Ongoing unraveling of a continental fauna: decline and extinction of Australian mammals since European settlement

Feline Encounters Down Under: Investigating the Activity of Cats and Native Wildlife at Sydney's North Head

Cats (Felis catus) are widespread across Australia, including within natural and protected areas, and in many areas, cats, including owned domestic cats, are not restricted in where or when they can roam. In Australia, cats have contributed to the decline of many native species and continue to be a problem for governments. North Head, Manly, is home to an endangered population of Long-nosed Bandicoot (Perameles nasuta) and the only mainland breeding colony of Little Penguin (Eudyptula minor) in New South Wales (NSW). Camera traps were installed for a 5-week period across North Head to determine the spatial and temporal distribution of cat activity. As well as capturing instances of cats, the cameras detected native animals such as birds, possums, Long-nosed Bandicoots and other small mammals. An analysis of the camera images showed cats could be found within protected areas of the headland (where cats are prohibited) and along the boundary with the adjacent suburban area of Manly. Cats were mostly detected during the night. There were high occurrences of overlap between cats and Long-nosed Bandicoots (Dhat 0.82), possums (Dhat 0.88) and other small mammals (Dhat 0.67). These findings indicate that cats are active across the Manly headland at the same time as native animals, both within protected areas where cats are prohibited and in adjacent residential areas, and this could have implications for these populations.

Vicariant speciation resulting from biogeographic barriers in the Australian tropics: The case of the red-cheeked dunnart (Sminthopsis virginiae)

Global biodiversity loss continues unabated, and in Australia, the rate of recent mammal extinctions is among the worst in the world. Meanwhile, the diversity among and within many endemic mammal species remains undescribed. This information is crucial to delineate species boundaries and thus inform decision-making for conservation. Sminthopsis virginiae (the red-cheeked dunnart) is a small, dasyurid marsupial found in four disjunct populations around the northern coast of Australia and New Guinea. There are three currently recognized subspecies, each occupying a distinct geographic location. Sminthopsis v. virginiae occurs in Queensland, S. v. rufigenis is distributed across New Guinea and the Aru Islands, and S. v. nitela has populations in the Top End of the Northern Territory and the Kimberley region of Western Australia. Previous molecular work has suggested the current subspecies definitions are not aligned with DNA sequence data, though the sampling was limited. We undertook a comprehensive genetic and morphological review of S. virginiae to clarify relationships within the species. This included mitochondrial (CR, 12S, and cytb) and nuclear (omega-globin, IRBP, and bfib7) loci, and morphometric analysis of skulls and whole wet-preserved specimens held in museums. Maximum Likelihood and Bayesian phylogenetic analyses resolved samples into two distinct clades, demarcated by the Gulf of Carpentaria in Australia's north. Sminthopsis. v. nitela was consistently separated from S. v. virginiae and S. v. rufigenis, based on the overall body and skull size and craniodental features, while S. v. virginiae and S. v. rufigenis were more difficult to distinguish from each other. Thus, we redescribed S. virginiae, recognizing two species, S. nitela (raised from subspecies) and S. virginiae (now comprising the subspecies S. v. virginiae and S. v. rufigenis). This study highlights the importance of recognizing cryptic mammal fauna to help address the gap in our knowledge about diagnosing diversity during a time of conservation crisis.

Density of a cryptic Australian small mammal: The threatened Julia Creek dunnart (Sminthopsis douglasi)

Globally, hundreds of mammal species face the threat of extinction in the coming decades, and in many cases, their ecology remains poorly understood. Fundamental ecological knowledge is crucial for effective conservation management of these species, but it is particularly lacking for small, cryptic mammals. The Julia Creek dunnart (Sminthopsis douglasi), a threatened, cryptic carnivorous marsupial that occurs in scattered populations in the central west of Queensland, Australia, was once so poorly studied that it was believed extinct. Sporadic research since its rediscovery in the early 1990s has revealed that S. douglasi is distributed across land at risk from many threats. Fundamental knowledge of S. douglasi population density is urgently required to inform conservation management at key sites, yet the species has historically proven hard to detect. Indeed, the status of the largest known population of S. douglasi, in Bladensburg National Park, is unknown. Here, we conducted a population study on S. douglasi at two sites within Bladensburg National Park via live mark-recapture surveys during 2022 and 2023. From likelihood-based spatially explicit capture-recapture (SECR) modelling we provide the first estimates of density and population size for S. douglasi. Live trapping resulted in captures of 49 individual S. douglasi (with 83 captures total, including recaptures). We estimated S. douglasi to occur at a density of 0.38 individuals ha-1 (0.25-0.58) at one site and 0.16 individuals ha-1 (0.09-0.27) at another site, with an estimated mean population size in suitable habitat at Bladensburg National Park of 1211 individuals (776-1646). Our S. douglasi density estimates were similar to that reported for other threatened small mammals in Australia. We also found evidence of extreme S. douglasi population fluctuations over time at Bladensburg National Park, which is of concern for its future conservation. Our study has provided the first estimate of density for S. douglasi, a threatened dasyurid species from the Mitchell Grass Downs of central western Queensland, Australia. Our research provides crucial population data to assist the management of this poorly studied species. We demonstrate a method that can be applied to species with low detection probability to ultimately help address the mammal extinction crisis faced by Australia and the rest of the world.

New uses for ancient middens: bridging ecological and evolutionary perspectives

Rodent middens provide a fine-scale spatiotemporal record of plant and animal communities over the late Quaternary. In the Americas, middens have offered insight into biotic responses to past environmental changes and historical factors influencing the distribution and diversity of species. However, few studies have used middens to investigate genetic or ecosystem level responses. Integrating midden studies with neoecology and experimental evolution can help address these gaps and test mechanisms underlying eco-evolutionary patterns across biological and spatiotemporal scales. Fully realizing the potential of middens to answer cross-cutting ecological and evolutionary questions and inform conservation goals in the Anthropocene will require a collaborative research community to exploit existing midden archives and mount new campaigns to leverage midden records globally.

How do invasive predators and their native prey respond to prescribed fire?

Fire shapes animal communities by altering resource availability and species interactions, including between predators and prey. In Australia, there is particular concern that two highly damaging invasive predators, the feral cat (Felis catus) and European red fox (Vulpes vulpes), increase their activity in recently burnt areas and exert greater predation pressure on the native prey due to their increased exposure. We tested how prescribed fire occurrence and extent, along with fire history, vegetation, topography, and distance to anthropogenic features (towns and farms), affected the activity (detection frequency) of cats, foxes, and the native mammal community in south-eastern Australia. We used camera traps to quantify mammal activity before and after a prescribed burn and statistically tested how the fire interacted with these habitat variables to affect mammal activity. We found little evidence that the prescribed fire influenced the activity of cats and foxes and no evidence of an effect on kangaroo or small mammal (<800 g) activity. Medium-sized mammals (800-2000 g) were negatively associated with prescribed fire extent, suggesting that prescribed fire has a negative impact on these species in the short term. The lack of a clear activity increase from cats and foxes is likely a positive outcome from a fire management perspective. However, we highlight that their response is likely dependent upon factors like fire size, severity, and prey availability. Future experiments should incorporate GPS-trackers to record fine-scale movements of cats and foxes in temperate ecosystems immediately before and after prescribed fire to best inform management within protected areas.

Fear of the human 'super predator' in native marsupials and introduced deer in Australia

Recent experiments have demonstrated that carnivores and ungulates in Africa, Asia, Europe and North America fear the human 'super predator' far more than other predators. Australian mammals have been a focus of research on predator naiveté because it is suspected they show atypical antipredator responses. To experimentally test if mammals in Australia also most fear humans, we quantified the responses of four native marsupials (eastern grey kangaroo, Bennett's wallaby, Tasmanian pademelon, common brushtail possum) and introduced fallow deer to playbacks of predator (human, dog, Tasmanian devil, wolf) or non-predator control (sheep) vocalizations. Native marsupials most feared the human 'super predator', fleeing humans 2.4 times more often than the next most frightening predator (dogs), and being most, and significantly, vigilant to humans. These results demonstrate that native marsupials are not naïve to the peril humans pose, substantially expanding the taxonomic and geographic scope of the growing experimental evidence that wildlife worldwide generally perceive humans as the planet's most frightening predator. Introduced fallow deer fled humans, but not more than other predators, which we suggest may result from their being introduced. Our results point to both challenges concerning marsupial conservation and opportunities for exploiting fear of humans as a wildlife management tool.

Boom-bust population dynamics drive rapid genetic change

Increasing environmental threats and more extreme environmental perturbations place species at risk of population declines, with associated loss of genetic diversity and evolutionary potential. While theory shows that rapid population declines can cause loss of genetic diversity, populations in some environments, like Australia's arid zone, are repeatedly subject to major population fluctuations yet persist and appear able to maintain genetic diversity. Here, we use repeated population sampling over 13 y and genotype-by-sequencing of 1903 individuals to investigate the genetic consequences of repeated population fluctuations in two small mammals in the Australian arid zone. The sandy inland mouse (Pseudomys hermannsburgensis) experiences marked boom-bust population dynamics in response to the highly variable desert environment. We show that heterozygosity levels declined, and population differentiation (FST) increased, during bust periods when populations became small and isolated, but that heterozygosity was rapidly restored during episodic population booms. In contrast, the lesser hairy-footed dunnart (Sminthopsis youngsoni), a desert marsupial that maintains relatively stable population sizes, showed no linear declines in heterozygosity. These results reveal two contrasting ways in which genetic diversity is maintained in highly variable environments. In one species, diversity is conserved through the maintenance of stable population sizes across time. In the other species, diversity is conserved through rapid genetic mixing during population booms that restores heterozygosity lost during population busts.

Scavenging with invasive species

Carrion acts as a hotspot of animal activity within many ecosystems globally, attracting scavengers that rely on this food source. However, many scavengers are invasive species whose impacts on scavenging food webs and ecosystem processes linked to decomposition are poorly understood. Here, we use Australia as a case study to review the extent of scavenging by invasive species that have colonised the continent since European settlement, identify the factors that influence their use of carcasses, and highlight the lesser-known ecological effects of invasive scavengers. From 44 published studies we identified six invasive species from 48 vertebrates and four main groups of arthropods (beetles, flies, ants and wasps) that scavenge. Invasive red foxes (Vulpes vulpes), domestic dogs (Canis familiaris), feral pigs (Sus scrofa), black rats (Rattus rattus) and feral cats (Felis catus) were ranked as highly common vertebrate scavengers. Invasive European wasps (Vespula germanica) are also common scavengers where they occur. We found that the diversity of native vertebrate scavengers is lower when the proportion of invasive scavengers is higher. We highlight that the presence of large (apex) native vertebrate scavengers can decrease rates of scavenging by invasive species, but that invasive scavengers can monopolise carcass resources, outcompete native scavengers, predate other species around carcass resources and even facilitate invasion meltdowns that affect other species and ecological processes including altered decomposition rates and nutrient cycling. Such effects are likely to be widespread where invasive scavengers occur and suggest a need to determine whether excessive or readily available carcass loads are facilitating or exacerbating the impacts of invasive species on ecosystems globally.

The genetic signature left by the range expansion of red foxes in Australia is detectable after more than 80 years of population stability

Reconstructing biological invasions from historical sources can provide insights into how they occur but are difficult to do when invasions are poorly documented. Genetic signatures left by invaders can also offer insights into invasion routes, points of origin and general biology but often present conclusions that are contradictory to expectations. Here, we test the ability of continental-wide microsatellite genotype data from 29 loci and 3122 samples to reconstruct the well-documented invasion of red foxes Vulpes vulpes from the United Kingdom into Australia over 150 years ago, an invasion that has led to the extinction of many native species. Our analysis reveals several key signals of invasion evident in Australian foxes. They display lower levels of diversity than foxes sampled from the UK, exhibit clines in diversity from the point of introduction (south-east Australia) to the edge of their range, and show strong evidence of allele surfing in westerly and north-easterly directions. These characteristics are consistent with a single point of origin followed by rapid expansion in westerly and north-easterly directions as suggested by historical records. We also find little genetic structure in foxes across Australia with only the vast Nullarbor Plains and Great Victoria Desert region presenting a detectable barrier to their dispersal. As such, no mainland region within the current range of foxes can be considered genetically isolated and therefore appropriate for localised eradication efforts. Overall, our analyses demonstrate the ability of comprehensive population genetic studies to reconstruct invasion histories even after more than 80 years since colonisation was stabilised.

Genomic Analyses Capture the Human-Induced Demographic Collapse and Recovery in a Wide-Ranging Cervid

The glacial cycles of the Quaternary heavily impacted species through successions of population contractions and expansions. Similarly, populations have been intensely shaped by human pressures such as unregulated hunting and land use changes. White-tailed and mule deer survived in different refugia through the Last Glacial Maximum, and their populations were severely reduced after the European colonization. Here, we analyzed 73 resequenced deer genomes from across their North American range to understand the consequences of climatic and anthropogenic pressures on deer demographic and adaptive history. We found strong signals of climate-induced vicariance and demographic decline; notably, multiple sequentially Markovian coalescent recovers a severe decline in mainland white-tailed deer effective population size (Ne) at the end of the Last Glacial Maximum. We found robust evidence for colonial overharvest in the form of a recent and dramatic drop in Ne in all analyzed populations. Historical census size and restocking data show a clear parallel to historical Ne estimates, and temporal Ne/Nc ratio shows patterns of conservation concern for mule deer. Signatures of selection highlight genes related to temperature, including a cold receptor previously highlighted in woolly mammoth. We also detected immune genes that we surmise reflect the changing land use patterns in North America. Our study provides a detailed picture of anthropogenic and climatic-induced decline in deer diversity and clues to understanding the conservation concerns of mule deer and the successful demographic recovery of white-tailed deer.

Spider webs capture environmental DNA from terrestrial vertebrates

Environmental DNA holds significant promise as a non-invasive tool for tracking terrestrial biodiversity. However, in non-homogenous terrestrial environments, the continual exploration of new substrates is crucial. Here we test the hypothesis that spider webs can act as passive biofilters, capturing eDNA from vertebrates present in the local environment. Using a metabarcoding approach, we detected vertebrate eDNA from all analyzed spider webs (N = 49). Spider webs obtained from an Australian woodland locality yielded vertebrate eDNA from 32 different species, including native mammals and birds. In contrast, webs from Perth Zoo, less than 50 km away, yielded eDNA from 61 different vertebrates and produced a highly distinct species composition, largely reflecting exotic species hosted in the zoo. We show that higher animal biomass and proximity to animal enclosures increased eDNA detection probability in the zoo. Our results indicate a tremendous potential for using spider webs as a cost-effective means to monitor terrestrial vertebrates.

Theory and classification of mass extinction causation

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide (i.e. meteor) impacts, large igneous province (LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers (e.g. solar flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle changes. In this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial during the Late Ordovician and Late Devonian events, carbon release associated with modern anthropogenic climate warming, and little to no carbon-cycle impact due to certain types of ecosystem change (e.g. the advent of the first predators around the end-Ediacaran; the appearance of Paleolithic human hunters in Australasia and the Americas). Broadly speaking, studies of mass extinction causation have suffered from insufficiently critical thinking-an impartial survey of the extant evidence shows that (i) hypotheses of a common ultimate cause (e.g. bolide impacts or LIP eruptions) for all Big Five mass extinctions are suspect given manifest differences in patterns of environmental and biotic change among them; (ii) the Late Ordovician and Late Devonian events were associated with carbon burial and long-term climatic cooling, i.e. changes that are inconsistent with a bolide-impact or LIP-eruption mechanism; and (iii) claims of periodicity in Phanerozoic mass extinctions depended critically on the now-disproven idea that they shared a common extrinsic trigger (i.e. bolide impacts).

Housework or vigilance? Bilbies alter their burrowing activity under threat of predation by feral cats

Behavioral adjustments to predation risk not only impose costs on prey species themselves but can also have cascading impacts on whole ecosystems. The greater bilby (Macrotis lagotis) is an important ecosystem engineer, modifying the physical environment through their digging activity, and supporting a diverse range of sympatric species that use its burrows for refuge and food resources. The bilby has experienced a severe decline over the last 200 years, and the species is now restricted to ~20% of its former distribution. Introduced predators, such as the feral cat (Felis catus), have contributed to this decline. We used camera traps to monitor bilby burrows at four sites in Western Australia, where bilbies were exposed to varying levels of cat predation threat. We investigated the impact of feral cats on bilby behavior at burrows, particularly during highly vulnerable periods when they dig and clear away soil or debris from the burrow entrance as they perform burrow maintenance. There was little evidence that bilbies avoided burrows that were visited by a feral cat; however, bilbies reduced the time spent performing burrow maintenance in the days following a cat visit (P = 0.010). We found the risk posed to bilbies varied over time, with twice the cat activity around full moon compared with dark nights. Given bilby burrows are an important resource in Australian ecosystems, predation by feral cats and the indirect impact of cats on bilby behavior may have substantial ecosystem function implications.

Environmental variables influence patterns of mammal co-occurrence following introduced predator control

Co-occurring species often overlap in their use of resources and can interact in complex ways. However, shifts in environmental conditions or resource availability can lead to changes in patterns of species co-occurrence, which may be exacerbated by global escalation of human disturbances to ecosystems, including conservation-directed interventions. We investigated the relative abundance and co-occurrence of two naturally sympatric mammal species following two forms of environmental disturbance: wildfire and introduced predator control. Using 14 years of abundance data from repeat surveys at long-term monitoring sites in south-eastern Australia, we examined the association between a marsupial, the common brushtail possum Trichosurus vulpecula, and a co-occurring native rodent, the bush rat Rattus fuscipes. We asked: In a fox-controlled environment, are the abundances of common brushtail possums and bush rats affected by environmental disturbance and each other's presence? Using Bayesian regression models, we tested hypotheses that the abundance of each species would vary with changes in environmental and disturbance variables, and that the negative association between bush rats and common brushtail possums was stronger than the association between bush rats and disturbance. Our analyses revealed that bush rat abundance varied greatly in relation to environmental and disturbance variables, whereas common brushtail possums showed relatively limited variation in response to the same variables. There was a negative association between common brushtail possums and bush rats, but this association was weaker than the initial decline and subsequent recovery of bush rats in response to wildfires. Using co-occurrence analysis, we can infer negative relationships in abundance between co-occurring species, but to understand the impacts of such associations, and plan appropriate conservation measures, we require more information on interactions between the species and environmental variables. Co-occurrence can be a powerful and novel method to diagnose threats to communities and understand changes in ecosystem dynamics.

Use of carrion fly iDNA metabarcoding to monitor invasive and native mammals

Severely fragmented habitats increase the risk of extirpation of native mammal populations through isolation, increased edge effects, and predation. Therefore, monitoring the movement of mammal populations through anthropogenically altered landscapes can inform conservation. We used metabarcoding of invertebrate-derived DNA (iDNA) from carrion flies (Calliphoridae and Sarcophagidae) to track mammal populations in the wheat belt of southwestern Australia, where widespread clearing for agriculture has removed most of the native perennial vegetation and replaced it with an agricultural system. We investigated whether the localization of the iDNA signal reflected the predicted distribution of 4 native species-echidna (Tachyglossus aculeatus), numbat (Myrmecobius fasciatus), woylie (Bettongia penicillata), and chuditch (Dasyurus geoffroii)-and 2 non-native, invasive mammal species-fox (Vulpes vulpes) and feral cat (Felis catus). We collected bulk iDNA samples (n = 150 samples from 3428 carrion flies) at 3 time points from 3 conservation reserves and 35 road edges between them. We detected 14 of the 40 mammal species known from the region, including our target species. Most detections of target taxa were in conservation reserves. There were a few detections from road edges. We detected foxes and feral cats throughout the study area, including all conservation reserves. There was a significant difference between the diversity (F3, 98  = 5.91, p < 0.001) and composition (F3, 43  = 1.72, p < 0.01) of taxa detections on road edges and conservation reserves. Conservation reserves hosted more native biodiversity than road edges. Our results suggest that the signals from iDNA reflect the known distribution of target mammals in this region. The development of iDNA methods shows promise for future noninvasive monitoring of mammals. With further development, iDNA metabarcoding could inform decision-making related to conservation of endangered taxa, invasive species management, and impacts of habitat fragmentation.

Mutilation of the tree of life via mass extinction of animal genera

Mass extinctions during the past 500 million y rapidly removed branches from the phylogenetic tree of life and required millions of years for evolution to generate functional replacements for the extinct (EX) organisms. Here we show, by examining 5,400 vertebrate genera (excluding fishes) comprising 34,600 species, that 73 genera became EX since 1500 AD. Beyond any doubt, the human-driven sixth mass extinction is more severe than previously assessed and is rapidly accelerating. The current generic extinction rates are 35 times higher than expected background rates prevailing in the last million years under the absence of human impacts. The genera lost in the last five centuries would have taken some 18,000 y to vanish in the absence of human beings. Current generic extinction rates will likely greatly accelerate in the next few decades due to drivers accompanying the growth and consumption of the human enterprise such as habitat destruction, illegal trade, and climate disruption. If all now-endangered genera were to vanish by 2,100, extinction rates would be 354 (average) or 511 (for mammals) times higher than background rates, meaning that genera lost in three centuries would have taken 106,000 and 153,000 y to become EX in the absence of humans. Such mutilation of the tree of life and the resulting loss of ecosystem services provided by biodiversity to humanity is a serious threat to the stability of civilization. Immediate political, economic, and social efforts of an unprecedented scale are essential if we are to prevent these extinctions and their societal impacts.

Genetic mixing in conservation translocations increases diversity of a keystone threatened species, Bettongia lesueur

Translocation programmes are increasingly being informed by genetic data to monitor and enhance conservation outcomes for both natural and established populations. These data provide a window into contemporary patterns of genetic diversity, structure and relatedness that can guide managers in how to best source animals for their translocation programmes. The inclusion of historical samples, where possible, strengthens monitoring by allowing assessment of changes in genetic diversity over time and by providing a benchmark for future improvements in diversity via management practices. Here, we used reduced representation sequencing (ddRADseq) data to report on the current genetic health of three remnant and seven translocated boodie (Bettongia lesueur) populations, now extinct on the Australian mainland. In addition, we used exon capture data from seven historical mainland specimens and a subset of contemporary samples to compare pre-decline and current diversity. Both data sets showed the significant impact of population founder source (whether multiple or single) on the genetic diversity of translocated populations. Populations founded by animals from multiple sources showed significantly higher genetic diversity than the natural remnant and single-source translocation populations, and we show that by mixing the most divergent populations, exon capture heterozygosity was restored to levels close to that observed in pre-decline mainland samples. Relatedness estimates were surprisingly low across all contemporary populations and there was limited evidence of inbreeding. Our results show that a strategy of genetic mixing has led to successful conservation outcomes for the species in terms of increasing genetic diversity and provides strong rationale for mixing as a management strategy.

Abundance and population growth estimates for bare-nosed wombats

Wildlife managers often rely on population estimates, but estimates can be challenging to obtain for geographically widespread species. Spotlight surveys provide abundance data for many species and, when conducted over wide spatial scales, have potential to provide population estimates of geographically widespread species. The bare-nosed wombat (Vombatus ursinus) has a broad geographical range and is subject to spotlight surveys. We used 19 years (2002-2020) of annual spotlight surveys to provide the first estimates of population abundance for two of the three extant bare-nosed wombat subspecies: V. u. ursinus on Flinders Island; and V. u. tasmaniensis on the Tasmanian mainland. Using distance sampling methods, we estimated annual rates of change and 2020 population sizes for both subspecies. Tasmanian mainland surveys included habitat data, which allowed us to also look for evidence of habitat associations for V. u. tasmaniensis. The average wombat density estimate was higher on Flinders Island (0.42 ha-1, 95% CI = 0.25-0.79) than on the Tasmanian mainland (0.11 ha-1, CI = 0.07-0.19) and both wombat subspecies increased over the 19-year survey period with an estimated annual growth rate of 2.90% (CI = -1.7 to 7.3) on Flinders Island and 1.20% (CI = -1.1 to 2.9) on mainland Tasmania. Habitat associations for V. u. tasmaniensis were weak, possibly owing to survey design; however, we detected regional variation in density for this subspecies. We estimated the population size of V. u. ursinus to be 71,826 (CI = 43,913-136,761) on Flinders Island, which when combined with a previously published estimate of 2599 (CI = 2254-2858) from Maria Island, where the subspecies was introduced, provides a total population estimate. We also estimated 840,665 (CI = 531,104-1,201,547) V. u. tasmaniensis on mainland Tasmania. These estimates may be conservative, owing to individual heterogeneity in when wombats emerge from burrows. Although these two subspecies are not currently threatened, our population estimates provide an important reference when assessing their population status in the future, and demonstrate how spotlight surveys can be valuable to inform management of geographically widespread species.

Hiding in plain sight: two new species of diminutive marsupial (Dasyuridae: Planigale) from the Pilbara, Australia

Many of Australias smaller marsupial species have been taxonomically described in just the past 50 years, and the Dasyuridae, a speciose family of carnivores, is known to harbour many cryptic taxa. Evidence from molecular studies is being increasingly utilised to help revise species boundaries and focus taxonomic efforts, and research over the past two decades has identified several undescribed genetic lineages within the dasyurid genus Planigale. Here, we describe two new species, Planigale kendricki sp. nov. (formerly known as Planigale 1) and P. tealei sp. nov. (formerly known as Planigale sp. Mt Tom Price). The two new species have broadly overlapping distributions in the Pilbara region of Western Australia. The new species are genetically distinct from each other and from all other members of the genus, at both mitochondrial and nuclear loci, and morphologically, in both external and craniodental characters. The new species are found in regional sympatry within the Pilbara but occupy different habitat types at local scales. This work makes a start at resolving the cryptic diversity within Planigale at a time when small mammals are continuing to decline throughout Australia.

Loss of terrestrial biodiversity in Australia: Magnitude, causation, and response

Australia's biota is species rich, with high rates of endemism. This natural legacy has rapidly diminished since European colonization. The impacts of invasive species, habitat loss, altered fire regimes, and changed water flows are now compounded by climate change, particularly through extreme drought, heat, wildfire, and flooding. Extinction rates, already far exceeding the global average for mammals, are predicted to escalate across all taxa, and ecosystems are collapsing. These losses are symptomatic of shortcomings in resourcing, law, policy, and management. Informed by examples of advances in conservation practice from invasive species control, Indigenous land management, and citizen science, we describe interventions needed to enhance future resilience. Many characteristics of Australian biodiversity loss are globally relevant, with recovery requiring society to reframe its relationship with the environment.

Further investigation of lead exposure as a potential threatening process for a scavenging marsupial species

There is a growing recognition of the harmful effects of lead exposure on avian and mammalian scavengers. This can lead to both lethal and non-lethal effects which may negatively impact wildlife populations. Our objective was to assess medium-term lead exposure in wild Tasmanian devils (Sarcophilus harrisii). Frozen liver samples (n = 41), opportunistically collected in 2017-2022, were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to determine liver lead concentrations. These results were then used to calculate the proportion of animals with elevated lead levels (>5 mg/kg dry weight) and examine the role of explanatory variables that may have influenced the results. The majority of samples analysed were from the south-east corner of Tasmania, within 50 km of Hobart. No Tasmanian devil samples were found to have elevated lead levels. The median liver lead concentration was 0.17 mg/kg (range 0.05-1.32 mg/kg). Female devils were found to have significantly higher liver lead concentrations than males (P = 0.013), which was likely related to lactation, but other variables (age, location, body mass) were not significant. These results suggest that wild Tasmanian devil populations currently show minimal medium-term evidence of exposure to lead pollution, although samples were concentrated in peri-urban areas. The results provide a baseline level which can be used to assess the impact of any future changes in lead use in Tasmania. Furthermore, these data can be used as a comparison for lead exposure studies in other mammalian scavengers, including other carnivorous marsupial species.

Diet of the Dingo in Subtropical Australian Forests: Are Small, Threatened Macropods at Risk?

Carnivores fulfil important ecological roles in natural systems yet can also jeopardise the persistence of threatened species. Understanding their diet is, therefore, essential for managing populations of carnivores, as well as those of their prey. This study was designed to better understand the diet of an Australian apex predator, the dingo, and determine whether it poses a threat to at-risk small macropods in two floristically different yet geographically close reserves in subtropical Australia. Based on an analysis of 512 scats, dingo diets comprised 34 different prey taxa, of which 50% were common between reserves. Our findings add support to the paradigm that dingoes are opportunistic and generalist predators that prey primarily on abundant mammalian fauna. Their diets in the Border Ranges were dominated by possum species (frequency of occurrence (FOC) = 92.5%), while their diets in Richmond Range were characterised by a high prevalence of pademelon species (FOC = 46.9%). Medium-sized mammals were the most important dietary items in both reserves and across all seasons. The dietary frequency of medium-sized mammals was generally related to their availability (indexed by camera trapping); however, the avoidance of some species with high availability indicates that prey accessibility may also be important in dictating their dietary choices. Other prey categories were supplementary to diets and varied in importance according to seasonal changes in their availability. The diets included two threatened macropods, the red-legged pademelon and black-striped wallaby. Our availability estimates, together with earlier dietary studies spanning 30 years, suggest that the red-legged pademelon is resilient to the observed predation. The black-striped wallaby occurred in only two dingo scats collected from Richmond Range and was not detected by cameras so the threat to this species could not be determined. Two locally abundant but highly threatened species (the koala and long-nosed potoroo) were not detected in the dingoes' diets, suggesting dingoes do not at present pose a threat to these populations. Our study highlights the importance of site-based assessments, population monitoring and including data on prey availability in dietary investigations.

Paleoenvironments shaped the exchange of terrestrial vertebrates across Wallace's Line

Faunal turnover in Indo-Australia across Wallace's Line is one of the most recognizable patterns in biogeography and has catalyzed debate about the role of evolutionary and geoclimatic history in biotic interchanges. Here, analysis of more than 20,000 vertebrate species with a model of geoclimate and biological diversification shows that broad precipitation tolerance and dispersal ability were key for exchange across the deep-time precipitation gradient spanning the region. Sundanian (Southeast Asian) lineages evolved in a climate similar to the humid "stepping stones" of Wallacea, facilitating colonization of the Sahulian (Australian) continental shelf. By contrast, Sahulian lineages predominantly evolved in drier conditions, hampering establishment in Sunda and shaping faunal distinctiveness. We demonstrate how the history of adaptation to past environmental conditions shapes asymmetrical colonization and global biogeographic structure.

Small mammals reduce activity during high moon illumination under risk of predation by introduced predators

Predation influences prey survival and drives evolution of anti-predator behaviour. Anti-predator strategies by prey are stimulated by direct encounters with predators, but also by exposure to indicators of risk such as moonlight illumination and vegetation cover. Many prey species will suffer increased risk on moonlit nights, but risk may be reduced by the presence of dense vegetation. Determining the role of vegetation in reducing perceived risk is important, especially given predictions of increased global wildfire, which consumes vegetation and increases predation. We used remote cameras in southeastern Australia to compare support for the predation risk and habitat-mediated predation risk hypotheses. We examined the influence of moonlight and understorey cover on seven 20-2500 g mammalian prey species and two introduced predators, red foxes and feral cats. Activity of all prey species reduced by 40-70% with increasing moonlight, while one species (bush rat) reduced activity in response to increasing moonlight more sharply in low compared to high understorey cover. Neither predator responded to moonlight. Our findings supported the predation risk hypothesis and provided limited support for the habitat-mediated predation risk hypothesis. For prey, perceived costs of increased predation risk on moonlit nights outweighed any benefits of a brighter foraging environment.

Understanding the Factors Influencing Cat Containment: Identifying Opportunities for Behaviour Change

There are over 5 million pet cats in Australia managed on a spectrum from fully indoors to completely outdoor free roaming. Roaming cats threaten biodiversity, can create a nuisance and are at risk of accidents and injury. Hence, there is substantial interest in behaviour change interventions to increase cat containment. An online questionnaire collected information on cat owner demographics, the number of cats owned, current containment behaviours and an agreement with 15 capability, opportunity and motivation (COM) items. Responses were received from 4482 cat owners. More than half (65%) indicated that they currently keep their cat(s) fully contained. Another 24% practiced a night curfew. Owners' psychological capability had the greatest influence on containment behaviour. Motivation (community- and cat welfare-framed), living in an apartment and renting were also associated with a greater likelihood of containment. Cat owners not currently containing their cats could be divided into six profiles who differed on agreement with COM themes, age, future intentions, current behaviour, location and gender. Understanding differences between cat owner segments can assist with designing behaviour change interventions. Increasing cat owners' psychological capability to contain their cats and encouraging the adoption of a night curfew as a first step towards 24 h containment are recommended.

Habitat loss for black flying foxes and implications for Hendra virus

Context

Environmental change impacts natural ecosystems and wildlife populations. In Australia, native forests have been heavily cleared and the local emergence of Hendra virus (HeV) has been linked to land-use change, winter habitat loss, and changing bat behavior.

Objectives

We quantified changes in landscape factors for black flying foxes (Pteropus alecto), a reservoir host of HeV, in sub-tropical Queensland, Australia from 2000-2020. We hypothesized that native winter habitat loss and native remnant forest loss were greatest in areas with the most human population growth.

Methods

We measured the spatiotemporal change in human population size and native 'remnant' woody vegetation extent. We assessed changes in the observed P. alecto population and native winter habitats in bioregions where P. alecto are observed roosting in winter. We assessed changes in the amount of remnant vegetation across bioregions and within 50 km foraging buffers around roosts.

Results

Human populations in these bioregions grew by 1.18 M people, mostly within 50 km foraging areas around roosts. Remnant forest extent decreased overall, but regrowth was observed when policy restricted vegetation clearing. Winter habitats were continuously lost across all spatial scales. Observed roost counts of P. alecto declined.

Conclusion

Native remnant forest loss and winter habitat loss were not directly linked to spatial human population growth. Rather, most remnant vegetation was cleared for indirect human use. We observed forest loss and regrowth in response to state land clearing policies. Expanded flying fox population surveys will help better understand how land-use change has impacted P. alecto distribution and Hendra virus spillover.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10980-023-01642-w.

Effects of different management strategies on long-term trends of Australian threatened and near-threatened mammals

Monitoring is critical to assess management effectiveness, but broadscale systematic assessments of monitoring to evaluate and improve recovery efforts are lacking. We compiled 1808 time series from 71 threatened and near-threatened terrestrial and volant mammal species and subspecies in Australia (48% of all threatened mammal taxa) to compare relative trends of populations subject to different management strategies. We adapted the Living Planet Index to develop the Threatened Species Index for Australian Mammals and track aggregate trends for all sampled threatened mammal populations and for small (<35 g), medium (35-5500 g), and large mammals (>5500 g) from 2000 to 2017. Unmanaged populations (42 taxa) declined by 63% on average; unmanaged small mammals exhibited the greatest declines (96%). Populations of 17 taxa in havens (islands and fenced areas that excluded or eliminated introduced red foxes [Vulpes vulpes] and domestic cats [Felis catus]) increased by 680%. Outside havens, populations undergoing sustained predator baiting initially declined by 75% but subsequently increased to 47% of their abundance in 2000. At sites where predators were not excluded or baited but other actions (e.g., fire management, introduced herbivore control) occurred, populations of small and medium mammals declined faster, but large mammals declined more slowly, than unmanaged populations. Only 13% of taxa had data for both unmanaged and managed populations; index comparisons for this subset showed that taxa with populations increasing inside havens declined outside havens but taxa with populations subject to predator baiting outside havens declined more slowly than populations with no management and then increased, whereas unmanaged populations continued to decline. More comprehensive and improved monitoring (particularly encompassing poorly represented management actions and taxonomic groups like bats and small mammals) is required to understand whether and where management has worked. Improved implementation of management for threats other than predation is critical to recover Australia's threatened mammals.

Identifying the most effective behavioural assays and predator cues for quantifying anti-predator responses in mammals: a systematic review

BACKGROUND

Mammals, globally, are facing population declines. Protecting and breeding threatened populations inside predator-free havens and translocating them back to the wild is commonly viewed as a solution. These approaches can expose predator-naïve animals to predators they have never encountered and as a result, many conservation projects have failed due to the predation of individuals that lacked appropriate anti-predator responses. Hence, robust ways to measure anti-predator responses are urgently needed to help identify naïve populations at risk, to select appropriate animals for translocation, and to monitor managed populations for changes in anti-predator traits. Here, we undertake a systematic review that collates existing behavioural assays of anti-predator responses and identifies assay types and predator cues that provoke the greatest behavioural responses.

METHODS

We retrieved articles from academic bibliographic databases and grey literature sources (such as government and conservation management reports), using a Boolean search string. Each article was screened against eligibility criteria determined using the PICO (Population-Intervention-Comparator-Outcome) framework. Using data extracted from each article, we mapped all known behavioural assays for quantifying anti-predator responses in mammals and examined the context in which each assay has been implemented (e.g., species tested, predator cue characteristics). Finally, with mixed effects modelling, we determined which of these assays and predator cue types elicit the greatest behavioural responses based on standardised difference in response between treatment and control groups.

REVIEW FINDINGS

We reviewed 5168 articles, 211 of which were eligible, constituting 1016 studies on 126 mammal species, a quarter of which are threatened by invasive species. We identified six major types of behavioural assays: behavioural focals, capture probability, feeding station, flight initiation distance, giving-up density, and stimulus presentations. Across studies, there were five primary behaviours measured: activity, escape, exploration, foraging, and vigilance. These behaviours yielded similar effect sizes across studies. With regard to study design, however, studies that used natural olfactory cues tended to report larger effect sizes than those that used artificial cues. Effect sizes were larger in studies that analysed sexes individually, rather than combining males and females. Studies that used 'blank' control treatments (the absence of a stimulus) rather than a treatment with a control stimulus had higher effect sizes. Although many studies involved repeat measures of known individuals, only 15.4% of these used their data to calculate measures of individual repeatability.

CONCLUSIONS

Our review highlights important aspects of experimental design and reporting that should be considered. Where possible, studies of anti-predator behaviour should use appropriate control treatments, analyse males and females separately, and choose organic predator cues. Studies should also look to report the individual repeatability of behavioural traits, and to correctly identify measures of uncertainty (error bars). The review highlights robust methodology, reveals promising techniques on which to focus future assay development, and collates relevant information for conservation managers.

Right-way fire in Australia's spinifex deserts: An approach for measuring management success when fire activity varies substantially through space and time

Indigenous Australians used fire in spinifex deserts for millennia. These practices mostly ceased following European colonisation, but many contemporary Indigenous groups seek to restore 'right-way fire' practices, to meet inter-related social, economic, cultural and biodiversity objectives. However, measuring and reporting on the fire pattern outcomes of management is challenging, because the spatio-temporal patterns of right-way fire are not clearly defined, and because spatio-temporal variability in rainfall makes fire occurrence highly variable in these desert environments. We present an approach for measuring and reporting on fire management outcomes to account for spatio-temporal rainfall variability. The purpose is to support Indigenous groups to assess performance against their management targets, and lay the groundwork for developing an accredited method for valuing combined social, cultural and biodiversity outcomes. We reviewed fire management plans of desert Indigenous groups to identify spatial fire pattern indicators for right-way fire in spinifex deserts. We integrated annual rainfall surfaces with time-since fire mapping (using Landsat imagery) to create a new spatial dataset of accumulated rainfall-since-last-fire, that better represents post-fire vegetation recovery as categorised by local Indigenous people. The fire pattern indicators were merged into a single score using an environmental accounting approach. To strengthen interpretation, we developed an approach for identifying a control area with matching vegetation and fire history, up to the point of management. We applied these methods to a 125,000 ha case study area: Durba Hills, managed by the Martu people of Western Australia. Using a 20-year time series, we show that since right-way fire management at Durba Hills was re-introduced (2009), the fire pattern indicators have improved compared to those in the matched control area, and the composite result is closer to the fine-scaled mosaic of right-way fire pattern targets. Our approach could be used by Indigenous groups to track performance, and inform annual fire management planning. As the indicators are standardised for rainfall variation, results from multiple sites can be aggregated to track changes in performance at larger scales. Finally, our approach could be adapted for other fire-prone areas, both in Australia and internationally with high spatio-temporal rainfall variability, to improve management planning and evaluation.

Seasonal Movement Patterns of Urban Domestic Cats Living on the Edge in an African City

Domestic cats (Felis catus) are amongst the most destructive invasive vertebrates globally, depredating billions of native animals annually. The size and seasonal variation of their geographical “footprint” is key to understanding their effects on wildlife, particularly if they live near conservation areas. Here we report the first GPS-tracking studies of free-roaming owned cats in the city of Cape Town, South Africa. A total of 23 cats was tracked (14 cats in summer, 9 in winter) using miniature (22 g) GPS locators in 2010–2011. In summer, all cats living on the urban-edge (UE: n = 7) made extensive use of protected areas, while only one of seven urban (U) cats (>150 m from the edge) did so. In winter two of four UE and two of five U cats entered protected areas. Home ranges (95% kernel density estimates) were significantly larger in summer (3.00 ± 1.23 ha) than winter (0.87 ± 0.25 ha) and cats ventured further from their homes in summer (maximum 849 m) than in winter (max 298 m). The predation risk posed by caracal (Caracal caracal) may limit the time cats spend in protected areas, but our results suggest that cat buffers around conservation areas should be at least ~600 m wide to reduce impacts to native fauna.

Pathways to coexistence with dingoes across Australian farming landscapes

Introduction

Agriculture and biodiversity conservation are both vitally important human activities that overlap geographically and are often in conflict. Animal agriculture has been implicated in species loss and the degradation of ecosystems due to land clearing, overgrazing, and conflicts with large carnivores such as dingoes (Canis dingo). This paper explores the potential for transformation in Australian commercial livestock production from human-dingo conflict towards social-ecological coexistence.

Method

A qualitative model that depicts transformative change was developed from field observations and twenty-one in-depth interviews with livestock producers, conservation researchers, grazing industry representatives and policy makers across Australia. The model articulates the current state of dingo management and the drivers of system change.

Results

Seven pathways are described to catalyse transformation from routine lethal management of dingoes towards a future vision that embeds mutually beneficial coexistence. Central to transformation is the adoption by livestock producers of preventive non-lethal innovations supported by a new farming movement, Predator Smart Farming, that balances livestock grazing and wildlife conservation values to unlock the resilience of landscapes, animals (domesticated and wild) and livelihoods. Other key pathways include targeted research, capacity building, outreach and knowledge sharing networks; institutional (policy, legislation, and economic incentives) and cultural change; public awareness raising and advocacy to reduce lethal control; and greater involvement of Indigenous Australians in decisions relating to wildlife management.

Discussion

The seven transition pathways are discussed in relation to how they can collectively foster coexistence with dingoes in extensive rangelands grazing systems. International examples of interventions are used to illustrate the types of successful actions associated with each pathway that could inform action in Australia. The findings have implications for coexistence with large carnivores in rangeland ecosystems globally.

pH-Responsive Polymer Implants for the Protection of Native Mammals: Assessment of Material Properties and Poison Incorporation on Performance

Efforts to mitigate the effects of feral cats through the management of remnant or reintroduced populations of threatened species, are often unsuccessful due to predation by control-averse feral cats, or 'problem individuals'. In order to target these animals, we have developed the Population Protecting Implant (PPI). PPIs are designed to be implanted subcutaneously in a native animal. If the animal is preyed upon, and the implant ingested by a feral cat, release of a toxic payload is triggered in the acidic stomach environment and the problem individual is eliminated. We introduce the first toxic implant incorporating the poison sodium fluoroacetate. Manufactured via fluidised-bed spray coating, toxic implants exhibited uniform reverse enteric coatings and low intra-batch variation. Toxic implants were found to exhibit favourable stability at subcutaneous pH in vitro, and rapidly release their toxic payload in vitro at gastric pH. However, limited stability was demonstrated in rats in vivo (~39-230 d), due to the use of a filament scaffold to enable coating and was likely exacerbated by metachromatic interactions caused by 1080. This work highlights that future development of the PPIs should primarily focus on removal of the filament scaffold, to afford implants with increased in vivo stability.

Changing plant functional diversity over the last 12,000 years provides perspectives for tracking future changes in vegetation communities

Plant communities are largely reshaped by climate and the environment over millennia, providing a powerful tool for understanding their response to future climates. Using a globally applicable functional palaeocological approach, we provide a deeper understanding of fossil pollen-inferred long-term response of vegetation to past climatic disturbances based on changes in functional trait composition. Specifically, we show how and why the ecological strategies exhibited by vegetation have changed through time by linking observations of plant traits to multiple pollen records from southeast Australia to reconstruct past functional diversity (FD, the value and the range of species traits that influence ecosystem functioning). The drivers of FD changes were assessed quantitatively by comparing FD reconstructions to independent records of past climates. During the last 12,000 years, peaks in FD were associated with both dry and wet climates in southeast Australia, with shifts in leaf traits particularly pronounced under wet conditions. Continentality determined the degree of stability maintained by high FD, with the greatest seen on the mainland. We expect projected frequent drier conditions in southeast Australia over coming decades to drive changes in vegetation community functioning and productivity mirroring the functional palaeocological record, particularly in western Tasmania and western southeast mainland.

Diel niche variation in mammalian declines in the Anthropocene

Biodiversity is being eroded worldwide. Many human pressures are most forcefully exerted or have greatest effect during a particular period of the day. Therefore when species are physically active (their diel niche) may influence their risk of population decline. We grouped 5032 terrestrial extant mammals by their dominant activity pattern (nocturnal, crepuscular, cathemeral and diurnal), and determine variation in population decline across diel niches. We find an increased risk of population decline in diurnal (52.1% of species), compared to nocturnal (40.1% of species), crepuscular (39.1% of species) and cathemeral (43.0% of species) species, associated with the larger proportion of diurnal mammals that are primates. Those species with declining populations whose activity predominantly coincides with that of humans (cathemeral, diurnal) face an increased number of anthropogenic threats than those principally active at night, with diurnal species more likely to be declining from harvesting. Across much of the land surface habitat loss is the predominant driver of population decline, however, harvesting is a greater threat to day-active species in sub-Saharan Africa and mainland tropical Asia, associated with declines in megafauna and arboreal foragers. Deepening understanding of diel variation in anthropogenic pressures and resulting population declines will help target conservation actions.

A mini-review on the impact of common gorse in its introduced ranges

It is indisputable that invasive plant species strongly impact the ecosystems they invade. Many of such impacts can be negative and threaten the local species through competition, environmental change, or habitat loss. However, introduced plants may also have positive roles in the ecosystems they invade. This review extracted information from reports on common gorse (Ulex europaeus), one of the top 100 invasive plants on the earth, including its detrimental effects and potential beneficial roles in invaded ecosystems. The reduction of native fauna and flora are the main harmful effects of common gorse identified by the literature review. Soil impoverishment and fire hazards are other negative impacts reported for common gorse that could affect agricultural systems and local economies. Despite the negative impacts, reports of positive ecological services provided by common gorse also exist, e.g., as a nursery plant or habitat for endangered native animals. We also reviewed the known human uses of this plant that could support management strategies through harvest and benefit the local communities, including its use as biofuel, raw matter for xylan extraction, medicine, and food. Finally, our review identified the gaps in the literature regarding the understanding of the beneficial role of common gorse on native ecosystems and potential human uses, especially in the tropics.

The spatial influences of organic farming and environmental heterogeneity on biodiversity in South Australian landscapes

The potential link between certified organic farming and biodiversity and conservation remains unexplored in Australia, despite the country having the world's largest amount of certified organic farmland and unprecedented biodiversity loss. This study modelled the spatial effects of organic farming (intensity of local farming systems), environmental heterogeneity, and urbanisation on two widely studied environmental taxa - vascular plant and bird species richness (surrogate measures of biodiversity) - in South Australia, using a unique certified organic farming postcode level dataset from 2001 to 2016 (N = 5440). The spatial Durbin error model results confirmed the positive spatial congruence of organic farming with greater vascular plant species richness, whereas only weak to no significant evidence was found for bird species richness. Landscape features (habitat heterogeneity) and green vegetation (a proxy indicator of resource availability) - rather than organic farming - appeared to be most associated with bird species richness. Both plant and bird species richness were positively associated with habitat heterogeneity (land cover diversity and elevation range), plant productivity and proportion of conservation land and water bodies. Whereas, increased anthropogenic land use for cropping and horticultural farming, soil type diversity and proximity to the coast significantly reduced species richness of both taxa. The results suggest that a multi-scale spatially refined biodiversity conservation strategy, with spatial targeting that promotes low intensive farming systems and increases landscape heterogeneity to provide quality habitat (a whole of landscape approach by incorporating private agricultural landholders), could be beneficial for biodiversity conservation.

Can native predators be used as a stepping stone to reduce prey naivety to novel predators?

Predator naivety negatively affects reintroduction success, and this threat is exacerbated when prey encounters predators with which they have had no evolutionary experience. While methods have been developed to inculcate fear into such predator-naïve individuals, none have been uniformly successful. Exposing ontogenetically- and evolutionary-naïve individuals first to native predators may be an effective stepping stone to improved responses to evolutionarily novel predators. We focused on greater bilbies (Macrotis lagotis) and capitalized on a multi-year mammalian recovery experiment whereby western quolls (Dasyurus geoffroii) were reintroduced into parts of a large fenced reserve that contained a population of naïve bilbies. We quantified a suite of anti-predator behaviors and measures of general wariness across quoll-exposed and quoll-naive bilby populations. We then translocated both quoll-exposed and quoll-naïve individuals into a large enclosure that contained feral cats (Felis catus) and monitored several behaviors. We found that bilbies can respond appropriately to quolls but found only limited support that experience with quolls better-prepared bilbies to respond to cats. Both populations of bilbies rapidly modified their behavior in a similar manner after their reintroduction to a novel environment. These results may have emerged due to insufficient prior exposure to quolls, inappropriate behavioral tests, or insufficient predation risk during cat exposure. Alternatively, quolls and cats are only distantly related and may not share sufficient similarities in their predatory cues or behavior to support such a learning transfer. Testing this stepping stone hypothesis with more closely related predator species and under higher predation risk would be informative.

Distinctive diets of eutherian predators in Australia

Introduction of the domestic cat and red fox has devastated Australian native fauna. We synthesized Australian diet analyses to identify traits of prey species in cat, fox and dingo diets, which prey were more frequent or distinctive to the diet of each predator, and quantified dietary overlap. Nearly half (45%) of all Australian terrestrial mammal, bird and reptile species occurred in the diets of one or more predators. Cat and dingo diets overlapped least (0.64 ± 0.27, n = 24 location/time points) and cat diet changed little over 55 years of study. Cats were more likely to have eaten birds, reptiles and small mammals than foxes or dingoes. Dingo diet remained constant over 53 years and constituted the largest mammal, bird and reptile prey species, including more macropods/potoroids, wombats, monotremes and bandicoots/bilbies than cats or foxes. Fox diet had greater overlap with both cats (0.79 ± 0.20, n = 37) and dingoes (0.73 ± 0.21, n = 42), fewer distinctive items (plant material, possums/gliders) and significant spatial and temporal heterogeneity over 69 years, suggesting the opportunity for prey switching (especially of mammal prey) to mitigate competition. Our study reinforced concerns about mesopredator impacts upon scarce/threatened species and the need to control foxes and cats for fauna conservation. However, extensive dietary overlap and opportunism, as well as low incidence of mesopredators in dingo diets, precluded resolution of the debate about possible dingo suppression of foxes and cats.

Measuring the Impact of Conservation: The Growing Importance of Monitoring Fauna, Flora and Funga

Many stakeholders, from governments to civil society to businesses, lack the data they need to make informed decisions on biodiversity, jeopardising efforts to conserve, restore and sustainably manage nature. Here we review the importance of enhancing biodiversity monitoring, assess the challenges involved and identify potential solutions. Capacity for biodiversity monitoring needs to be enhanced urgently, especially in poorer, high-biodiversity countries where data gaps are disproportionately high. Modern tools and technologies, including remote sensing, bioacoustics and environmental DNA, should be used at larger scales to fill taxonomic and geographic data gaps, especially in the tropics, in marine and freshwater biomes, and for plants, fungi and invertebrates. Stakeholders need to follow best monitoring practices, adopting appropriate indicators and using counterfactual approaches to measure and attribute outcomes and impacts. Data should be made openly and freely available. Companies need to invest in collecting the data required to enhance sustainability in their operations and supply chains. With governments soon to commit to the post-2020 global biodiversity framework, the time is right to make a concerted push on monitoring. However, action at scale is needed now if we are to enhance results-based management adequately to conserve the biodiversity and ecosystem services we all depend on.

Bioturbation by echidna (

Bioturbation by digging animals is important for key forest ecosystem processes such as soil turnover, decomposition, nutrient cycling, water infiltration, seedling recruitment, and fungal dispersal. Despite their widespread geographic range, little is known about the role of the short-beaked echidna (Tachyglossus aculeatus) in forest ecosystems. We measured the density and size of echidna diggings in the Northern Jarrah Forest, south-western Australia, to quantify the contribution echidna make to soil turnover. We recorded an overall density of 298 echidna diggings per hectare, 21% of which were estimated to be less than 1 month old. The average size of digs was 50 ± 25 mm in depth and 160 ± 61 mm in length. After taking into account seasonal digging rates, we estimated that echidnas turn over 1.23 tonnes of soil ha−1 year−1 in this forest, representing an important role in ecosystem dynamics. Our work contributes to the growing body of evidence quantifying the role of these digging animals as critical ecosystem engineers. Given that the echidna is the only Australian digging mammal not severely impacted by population decline or range reduction, its functional contribution to health and resilience of forest ecosystems is increasingly important due to the functional loss of most Australian digging mammals.

Using PVA and captive breeding to balance trade-offs in the rescue of the island dibbler onto a new island ark

In the face of the current global extinction crisis, it is critical we give conservation management strategies the best chance of success. Australia is not exempt from global trends with currently the world’s greatest mammal extinction rate (~ 1 per 8 years). Many more are threatened including the dibbler (Parantechinus apicalis) whose remnant range has been restricted to Western Australia at just one mainland site and two small offshore islands—Whitlock Island (5 ha) and Boullanger Island (35 ha). Here, we used 14 microsatellite markers to quantify genetic variation in the remaining island populations from 2013 to 2018 and incorporated these data into population viability analysis (PVA) models, used to assess factors important to dibbler survival and to provide guidance for translocations. Remnant population genetic diversity was low (< 0.3), and populations were highly divergent from each other (pairwise F_STs 0.29–0.52). Comparison of empirical data to an earlier study is consistent with recent declines in genetic diversity and models projected increasing extinction risk and declining genetic variation in the next century. Optimal translocation scenarios recommend 80 founders for new dibbler populations—provided by captive breeding—and determined the proportion of founders from parental populations to maximise genetic diversity and minimise harvesting impact. The goal of our approach is long-term survival of genetically diverse, self-sustaining populations and our methods are transferable. We consider mixing island with mainland dibblers to reinforce genetic variation.