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Watchorn DJ, Doherty TS, Wilson BA, Garkaklis MJ, Driscoll DA. How do invasive predators and their native prey respond to prescribed fire? Ecol Evol 2024; 14:e11450. [PMID: 38783847 PMCID: PMC11112300 DOI: 10.1002/ece3.11450] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2023] [Revised: 04/30/2024] [Accepted: 05/07/2024] [Indexed: 05/25/2024] Open
Abstract
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.
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Affiliation(s)
- Darcy J. Watchorn
- School of Life and Environmental Sciences (Burwood Campus)Deakin UniversityGeelongVictoriaAustralia
| | - Tim S. Doherty
- School of Life and Environmental SciencesThe University of SydneySydneyNew South WalesAustralia
- Biodiversity and Conservation ScienceDepartment of Biodiversity, Conservation and AttractionsWoodvaleWestern AustraliaAustralia
| | - Barbara A. Wilson
- School of Life and Environmental Sciences (Burwood Campus)Deakin UniversityGeelongVictoriaAustralia
| | | | - Don A. Driscoll
- School of Life and Environmental Sciences (Burwood Campus)Deakin UniversityGeelongVictoriaAustralia
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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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Nishimoto M, Miyashita T, Yokomizo H, Matsuda H, Imazu T, Takahashi H, Hasegawa M, Fukasawa K. Spatial optimization of invasive species control informed by management practices. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02261. [PMID: 33219543 PMCID: PMC8047888 DOI: 10.1002/eap.2261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 07/28/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
Optimization of spatial resource allocation is crucial for the successful control of invasive species under a limited budget but requires labor-intensive surveys to estimate population parameters. In this study, we devised a novel framework for the spatially explicit optimization of capture effort allocation using state-space population models from past capture records. We applied it to a control program for invasive snapping turtles to determine effort allocation strategies that minimize the population density over the whole area. We found that spatially heterogeneous density dependence and capture pressure limit the abundance of snapping turtles. Optimal effort allocation effectively improved the control effect, but the degree of improvement varied substantially depending on the total effort. The degree of improvement by the spatial optimization of allocation effort was only 3.21% when the total effort was maintained at the 2016 level. However, when the total effort was increased by two, four, and eight times, spatial optimization resulted in improvements of 4.65%, 8.33%, and 20.35%, respectively. To achieve the management goal for snapping turtles in our study area, increasing the current total effort by more than four times was necessary, in addition to optimizing the spatial effort. The snapping turtle population is expected to reach the target density one year after the optimal management strategy is implemented, and this rapid response can be explained by high population growth rate coupled with density-dependent feedback regulation. Our results demonstrated that combining a state-space model with optimization makes it possible to adaptively improve the management of invasive species and decision-making. The method used in this study, based on removal records from an invasive management program, can be easily applied to monitoring data for wildlife and pest control management using traps in a variety of ecosystems.
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Affiliation(s)
- Makoto Nishimoto
- Graduate School of Agricultural and Life SciencesUniversity of Tokyo1‐1‐1 Yayoi, Bunkyo‐kuTokyo113‐8657Japan
| | - Tadashi Miyashita
- Graduate School of Agricultural and Life SciencesUniversity of Tokyo1‐1‐1 Yayoi, Bunkyo‐kuTokyo113‐8657Japan
| | - Hiroyuki Yokomizo
- National Institute for Environmental StudiesCenter for Health and Environmental Risk Research16‐2 OnogawaTsukubaIbaraki305‐8506Japan
| | - Hiroyuki Matsuda
- Faculty of Environment and Information SciencesYokohama National University79‐7 Tokiwadai, Hodogaya‐kuYokohama240‐8501Japan
| | - Takeshi Imazu
- Environmental and Community Affairs DepartmentNature Conservation DivisionChiba Biodiversity CenterChiba Prefectural Government 955‐2 Aoba‐cho, Chuo‐kuChiba CityChiba260‐8682Japan
| | - Hiroo Takahashi
- Japan Wildlife Research Center3‐3‐7 Kotobashi, Sumida‐kuTokyo130‐8606Japan
| | - Masami Hasegawa
- Faculty of ScienceToho University2‐2‐1 MiyamaFunabashiChiba274‐8510Japan
| | - Keita Fukasawa
- National Institute for Environmental StudiesCenter for Environmental Biology and Ecosystem Studies16‐2 OnogawaTsukubaIbaraki305‐8506Japan
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Batavia C, Nelson MP, Wallach AD. The moral residue of conservation. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2020; 34:1114-1121. [PMID: 31953967 DOI: 10.1111/cobi.13463] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Revised: 01/04/2020] [Accepted: 01/11/2020] [Indexed: 05/23/2023]
Abstract
Should conservationists use lethal management to control introduced wildlife populations? Should they kill individual animals to protect endangered species? Are trade-offs that prioritize some values at the expense of others morally appropriate? These sorts of ethical questions are common in conservation. In debating such questions, conservationists often seem to presume 1 of 2 possible answers: the act in question is right or it is wrong. But morality in conservation is considerably more complex than this simple binary suggests. A robust conservation ethic requires a vocabulary that gives voice to the uncertainty and unease that arise when what seems to be the best available course of action also seems to involve a measure of wrongdoing. The philosophical literature on moral residue and moral dilemmas supplies this vocabulary. Moral dilemmas arise when one must neglect certain moral requirements to fulfill others. Under such circumstances, even the best possible decision leaves a moral residue, which is experienced emotionally as some form of grief. Examples of conservation scenarios that leave a moral residue include management of introduced rabbits in Australia, trophy hunting in Africa, and forest management trade-offs in the Pacific Northwest. Moral residue is integral to the moral experience of conservationists today, and grief is an appropriate response to many decisions conservationists must make. Article impact statement: Defensible conservation decisions may neglect moral requirements, leaving a moral residue; conservationists should respond with grief.
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Affiliation(s)
- Chelsea Batavia
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR, 97331, U.S.A
| | - Michael Paul Nelson
- Department of Forest Ecosystems and Society, Oregon State University, 321 Richardson Hall, Corvallis, OR, 97331, U.S.A
| | - Arian D Wallach
- Centre for Compassionate Conservation, Faculty of Science, University of Technology Sydney, Ultimo, NSW, 2007, Australia
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Short-term pain before long-term gain? Suppression of invasive primary prey temporarily increases predation on native lizards. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02239-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Porteus TA, Reynolds JC, McAllister MK. Population dynamics of foxes during restricted-area culling in Britain: Advancing understanding through state-space modelling of culling records. PLoS One 2019; 14:e0225201. [PMID: 31743363 PMCID: PMC6863561 DOI: 10.1371/journal.pone.0225201] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 10/23/2019] [Indexed: 11/18/2022] Open
Abstract
Lethal control is widely employed to suppress the numbers of target wildlife species within restricted management areas. The success of such measures is expected to vary with local circumstances affecting rates of removal and replacement. There is a need both to evaluate success in individual cases and to understand variability and its causes. In Britain, red fox (Vulpes vulpes) populations are culled within the confines of shooting estates to benefit game and wildlife prey species. We developed a Bayesian state-space model for within-year fox population dynamics within such restricted areas and fitted it to data on culling effort and success obtained from gamekeepers on 22 shooting estates of 2 to 36 km2. We used informative priors for key population processes—immigration, cub recruitment and non-culling mortality–that could not be quantified in the field. Using simulated datasets we showed that the model reliably estimated fox density and demographic parameters, and we showed that conclusions drawn from real data were robust to alternative model assumptions. All estates achieved suppression of the fox population, with pre-breeding fox density on average 47% (range 20%–90%) of estimated carrying capacity. As expected, the number of foxes killed was a poor indicator of effectiveness. Estimated rates of immigration were variable among estates, but in most cases indicated rapid replacement of culled foxes so that intensive culling efforts were required to maintain low fox densities. Due to this short-term impact, control effort focussed on the spring and summer period may be essential to achieve management goals for prey species. During the critical March-July breeding period, mean fox densities on all estates were suppressed below carrying capacity, and some maintained consistently low fox densities throughout this period. A similar model will be useful in other situations to quantify the effectiveness of lethal control on restricted areas.
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Affiliation(s)
- Tom A Porteus
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Jonathan C Reynolds
- Game & Wildlife Conservation Trust, Fordingbridge, Hampshire, United Kingdom
| | - Murdoch K McAllister
- Institute for the Oceans and Fisheries, University of British Columbia, Vancouver, BC, Canada
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The short-term response of feral cats to rabbit population decline: Are alternative native prey more at risk? Biol Invasions 2019. [DOI: 10.1007/s10530-019-02131-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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