling survival and seed removal were 1·7 times greater and 2·1 times lower in areas where dingoes were rare than common. Our study provides evidence linking the suppression of an apex predator to the historic encroachment of shrubs. We contend that trophic cascades induced by apex predator extirpation may be an overlooked driver of shrub encroachment.

The exploitation ecosystems hypothesis (EEH) makes predictions about trophic interactions along gradients of primary productivity. The EEH has been shown to apply to a wide range of terrestrial environments but its applicability to arid environments has received little attention. One reason for this is that arid environments may not satisfy the assumptions of the EEH because dearth of water may limit biological activity in both temporal and spatial contexts. The EEH predicts that herbivore biomass should increase linearly with primary productivity in the absence of predators; but when predators are present herbivore biomass will remain relatively constant due to top–down regulation. We tested this prediction in an arid environment using rainfall as a proxy of primary productivity and an index of the abundance of the dominant herbivores (kangaroos Macropus spp.). We compared an index of kangaroo abundance at 18 areas situated along a gradient of mean annual rainfall in areas where a top predator (the dingo Canis lupus dingo) was rare and common. We also explored the relationship between the density of artificial water points (AWPs) and kangaroo abundance to investigate if the resource subsidy provided by AWPs allows kangaroos to persist in high numbers. Consistent with the EEH, kangaroo abundance showed a weak relationship with mean annual rainfall in the presence of dingoes but increased with increasing annual rainfall in the absence of dingoes. The density of AWPs was a poor predictor of kangaroo abundance. Our analysis of macro-ecological patterns suggests that kangaroo populations are primarily top–down regulated in the presence of dingoes, but are bottom–up regulated in the absence of dingoes. Our findings provide evidence that top–down regulation can prevail over bottom–up regulation of herbivore populations in arid ecosystems and highlights the usefulness of the EEH as a predictor of macro-ecological patterns of species abundance.

The mesopredator release hypothesis (MRH) predicts that a reduced abundance of top-order predators results in an increase in the abundance of smaller predators due to the cessation of intraguild predation and competition. In turn, small prey preferred by mesopredators are predicted to benefit from the suppressive effects of top-order predators on mesopredators. In support of the MRH a growing body of evidence shows that Australia’s largest terrestrial predator, the dingo (Canis lupus dingo, body mass of 15–25 kg), might suppress the abundance of the smaller invasive red fox (Vulpes vulpes, body mass of 3.5–7.5 kg). Foxes are implicated in the declines of native rodents and marsupials in arid Australia; where foxes are rare, native prey species are more likely to persist. However, the mechanism by which dingoes suppress fox populations and benefit native mammal species is not well understood. We used scat analysis and prey selectivity indexes to examine the potential for dietary competition between dingoes and foxes at 3 arid sites. Dietary overlap between dingoes and foxes was high (85%) at all sites. Dingoes and foxes preferentially selected identical prey types in greater proportion to their relative abundance at all sites, but foxes tended to consume smaller prey than dingoes. Dingoes consumed more large- (.999 g) and medium-sized (100–999 g) mammals, and foxes consumed greater numbers of smaller (,100 g) mammals. At 2 sites rabbits were the most frequently occurring prey for both predators and were consumed in greater proportion than their abundance. The extensive dietary overlap and preferential selection by the predators for the same prey suggest that considerable potential exists for dietary competition between these predators. Fox remains found in dingo scats provided evidence of intraguild predation. Our results support the notions that dingoes could suppress fox populations through both dietary competition and direct killing and that this suppression of foxes could benefit small prey.

Scale matters when assessing population trends. Whereas traditional field-based ecological surveys are generally restricted to small temporal and spatial scales, community (citizen science) surveys allow wider consideration of population trends. We used repeat community surveys (completed in 2006 and 2015) to assess population change in koalas (Phascolarctos cinereus) across an area of 36 900 km2 in the north-west of New South Wales. In both community surveys we asked respondents to record the location of their koala sightings as well as those of eight other common species. We further asked respondents about their perceptions of population change. Through three different measures (likelihood of koala occurrence, number of koalas observed per respondent, and the perception of population change), we found that koala numbers were declining across the region during the study period. The timing and broad and consistent geographic spread of the decline suggests that broad-scale environmental factors, such as weather, are important drivers of this change. This information will allow managers to place conservation efforts into an appropriate spatial context. While such information sourced from the community can provide critical information on threatened species, including the koala, this study highlights the limits of such information.

In arid environments, ecological refuges are often conceptualised as places where animal species can persist through drought owing to the localised persistence of moisture and nutrients. The mesopredator release hypothesis (MRH) predicts that reduced abundance of top-order predators results in an increase in the abundance of smaller predators (mesopredators) and consequently has detrimental impacts on the prey of the smaller predators. Thus according to the MRH, the existence of larger predators may provide prey with refuge from predation. In this study, we investigated how the abundance of an endangered rodent Notomys fuscus is affected by Australia's largest predator, the dingo Canis lupus dingo, introduced mesopredators, introduced herbivores, kangaroos and rainfall. Our surveys showed that N. fuscus was more abundant where dingoes occurred. Generalised linear modelling showed that N. fuscus abundance was associated positively with dingo activity and long-term annual rainfall and negatively with red fox Vulpes vulpes activity. Our results were consistent with the hypothesis that areas with higher rainfall and dingoes provide N. fuscus with refuge from drought and predation by invasive red foxes, respectively. Top-order predators, such as dingoes, could have an important functional role in broad-scale biodiversity conservation programmes by reducing the impacts of mesopredators.

Alien predators can have catastrophic effects on ecosystems and are thought to be much more harmful to biodiversity than their native counterparts. However, trophic cascade theory and the mesopredator release hypothesis predict that the removal of top predators will result in the reorganization of trophic webs and loss of biodiversity. Using field data collected throughout arid Australia, we provide evidence that removal of an alien top-predator, the dingo, has cascading effects through lower trophic levels. Dingo removal was linked to increased activity of herbivores and an invasive mesopredator, the red fox ( Vulpes vulpes ), and to the loss of grass cover and native species of small mammals. Using species distribution data, we predict that reintroducing or maintaining dingo populations would produce a net benefit for the conservation of threatened native mammals across greater than 2.42 × 10 6 km 2 of Australia. Our study provides evidence that an alien top predator can assume a keystone role and be beneficial for biodiversity conservation, and also that mammalian carnivores more generally can generate strong trophic cascades in terrestrial ecosystems.

Managers of wildlife populations with a wide geographical range are understandably interested in the question of whether they can manage a broader population with a single conservation strategy (e.g. covering a set of adjacent management regions, referred to as 'catchments' in Australia) or whether separate strategies are required for individual catchments. We addressed this question using data from a statewide, community wildlife survey to quantify Koala (Phascolarctos cinereus) habitat relationships in the catchments of four adjacent Catchment Management Authorities or CMA (>10 000 km2) of New South Wales, Australia and then tested whether these habitat relationships were similar across catchments. Although the results were constrained by the coarse resolution of the community survey and environmental data, we were able to model broad-scale patterns of habitat use. Model explanatory power and cross-regional predictability was low, but consistent with Koala ecology. Two environmental variables emerged as having a strong relationship with Koala presence - mean elevation and percentage of fertile soils - the importance of which varied among catchments depending on land-use patterns. The results highlight the need for local wildlife management plans, not a single plan covering multiple catchments.

The koala (Phascolarctos cinereus) occupies a broad range of eastern and southern Australia, extending over tropical coastal, semiarid inland and temperate regions. In many areas koala populations are under threat, in particular from the direct and indirect effects of ongoing habitat destruction due to increased urbanisation and other anthropogenic processes. Climate change presents additional threats to the integrity of koala habitats because many species of food and non-food trees have narrow climate envelopes and are unable to adapt to altered temperatures and rainfall. Climate extremes also produce physiological stresses in koalas that may increase the likelihood of outbreaks of chlamydiosis and other diseases. Climate change–related increases in the relative content of toxic chemicals in leaves are further stresses to the koala after ingestion. In addition, populations that originated from a small number of founder individuals are at potential risk due to their relatively low genetic diversity. Strategies that maintain residual habitat fragments and promote the construction of new refugia are now being formulated. Modelling of the impact of habitat metrics on koala distribution is providing important information that can be used in the rehabilitation of koala refugia. In future these models could be augmented with metrics that describe koala homeostasis to inform local conservation strategies. These considerations are also relevant for the maintenance of other taxa in the wider ecosystem that are also at risk from habitat destruction and climate change.

The roles that top predators play in regulating the structure and function of ecosystems have long been controversial. This is particularly the case when predators pose adverse risks for human life and/or economic interests. The critique of literature on dingoes and their ecological roles in Australia provided by Allen et al. (2011) shows that top predators remain a potentially polarising issue. In opposition to Allen et al. we argue that these widespread patterns of species’ abundances, attributed to the effects of dingoes and evident at scales ranging from the foraging behaviour of individuals through to continental scale patterns of species abundances, constitute strong support for the mesopredator release hypothesis and provide evidence that dingoes benefit biodiversity conservation by inducing community wide trophic cascades. Harnessing the positive ecological effects of dingoes while at the same time minimising their impacts on agriculture is a major socio-political challenge in Australia [Current Zoology 57 (5): 668–670]. A response to Benjamin L. ALLEN et al. 2011 [Current Zoology, 57 (5): 568–583]

Invasive predators can impose strong selection pressure on species that evolved in their absence and drive species to extinction. Interactions between coexisting predators may be particularly strong, as larger predators frequently kill smaller predators and suppress their abundances. Until 3500 years ago the marsupial thylacine was Australia's largest predator. It became extinct from the mainland soon after the arrival of a morphologically convergent placental predator, the dingo, but persisted in the absence of dingoes on the island of Tasmania until the 20th century. As Tasmanian thylacines were larger than dingoes, it has been argued that dingoes were unlikely to have caused the extinction of mainland thylacines because larger predators are rarely killed by smaller predators. By comparing Holocene specimens from the same regions of mainland Australia, we show that dingoes were similarly sized to male thylacines but considerably larger than female thylacines. Female thylacines would have been vulnerable to killing by dingoes. Such killing could have depressed the reproductive output of thylacine populations. Our results support the hypothesis that direct killing by larger dingoes drove thylacines to extinction on mainland Australia. However, attributing the extinction of the thylacine to just one cause is problematic because the arrival of dingoes coincided with another the potential extinction driver, the intensification of the human economy.

Agricultural practices, including habitat alteration and application of agricultural chemicals, can impact wildlife resulting in their decline. Determining which of these practices are contributing to declines is essential if the declines are to be reversed. In this study, the health of two geographically separated sleepy lizard (Tiliqua rugosa) populations was compared between a rangeland environment and cropping environment using linear body size index (LBSI) and haematology. Animals in the cropping site were smaller, suggesting genetic differences as the result of geographical isolation. The animals in the cropping site had a lower LBSI and many were experiencing a regenerative anaemia. The anaemia was postulated to be the cause of the low LBSI. The anaemia appeared to be the result of haemolysis and was likely to be caused by exposure to agricultural chemicals applied in the cropping site but not the rangeland site. Elevated white blood cell counts in lizards in the rangeland site suggested that they were experiencing an inflammatory disease of possible ecological significance. Together, these results demonstrate the value of combining physical and haematological parameters when studying the impact of agricultural practices on wildlife. They also show that reptiles may be useful as sentinel species for livestock and humans.

Disruption to species-interaction networks caused by irruptions of herbivores and mesopredators following extirpation of apex predators is a global driver of ecosystem reorganization and biodiversity loss. Most studies of apex predators' ecological roles focus on effects arising from their interactions with herbivores or mesopredators in isolation, but rarely consider how the effects of herbivores and mesopredators interact. Here, we provide evidence that multiple cascade pathways induced by lethal control of an apex predator, the dingo, drive unintended shifts in forest ecosystem structure. We compared mammal assemblages and understorey structure at seven sites in southern Australia. Each site comprised an area where dingoes were poisoned and an area without control. The effects of dingo control on mammals scaled with body size. Activity of herbivorous macropods, arboreal mammals and a mesopredator, the red fox, were greater, but understorey vegetation sparser and abundances of small mammals lower, where dingoes were controlled. Structural equation modelling suggested that both predation by foxes and depletion of understorey vegetation by macropods were related to small mammal decline at poisoned sites. Our study suggests that apex predators’ suppressive effects on herbivores and mesopredators occur simultaneously and should be considered in tandem in order to appreciate the extent of apex predators’ indirect effects.

Global Positioning System (GPS) wildlife telemetry collars are being used increasingly to understand the movement patterns of wild mammals. However, there are few published studies on which to gauge their general utility and success. This paper highlights issues faced by some of the first researchers to use GPS technology for terrestrial mammal tracking in Australia. Our collated data cover 24 studies where GPS collars were used in 280 deployments on 13 species, including dingoes or other wild dogs (Canis lupus dingo and hybrids), cats (Felis catus), foxes (Vulpes vulpes), kangaroos (Macropus giganteus), koalas (Phascolarctos cinereus), livestock guardian dogs (C. l. familiaris), pademelons (Thylogale billardierii), possums (Trichosurus cunninghami), quolls (Dasyurus geoffroii and D. maculatus), wallabies (Macropus rufogriseus and Petrogale lateralis), and wombats (Vombatus ursinus). Common problems encountered were associated with collar design, the GPS, VHF and timed-release components, and unforseen costs in retrieving and refurbishing collars. We discuss the implications of collar failures for research programs and animal welfare, and suggest how these could be avoided or improved. Our intention is to provide constructive advice so that researchers and manufacturers can make informed decisions about using this technology, and maximise the many benefits of GPS while reducing the risks.

In Australia, the genetic integrity of dingoes (Canis lupus dingo) is threatened through hybridisation with feral dogs and consequently the identification of the modern ‘pure’ dingo is ambiguous. There are no accurate classification techniques for dingoes and dingo–dog hybrids in the wild. Genetics, skull morphology and visual assessment are methods currently used, but they often yield contrasting results. We tested skull morphological and visual assessment methods for classifying wild canids in south-eastern New South Wales and examined temporal and geographic trends in skull morphology. Published equations based on discriminant functions revealed varying percentages of dingoes, dogs and their hybrids over time, and did not yield similar results to visual assessment methods. Skull characteristics generally became larger over time but have recently stabilised. Changes in the morphology of the molars were consistent with the occurrence of hybridisation with dogs. Geographic variation was apparent and consistent with Bergmann’s Law, with skulls increasing in size with altitude. This study highlights the importance for improved classification methods of wild canids and the importance of considering geographical variation in morphological studies.

The present study demonstrates one solution to a problem faced by managers of species of conservation concern – how to develop broad-scale maps of populations, within known general distribution limits, for the purpose of targeted management action. We aimed to map the current populations of the koala, Phascolarctos cinereus, in New South Wales, Australia. This cryptic animal is widespread, although patchily distributed. It principally occurs on private property, and it can be hard to detect. We combined a map-based mail survey of rural and outer-urban New South Wales with recent developments in estimating site occupancy and species-detection parameters to determine the current (2006) distribution of the koala throughout New South Wales. We were able to define the distribution of koalas in New South Wales at a level commensurate with previous community and field surveys. Comparison with a 1986 survey provided an indication of changes in relative koala density across the state. The 2006 distribution map allows for local and state plans, including the 2008 New South Wales Koala Recovery Plan, to be more effectively implemented. The application of this combined technique can now be extended to a suite of other iconic species or species that are easily recognised by the public.

There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats. Allen et al. (2013) claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning. We show that this claim is not supported by the data and analysis reported in Allen et al.'s paper. © 2014 Johnson et al.; licensee BioMed Central Ltd.