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Geary WL, Tulloch AIT, Ritchie EG, Doherty TS, Nimmo DG, Maxwell MA, Wayne AF. Identifying historical and future global change drivers that place species recovery at risk. GLOBAL CHANGE BIOLOGY 2023; 29:2953-2967. [PMID: 36864646 DOI: 10.1111/gcb.16661] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 11/28/2022] [Indexed: 05/03/2023]
Abstract
Ecosystem management in the face of global change requires understanding how co-occurring threats affect species and communities. Such an understanding allows for effective management strategies to be identified and implemented. An important component of this is differentiating between factors that are within (e.g. invasive predators) or outside (e.g. drought, large wildfires) of a local manager's control. In the global biodiversity hotspot of south-western Australia, small- and medium-sized mammal species are severely affected by anthropogenic threats and environmental disturbances, including invasive predators, fire, and declining rainfall. However, the relative importance of different drivers has not been quantified. We used data from a long-term monitoring program to fit Bayesian state-space models that estimated spatial and temporal changes in the relative abundance of four threatened mammal species: the woylie (Bettongia penicillata), chuditch (Dasyurus geoffroii), koomal (Trichosurus vulpecula) and quenda (Isoodon fusciventor). We then use Bayesian structural equation modelling to identify the direct and indirect drivers of population changes, and scenario analysis to forecast population responses to future environmental change. We found that habitat loss or conversion and reduced primary productivity (caused by rainfall declines) had greater effects on species' spatial and temporal population change than the range of fire and invasive predator (the red fox Vulpes vulpes) management actions observed in the study area. Scenario analysis revealed that a greater extent of severe fire and further rainfall declines predicted under climate change, operating in concert are likely to further reduce the abundance of these species, but may be mitigated partially by invasive predator control. Considering both historical and future drivers of population change is necessary to identify the factors that risk species recovery. Given that both anthropogenic pressures and environmental disturbances can undermine conservation efforts, managers must consider how the relative benefit of conservation actions will be shaped by ongoing global change.
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Affiliation(s)
- William L Geary
- School of Life and Environmental Sciences (Burwood Campus), Centre for Integrative Ecology, Deakin University, Geelong, Victoria, Australia
- Biodiversity Division, Department of Environment, Land, Water and Planning, East Melbourne, Victoria, Australia
| | - Ayesha I T Tulloch
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
- School of Biology and Environmental Science, Queensland University of Technology, Brisbane, Queensland, Australia
| | - Euan G Ritchie
- School of Life and Environmental Sciences (Burwood Campus), Centre for Integrative Ecology, Deakin University, Geelong, Victoria, Australia
| | - Tim S Doherty
- School of Life and Environmental Sciences, The University of Sydney, Sydney, New South Wales, Australia
| | - Dale G Nimmo
- Gulbali Institute, School of Agricultural, Environmental and Veterinary Sciences, Charles Sturt University, New South Wales, Albury, Australia
| | - Marika A Maxwell
- Department of Biodiversity, Conservation and Attractions, Manjimup, Western Australia, Australia
| | - Adrian F Wayne
- Department of Biodiversity, Conservation and Attractions, Manjimup, Western Australia, Australia
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Palmer R, Anderson H, Richards B, Craig MD, Gibson L. Does aerial baiting for controlling feral cats in a heterogeneous landscape confer benefits to a threatened native meso-predator? PLoS One 2021; 16:e0251304. [PMID: 33961676 PMCID: PMC8104397 DOI: 10.1371/journal.pone.0251304] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 04/24/2021] [Indexed: 11/19/2022] Open
Abstract
Introduced mammalian predators can have devastating impacts on recipient ecosystems and disrupt native predator–prey relationships. Feral cats (Felis catus) have been implicated in the decline and extinction of many Australian native species and developing effective and affordable methods to control them is a national priority. While there has been considerable progress in the lethal control of feral cats, effective management at landscape scales has proved challenging. Justification of the allocation of resources to feral cat control programs requires demonstration of the conservation benefit baiting provides to native species susceptible to cat predation. Here, we examined the effectiveness of a landscape-scale Eradicat® baiting program to protect threatened northern quolls (Dasyurus hallucatus) from feral cat predation in a heterogeneous rocky landscape in the Pilbara region of Western Australia. We used camera traps and GPS collars fitted to feral cats to monitor changes in activity patterns of feral cats and northern quolls at a baited treatment site and unbaited reference site over four years. Feral cat populations appeared to be naturally sparse in our study area, and camera trap monitoring showed no significant effect of baiting on cat detections. However, mortality rates of collared feral cats ranged from 18–33% after baiting, indicating that the program was reducing cat numbers. Our study demonstrated that feral cat baiting had a positive effect on northern quoll populations, with evidence of range expansion at the treatment site. We suggest that the rugged rocky habitat preferred by northern quolls in the Pilbara buffered them to some extent from feral cat predation, and baiting was sufficient to demonstrate a positive effect in this relatively short-term project. A more strategic approach to feral cat management is likely to be required in the longer-term to maximise the efficacy of control programs and thereby improve the conservation outlook for susceptible threatened fauna.
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Affiliation(s)
- Russell Palmer
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
| | - Hannah Anderson
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
| | - Brooke Richards
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
| | - Michael D. Craig
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
- School of Biological Sciences, University of Western Australia, Western Australia, Australia
- Environmental and Conservation Sciences, Murdoch University, Western Australia, Australia
| | - Lesley Gibson
- Biodiversity and Conservation Science, Department of Biodiversity, Conservation and Attractions, Western Australia, Australia
- School of Biological Sciences, University of Western Australia, Western Australia, Australia
- * E-mail:
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Wilson BA, Garkaklis MJ. Patterns of decline of small mammal assemblages in vegetation communities of coastal south-east Australia: identification of habitat refuges. AUSTRALIAN MAMMALOGY 2021. [DOI: 10.1071/am20032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Since European settlement Australian native mammals have experienced significant extinctions and severe declines in the range and abundance of populations. Longitudinal studies are required to identify declines and activate timely management. Population studies of native small mammal communities were conducted across the eastern Otway Ranges during 1975–2007; however, their subsequent status was unknown. We aimed to: compare the current occurrence and abundance of species and communities (2013–18) to those in previous decades across major vegetation communities (heathy woodland, low forest, sand heathland, headland scrub, coastal dunes and estuarine wetland), and identify change characteristics and management priorities. Live trapping was employed to assess mammals at 30 sites across seven vegetation communities. In total, 67% of sites exhibited large to severe decreases in abundance and only 3% of sites had more than four species compared to 27% in earlier decades. Declines occurred following wildfire and drought, with drivers likely to be multifactorial. While regional declines were significant, higher mammal abundance (two- to six-fold) and native species richness were recorded at coastal dune sites, indicating that this community provides important mammal refuges. Identification of refuges across the landscape and their protection from inappropriate fire and predators should be management priorities.
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Duncan RP, Dexter N, Wayne A, Hone J. Eruptive dynamics are common in managed mammal populations. Ecology 2020; 101:e03175. [DOI: 10.1002/ecy.3175] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 06/18/2020] [Accepted: 06/29/2020] [Indexed: 11/06/2022]
Affiliation(s)
- Richard P. Duncan
- Institute for Applied Ecology University of Canberra Canberra Australian Capital Territory2601Australia
| | - Nick Dexter
- Booderee National ParkParks Australia Village Road Jervis Bay Jervis Bay Territory2540Australia
| | - Adrian Wayne
- Department of Biodiversity, Conservation and Attractions Locked Bag 2 Manjimup Western Australia6258Australia
| | - Jim Hone
- Institute for Applied Ecology University of Canberra Canberra Australian Capital Territory2601Australia
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Hradsky BA. Conserving Australia’s threatened native mammals in predator-invaded, fire-prone landscapes. WILDLIFE RESEARCH 2020. [DOI: 10.1071/wr19027] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
Inappropriate fire regimes and predation by introduced species each pose a major threat to Australia’s native mammals. They also potentially interact, an issue that is likely to be contributing to the ongoing collapse of native mammal communities across Australia. In the present review, I first describe the mechanisms through which fire could create predation pinch points, exacerbating the impacts of predators, including red foxes, Vulpes vulpes, and feral cats, Felis catus, on their native mammalian prey. These mechanisms include a localised increase in predator activity (a numerically mediated pathway) and higher predator hunting success after fire (a functionally moderated pathway), which could both increase native mammal mortality and limit population recovery in fire-affected landscapes. Evidence for such interactions is growing, although largely based on unreplicated experiments. Improving native mammal resilience to fire in predator-invaded landscapes requires addressing two key questions: how can the impacts of introduced predators on native mammals in fire-affected areas be reduced; and, does a reduction in predation by introduced species result in higher native mammal survival and population recovery after fire? I then examine potential management options for reducing predator impacts post-fire. The most feasible are landscape-scale predator control and the manipulation of fire regimes to create patchy fire scars. However, robust field experiments with adequate statistical power are required to assess the effectiveness of these approaches and preclude null (e.g. compensatory mortality) or adverse (e.g. mesopredator or competitor release) outcomes. Ongoing predator management and prescribed burning programs provide an opportunity to learn through replicated natural experiments as well as experimental manipulations. Standardised reporting protocols and cross-jurisdiction monitoring programs would help achieve necessary spatial and environmental replication, while multi-trophic, spatially explicit simulation models could help synthesise findings from disparate study designs, predict management outcomes and generate new hypotheses. Such approaches will be key to improving management of the complex mechanisms that drive threatened native mammal populations in Australia’s predator-invaded, fire-prone landscapes.
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Comer S, Clausen L, Cowen S, Pinder J, Thomas A, Burbidge AH, Tiller C, Algar D, Speldewinde P. Integrating feral cat (Felis catus) control into landscape-scale introduced predator management to improve conservation prospects for threatened fauna: a case study from the south coast of Western Australia. WILDLIFE RESEARCH 2020. [DOI: 10.1071/wr19217] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Abstract
ContextFeral cat predation has had a significant impact on native Australian fauna in the past 200 years. In the early 2000s, population monitoring of the western ground parrot showed a dramatic decline from the pre-2000 range, with one of three meta-populations declining to very low levels and a second becoming locally extinct. We review 8 years of integrated introduced predator control, which trialled the incorporation of the feral cat bait Eradicat® into existing fox baiting programs.
AimsTo test the efficacy of integrating feral cat control into an existing introduced predator control program in an adaptive management framework conducted in response to the decline of native species. The objective was to protect the remaining western ground parrot populations and other threatened fauna on the south coast of Western Australia.
MethodsA landscape-scale feral cat and fox baiting program was delivered across south coast reserves that were occupied by western ground parrots in the early 2000s. Up to 500000ha of national parks and natures reserves were baited per annum. Monitoring was established to evaluate both the efficacy of landscape-scale baiting in management of feral cat populations, and the response of several native fauna species, including the western ground parrot, to an integrated introduced predator control program.
Key resultsOn average, 28% of radio-collared feral cats died from Eradicat® baiting each year, over a 5-year period. The results varied from 0% to 62% between years. Changes in site occupancy by feral cats, as measured by detection on camera traps, was also variable, with significant declines detected after baiting in some years and sites. Trends in populations of native fauna, including the western ground parrot and chuditch, showed positive responses to integrated control of foxes and cats.
ImplicationsLandscape-scale baiting of feral cats in ecosystems on the south coast of Western Australia had varying success when measured by direct knockdown of cats and site occupancy as determined by camera trapping; however, native species appeared to respond favourably to integrated predator control. For the protection of native species, we recommend ongoing baiting for both foxes and feral cats, complemented by post-bait trapping of feral cats. We advocate monitoring baiting efficacy in a well designed adaptive management framework to deliver long-term recovery of threatened species that have been impacted by cats.
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Mesocarnivores affect hispid cotton rat (Sigmodon hispidus) body mass. Sci Rep 2019; 9:14615. [PMID: 31602009 PMCID: PMC6787243 DOI: 10.1038/s41598-019-51168-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/25/2019] [Indexed: 11/24/2022] Open
Abstract
Predator communities are changing worldwide: large carnivores are declining while mesocarnivores (medium-sized mammalian predators) are increasing in number and ecological influence. Predator choice of prey is not random and different predators select prey with different characteristics. Changes in predator communities can change predation patterns experienced by prey. Little is known about how mesocarnivore communities influence prey morphology. We used 14 years of mark-recapture data to investigate how mesocarnivore exclusion affected body mass of hispid cotton rats (Sigmodon hispidus). Finding adult male cotton rats were 9% heavier with mesocarnivore exclusion, we developed hypotheses to explain this observation. Greater adult male body mass in exclosures resulted from: (1) a non-significant trend of increased survival of large males, (2) faster juvenile male growth during the fall and a similar non-significant trend among adult males, and (3) spatial partitioning by size among males. Taxa-specific predation rates (i.e., rates of predation by snakes, raptors, or mesocarnivores) did not differ among male body mass classes. Mesocarnivores disproportionately preyed on large females while raptors targeted small females, but female body mass was not influenced by mesocarnivore exclusion. Changes in predator communities can result in multiple small effects that collectively result in large differences in prey morphology.
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Scheele BC, Legge S, Armstrong DP, Copley P, Robinson N, Southwell D, Westgate MJ, Lindenmayer DB. How to improve threatened species management: An Australian perspective. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2018; 223:668-675. [PMID: 29975894 DOI: 10.1016/j.jenvman.2018.06.084] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Revised: 05/25/2018] [Accepted: 06/26/2018] [Indexed: 06/08/2023]
Abstract
Targeted threatened species management is a central component of efforts to prevent species extinction. Despite the development of a range of management frameworks to improve conservation outcomes over the past decade, threatened species management is still commonly characterised as ad hoc. Although there are notable successes, many management programs are ineffective, with relatively few species experiencing improvements in their conservation status. We identify underlying factors that commonly lead to ineffective and inefficient management. Drawing attention to some of the key challenges, and suggesting ways forward, may lead to improved management effectiveness and better conservation outcomes. We highlight six key areas where improvements are needed: 1) stakeholder engagement and communication; 2) fostering strong leadership and the development of achievable long-term goals; 3) knowledge of target species' biology and threats, particularly focusing on filling knowledge gaps that impede management, while noting that in many cases there will be a need for conservation management to proceed initially despite knowledge gaps; 4) setting objectives with measurable outcomes; 5) strategic monitoring to evaluate management effectiveness; and 6) greater accountability for species declines and failure to recover species to ensure timely action and guard against complacency. We demonstrate the importance of these six key areas by providing examples of innovative approaches leading to successful species management. We also discuss overarching factors outside the realm of management influence that can help or impede conservation success. Clear recognition of factors that make species' management more straightforward - or more challenging - is important for setting realistic management objectives, outlining strategic action, and prioritising resources. We also highlight the need to more clearly demonstrate the benefit of current investment, and communicate that the risk of under-investment is species extinctions. Together, improvements in conservation practice, along with increased resource allocation and re-evaluation of the prioritisation of competing interests that threaten species, will help enhance conservation outcomes for threatened species.
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Affiliation(s)
- B C Scheele
- Fenner School of Environment and Society, The Australian National University, Canberra, Australia; National Environmental Science Programme, Threatened Species Recovery Hub, Australia.
| | - S Legge
- Fenner School of Environment and Society, The Australian National University, Canberra, Australia; National Environmental Science Programme, Threatened Species Recovery Hub, Australia
| | - D P Armstrong
- Wildlife Ecology Group, Massey University, Palmerston North, New Zealand
| | - P Copley
- Parks and Regions, Department of Environment, Water and Natural Resources, South Australia, Australia
| | - N Robinson
- Fenner School of Environment and Society, The Australian National University, Canberra, Australia; National Environmental Science Programme, Threatened Species Recovery Hub, Australia
| | - D Southwell
- National Environmental Science Programme, Threatened Species Recovery Hub, Australia; Quantitative and Applied Ecology Group, School of BioSciences, University of Melbourne, Victoria, Australia
| | - M J Westgate
- Fenner School of Environment and Society, The Australian National University, Canberra, Australia
| | - D B Lindenmayer
- Fenner School of Environment and Society, The Australian National University, Canberra, Australia; National Environmental Science Programme, Threatened Species Recovery Hub, Australia
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Hunter DO, Lagisz M, Leo V, Nakagawa S, Letnic M. Not all predators are equal: a continent‐scale analysis of the effects of predator control on Australian mammals. Mamm Rev 2018. [DOI: 10.1111/mam.12115] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Daniel O. Hunter
- Centre for Ecosystem Science University of New South Wales NSW 2052 Sydney Australia
| | - Malgorzata Lagisz
- Evolution & Ecology Research Centre and School of Biological Earth and Environmental Sciences, University of New South Wales NSW 2052 Sydney Australia
| | - Viyanna Leo
- Centre for Ecosystem Science University of New South Wales NSW 2052 Sydney Australia
| | - Shinichi Nakagawa
- Evolution & Ecology Research Centre and School of Biological Earth and Environmental Sciences, University of New South Wales NSW 2052 Sydney Australia
| | - Mike Letnic
- Centre for Ecosystem Science University of New South Wales NSW 2052 Sydney Australia
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Radford JQ, Woinarski JCZ, Legge S, Baseler M, Bentley J, Burbidge AA, Bode M, Copley P, Dexter N, Dickman CR, Gillespie G, Hill B, Johnson CN, Kanowski J, Latch P, Letnic M, Manning A, Menkhorst P, Mitchell N, Morris K, Moseby K, Page M, Ringma J. Degrees of population-level susceptibility of Australian terrestrial non-volant mammal species to predation by the introduced red fox (Vulpes vulpes) and feral cat (Felis catus). WILDLIFE RESEARCH 2018. [DOI: 10.1071/wr18008] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context
Over the last 230 years, the Australian terrestrial mammal fauna has suffered a very high rate of decline and extinction relative to other continents. Predation by the introduced red fox (Vulpes vulpes) and feral cat (Felis catus) is implicated in many of these extinctions, and in the ongoing decline of many extant species.
Aims
To assess the degree to which Australian terrestrial non-volant mammal species are susceptible at the population level to predation by the red fox and feral cat, and to allocate each species to a category of predator susceptibility.
Methods
We collated the available evidence and complemented this with expert opinion to categorise each Australian terrestrial non-volant mammal species (extinct and extant) into one of four classes of population-level susceptibility to introduced predators (i.e. ‘extreme’, ‘high’, ‘low’ or ‘not susceptible’). We then compared predator susceptibility with conservation status, body size and extent of arboreality; and assessed changes in the occurrence of species in different predator-susceptibility categories between 1788 and 2017.
Key results
Of 246 Australian terrestrial non-volant mammal species (including extinct species), we conclude that 37 species are (or were) extremely predator-susceptible; 52 species are highly predator-susceptible; 112 species are of low susceptibility; and 42 species are not susceptible to predators. Confidence in assigning species to predator-susceptibility categories was strongest for extant threatened mammal species and for extremely predator-susceptible species. Extinct and threatened mammal species are more likely to be predator-susceptible than Least Concern species; arboreal species are less predator-susceptible than ground-dwelling species; and medium-sized species (35 g–3.5kg) are more predator-susceptible than smaller or larger species.
Conclusions
The effective control of foxes and cats over large areas is likely to assist the population-level recovery of ~63 species – the number of extant species with extreme or high predator susceptibility – which represents ~29% of the extant Australian terrestrial non-volant mammal fauna.
Implications
Categorisation of predator susceptibility is an important tool for conservation management, because the persistence of species with extreme susceptibility will require intensive management (e.g. predator-proof exclosures or predator-free islands), whereas species of lower predator susceptibility can be managed through effective landscape-level suppression of introduced predators.
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