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Hohnen R, James AI, Jennings P, Murphy BP, Berris K, Legge SM, Dickman CR, Woinarski JCZ. Abundance and detection of feral cats decreases after severe fire on Kangaroo Island, Australia. AUSTRAL ECOL 2023. [DOI: 10.1111/aec.13294] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Affiliation(s)
- Rosemary Hohnen
- National Environmental Science Program Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods Charles Darwin University Northwest Territories Casurina Australia
- NRM South Tasmania South Hobart Australia
| | - Alex I. James
- Kangaroo Island Landscape Board South Australia Kingscote Australia
| | - Paul Jennings
- Kangaroo Island Landscape Board South Australia Kingscote Australia
| | - Brett P. Murphy
- National Environmental Science Program Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods Charles Darwin University Northwest Territories Casurina Australia
| | - Karleah Berris
- Kangaroo Island Landscape Board South Australia Kingscote Australia
| | - Sarah M. Legge
- National Environmental Science Program Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods Charles Darwin University Northwest Territories Casurina Australia
- National Environmental Science Program Threatened Species Recovery Hub University of Queensland Queensland St. Lucia Australia
- National Environmental Science Program Threatened Species Recovery Hub, Fenner School of Society and Environment The Australian National University Australian Capital Territory Canberra Australia
| | - Chris R. Dickman
- National Environmental Science Program Threatened Species Recovery Hub, Desert Ecology Research Group, School of Life and Environmental Sciences The University of Sydney New South Wales Camperdown Australia
| | - John C. Z. Woinarski
- National Environmental Science Program Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods Charles Darwin University Northwest Territories Casurina Australia
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Bergstrom BJ, Scruggs SB, Vieira EM. Tropical savanna small mammals respond to loss of cover following disturbance: A global review of field studies. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1017361] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Small-mammal faunas of tropical savannas consist of endemic assemblages of murid rodents, small marsupials, and insectivores on four continents. Small mammals in tropical savannas are understudied compared to other tropical habitats and other taxonomic groups (e.g., Afrotropical megafauna or Neotropical rainforest mammals). Their importance as prey, ecosystem engineers, disease reservoirs, and declining members of endemic biodiversity in tropical savannas compels us to understand the factors that regulate their abundance and diversity. We reviewed field studies published in the last 35 years that examined, mostly experimentally, the effects of varying three primary endogenous disturbances in tropical savanna ecosystems—fire, large mammalian herbivory (LMH), and drought—on abundance and diversity of non-volant small mammals. These disturbances are most likely to affect habitat structure (cover or concealment), food availability, or both, for ground-dwelling small mammalian herbivores, omnivores, and insectivores. Of 63 studies (included in 55 published papers) meeting these criteria from the Afrotropics, Neotropics, and northern Australia (none was found from southern Asia), 29 studies concluded that small mammals responded (mostly negatively) to a loss of cover (mostly from LMH and fire); four found evidence of increased predation on small mammals in lower-cover treatments (e.g., grazed or burned). Eighteen studies concluded a combination of food- and cover-limitation explained small-mammal responses to endogenous disturbances. Only two studies concluded small-mammal declines in response to habitat-altering disturbance were caused by food limitation and not related to cover reduction. Evidence to date indicates that abundance and richness of small savanna mammals, in general (with important exceptions), is enhanced by vegetative cover (especially tall grass, but sometimes shrub cover) as refugia for these prey species amid a “landscape of fear,” particularly for diurnal, non-cursorial, and non-fossorial species. These species have been called “decreasers” in response to cover reduction, whereas a minority of small-mammal species have been shown to be “increasers” or disturbance-tolerant. Complex relationships between endogenous disturbances and small-mammal food resources are important secondary factors, but only six studies manipulated or measured food resources simultaneous to habitat manipulations. While more such studies are needed, designing effective ones for cryptic consumer communities of omnivorous dietary opportunists is a significant challenge.
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Hernandez‐Santin L, Goldizen AW, Fisher DO. Northern quolls in the Pilbara persist in high‐quality habitat, despite a decline trajectory consistent with range eclipse by feral cats. CONSERVATION SCIENCE AND PRACTICE 2022. [DOI: 10.1111/csp2.12733] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Affiliation(s)
- Lorna Hernandez‐Santin
- School of Biological Sciences University of Queensland St. Lucia Queensland Australia
- Centre for Mined Land Rehabilitation Sustainable Minerals Institute, University of Queensland St. Lucia Queensland Australia
| | - Anne W. Goldizen
- School of Biological Sciences University of Queensland St. Lucia Queensland Australia
| | - Diana O. Fisher
- School of Biological Sciences University of Queensland St. Lucia Queensland Australia
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Radford IJ, Corey B, Carnes K, Shedley E, McCaw L, Woolley LA. Landscape-Scale Effects of Fire, Cats, and Feral Livestock on Threatened Savanna Mammals: Unburnt Habitat Matters More Than Pyrodiversity. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.739817] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Northern Australia has undergone significant declines among threatened small and medium-sized mammals in recent decades. Conceptual models postulate that predation by feral cats is the primary driver, with changed disturbance regimes from fire and feral livestock in recent decades reducing habitat cover and exacerbating declines. However, there is little guidance on what scale habitat and disturbance attributes are most important for threatened mammals, and what elements and scale of fire mosaics actually support mammals. In this study, we test a series of hypotheses regarding the influence of site-scale (50 × 50 m) habitat and disturbance attributes, as well as local-scale (1 km radius), meta-local scale (3 km), landscape-scale (5 km) and meta-landscape scale (10 km) fire mosaic attributes on mammal abundance and richness. We found that habitat cover (rock, perennial grass, and shrub cover) at the site-scale had a positive effect, and disturbance factors (feral cats, fire, feral livestock) had a negative influence on mammal abundance and richness. Models supported site-scale habitat and disturbance factors as more important for mammals than broader-scale (local up to meta-landscape scale) fire mosaic attributes. Finally, we found that increasing the extent of ≥ 4 year unburnt habitat, and having an intermediate percentage (ca. 25%) of recently burnt (1-year burnt) habitat within the mosaic, were the most important functional elements of the fire mosaic at broad scales for mammals. Contrary to expectations, diversity of post-fire ages (‘pyrodiversity’) was negatively associated with mammal abundance and richness. These results highlight the need for management to promote retention of longer unburnt vegetation in sufficient patches across savanna landscapes (particularly of shrub and fruiting trees), maintain low-intensity patchy fire regimes, reduce the extent of intense late dry season wildfires, and to reduce the impact of feral livestock. This study provides further evidence for the role of feral cats in northern Australian mammal declines, and highlights the need for increased research into the efficacy of cat control methodologies in reducing biodiversity impacts in these extensive landscapes.
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Penton CE, Davies HF, Radford IJ, Woolley LA, Rangers TL, Murphy BP. A Hollow Argument: Understory Vegetation and Disturbance Determine Abundance of Hollow-Dependent Mammals in an Australian Tropical Savanna. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.739550] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Native mammals are suffering widespread and ongoing population declines across northern Australia. These declines are likely driven by multiple, interacting factors including altered fire regimes, predation by feral cats, and grazing by feral herbivores. In addition, the loss of tree hollows due to frequent, intense fires may also be contributing to the decline of hollow-dependent mammals. We currently have little understanding of how the availability of tree hollows influences populations of hollow-dependent mammals in northern Australian savannas. Here, we test the hypothesis that the abundance of hollow-dependent mammals is higher in areas with a greater availability of tree hollows. We used camera-trap data from 82 sites across the savannas of Melville Island, the largest island in monsoonal northern Australia. Royle–Nichols abundance-induced heterogeneity models were used to investigate the biophysical correlates of the abundance of three threatened mammals: northern brushtail possum (Trichosurus vulpecula arnhemensis), black-footed tree-rat (Mesembriomys gouldii), and brush-tailed rabbit-rat (Conilurus penicillatus). Our analyses included two variables that reflect the availability of tree hollows: the density of tree hollows, estimated from the ground, and the density of large eucalypt trees (Eucalyptus and Corymbia spp.). We found no evidence that the abundance of the three hollow-dependent mammals is positively associated with the availability of tree hollows on Melville Island. Despite their reliance on hollow-bearing trees for denning, the abundance of these mammals appears to be more strongly associated with other factors, such as the characteristics of the understory (i.e., shrub density), which affords protection from predators (including feral cats) and access to food resources. Future conservation management should aim to maintain a dense, diverse understory by managing fire and feral herbivores to facilitate the persistence of hollow-dependent mammals across northern Australia.
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von Takach B, Penton CE, Murphy BP, Radford IJ, Davies HF, Hill BM, Banks SC. Population genomics and conservation management of a declining tropical rodent. Heredity (Edinb) 2021; 126:763-775. [PMID: 33664461 PMCID: PMC8102610 DOI: 10.1038/s41437-021-00418-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Revised: 02/15/2021] [Accepted: 02/16/2021] [Indexed: 01/31/2023] Open
Abstract
Conservation management is improved by incorporating information about the spatial distribution of population genetic diversity into planning strategies. Northern Australia is the location of some of the world's most severe ongoing declines of endemic mammal species, yet we have little genetic information from this regional mammal assemblage to inform a genetic perspective on conservation assessment and planning. We used next-generation sequencing data from remnant populations of the threatened brush-tailed rabbit-rat (Conilurus penicillatus) to compare patterns of genomic diversity and differentiation across the landscape and investigate standardised hierarchical genomic diversity metrics to better understand brush-tailed rabbit-rat population genomic structure. We found strong population structuring, with high levels of differentiation between populations (FST = 0.21-0.78). Two distinct genomic lineages between the Tiwi Islands and mainland are also present. Prioritisation analysis showed that one population in both lineages would need to be conserved to retain at least ~80% of alleles for the species. Analysis of standardised genomic diversity metrics showed that approximately half of the total diversity occurs among lineages (δ = 0.091 from grand total γ = 0.184). We suggest that a focus on conserving remnant island populations may not be appropriate for the preservation of species-level genomic diversity and adaptive potential, as these populations represent a small component of the total diversity and a narrow subset of the environmental conditions in which the species occurs. We also highlight the importance of considering both genomic and ecological differentiation between source and receiving populations when considering translocations for conservation purposes.
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Affiliation(s)
- Brenton von Takach
- grid.1043.60000 0001 2157 559XResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia
| | - Cara E. Penton
- grid.1043.60000 0001 2157 559XResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia
| | - Brett P. Murphy
- grid.1043.60000 0001 2157 559XResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia ,grid.1043.60000 0001 2157 559XNESP Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia
| | - Ian J. Radford
- grid.452589.70000 0004 1799 3491Department of Biodiversity, Conservation and Attractions, Kununurra, WA Australia
| | - Hugh F. Davies
- grid.1043.60000 0001 2157 559XResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia ,grid.1043.60000 0001 2157 559XNESP Threatened Species Recovery Hub, Research Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia
| | - Brydie M. Hill
- grid.483876.60000 0004 0394 3004Flora and Fauna Division, Department of Environment, Parks and Water Security, Northern Territory Government, Darwin, Northern Territory Australia
| | - Sam C. Banks
- grid.1043.60000 0001 2157 559XResearch Institute for the Environment and Livelihoods, Charles Darwin University, Darwin, Northern Territory Australia
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Tuft K, Legge S, Frank ASK, James AI, May T, Page E, Radford IJ, Woinarski JCZ, Fisher A, Lawes MJ, Gordon IJ, Johnson CN. Cats are a key threatening factor to the survival of local populations of native small mammals in Australia’s tropical savannas: evidence from translocation trials with Rattus tunneyi. WILDLIFE RESEARCH 2021. [DOI: 10.1071/wr20193] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Abstract
ContextInvasive predators are a key threat to biodiversity worldwide. In Australia, feral cats are likely to be responsible for many extinctions of native mammal species in the south and centre of the continent.
AimsHere we examine the effect of feral cats on native rodent populations in the second of two translocation experiments.
MethodsIn a wild-to-wild translocation, we introduced pale field rats, Rattus tunneyi, whose populations are declining in the wild, into two pairs of enclosures where accessibility by feral cats was manipulated.
Key resultsIndividual rats translocated into enclosures accessible to cats were rapidly extirpated after cats were first detected visiting the enclosures. Rats in the enclosure not exposed to cats were 6.2 times more likely to survive than those exposed to cats. Two individual cats were responsible for the deaths of all but 1 of 18 cat-accessible rats. Rats in the site with denser ground cover persisted better than in the site with more open cover.
ConclusionsThese results are consistent with our previous study of a different native rat species in the same experimental setup, and provide further evidence that, even at low densities, feral cats can drive local populations of small mammals to extinction.
ImplicationsEffective feral cat control may be necessary to enable recovery of small mammals.
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Davies HF, Visintin C, Gillespie GR, Murphy BP. Investigating the effects of fire management on savanna biodiversity with grid‐based spatially explicit population simulations. J Appl Ecol 2020. [DOI: 10.1111/1365-2664.13801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Hugh F. Davies
- NESP Threatened Species Recovery Hub Research Institute for the Environment and LivelihoodsCharles Darwin University Casuarina NT Australia
| | - Casey Visintin
- Quantitative and Applied Ecology Group School of BioSciences University of Melbourne Parkville Vic. Australia
| | - Graeme R. Gillespie
- Department of Environment and Natural Resources Northern Territory Government Berrimah NT Australia
| | - Brett P. Murphy
- NESP Threatened Species Recovery Hub Research Institute for the Environment and LivelihoodsCharles Darwin University Casuarina NT Australia
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von Takach B, Scheele BC, Moore H, Murphy BP, Banks SC. Patterns of niche contraction identify vital refuge areas for declining mammals. DIVERS DISTRIB 2020. [DOI: 10.1111/ddi.13145] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Brenton von Takach
- Research Institute for the Environment and Livelihoods Charles Darwin University Darwin NT Australia
| | - Ben C. Scheele
- Fenner School of Environment and Society Australian National University Canberra ACT Australia
- National Environmental Science Program Threatened Species Recovery Hub Australia
| | - Harry Moore
- School of Environmental Science Institute for Land, Water and Society Charles Sturt University Albury NSW Australia
| | - Brett P. Murphy
- Research Institute for the Environment and Livelihoods Charles Darwin University Darwin NT Australia
- National Environmental Science Program Threatened Species Recovery Hub Australia
| | - Sam C. Banks
- Research Institute for the Environment and Livelihoods Charles Darwin University Darwin NT Australia
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Legge S, Woinarski JCZ, Dickman CR, Doherty TS, McGregor H, Murphy BP. Cat ecology, impacts and management in Australia. WILDLIFE RESEARCH 2020. [DOI: 10.1071/wrv47n8_ed] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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