Article
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Feral cats (Felis catus) have devastated wildlife globally. In Australia, feral cats are implicated in most recent mammal extinctions and continue to threaten native species. Cat control is a high-profile priority for Australian policy, research and management. To develop the evidence-base to support this priority, we first review information on cat presence/absence on Australian islands and mainland cat-proof exclosures, finding that cats occur across >99.8% of Australia's land area. Next, we collate 91 site-based feral cat density estimates in Australia and examine the influence of environmental and geographic influences on density. We extrapolate from this analysis to estimate that the feral cat population in natural environments fluctuates between 1.4 million (95% confidence interval: 1.0–2.3 million) after continent-wide droughts, to 5.6 million (95% CI: 2.5–11 million) after extensive wet periods. We estimate another 0.7 million feral cats occur in Australia's highly modified environments (urban areas, rubbish dumps, intensive farms). Feral cat densities are higher on small islands than the mainland, but similar inside and outside conservation land. Mainland cats reach highest densities in arid/semi-arid areas after wet periods. Regional variation in cat densities corresponds closely with attrition rates for native mammal fauna. The overall population estimate for Australia's feral cats (in natural and highly modified environments), fluctuating between 2.1 and 6.3 million, is lower than previous estimates, and Australian feral cat densities are lower than reported for North America and Europe. Nevertheless, cats inflict severe impacts on Australian fauna, reflecting the sensitivity of Australia's native species to cats and reinforcing that policy, research and management to reduce their impacts is critical.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... The map of feral cat density in Australia, used by Woinarski et al., is from 1992. It points to the problem of gaining a clear picture of occurrence, especially over an area as large as Australia, even for an invasive carnivore as lethal as a cat for our native fauna, although Legge et al. (2017) found that feral cats are present on over 99.8% of Australia. The maps in Legge et al. (2017) show the sharp changes in model predictions for cat density in natural environments during dry-average rainfall conditions and after extensive rainfall. ...
... It points to the problem of gaining a clear picture of occurrence, especially over an area as large as Australia, even for an invasive carnivore as lethal as a cat for our native fauna, although Legge et al. (2017) found that feral cats are present on over 99.8% of Australia. The maps in Legge et al. (2017) show the sharp changes in model predictions for cat density in natural environments during dry-average rainfall conditions and after extensive rainfall. Feral cat density is fairly uniform across the continent during average-dry conditions, but extensive rainfall events cause an estimated increase in population size in natural environments from 1.4 million after continent-wide droughts to 5.6 million after ...
... It could be explained simply by considering that people know their own dogs and those of their neighbours, and other dogs, such as those dogs without a collar, are dingoes or wild dogs. Nevertheless, there is the real possibility that domestic dogs are an important source of harm to native animals in NSW, and a particular threat to vulnerable and endangered species, a point already well made globally by Doherty et al. (2017). ...
Article
Full-text available
We used two survey methods-citizen science for private land and cameras for protected areas-to map the distribution of dingoes/wild dogs and foxes in NSW. Dingo/wild dog records were mostly confined to the east coast and ranges, with scattered locations in western NSW. This contrasts to the distribution of foxes, in which occupancy was high across most of the state. Data from 200 WildCount camera sites within protected areas also showed marked differences in the distribution of the two canid species. At the scale of the state, dingoes/wild dogs are uncommon, with the greatest concentration being in the northeast of the state, as well as a marked presence in the southeast. Foxes are common and widespread within protected areas, but less common in the northeast of the state. The camera data also indicated that feral cats are widespread within protected areas. The second aim of our study was to examine the WildCount data for behavioural patterns of the canid species. Foxes and dingoes/wild dogs significantly separated within two sub-formations of dry sclerophyll forest based on the Keith (2004) classification of NSW vegetation. From species pairwise interactions at sites, we found only limited evidence for significant interactions, and then only for the co-occurrence of fox-rabbit and fox-swamp wallaby, but no avoidance for any of the predators with each other. Camera records of the time of day of being active showed little effect of the presence of dingoes/wild dogs on the times of activity of foxes, but foxes curtailed the activity times of dingoes/wild dogs. From the analysis of inter-animal times at sites where both canids were recorded, there was little difference between the time since the other species was present. Thus, there was no evidence that dingoes/wild dogs or foxes inhibit the other from being at a site. We concluded that at the landscape level, both vegetation type and land tenure play a role in the interactions between dingoes/wild dogs and foxes. We also concluded that citizen science and cameras are complementary, not alternative techniques, especially as they sample different land tenures, and that cameras in protected areas and occupancy from citizen science have produced higher resolution maps and behaviour patterns than have been previously available. We can confirm that foxes are a ubiquitous threat throughout NSW, whereas dingoes/wild dogs are concentrated into a much smaller area of eastern, particularly northeastern , NSW.
... To avoid pseudoreplication, density estimates from the same location were averaged, reducing the dataset to 44 spatially distinct density estimates, including six from highly modified environments ( Figure S1b). To analyse the fox density data, we took the same approach as that used by Legge et al. (2017) for modelling cat density across Australia. ...
... The recent analyses of the numbers of animals killed by cats in Australia Woinarski et al., 2018) considered three components of the overall Australian cat population: pet cats, feral cats in highly modified environments (e.g., urban areas) and feral cats in largely natural environments [as defined by Legge et al. (2017)]. A comparable subdivision is not used in our assessment of fox diet because foxes are not kept as pets, and because we included parameters relating to habitat modification in our modelling. ...
... Such tolls help contextualise the relative predation threats imposed by both species (Loss et al., 2012) Note: Values relating to foxes are from this study. Values relating to cats have been sourced from Legge et al. (2017), , Woinarski et al. (2018), Murphy et al. (2019) and Legge et al. (2020). Confidence intervals for the estimated number of animals eaten by cats were not provided by the original sources and therefore have not been provided here. ...
Article
Full-text available
Aim Introduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial. Location Australia. Methods We draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by (i) modelling continental‐scale spatial variation in fox density, (ii) modelling spatial variation in the frequency of occurrence of prey groups in fox diet, (iii) analysing the number of prey individuals within dietary samples and (iv) discounting animals taken as carrion. We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies. Results Foxes kill more reptiles, birds and mammals (peaking at 1071 km⁻² year⁻¹) than cats (55 km⁻² year⁻¹) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent – mainly the arid central and tropical northern regions (and on most Australian islands) – cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals. Main conclusions This continental‐scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia's poor contemporary conservation record.
... The significant impacts of feral cats are typified by the dire state of many native mammal species across Australia. Since their introduction following European arrival in 1788, feral cats have proliferated across the Australian mainland, Tasmania and most other large islands (Legge et al. 2017). Over this period, feral cats have been a primary contributor to Australia's extraordinarily high rate of mammal extinction , and directly caused the failure of numerous threatened species reintroduction programs (Hardman et al. 2016;Short 2016). ...
... Over this period, feral cats have been a primary contributor to Australia's extraordinarily high rate of mammal extinction , and directly caused the failure of numerous threatened species reintroduction programs (Hardman et al. 2016;Short 2016). Despite their impact on Australian biodiversity, there are limited options currently available for the broad-scale control of feral cats (Legge et al. 2017). As a result, the ecological impacts of feral cats are continuing largely unabated. ...
... The mean density of feral cats estimated for Melville Island compared with other spatially-explicit capturerecapture estimates of feral cat density from across northern Australia(Stokeld et al. 2016;McGregor et al. 2016a;Legge et al. 2017). Error bars indicate the 95% confidence interval. ...
Article
Full-text available
Despite contributing to the ongoing collapse of native mammal populations across northern Australian savannas, we have limited understanding of the ecological constraints of feral cat population density in this system. Addressing such knowledge gaps is a crucial step towards mitigating the impacts of feral cats, and is particularly important for the large islands off northern Australia that remain as strongholds for numerous species vulnerable to cat predation. Here, we investigated cat density across Melville and Bathurst Island, two large islands in Australia’s monsoon tropics.We deployed large grids (~13 km2) of 70 camera-traps at four locations to investigate how feral cat density varies under different combinations of fire frequency, and feral herbivore presence. Using spatially-explicit capture-recapture models, we estimated feral cat density on Melville Island to be 0.15 cats km�2. We did not record any cat detections on Bathurst Island. Using simulations, we predicted that if cat density on Bathurst Island was equal to that on Melville Island, we would have expected to record 27.9 detections of 9.9 individual cats. Our results, coupled with other recent surveys, suggest that the density of cats is much lower on Bathurst Island than the adjacent Melville Island. The absence of feral herbivores on Bathurst Island may have contributed to this variation in cat density. Management that enhances understorey vegetation density, through feral herbivore control, as well as fire management, could help mitigate the impact of feral cats on northern Australian savanna biodiversity.
... An estimated 2-6 million feral cats occupy over 99% of Australia's 7.7 million km 2 land area, including many islands (Legge et al., 2017), making the control of feral cats and their impacts a landscape-scale challenge. However, safe and efficacious control options to reduce feral cat population size and impacts are currently limited. ...
... For example, only one feral cat was detected encountering a bait at TNP, and no baits were consumed by cats ( Table S2a). The population density at TNP was estimated at 0.43 cats km −2 , around 59% higher than the national average density of 0.27 cats km −2 (Fancourt et al., 2019;Legge et al., 2017), suggesting that cat density was not so low as to limit the potential for access to baits by more than a very low number of cats. Similarly, Integr Environ Assess Manag 2021:1-21 © 2021 State of Queensland © 2021 SETAC wileyonlinelibrary.com/journal/ieam ...
Article
Feral cats pose a significant threat to wildlife, agriculture and human health through predation, disease transmission and competition with native animals. Controlling feral cats and their impacts, however, is challenging. New and emerging 1080‐based feral cat baits have shown promising results in western and central Australia, however the safety of these new baits for non‐target species in eastern Australia, where many native animals are more sensitive to 1080 than their western conspecifics, has not been assessed. We investigated the uptake by non‐target animals of 499 toxic Eradicat® baits across five different eastern Australian environs, and the uptake of non‐toxic Eradicat® and Hisstory® baits at an additional two sites. Using field‐based observations of species eating or removing baits, we determined that 13 non‐target species (eight mammals, four birds, one reptile) were at high risk of individual mortality, with individuals of 11 of those 13 species (seven mammals, four birds) observed consuming enough toxic Eradicat® in a single visit to ingest a lethal dose of 1080. Feral cats (the target species) consumed only 3.1% of monitored baits, which was only 52% of the 31 baits they encountered. We recommend undertaking targeted population monitoring of species identified at high risk of individual mortality, to determine whether Eradicat® baits present a population‐level risk to these species. Our findings suggest that the small‐sized Eradicat® baits present a greater risk to non‐target species in eastern Australia than the larger traditional 1080‐based meat baits used for the control of wild dogs and foxes. Our study highlights the importance of performing risk assessments for different bait types, even when the same toxin is used, and of performing site‐specific non‐target risk assessments of new baits such as Eradicat® to assist developing guidelines for their safe and effective use in different environs. This article is protected by copyright. All rights reserved.
... Red foxes (Vulpes vulpes) and feral cats (Felis catus) co-occur throughout much of Australia (Legge et al. 2017;Fairfax 2019) and they are considered to have compounding and complementary impacts (Stobo-Wilson et al. 2021). Foxes are often considered the more damaging invasive predator, implicated in the decline of a broad suite of Australian mammals (Saunders et al. 2010) especially those considered in the critical weight range (Burbidge and McKenzie 1989;Johnson and Isaac 2009). ...
... But it also has a history of exotic predator presence. Feral cat abundances vary across the island, having been reported as high as 3.4 cats/km 2 (Legge et al. 2017) and concerns exist about their potential response to fox eradication (Rendall et al. 2021a). Invasive prey species including European rabbits (Oryctolagus cuniculus), black rats (Rattus rattus) and house mice (Mus musculus) are all abundant across the island (Kirkwood and Johnston 2006;Rendall et al. 2014) and have been present and observed regularly island wide throughout both time periods (Kirkwood and Johnston 2006). ...
Article
Full-text available
Invasive species control has resulted in unintended consequences where the control of one species causes increased impacts of a co-occurring species. Red foxes (Vulpes vulpes) and feral cats (Felis catus) co-occur throughout Australia-with control and regulation of fox's commonplace, a greater understanding of how feral cats will respond in the absence of foxes is needed. In this study we use feral cat diet to assess potential prey switching after red fox control. Feral cat stomach contents were sampled between 1983 and 1994 on Phillip Island, Victoria, Australia when both feral cats and red foxes were abundant; and again from 2016 to 2019 when foxes were eradicated. A total of 277 feral cats were sampled between 1983-1994 and 415 from 2016 to 2019. Although we did not track feral cat diet throughout the red fox decline, diet comparisons between the two time periods suggest no substantial shift in feral cat diet with only slight increases in invertebrates and black rats observed. Invasive prey (European rabbits, black rats, and house mice) still formed the majority of feral cat diet. We further reinforce the role of seasonality, surrounding land use and sex as factors influencing cat diet. Our results suggest red fox control in the presence of cats may still achieve conservation benefits with feral cats maintaining a comparable diet, dominated by invasive species, despite fox control-though this may be context dependent. Given the abundance and frequency of invasive prey species within cat diet, we further support the idea that invasive prey control could be a viable indirect method to control the impacts of feral cats.
... Prior to 2016, a range of different predator control efforts including baiting, trapping and shooting had been undertaken across the site to target wild dogs and feral cats that threaten the last naturally occurring wild population of the endangered bridled nailtail wallaby (Onychogalea frenata) (Department of Environment and Resource Management 2011;Fisher et al. 2001). However, despite historic control efforts, feral cats remained abundant and active across the site (Fancourt et al. 2019), with cat densities at the site (0.43 cats/km 2 ; Table B1 in Legge et al. 2017) around 59% higher than the national average of 0.27 cats/km 2 (Legge et al. 2017). In 2016, the QC Bait was also found to be ineffective at reducing the site's cat population (Fancourt et al. 2021a). ...
... Prior to 2016, a range of different predator control efforts including baiting, trapping and shooting had been undertaken across the site to target wild dogs and feral cats that threaten the last naturally occurring wild population of the endangered bridled nailtail wallaby (Onychogalea frenata) (Department of Environment and Resource Management 2011;Fisher et al. 2001). However, despite historic control efforts, feral cats remained abundant and active across the site (Fancourt et al. 2019), with cat densities at the site (0.43 cats/km 2 ; Table B1 in Legge et al. 2017) around 59% higher than the national average of 0.27 cats/km 2 (Legge et al. 2017). In 2016, the QC Bait was also found to be ineffective at reducing the site's cat population (Fancourt et al. 2021a). ...
Article
Full-text available
Reducing the damage caused by feral cats (Felis catus) to wildlife, livestock and human health is a key objective for many land managers and human health agencies globally. The lack of safe and efficacious lethal control tools in many regions, however, makes the control of feral cats and their impacts challenging. We performed a baiting trial in central Queensland to measure the efficacy and safety of Eradicat®, a feral cat bait currently approved for use only in the state of Western Australia, as a potential tool for the broadscale control of feral cats in eastern Australian environments. We used camera traps, cat-borne GPS collars and chemical residue analysis to monitor mortality and changes in feral cat populations following baiting. We also used camera traps and bird count surveys to monitor the response of key at-risk non-target species, specifically wild dogs (Canis familiaris), common brush-tailed possums (Trichosurus vulpecula) and 10 bird species at risk of consuming baits. Feral cat abundance reduced significantly (29–40%) following baiting, with reductions observed across 83% of the site. There were no significant changes in wild dog, possum or potentially bait-consuming bird populations following baiting. Our findings suggest that Eradicat® could potentially be a safe and efficacious tool for the landscape control of feral cats at some sites in eastern Australia. Future research is required to test the safety and efficacy of Eradicat® at other sites in eastern Australia, as suites of non-target species will vary among sites in different environments.
... Despite the observed decreasing populations and extinction of many wild animals, especially small mammals and birds (Veitch, 1985;Dowding and Murphy, 2001;Medway, 2004;Hughes et al., 2008;Bonnaud et al., 2009;Faulquier et al., 2009) in closed island ecosystems (Liberg 1984;Woods et al., 2003;Bonnaud et al., 2011;Medina et al., 2011) and on the scale of a country and the continent (Barratt 1997;Beckerman et al., 2007;Baker et al., 2008;Dauphiné and Cooper, 2009;Bonnington et al., 2013;Legge et al., 2017;Woinarski et al., 2017) little is known about the niches overlaping between cats as predator and birds as potential prey. This is probably caused by difficulties in performing a joint assessment of cat and bird densities in spatially large domains. ...
... The obtained results based on a predictive modelling approach, along with numerous studies conducted in: urban and suburban USA ecosystems, rural areas in Poland, Italy and England as well as on the continental scale, e.g Australia clearly proves that cats have a negative impact on native fauna of both birds and small mammals, including bats (Dunn and Tessaglia, 1993;Lepczyk et al., 2003;Loss et al., 2013;Legge et al., 2017;Krauze-Gryz et al., 2012a, 2012bLoss and Marra, 2017;Mori et al., 2019Baker et al., 2008). However, the question remains unanswered whether on a wide spatial scale of a country and/or a continent, cats can lead to local extinction of prey species. ...
Article
Ecological interactions between native species are often disturbed by invasive species. However, to understand their impact on wild native animal populations on a country scale it is necessary to develop a predictive model. Therefore, I followed the species density distribution modelling approach to explore how feral domestic cats (Felis catus) along with environmental predictors determined densities of two bird species, the Yellowhammer (Emberiza citrinella) and the Yellow Wagtail (Motacilla flava) on the whole area of Poland. As a modelling method, I used the Generalised Additive Model to develop two models for each of the two bird species: The first with the feral cat density as an additional predictor, and the second without it. As a result, I demonstrated the negative impact of cat density on native bird populations, illustrated by reduced density of the two studied species in their preferred habitats, in which cats reached a high density. Although it cannot be explicitly asserted that cats lead to a local extinction of the two bird species, these predators should not be underestimated. In many locations feral populations are fed with new individuals, and they do not follow the same internal mechanisms regulating their population as the native bird fauna. Thus, on a large spatial scale species density distribution models of birds should include cats’ population size as an additional predictor when this predator's environmental preferences overlap with preferences of the studied target groups.
... Feral cats occur in heterogeneous abundances across 99.8% of Australia and many of its larger territorial islands, from deserts to tropical woodlands [17]. Their population size fluctuates between 1.4 and 5.6 million, depending on available prey, which generally correlates with wetter conditions [17]. ...
... Feral cats occur in heterogeneous abundances across 99.8% of Australia and many of its larger territorial islands, from deserts to tropical woodlands [17]. Their population size fluctuates between 1.4 and 5.6 million, depending on available prey, which generally correlates with wetter conditions [17]. They are opportunistic, generalist carnivores that kill millions of native animals every day, including 3.2 million mammals, 1.2 million birds, 1.9 million reptiles, 0.25 million frogs and 3 million invertebrates [18]. ...
Article
Full-text available
Feral cats are one of the most damaging predators on Earth. They can be found throughout most of Australia’s mainland and many of its larger islands, where they are adaptable predators responsible for the decline and extinction of many species of native fauna. Managing feral cat populations to mitigate their impacts is a conservation priority. Control strategies can be better informed by knowledge of the locations that cats frequent the most. However, this information is rarely captured at the population level and therefore requires modelling based on observations of a sample of individuals. Here, we use movement data from collared feral cats to estimate home range sizes by gender and create species distribution models in the Pilbara bioregion of Western Australia. Home ranges were estimated using dynamic Brownian bridge movement models and split into 50% and 95% utilisation distribution contours. Species distribution models used points intersecting with the 50% utilisation contours and thinned by spacing points 500 m apart to remove sampling bias. Male cat home ranges were between 5 km2 (50% utilisation) and 34 km2 (95% utilisation), which were approximately twice the size of the female cats studied (2–17 km2). Species distribution modelling revealed a preference for low-lying riparian habitats with highly productive vegetation cover and a tendency to avoid newly burnt areas and topographically complex, rocky landscapes. Conservation management can benefit by targeting control effort in preferential habitat.
... However, more recent studies detected more widespread population decline for some northern Australian small mammal species (Woinarski et al. 2001(Woinarski et al. , 2010Lawes et al. 2015), raising concern over a potential second wave of Australian mammal extinctions in the tropics . Foxes have not colonised northern Australia; rather, predation by feral cats has been implicated as one of the probable causes of mammal decline in the north Legge et al. 2017). Additionally, the changes in fire regimes that occurred after the shift from Aboriginal to unmanaged fires resulted in higher fire frequency, intensity and extent in tropical savannas, causing substantial habitat alterations (Yibarbuk et al. 2001;Bowman et al. 2004), although in recent years fire management programs have expanded across north Australia (Fitzsimons et al. 2012;Russell-Smith and Whitehead 2015;Russell-Smith et al. 2017;Vigilante et al. 2017), with some potential benefits for small mammals (Radford et al. 2020). ...
... Fire is frequent across tropical savannas, the dominant vegetation type in the monsoon portion of the Australian tropics (Bowman et al. 2010). Likewise, cats have colonised almost all of Australia (Legge et al. 2017). Consequently, most experimental studies on the effects of fire or cats on mammals are spatially constrained when based on artificial exclosures , or temporally limited when extended to entire landscapes (Andersen et al. 2005). ...
Article
ContextPopulations of native mammals are declining at an alarming rate in many parts of tropical northern Australia. Fire regimes are considered a contributing factor, but this hypothesis is difficult to test because of the ubiquity of fire. AimsThis preliminary study investigated relative abundance and richness of small mammals on a gradient of fire regimes in the Uunguu Indigenous Protected Area (north Kimberley, Australia). Methods Species were sampled using 40 unbaited camera traps, positioned for a year on 20 transects crossing the rainforest–savanna boundary at locations with comparable environment and geology but varying fire history. The relative importance of the factors ‘fire frequency’, ‘late dry season fire frequency’, ‘time since burnt’ and ‘vegetation type’ as predictors of the number of small mammal species and detections was tested using Spatial Generalised Linear Mixed Models to account for spatial autocorrelation. Key resultsNine species of small mammals were observed. Mammals were more abundant and diverse in locations with low overall fire frequency, which was a better predictor than late dry season fire frequency or time since burnt. The model including fire frequency and vegetation explained the highest proportion of total variation in mammal diversity (R2=42.0%), with most of this variation explained by fire frequency alone (R2=40.5%). The best model for number of detections (R2=20.9%) included both factors. Conclusions In the north Kimberley, small mammals are likely to be more abundant and diverse in areas with low fire frequency. ImplicationsThis natural experiment supports the theory that frequent fires are contributing to the decline of small mammals observed across northern Australia.
... Our camera trapping method provided an effective way to monitor variations in feral cat abundance, and the consistency of its estimation calculated with GI, MKTBA and densities via SECR should prove widely useful. The GI could be used to monitor changes in the feral cat population as an alternative to SECR estimations, which require more time and can be used to respond to more specific research questions (Bengsen et al. 2012;Legge et al. 2017). However, conclusions are often based on relative abundance indices, and this kind of index does not consider important parameters such as variable detection (Sollman et al. 2013). ...
... However, it is lower than at other locations: one Salomon island (Lavery et al. 2020), Great Britain (Langham and Porter 1991), Europe (Liberg 1980), New Zealand (Macdonald et al. 1987), United States (Warner 1985), and highly modified landscapes in Australia . According to the model by Legge et al. (2017), the feral cat density at Pindaï Peninsula (1.6 cats/ km²) is higher than expected (0.5-1 cat/ km²). This unexpected density illustrates the importance of specifically evaluating animal densities at each site before management actions start, especially given that New Caledonia tends to use base data from Australia. ...
Article
Full-text available
Invasive feral cats threaten biodiversity at a global scale. Mitigating feral cat impacts and reducing their populations has therefore become a global conservation priority, especially on islands housing high endemic biodiversity. The New Caledonian archipelago is a biodiversity hotspot showing outstanding terrestrial species richness and endemism. Feral cats prey upon at least 44 of its native vertebrate species, 20 of which are IUCN Red-listed threatened species. To test the feasibility and efficiency of culling, intensive culling was conducted in a peninsula of New Caledonia (25.6 km²) identified as a priority site for feral cat management. Live-trapping over 38 days on a 10.6 km² area extirpated 36 adult cats, an estimated 44% of the population. However, three months after culling, all indicators derived from camera-trapping (e.g., abundance, minimum number of individuals and densities) suggest a return to pre-culling levels. Compensatory immigration appears to explain this unexpectedly rapid population recovery in a semi-isolated context. Since culling success does not guarantee a long-term effect, complementary methods like fencing and innovative automated traps need to be used, in accordance with predation thresholds identified through modelling, to preserve island biodiversity. Testing general assumptions on cat management, this article contributes important insights into a challenging conservation issue for islands and biodiversity hotspots worldwide.
... From analysis of 91 site-based feral cat density estimates in Australia, the mean density of feral cats on the Australian continent is 0.27 cats km −2 (95% confidence interval = 0.18-0.45 cats km −2 ) [47]. Feral cat density varies, however, among habitat types, and estimates suggest that there tend to be more feral cats in the southern half of Australia or in arid areas such as Matuwa (>1.5 cats km −2 after wet periods), and lower numbers in tropical and subtropical areas such as Shamrock Station [47]. ...
... cats km −2 ) [47]. Feral cat density varies, however, among habitat types, and estimates suggest that there tend to be more feral cats in the southern half of Australia or in arid areas such as Matuwa (>1.5 cats km −2 after wet periods), and lower numbers in tropical and subtropical areas such as Shamrock Station [47]. Our estimate of cat abundance on Shamrock Station is in line with the expected density for a non-controlled feral cat population in the region after a wet period. ...
Article
Full-text available
Environmental damage caused by the intensification of agriculture may be compensated by implementing conservation projects directed towards reducing threatening processes and conserving threatened native species. In Australia, feral cats (Felis catus) have been a ubiquitous threatening process to Australian fauna since European colonisation. On Shamrock Station, in the north-west of Western Australia, the Argyle Cattle Company has proposed intensifying agriculture through the installation of irrigation pivots. There is concern that irrigating land and storing agricultural produce may indirectly increase the abundance of feral cats and European red foxes (Vulpes vulpes) on the property, which in turn may negatively impact threatened bilbies (Macrotis lagotis) that also inhabit the property. Feral cat control is required under the approved management plan for this project to mitigate this potential impact. Our baseline study revealed a high density of feral cats on Shamrock Station (0.87 cats km−2) and dietary data that suggest the current native mammal assemblage on Shamrock Station is depauperate. Given the high density of feral cats in this area, the effective control of this introduced predator is likely to confer benefits to the bilby and other native species susceptible to cat predation. We recommend ongoing monitoring of both native species and feral cats to determine if there is a benefit in implementing feral cat control around areas of intensive agriculture and associated cattle production.
... There are estimated to be somewhere around 1.4 to 3.4 million feral cats across Australia, around one feral cat per four square kilometers [160]. There is no doubt that feral cats eat large numbers of native fauna [161][162][163] but the studies are not conclusive on the actual effects on prey populations generally [162][163][164], and observed effects do not necessarily equate to causation [160]. ...
... There are estimated to be somewhere around 1.4 to 3.4 million feral cats across Australia, around one feral cat per four square kilometers [160]. There is no doubt that feral cats eat large numbers of native fauna [161][162][163] but the studies are not conclusive on the actual effects on prey populations generally [162][163][164], and observed effects do not necessarily equate to causation [160]. It has been argued that feral cats have led to the demise of mammalian fauna [23,29,43,44,156,165], and an exclusion study in the Kimberley region suggested that feral cats can extirpate local populations of native mammals [35]. ...
Article
Full-text available
Northern Australian biomes hold high biodiversity values within largely intact vegetation complexes, yet many species of mammals, and some other taxa, are endangered. Recently, six mammal species were added to the 20 or so already listed in the Australian endangered category. Current predictions suggest that nine species of mammal in northern Australia are in imminent danger of extinction within 20 years. We examine the robustness of the assumptions of status and trends in light of the low levels of monitoring of species and ecosystems across northern Australia, including monitoring the effects of management actions. The causes of the declines include a warming climate, pest species, changed fire regimes, grazing by introduced herbivores, and diseases, and work to help species and ecosystems recover is being conducted across the region. Indigenous custodians who work on the land have the potential and capacity to provide a significant human resource to tackle the challenge of species recovery. By working with non-Indigenous researchers and conservation managers, and with adequate support and incentives, many improvements in species' downward trajectories could be made. We propose a strategy to establish a network of monitoring sites based on a pragmatic approach by prioritizing particular bioregions. The policies that determine research and monitoring investment need to be re-set and new and modified approaches need to be implemented urgently. The funding needs to be returned to levels that are adequate for the task. At present resourcing levels, species are likely to become extinct through an avoidable attrition process .
... More so than elsewhere in the world, many separate studies have been gathered into a substantial evidence base on cat density and diet. This has allowed the following: robust analyses of cat distribution, population size and spatial variation in cat density across the Australian mainland and islands (Legge et al. 2017); estimates of the toll of predation of cats on animal groups; and identification of the native species most prone to cat predation (Woinarski et al. 2017a(Woinarski et al. , 2017bMurphy et al. 2019;Woolley et al. 2020). In this special issue, the final components of that series are presented, with estimates of the toll taken by cats in Australia on frogs ) and invertebrates . ...
... Hohnen et al. (2020a) and Miritis et al. (2020) estimate cat densities for Kangaroo Island and French Island respectively. This information is valuable because many islands (in Australia and globally) have very high conservation values, but cats reach higher densities on islands than on the mainland (Legge et al. 2017), and island-specific density information is required to inform cat-eradication efforts. ...
... 2;Hone 2016) is analogous to the situation with the abundance of feral cats in Australia. Many publications reported abundance around 18 million feral cats (Hone and Buckmaster 2014) when a rigorous assessment later estimated abundance as 2.1 to 6.3 million (Legge et al. 2017). The method used in the present study of combining abundance estimates differs from the approach used to assess trends of wild boar (Sus scrofa) in Europe (Massei et al. 2015). ...
Article
Full-text available
The abundance of feral pigs in Australia has been estimated previously and been a topic of some debate. This study aims to update a previous estimate of abundance (13.5 million, 95% CI: 3.5 million to 23.5 million) of feral pigs in Australia. Abundance estimates for the 1970s, 1980s, 1990s, 2000s and 2010s were collated from published literature. Mean abundances in the middle decades were estimated using the ratio method. The average abundance of feral pigs varied from 4.4 million (95% CI: 2.4 million to 6.3 million) in the 1980s, to 3.0 million (95% CI: 2.3 million to 3.7 million) in the 1990s, to 3.2 million (95% CI: 2.4 million to 4.0 million) in the 2000s. Mean density across all 142 studies was 1.03 pigs km–2. The average abundance of feral pigs in Australia during the 1980s to 2000s was much lower and more precise than estimated previously, so scientists and managers should update their use of abundance estimates. Density estimates are above, and below, estimates of threshold host densities for infectious exotic disease establishment.
... Native Australian rodents have been in contact with cats for the last 200 years and, like small mammals elsewhere in the world, face significant threats from domestic cat predation (e.g. Dickman 2009;Woinarski et al. 2015;Flockhart et al. 2016;Kikillus et al. 2017;Legge et al. 2017). This vulnerability likely arises when prey are naïve to the threat that domestic cats present (Banks and Dickman 2007;Banks et al. 2018). ...
Article
Full-text available
Understanding wild animal responses to stressors underpins effective wildlife management. In order for responses to stressors to be correctly interpreted, it is critical that measurements are taken on wild animals using minimally invasive techniques. Studies investigating wild animal responses to stressors often measure either a single physiological or behavioural variable, but whether such responses are comparable and concordant remains uncertain. We investigated this question in a pilot study that measured responses of wild-caught urban brown and black rats ( Rattus norvegicus , Rattus rattus ) to fur-based olfactory cues from a predator, the domestic cat ( Felis catus ); a novel herbivore, the koala ( Phascolarctos cinereus ); and a familiar herbivore and competitor, the common brushtail possum ( Trichosurus vulpecula ). Physiological responses, measured by assaying faecal glucocorticoid metabolites, were compared to behavioural responses observed via video recordings. We found that physiological and behavioural responses to stressors were expressed concordantly. There was no sizeable physiological response observed, and the behavioural response when considered across the night was negligible. However, the behavioural response to the predator and competitor cues changed across the observation period, with activity increasing with increasing hours of exposure. Our results indicate that responses of wild rodents to cues are nuanced, with stress responses modulated by behaviour changes that vary over time according to the severity of the perceived threat as animals gather further information. If the physiological response alone had been assessed, this moderated response may not have been evident, and in terms of wildlife management, vital information would have been lost.
... Domestic animals were found to be responsible for 14% of the hospitalisations and 78% of the attacked animals did not survive. Many papers have highlighted and quantified the impact on reptiles, small birds and mammals due to feral cats (Churcher and Lawton 1987;Woods et al. 2003;Kays and DeWan 2004;Baker et al. 2005;Dickman 2009;Legge et al. 2017;. In the collection of the Museum of Natural History of Genoa, for example, there are 14 birds, 13 mammals and one reptile from Liguria and Piedmont Regions that were killed by cats between 1997 and 2019 (Table 3). ...
Article
Full-text available
Wildlife recovery centres are widespread worldwide and their goal is the rehabilitation of wildlife and the subsequent release of healthy animals to appropriate habitats in the wild. The activity of the Genoese Wildlife Recovery Centre (CRAS) from 2015 to 2020 was analysed to assess its contribution to the conservation of biodiversity and to determine the main factors affecting the survival rate of the most abundant species. In particular, the analyses focused upon the cause, provenance and species of hospitalised animals, the seasonal distribution of recoveries and the outcomes of hospitalisation in the different species. In addition, an in-depth analysis of the anthropogenic causes was conducted, with a particular focus on attempts of preda-tion by domestic animals, especially cats. Significantly, 96.8% of animals hospitalised came from Liguria, the region in northwestern Italy where CRAS is located, with 44.8% coming from the most populated and urbanised areas of Genoa, indicating a positive correlation between population density and the number of recoveries. A total of 5881 wild animals belonging to 162 species were transferred to CRAS during the six years study period. The presence of summer migratory bird species and the high reproductive rates of most animals in summer resulted in a corresponding seasonal peak of treated animals. Birds represented 80.9% of entries; mammals accounted for 18.6% of hospitalisations; and about 0.5% of the entries were represented by reptiles and amphibians. Species protected by CITES and/or in IUCN Red List amounted to 8% of the total number of individuals. Consistent with results recorded elsewhere from Italy and other European countries, 53.9% of the specimens treated were released in nature; 4.7% were euthanised and 41.4% died. There was a significant difference between taxa in the frequency of individuals that were released, died or euthanised due to the intrinsic characteristics of species (more resistant or more adaptable to captivity than others) and/or to the types of debilitative occurrences common to each species (e.g. A peer-reviewed open-access journal Gabriele Dessalvi et al. / Nature Conservation 44: 1-20 (2021) 2 infections, wounds, traumas, fractures). A total of 14.2% of wildlife recovery was from injuries caused with certainty by people or domestic animals (human impact), with 54.3% of these hospitalised animals having been victims of predation attempts by domestic animals, mainly cats. The percentage of release in nature of animals hospitalised following human impact was significantly lower than overall cases (31.2% vs. 53.9%) due to the greater severity of the injuries. The percentage of animals released showed a further reduction to 27.1% amongst victims of predation attempts by pets. The work of Rehabilitation/Recovery Centres contributes to wildlife conservation. In particular, the CRAS in Genoa is a Centre with an increasing level of activity concerning the rehabilitation of species under CITES protection and/or included on the IUCN Red List. The contribution and experience of CRAS operators is critical for the success of 'information campaigns' aimed at limiting the number of stray dogs and cats because of their impact on wildlife. Therefore , the activity of a properly-managed CRAS can significantly contribute both directly and indirectly to wildlife conservation, resulting in important territorial safeguards for the protection of biodiversity.
... A large proportion of this difference is due to differences in density. Average densities of cats in the Midlands (0.9 cats km −2 [18]) are higher than the national average of 0.27 cats km −2 [24]. Although differences in encounter rates between cats and quolls may, therefore, be exaggerated compared to other regions, the large, exclusive home ranges of female quolls [25] mean that this species is never present in high densities, and estimates from this study (0.4 quolls km −2 , [18]) are equivalent to the highest previously recorded densities (0.3 quolls km −2 , [25]). ...
Article
Full-text available
Alien mammalian carnivores have contributed disproportionately to global loss of biodiversity. In Australia, predation by the feral cat and red fox is one of the most significant causes of the decline of native vertebrates. To discover why cats have greater impacts on prey than native predators, we compared the ecology of the feral cat to a marsupial counterpart, the spotted-tailed quoll. Individual prey are 20–200 times more likely to encounter feral cats, because of the combined effects of cats' higher population densities, greater intensity of home-range use and broader habitat preferences. These characteristics also mean that the costs to the prey of adopting anti-predator behaviours against feral cats are likely to be much higher than adopting such behaviours in response to spotted-tailed quolls, due to the reliability and ubiquity of feral cat cues. These results help explain the devastating impacts of cats on wildlife in Australia and other parts of the world.
... At a global or continental scale, few data are available concerning total population size of non-native animals, with notable exceptions for feral pigs and cats in Australia (Hone, 1990;Legge et al., 2017). For carp, population estimates are limited to specific case-study lakes or river reaches and these have not been 'scaled-up' to examine the national situation (Brown and Walker, 2004;Forsyth et al., 2013;Koehn et al., 2018). ...
Article
Full-text available
Common carp (Cyprinus carpio) are one of the world's most destructive vertebrate pests. In Australia, they dominate many aquatic ecosystems causing a severe threat to aquatic plants, invertebrates, water quality, native fish and social amenity. The Australian Government is considering release of cyprinid herpesvirus-3 (CyHV-3) as a control measure and consequently a robust, continental-scale estimate of the carp population and biomass is essential to inform planning and risk management. Here, we pioneer a novel model-based approach to provide the first estimate of carp density (no/ha) and biomass density (kg/ha) at river reach/waterbody, basin and continental scales. We built a spatial layer of rivers and waterbodies, classified aquatic habitats and calculated the area of each throughout the range of carp in Australia. We then developed a database of fishery-independent electrofishing catch-per-unit-effort (CPUE) for habitat types, containing catch information for 574,145 carp caught at 4831 sites. Eastern Australia accounted for 96% of carp biomass and 92% of the total available wetted habitat area (16,686 km²) was occupied. To correct these data for variable detection efficiencies, we used existing electrofishing data and undertook additional field experiments to establish relationships between relative and absolute abundances. We then scaled-up site-based estimates to habitat types to generate continental estimates. The number of carp was estimated at 199.2 M (95%Crl: 106 M to 357.6 M) for an ‘average’ hydrological scenario and 357.5 M (95%Crl: 178.9 M to 685.1 M) for a ‘wet’ hydrological scenario. In eastern Australia, these numbers correspond with biomasses of 205,774 t (95%Crl: 117,532–356,482 t) (average scenario) and 368,357 t (95%Crl: 184,234–705,630 t) (wet scenario). At a continental scale the total biomass was estimated at 215,456 t for an ‘average’ hydrological scenario. Perennial lowland rivers had the highest CPUE and greatest biomass density (up to 826 kg/ha) and the modelled biomass exceeded a density-impact threshold of 80–100 kg/ha in 54% of wetlands and 97% of stream area in large lowland rivers. The continental-scale biomass estimates provide a baseline for focusing national conservation strategies to reduce carp populations below thresholds needed to restore aquatic ecosystems at a range of spatial scales.
... The increased risk for younger cats is likely due to a combination of factors such as a lack of experience and higher energy levels, resulting in a greater propensity to roam [57]. It has also been found that older cats are less likely to engage in risk-taking behaviours, including crossing roads [58]. Results from this study suggest owners may recognise that potentially risky behaviours may be more common in junior cats because this age group had greater odds of being kept as indoor-only cats compared to adult cats. ...
Article
Full-text available
Outdoor access for owned domestic cats (Felis catus) is a divisive issue. Cat safety, mental and physical wellbeing, infectious diseases, and wildlife depredation are cited as factors influencing owners; however, the degree of consideration each factor receives has not been quantified. This study (i) analysed which demographic variables are associated with greater odds of cats having indoor or outdoor lifestyles, (ii) identified which factors owners consider when making a choice on lifestyle and any regional variations, and (iii) identified if owners consider the different lifestyle options available and recognise their associated benefits. A series of online surveys were used for data collection. Binary logistic regression models were used to generate odds ratios assessing if demographic variables were significantly associated with cat lifestyle. Quantitative analysis of factors considered when deciding on cat lifestyle was accompanied by a thematic analysis of rich-text open-ended responses, providing nuanced insight into the rationale and elucidating additional factors considered. Of the demographic variables tested, 10/12 were significantly associated with lifestyle. Variables with higher odds of indoor-only lifestyles were owners being 26-35 years old, multi-cat households,
... (The Victorian Naturalist 137(6), 2020,[228][229][230][231][232][233][234][235][236][237][238][239] Feral Cats Felis catus were introduced into Australia at multiple coastal locations between 1824 and 1886 (Abbott 2002(Abbott , 2008. Since these introductions, they have established populations across the entire continent with islands and predator-fenced reserves forming the only Feral Cat-free areas (Rolls 1969;Legge et al. 2017). The impacts of Feral Cat predation on Australian native fauna are widely reported (Dickman 1996;Hilmer et al. 2010a;Doherty et al. 2015Doherty et al. , 2017Woinarski et al. 2017a;2017b;2018) and there is increasing concern about the impact of cat-mediated disease transmission on both wildlife and agricultural livestock (Groenewegen 2018;Taggart et al. 2019). ...
Article
Full-text available
Feral Cats (Felis catus) impact native wildlife species through direct predation and transmission of parasites. In July 2018, the Government of Victoria declared Feral Cats to be a pest in specific Crown land tenures and subsequently made changes to regulations to provide opportunity for use of additional control tools. This coincided with an Australian Government initiative to create Feral Free Safe Havens on islands and fenced exclosures. French Island was one of the islands nominated in this strategy and has had over 1100 Feral Cats removed since 2010. In conjunction, there has been increased awareness throughout the island community about the responsibilities of Domestic Cat owners. This paper presents the current regulatory environment and discusses how it impacts on a proposal to eradicate the Feral Cat population on French Island, Victoria.
... Consequently, and due to increasing evidence of declines and extinctions of native species from feral cat predation, the impact of the feral cat on native Australian fauna has attracted significant attention in recent years (Woinarski et al. 2015;Legge et al. 2017). Synergistic relationships between the feral cat and other sympatric predators such as the fox and wild dog-dingo hybrids (Canis familiaris) and processes such as fire compound the challenges of managing feral cats, and interactions between these predatory species and other ecological processes are often complex (Allen et al. 2013;Doherty et al. 2015b;McGregor et al. 2016;Molsher et al. 2017). ...
Article
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.
... Bettongs and feral cats have co-existed in Tasmania since the early 1800s (Abbott 2008) without resulting in the extinction of the former. That said, cats are known to prey upon bettongs, and have been implicated in population declines and crashes in several species of Australian mammals (Legge et al. 2017;Radford et al. 2018), including a closely related species of bettong (Bannister et al. 2016). Cats have been used recently to test predator exposure as a tool to select against predator naïveté in the burrowing bettong Saxon-Mills et al. 2018;West et al. 2018). ...
Article
Full-text available
A large component of the anthropogenic biodiversity crisis is the loss of animal species. In response, there has been significant investment in reintroductions of species to their historical ranges. Predation by native and exotic predators, however, remains a barrier to success. Over the past 200 years, Australia has seen the highest rate of mammal extinction on earth, with mammals within a critical weight range (CWR: 35 g–5.5 kg) most affected due to predation by exotic predators. Populations of some threatened species now exist only in Tasmania, offshore islands, or predator-proof sanctuaries. The next critical step is to return native populations outside of predator-free areas, ‘beyond-the-fence’, on the continental mainland. Given our current inability to completely remove exotic predators from mainland ecosystems, how can we achieve successful mammal reintroductions? A potential solution is to drive adaptation of reintroduced animals towards predator-resistance by exposing them to low levels of predation. We propose the concept of a ‘Goldilocks Zone’—the ‘just right’ levels of predation needed to drive selection for predator-resistant native species, while ensuring population viability. We experimentally reintroduced a mammal, the eastern bettong (Bettongia gaimardi), to mainland Australia, 100 years after its local extinction. Using an intense baiting regime, we reduced the population density of the red fox (Vulpes vulpes), the main factor behind the eastern bettong’s extirpation from the continent. Reducing bait take to 15% of previous levels allowed differential survival among bettongs; some surviving under 100 days and others over 450 (~ 4 times longer than some similar trials with related species). Surviving individuals were generally larger at release than those that died earlier, implying selection for larger bettongs. Our results suggest that reducing predation could establish a Goldilocks Zone that could drive selection for bettongs with predator-resistant traits. Our work contributes to a growing body of literature that explores a shift towards harnessing evolutionary principles to combat the challenges posed by animal management and conservation.
... Across the Pilbara bioregion of Western Australia, feral cats, foxes, and wild dogs are common (Fig. 1). Feral cats and wild dogs are generally widespread, with foxes less widespread and found mostly near the coast and along the alluvial confines of major inland waterways (King and Smith 1988;Legge et al. 2017). Here, these predators overlap in distribution with several native species listed under the national EPBC Act as 'Matters of National Environmental Significance' (e.g. ...
Article
Full-text available
The effective control of wild dogs, feral cats and foxes is of primary interest to land managers, both for biodiversity conservation and for the protection of livestock. Control programs primarily target single species within the context of biodiversity conservation or livestock practices, but their effectiveness in depressing predator densities is unclear because monitoring is limited or not conducted. Here, we review and discuss the outcomes of a workshop to identify research priorities for managing predation on native fauna by introduced predators in the Pilbara bioregion in Western Australia. We suggest that the control of introduced predators will be most effective if it is implemented at a landscape-scale comprising integrated predator management that considers interspecific (predator) interactions combined with standardised monitoring to measure the effectiveness and benefits of control. Four research themes were identified: (1) collation and collection of baseline data, (2) effective monitoring of introduced predators, (3) understanding functional (ecological) roles of introduced predators within the different ecosystem contexts, and (4) identifying novel complementary approaches to protect threatened species. These themes collectively include research areas that invest in foundational, ecological and alternative biological parameters in research to close knowledge gaps related to the functional roles of introduced predators in the landscape. Addressing these research themes will assist land managers to achieve outcomes that address the needs of both biodiversity conservation and pastoral production. This framework is timely given the ongoing investment in offset funding being mobilised in the region.
... Bettongs were first introduced to the predator-free paddock surveyed in this experiment in 1999 (Moseby et al., 2011) and had a density of 64.29 bettongs per km 2 at the time of this experiment. In 2014, a population of bettongs (N ¼ 353) was moved from the predator-free paddock into a 'predator paddock' with a low density of feral cats intended to replicate the lower range of feral cat densities reported in arid Australia (Legge et al., 2017). Cat density within this paddock ranged from 0.04 to 1.84 per km 2 over the 4 years since bettongs were translocated, with an estimated maximum of 48 individuals (Moseby et al. , 2020. ...
Article
Full-text available
Predator-protected populations of threatened fauna are important for species conservation, although these animals can quickly become predator naïve and can lack appropriate antipredator behaviour to enable them to persist once released. Controlled predator exposure can improve predator recognition and encourage avoidance behaviour, but little is known about the escape responses or fleeing behaviour of prey species. We compared the escape behaviour of a small marsupial, the burrowing bettong, Bettongia lesueur, between two fenced populations: one that had been purposely exposed to feral cats, Felis catus, while the other had been maintained without exotic predators. To quantify escape behaviour, bettongs were trapped and released into a temporary runway and a threatening stimulus was introduced to encourage them to flee. Measures relating to reactivity (escape initiation), escape speed and flight path (protean characteristics: agility, path irregularity and straightness) were recorded from video footage. Cat-exposed bettongs were significantly heavier than those from the cat-naïve population. We found a significant effect of the interaction of treatment (‘cat-exposed’ or ‘cat-naïve’) and body mass on overall escape behaviour. These differences were attributed to increased reactivity and escape speed in cat-exposed bettongs, but not protean characteristics of their flight path. Cat-exposed bettongs fled at an intensity where body size affected their escape performance (larger animals performed longer bounds and achieved faster speeds), while this body size effect was not evident for cat-naïve animals. This result suggests the cat-naïve animals were not as motivated to flee. Introducing low levels of predation pressure can successfully promote the development of antipredator behaviour through selection and/or individual learning, including a heightened escape response. Controlled predator exposure may be able to address some types of prey naïvety and lead to increased survival outside predator-free sanctuaries.
... Invasive predators are often widespread and established across large areas. For example, feral cats have been resident in Australia for around 200 years and now occupy 99.8% of Australia's land area (Legge et al., 2017). Traditional techniques such as trapping, shooting and exclusion fencing can sometimes be effective at local scales, but are expensive, time-consuming and generally ineffective over large scales (Bengsen, 2015;Department of Environment, 2015). ...
Article
Reducing the impacts of invasive predators is a key objective for conservation managers, livestock producers and human health agencies globally. The efficacy of invasive predator control programs, however, is highly variable. To improve control efficacy, managers require a fundamental understanding of the factors that contribute to the success or failure of a control program. Using a predator baiting program as a case study, we measured the efficacy of baiting as a control tool to significantly reduce feral cat (Felis catus) populations. We used camera traps and cat-borne GPS collars to monitor changes in feral cat populations at a baited site and an unbaited site, using a Before-After, Control-Impact (BACI) design. We also identified five key elements required for a successful baiting program (bait encounter rate, availability, attractiveness, palatability and lethality) and simultaneously measured these to identify areas for potential improvement. Baiting was ineffective at reducing feral cat populations; collared cat mortality was only 11% (1/9), with camera traps revealing negligible reductions in the number of cat detection events (9%), naïve occupancy (15%), and no significant change in the relative abundance of feral cats (F1,54 = 0.8641, P = 0.357). Several factors contributed to the poor control efficacy. Bait encounter rates were low, with cats active along tracks (where baits were laid) <4% of the time. Cats encountered only 14% (7/50) of monitored baits, but none were eaten. Initially, baits appeared attractive to cats; however meat ants and desiccation rapidly decreased bait palatability. Bait availability to cats declined rapidly, with 36% of monitored baits (18/50) removed by non-target species within the first 48 hours. The mortality of one collared cat and chemical assays confirmed that, on average, each bait contained sufficient 1080 to kill a large (>5 kg) feral cat. Our findings suggest that altering bait deployment patterns, increasing bait densities and improving bait palatability could potentially improve the efficacy of baiting programs to reduce feral cat populations. Our study provides a framework to measure and evaluate the key elements that contribute to efficacy of pest control programs, and to identify opportunities for improving outcomes of future control programs.
... Australia has been characterized by a significant loss of its terrestrial mammal fauna, with exotic carnivores implicated in the decline or extinction of many species (Woinarski et al., 2015). Exotic predator control is therefore a major focus of conservation efforts (Australian Government, 2015;Legge et al., 2017). This is the case in the iconic Booderee National Park, where a fox baiting program was intensified in 2003 (Roberts et al., 2006), with commensurate significant reductions in the rate of bait take and sand plot detections of foxes within the park (Fig. 3). ...
Article
The conventional approach to conserving threatened biota is to identify drivers of decline, instigate actions to mitigate threatening processes, and monitor interventions to test their effectiveness and ensure target species recover. In Australia, predation by introduced predators is a threatening process for many native mammals. Here we report the results of a 15 year monitoring study in an iconic Australian reserve, Booderee National Park, where exotic Red Fox (Vulpes vulpes) populations have been controlled through an intensive poison baiting program since 2003. Unexpectedly, we documented the collapse of native mammal fauna during this period, including fully arboreal species that should be largely unaffected by fox predation – such as the nationally Vulnerable Greater Glider (Petauroides volans) and Common Ringtail Possum (Pseudocheirus peregrinus). We used path analysis to explore potential causes of these unexpected declines. We found no compelling evidence to support hypotheses that competition with increasing native species, native predator release, or increases in native herbivores underpinned mammal declines. Beyond the path analysis, data from other studies completed both inside Booderee National Park and outside (where intensive fox baiting does not occur yet depleted fauna species remain), allowed us to rule out several drivers of change. The temporal declines we documented for arboreal marsupials were not anticipated nor explained by any clear mechanism. We propose the use of experimentally-guided reintroductions and translocations to: (1) restore empty niches such as the currently vacant apex mammal predator niche, (2) reconstruct the now depleted arboreal marsupial guild, and (3) further test key hypotheses associated with mammal decline. We also suggest that given the potential for perverse outcomes following large-scale management interventions (even those where there is high confidence of success), wildlife managers should consider maintaining reference areas (where there is no management intervention). Finally, as the declines we documented were unexpected and rapid, there is a clear need to develop more sensitive early warning signals to alert conservation managers to impending problems, allowing them to alter management regimes before major declines occur.
... Significant habitat loss has occurred in Australia in the 250 years since European colonization (Bradshaw, 2012). During this time, red foxes and feral cats (Felis catus) were introduced and are now widespread and abundant across most of mainland Australia (Dickman, 1996;Legge et al., 2017). Foxes benefit from habitat fragmentation as they are generalist predators (Shapira, Sultan & Shanas, 2008;Bino et al., 2010;Graham et al., 2012) able to exploit human-modified landscapes (Saunders et al., 1995;Hradsky et al., 2017). ...
Article
Habitat fragmentation can have detrimental impacts on native predators globally through the loss of habitat and associated impacts from introduced predators.The endangered spotted-tailed quoll (Dasyurus maculatus) is the largest marsupial carni-vore on mainland Australia and is sympatric with an introduced predator, the red fox (Vulpes vulpes). Spotted-tailed quolls are considered a forest-dependent species and are often associated with large, intact forested habitats where abundance of prey is high and competition with foxes is low. Spotted-tailed quolls are known to persist in some fragmented habitats in sympatry with foxes; however, the mechanisms facilitating this coexistence are unclear. For 15 months in 2018-19, we used camera traps to investigate whether coexistence between quolls and foxes in a fragmented landscape was facilitated by spatial and/or temporal separation of activity. We found no evidence of spatial separation, with quolls detected on the majority of cameras where foxes were detected. There was considerable temporal overlap between quolls and foxes (D 1 = 0.71-0.81) and no evidence that fox presence influenced the temporal activity of quolls (D 1 = 0.76-0.80). Furthermore, there was no evidence of within-night spatiotemporal avoidance between quolls and foxes (R 2 < 0.01). Our findings suggest that quolls do not offset their spatial and temporal activity to avoid foxes in this fragmented landscape. The spatial and temporal sympatry between quolls and foxes is possibly facilitated by low fox density at this site, suggested by low fox detections. The lack of separation between quoll and fox activity could also explain why quolls become locally extinct in other fragmented landscapes because quolls may not modify their activity to avoid foxes. Future research should focus on investigating quoll and fox interactions along a gradient of fox densities and assess if higher fox densities influence spatial and temporal coexistence with quolls in fragmented landscapes.
... That is why it is useful in this collection of papers not to restrict our interest in human-cat interactions and the behaviors they yield to the domesticated cats eating preprepared cat food from a can or a dry food package and leaving their litter in an absorbent clay cat box. The cats that do live outside their "homes, " beyond the bounds of domesticity as we put it, and sometimes in large numbers (11,12), raise questions about human interests in and concerns about cats that merit attention even in a set of papers primarily focused on those human-cat interactions that occur within the bounds of domesticity. ...
Article
Full-text available
Although human interactions with cats are often even typically analyzed in the context of domesticity, with a focus on what sorts of interactions might make both people and cats “happy at home,” a large number of cats in the world live, for one reason or another, beyond the bounds of domesticity. Human interactions with these more or less free-living cats raise deeply controversial questions about how both the cats and the people they interact with should be sensibly managed, and about the moral imperatives that ought to guide the management of their interactions through the laws and public policies regulating both human interactions with pets and with wildlife. We review the geography of human interactions with cats living beyond the bounds of domesticity. We acknowledge the contributions made to ideas about how to manage cats by the animal protection movement. We review the tensions that have emerged over time between advocates for the eradication of free-living cats, because of the impacts they have on native wildlife species, and those who have imagined alternatives to eradication, most notably one or another variant of trap-neuter-return (TNR). The conflict over how best to deal with cats living beyond the bounds of domesticity and their wildlife impacts raises the prospect of stalemate, and we canvass and critique possibilities for moving beyond that stalemate.
... ekor kucing. Jumlah tersebut lebih rendah dibandingkan dengan populasi kucing di daerah lain, dan jumlah yang fluktuatif ini dipengaruhi oleh musim di benua tersebut (Legge et al., 2017). Penelitian ini menunjukkan bahwa jumlah feral cat di setiap daerah memiliki jumlah yang bervariasi. ...
Article
Full-text available
Abstrak: Feral cat merupakan kucing domestik liar yang umumnya hidup berkelompok di sekitar habitat manusia. Kucing domestik liar cenderung memanfaatkan sumber daya antropogenik dibanding mencari makan sendiri. Penelitian ini bertujuan untuk membandingkan serta menganalisis perilaku harian dan aktivitas pencarian makan antar kelompok kucing domestik liar di sekitar dua kantin Kampus Institut Pertanian Bogor (IPB). Metode scan sampling digunakan untuk mengamati aktivitas harian rata-rata dengan interval waktu 10 menit, selanjutnya metode ad libitum sampling untuk melihat perilaku makan dan interaksi antara kucing dengan manusia dalam mendapatkan makanan. Perilaku harian dibagi dalam 3 kategori, yaitu afiliatif, pemeliharaan diri, dan pertemuan negatif. Berdasarkan hasil penelitian, perilaku harian kucing di kedua kantin didominasi oleh perilaku perawatan diri (76,62% dan 65,17%), diikuti oleh perilaku afiliatif (18,06% dan 29,61%) dan perilaku negatif (5,32% dan 5,22%). Tidak terdapat perbedaan signifikan antara perilaku kucing di pagi hari dan siang hari (p-value >0,05). Interaksi antara kucing dan manusia yang memiliki frekuensi tertinggi yaitu perilaku kucing mendekati manusia. Tidak terdapat perbedaan signifikan pada interaksi antara kucing dan manusia di pagi hari dan siang hari (p-value> 0.05).
... Cats are abundant throughout the region, with estimated population densities of 0.03-0.14 cats ha À1 (Hamer et al. 2021), an order of magnitude higher than the estimated average density of 0.0027 cats ha À1 across Australia (Legge et al. 2017). The closest native analogue, the Spotted-tailed Quoll, occurs at densities between 0.002 and 0.007 quolls ha À1 (Hamer et al. 2021). ...
Article
Temperate woodlands are amongst the most threatened ecosystems in Australia because the land on which they occur is highly suited to agriculture. Two hundred years of habitat loss and fragmentation in the Midlands agricultural region in Tasmania have led to widespread declines in native vertebrates and landscapes with populations of predators including feral Cat (Felis catus) and the native-invasive Noisy Miner (Manorina melanocephala). Ecologists at the University of Tasmania co-designed mechanistic animal-centric research on mammals and birds in the Midlands to inform vegetation restoration carried out by Greening Australia that would support the recovery of wildlife species. We used species-appropriate technologies to assess the decisions made by individual animals to find food and shelter and to disperse across this fragmented landscape, and linked these, together with patterns of occupancy, across multiple spatial and temporal scales. We focussed on a native (Spotted-tailed Quoll, Dasyurus maculatus) and an invasive (feral Cat, Felis catus) carnivore, a woodland-specialist herbivore (Eastern Bettong, Bettongia gaimardi) and woodland birds including the native-invasive Noisy Miner. Our results, which show intense predatory and competitive pressure of cats and populations of Noisy Miner on native fauna, highlight how grounding restoration in the context of ecological interactions is essential to success in managing the impacts of invasive species in restored landscapes. Successful restoration will require innovative approaches in plantings and field experimentation with artificial refuges, to reduce habitat suitability for the Noisy Miner and cats and provide refuges for native mammals and birds to live in the landscape where cats also occur. Our results emphasise the significance of structural complexity of restoration plantings for supporting the recolonisation and persistence of native fauna. At large landscape-scale, we demonstrate the importance of retaining small habitat elements, including ancient paddock trees, pivot irrigation corners and small, degraded remnants, in facilitating occupancy and dispersal and, therefore, persistence of wild animals across this agricultural region.
... Feral cats (Felis catus), cats that live in the wild and can survive without human reliance or contact, are recognised as a key threatening process to native species in Australia [1][2][3] and around the world [4,5]. Predation by feral cats has been demonstrated to threaten the persistence of many native species [6,7], and causes billions of dollars damage to the natural and agricultural environment [8] alongside disease transmission [9]. ...
Article
Full-text available
Abstract: Feral cats are difficult to manage and harder to monitor. We analysed the cost and the efficacy of monitoring the pre-and post-bait abundance of feral cats via camera-traps or track counts using four years of data from the Matuwa Indigenous Protected Area. Additionally, we report on the recovery of the feral cat population and the efficacy of subsequent Eradicat ® aerial baiting programs following 12 months of intensive feral cat control in 2019. Significantly fewer cats were captured in 2020 (n = 8) compared to 2019 (n = 126). Pre-baiting surveys for 2020 and 2021 suggested that the population of feral cats on Matuwa was very low, at 5.5 and 4.4 cats/100 km, respectively, which is well below our target threshold of 10 cats/100 km. Post-baiting surveys then recorded 3.6 and 3.0 cats/100 km, respectively, which still equates to a 35% and 32% reduction in cat activity. Track counts recorded significantly more feral cats than camera traps and were cheaper to implement. We recommend that at least two methods of monitoring cats be implemented to prevent erroneous conclusions.
... Cats are putatively the primary threat to savanna mammals in northern Australia (Johnson, 2006;Frank et al., 2014;Ziembicki et al., 2015;McGregor et al., 2016;Tuft et al., 2021). While feral cats are ubiquitous across the entire study region (Legge et al., 2017), the few survey sites where cats were recorded all had very low mammal abundance and richness compared to sites where cats were not recorded. This suggests a strong local influence of cat activity on mammal populations where cat activity is high. ...
Article
Full-text available
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 Frontiers in Ecology and Evolution | www.frontiersin.org 1 November 2021 | Volume 9 | Article 739817 Radford et al. Savanna Mammals and Disturbance Mosaics 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.
... Free-roaming domestic cats (Felis catus; hereafter 'cats') are both common and found at high densities in urban areas worldwide (Hansen et al., 2018;Legge et al., 2016;Gehrt et al., 2013). Cats with outdoor access are subjected to numerous risks, including possible vehicle collisions (Rochlitz, 2003), heightened exposure to zoonotic disease (Gehrt et al., 2013;Roseveare et al., 2009), exposure to toxins (Tan et al., 2020;Berny et al., 2010), increased potential for abuse (Bonela Gomes et al., 2021), and possible predation by native predator species (Larson et al., 2020;Tan et al., 2020;Kays et al., 2015). ...
Article
The ecological impact of free-roaming domestic cats (Felis catus) is well-studied. However, despite receiving considerable attention in both the scientific and popular literature, predation behavior is rarely an explicit consideration when developing cat population management plans. We used motion-activated wildlife cameras to document predation events by cats in Washington, D.C. (U.S.A), and assessed the relationships between predation and local environmental characteristics. Our analyses reveal that predation by cats is greatest where supplemental food is most abundant, and that the probability of a cat preying upon a native species increases closer to forest edges. Conversely, we found that the probability of a cat depredating a non-native brown rat increases with increasing distance from forest edges. Therefore, we recommend the implementation of cat exclusionary buffer zones around urban forests and that free-roaming domestic cat management policies explicitly consider the spatial location of cat-feeding sites. Our findings provide a data-driven approach to free-roaming cat management.
... Feral cats (Felis catus), cats that live in the wild and can survive without human reliance or contact, are recognised as a key threatening process to native species in Australia [1][2][3] and around the world [4,5]. Predation by feral cats has been demonstrated to threaten the persistence of many native species [6,7], and causes billions of dollars damage to the natural and agricultural environment [8] alongside disease transmission [9]. ...
Preprint
Feral cats are both difficult to manage and harder to monitor. We analysed the cost-efficacy of monitoring the pre- and post-bait abundance of feral cats via camera-traps or track counts using four years of data from the Matuwa Indigenous protected Area. Additionally, we report on the recovery of the feral cat population and the efficacy of subsequent Eradicat® aerial baiting programs following 12 months of intensive feral cat control in 2019 that consisted of aerial baiting and leg-hold trapping. Significantly fewer cats were captured in 2020 (n = 8) compared to 2019 (n = 126). Pre-baiting surveys for 2020 and 2021 suggested that the population of feral cats on Matuwa was very low, at 5.5 and 4.4 cats/100 km respectively, which is well below our target threshold of 10 cats/100 km. Post-baiting surveys then recorded 3.6 and 3.0 cats/100 km respectively, which still equates to a 35% and 32% reduction in cat activity. Track counts recorded significantly more feral cats than camera traps and were cheaper to implement. We recommend that at least two methods of monitoring cats be implemented to prevent erroneous conclusions.
... Le site de Grande Anse abrite plusieurs espèces indigènes et endémiques insulaires avec des densités de chats élevées comparables à des zones urbaines(Legge et al. 2017). Au regard des impacts désastreux des chats sur la biodiversité native insulaire(Medina et al. 2011), Grande Anse représente un enjeu de conservation important où la gestion des chats errants doit être une des priorités. ...
Thesis
The southern coastal cliffs of Reunion Island (tropical island in the Western Indian Ocean) host a unique flora and fauna: the last populations of Manapany day gecko (Phelsuma inexpectata, an endemic reptile in critically endangered), relics of indigenous vegetation including endemic and/or threatened species (e.g.: Euphorbia viridula, Psiadia retusa, Latania lontaroides) and breeding colonies of three native seabirds (white-tailed tropicbirds, Phaethon lepturus ; brown noddies, Anous stolidus and wedge-tailed shearwaters, Ardenna pacifica). This biodiversity is threatened by habitat transformations due to invasive plants, human activities (urbanization and culture) and invasive mammals (especially cats, felis catus, and rodents). Moreover, little is known about biology and ecology of the native species, which does not allow the implementation of effective conservation strategy. Based on hand-in-hand collaboration between researchers (UMR ENTROPIE) and managers (CDL, NOI, AVE2M) working on different taxa, the aim of this thesis was to provide multispecies conservation prescriptions on cliffs study for the Manapany day gecko and the wedge-tailed shearwater. We undertook a progressive approach from describing of species conservation states through understanding threatening processes to the prescription and monitoring of management actions. Three research topics were targeted: (i) demography and reproductive biology, (ii) terrestrial habitat requirements, and (iii) impacts and management of invasive mammals (especially cats). Our results highlighted the critical conservation state of Manapany day geckos and wedge-tailed shearwaters populations. Invasive plants and mammals (especially cats) are threats to the conservation of native biodiversity. We provide several local and general conservation prescriptions, including management of invasive species, multispecies terrestrial habitat restoration and captive head-start program of Manapany day geckos. Several of these prescriptions were implemented during this thesis (invasive species management and captive breeding program) and monitored as part of active adaptive management approach. This multispecies study at the interface between research and management must be continued and supported by a strong federating regulatory tool as a National Nature Reserve (NNR). Keywords: Ardenna pacifica, biological invasions, captive head-start program, Capture-Mark-Recapture, cat control, cat tracking, conservation biology, Felis catus, habitat selection, multispecies management, Phelsuma inexpectata, population dynamics, Population Viability Analyses, Reunion Island, Spatial Mark-Resight, tropical island
... Between 25-85% of owned cats are kept indoors in the United States and Canada (25, 28) and >80% are sterilized (29), suggesting that while management strategies must account for both groups, unowned cats likely contribute the most to cat population replenishment and account for the majority of concerns. Unowned cats will also generally be found at higher density in modified environments where shelter-based programs tend to predominate, vs. natural habitats in which other methods may be deployed (30). Importantly, although public and published debate has tended to center on cat "colonies" (cats living in large aggregates around a food source), such groups account for <5% of unowned cats (31)(32)(33)(34)(35). Scattered individual cats accessing multiple food sources are difficult to detect compared to the more visible and troublesome groups. ...
Article
Full-text available
Substantial societal investment is made in the management of free-roaming cats by various methods, with goals of such programs commonly including wildlife conservation, public health protection, nuisance abatement, and/or promotion of cat health and welfare. While there has been a degree of controversy over some of the tactics employed, there is widespread agreement that any method must be scientifically based and sufficiently focused, intensive and sustained in order to succeed. The vast majority of free-roaming cat management in communities takes place through local animal shelters. Throughout the 20th century and into the 21st, this consisted primarily of ad hoc admission of cats captured by members of the public, with euthanasia being the most common outcome. In North America alone, hundreds of millions of cats have been impounded and euthanized and billions of dollars invested in such programs. Given the reliance on this model to achieve important societal goals, it is surprising that there has been an almost complete lack of published research evaluating its success. Wildlife conservation and public health protection will be better served when debate about the merits and pitfalls of methods such as Trap-Neuter-Return is grounded in the context of realistically achievable alternatives. Where no perfect answer exists, an understanding of the potential strengths and shortcomings of each available strategy will support the greatest possible mitigation of harm—the best, if still imperfect, solution. Animal shelter function will also benefit by discontinuing investment in methods that are ineffective as well as potentially ethically problematic. This will allow the redirection of resources to more promising strategies for management of cats as well as investment in other important animal shelter functions. To this end, this article reviews evidence regarding the potential effectiveness of the three possible shelter-based strategies for free-roaming cat management: the traditional approach of ad hoc removal by admission to the shelter; admission to the shelter followed by sterilization and return to the location found; and leaving cats in place with or without referral to mitigation strategies or services provided by other agencies.
... This has led to various local municipal councils introducing regulations such as designated cat-free zones, requirements for cats to wear bells, dusk to dawn curfews, and requirements to keep cats inside at all times (11,12). Although cat owners are subject to legislation regarding containment, in urban and peri-urban areas, between 0.7 and 1.5 million stray cats are fed by people who do not perceive they own them (13,14). In many countries other than Australia, trap-neuter-return is used as a method to control urban stray cats and involves desexing them and returning them to the location where they were caught, preferably with an identified carer (15)(16)(17)(18)(19). ...
Article
Concerns about the impact of pet dogs and cats on native wildlife populations have shaped pet control legislation, despite there being scant research of their impact in urban areas. Using an online questionnaire, we obtained data from 662 Australian dog and cat owners who had observed their pets capture prey in the previous 6 months. Of the pets observed to catch prey, dogs caught a median of 2 mammals, 2 birds, 2 reptiles, and 3 amphibians, whereas cats caught a median of 3 mammals, 2 birds, 4 reptiles, and 2 amphibians. Of mammals caught by dogs and cats, 88 and 93%, respectively, were identifiable as introduced mice, rats, and rabbits. Of pets that caught prey, a substantial proportion caught native animals (62% of dogs and 47% of cats). However, median numbers of native animals caught per dog (2) or cat (3) over 6 months were low. Small skinks and lizards comprised the greatest proportion for dogs and cats, but dogs also caught larger native prey (e.g., possums, kangaroos, and wallabies). Most birds caught by dogs and cats were common or introduced (dogs: crested pigeons and lorikeets; cats: noisy miners and rosellas). To design measures that will effectively protect Australia's native wildlife, thorough understanding of the role dogs and cats play in Australian urban ecosystems is required. These findings can inform that understanding, and assist with development of management strategies for urban dogs and cats, and as well as directing resources to efforts that will most protect urban wildlife.
... For example, predation by introduced predators is a key driver for post-fire mortality in native small mammals (McGregor et al., 2016). Variation in cat density has been mapped at a national scale (Legge et al., 2017), but such models are poor at predicting cat density at site scales, especially after severe fire. Post-fire control of introduced predators can be carried out at massive scales (e.g. ...
Article
Full-text available
Aim The incidence of major fires is increasing globally, creating extraordinary challenges for governments, managers and conservation scientists. In 2019–2020, Australia experienced precedent‐setting fires that burned over several months, affecting seven states and territories and causing massive biodiversity loss. Whilst the fires were still burning, the Australian Government convened a biodiversity Expert Panel to guide its bushfire response. A pressing need was to target emergency investment and management to reduce the chance of extinctions and maximise the chances of longer‐term recovery. We describe the approach taken to rapidly prioritise fire‐affected animal species. We use the experience to consider the organisational and data requirements for evidence‐based responses to future ecological disasters. Location Forested biomes of subtropical and temperate Australia, with lessons for other regions. Methods We developed assessment frameworks to screen fire‐affected species based on their pre‐fire conservation status, the proportion of their distribution overlapping with fires, and their behavioural/ecological traits relating to fire vulnerability. Using formal and informal networks of scientists, government and non‐government staff and managers, we collated expert input and data from multiple sources, undertook the analyses, and completed the assessments in 3 weeks for vertebrates and 8 weeks for invertebrates. Results The assessments prioritised 92 vertebrate and 213 invertebrate species for urgent management response; another 147 invertebrate species were placed on a watchlist requiring further information. Conclusions The priority species lists helped focus government and non‐government investment, management and research effort, and communication to the public. Using multiple expert networks allowed the assessments to be completed rapidly using the best information available. However, the assessments highlighted substantial gaps in data availability and access, deficiencies in statutory threatened species listings, and the need for capacity‐building across the conservation science and management sectors. We outline a flexible template for using evidence effectively in emergency responses for future ecological disasters.
... It is possible that a negative effect of domestic cats was not detectable given their low occurrence. While free-roaming cats do represent a large threat to biodiversity (Legge et al., 2017), dogs may be more harmful to native species occurrence where cats are uncommon (Morin et al., 2018). ...
Article
1. Land use intensification, by which habitat loss, habitat fragmentation, and increased land ownership subdivision occurs, represents one of the largest threats to biodiversity. The extent to which land use intensification affects the presence of native mesocarnivores is largely unexplored, with great implications for all working landscapes where agriculture and native wildlife co‐occur. 2. We obtained mesocarnivore detection/non‐detection data from 180 4‐km2 sampling units in agricultural landscapes of southern Chile from January‐April 2019. We used these data to (1) investigate the associations of private land ownership subdivision, forest fragmentation, and forest loss with the occurrence of mesocarnivores using single‐species occupancy models, (2) assess patterns of mesocarnivore co‐occurrence with free‐roaming domestic mesocarnivores (e.g., cats and dogs) using two‐species occupancy models, and (3) determine whether co‐occurrence of native and domestic mesocarnivores led to alterations in species’ temporal activity. 3. Land ownership subdivision, rather than habitat loss or fragmentation, had the greatest impact on native mesocarnivore occurrence, with some influence of domestic dogs. Mesocarnivore community occurrence varied from a native to domestic species composition as private land ownership subdivision increased. Native mesocarnivores altered their behaviour temporally when co‐occurring with domestics. Lastly, the presence of domestic dogs was associated with an absence of native mesocarnivores, which merits further investigation into the contribution of domestic dogs to a defaunation process in agricultural areas. 4. Policy implications. Our evidence supports focusing efforts in three key dimensions to advance biodiversity conservation in agricultural landscapes. First, private land subdivision represents a robust proxy for measuring anthropogenic impacts on mesocarnivores, and we advocate its use to inform agricultural policy to mitigate a potential defaunation process. Secondly, there is a need to further engage with landowners and evaluate values, motivation, willingness and action to protect remnant native vegetation and slow land use change. And, lastly, improvements to legislation and conservation marketing strategies on responsible pet ownership are critical to ameliorating the negative impacts of dogs on native wildlife species.
... Note: relative abundances should not be compared between Oolambeyan and the other three sites due to detectability differences. and semi-arid zone of Australia (0.18 cats/ km 2 : Legge et al. 2017). In contrast, our estimates are much lower than those of 0.89 cats/km 2 reported for Yathong by Newsome et al. (1989). ...
Article
The feral cat (Felis catus) is a key threat for many Australian native critical weight range animals (i.e. species of intermediate body mass between 35 and 5,500 g that are particularly susceptible to introduced predators) and estimates of cat abundance are required for assessing changes in population size. Camera trapping is a much used tool for monitoring and estimating population sizes, including with mark–resight techniques, for which the more robust estimators require individual identification. Many feral cats are individually marked, which potentially makes them suitable for such monitoring programmes. We sought to determine what proportion of cat images captured during a commonly used field deployment of camera traps could be individually identified, and whether aspects of camera trap deployment affected the rate of individual identification. Camera trap arrays were established in four conservation areas in south-west New South Wales, Australia, during 2017 (range 39–50 camera traps per site). The unlured camera traps were continuously deployed over 26 months, with five or 10 images captured per trigger. Where possible, cats were individually identified based on phenotypic characteristics. Over the deployment period (95,413 camera trap nights; CTN), we obtained 2.25 million images, of which 13,845 contained feral cats. Feral cat events (i.e. a series of images taken <5 minutes apart on the same camera trap) ranged from 0.004 to 0.047 events per CTN across the four conservation areas, with 85 individual cats identified. Depending on camera settings, few images could be assigned to a known individual (12.2–27.4% of feral cat events per site were of identifiable individuals). Minimum number known alive were 10–46 feral cats per site, with resultant quarterly densities ranging from 0.01 to 0.16 cats/km². With our current deployment, individual identification of feral cats was insufficient for estimating abundance or survival using individual mark–resight methods. Such deployment deficits limit the ecological conclusions that can be drawn from ours and similar studies.
... On a global scale, invasive generalist predators have caused extensive biodiversity loss (Medina et al. 2011;Doherty et al. 2016). In Australia, feral cats (Felis catus) are distributed right across the continent (Legge et al. 2017), have caused the extinction of at least 22 mammalian species, and are thought to have contributed to the extinction of many others (Woinarski et al. 2014). Cats negatively impact native wildlife through predation and competition, and also through their role in transmitting parasites and disease (Nishimura et al. 1999;Veitch 2001;Medway 2004;Phillips et al. 2007). ...
Article
Across Australia, feral cat (Felis catus) control and eradication programs are conducted to conserve threatened and vulnerable species. Controlling feral cats effectively at a landscape scale, particularly in remote woodland habitats, remains a significant challenge. Unfortunately, some standard feral cat control methods, such as shooting and cage trapping, require road access. Poison baiting is one of the few methods available to control feral cat populations in remote and inaccessable areas. We aimed to examine the impact of a Curiosity ® (Scientec Research PTY LTD, Melbourne, Australia) baiting program on the feral cat population found in continuous woodland habitat of the Dudley Peninsula, on Kangaroo Island, South Australia. The density of cats was monitored using camera traps set up across both treatment and control sites using a before-after control-impact approach. Feral cat density was calculated using a spatially explicit capture-recapture framework. In addition, 14 feral cats were GPS collared at the treatment site, and their status and location, before and after baiting, was monitored. At the treatment site after baiting, feral cat density fell from 1.18 ± 0.51 to 0.58 ± 0.22 cats km −2. In total, 14 feral cats were GPS collared, and of those, eight were detected within the treatment zone during and after bait deployment. Six of those eight cats died shortly after baiting, likely from bait consumption. A new individual cat was detected in the treatment zone within 10 days of baiting, and within 20 days, four new individuals were detected. Both before and after baiting, the number of feral cat detections was highest on roads, suggesting cat recolonisation of baited areas may be assisted by roads. Curiosity baiting was found to be an effective method for reducing the density of feral cats in continuous woodland habitats of Kangaroo Island. Roads may act as access routes aiding cat recolonisation. Curiosity baiting programs on Kangaroo Island (and elsewhere) would benefit from incorporating follow-up control, particularly along roads, to target feral cats re-colonising the area.
Article
Bartonella henselae is a zoonotic Gram-negative Bacillus associated with self-limited regional lymphadenopathy. In recent decades, an expanding spectrum of clinical manifestations has been described, in part, due to improved diagnostics. However, updated epidemiological data are sparse. We retrospectively reviewed the clinical features of 31 patients with B. henselae infection older than 15 years from 2005 to 2019, in the tropical Top End of Australia. Our annual disease incidence of 1.3 cases per 100,000 population is lower than that in the national database surveillances in the United States, but the hospitalization incidence of 0.9 per 100,000 population in our region is higher than those reported in the literature, with an average length of stay of 9 days. Patients were more commonly male, aboriginal, and aged less than 14 years (median age: 7 years), living in a rural setting with presentation during our monsoon season. The disease spectrum included lymph node disease (74%), organ peliosis, endocarditis, cutaneous lesions, parapharyngeal abscess, parotitis, and neurologic and ocular syndromes. Lymph node disease was far commoner in children than the more serious systemic B. henselae infections associated with adults (P = 0.074). Although no deaths were reported, significant morbidities were observed. Two endocarditis cases presented with glomerulonephritis, and hematological and neurological features mimicking vasculitis, and consequently received immunosuppressants. One case was only diagnosed after representation with serial embolic strokes. Given the heterogeneity of disease manifestations with nonspecific symptoms and significant consequences, a timely and accurate diagnosis is needed to avoid unnecessary treatments or interventions.
Article
Full-text available
Invasive predators, land clearing and altered fire regimes have been implicated in species decline and extinction worldwide. Enhanced knowledge of how these factors interact and influence medium-sized mammals is warranted. We tested three hypotheses using occupancy data for a diverse mammal assemblage including three threatened species, five common species, two introduced mesopredators and an apex predator in eastern Australia. We hypothesised that occupancy of mammal species within the assemblage would be influenced by (i) the physical environment (rainfall, vegetation type and elevation), (ii) habitat disturbance (number of fires and habitat fragmentation) and (iii) mesopredator release, whereby occupancy and/or detection of medium-sized mammals are influenced by mesopredators, the feral cat ( Felis catus ) and the red fox ( Vulpes vulpes ), which are influenced by an apex predator, the dingo ( Canis familiaris ). We utilised camera-trapping data from 173 sites (692 camera locations) across a north–south gradient spanning ~ 1500 km in eastern Australia. Although hypotheses i (physical environment) and ii (habitat disturbance) are not mutually exclusive, we show that the variables considered in each were only weakly correlated. We conducted occupancy modelling to investigate the physical environment and habitat disturbance hypotheses. We conducted co-occurrence modelling to investigate interactions between species. The physical environment hypothesis best supported occupancy models for six mammal species: red-necked pademelon ( Thylogale thetis ), bandicoots ( Isoodon macrourus and Perameles nasuta ), swamp wallaby ( Wallabia bicolor ), red-necked wallaby ( Macropus rufogriseus ), eastern grey kangaroo ( Macropus giganteus ) and feral cat. The disturbance hypothesis best supported occupancy models for four mammal species: long-nosed potoroo ( Potorous tridactylus ), red-necked pademelon and both mesopredators. Support for the mesopredator release hypothesis was equivocal. Large macropods showed site avoidance towards the red fox. Four species showed higher detection at sites where mesopredators were not detected. The fox showed a negative detection interaction to the dingo and the cat did not. Our study highlights how factors such as rainfall, land clearing, elevation and number of fires influence the occupancy of species within a diverse mammal assemblage at the macroecological scale. Our findings have implications for the conservation of threatened species in managed landscapes and suggestions for further research following the recent 2019–2020 wildfires.
Article
Full-text available
The choice of words we use often conveys specific meanings and tone to a topic. Hence, the words that we use in conservation science often have important ramifications in scientific, legal, and social contexts. The management of free-ranging cats is an important example, because of the animal welfare, predation, and public health implications. In this context, one set of words that has recently arisen outside of conservation but has particular relevance for it and many other fields is ‘community cat.’ As we note, through an evaluation of the literature, ‘community cat’ is almost always used as a synonym for unowned, free-ranging cats. Such rebranding is significant for conservation, policy, and management because it implies community ownership of animals without, in many cases, explicit agreement from the community. As such, there is a need to understand the history of the term, what it really means, and its implications for the advancement of conservation biology, natural resource management, veterinary medicine, and animal welfare.
Article
Drylands range across more than half of the global terrestrial area and harbour about a quarter of continental vertebrate species, many of them endemic. However, this fauna is being increasingly threatened, in particular the one that inhabits deserts, one of the last biomes on earth. This work tracks the most relevant global change drivers acting on drylands, especially in deserts and arid regions, the conservation actions being developed, and the research needs for vertebrate conservation, following IUCN standar-dised classification schemes. Using the Sahara-Sahel wetlands as case study, it is provided a detailed examination of these aspects to support regional biodiversity conservation and human welfare. Deserts and arid regions are threatened by the synergistic effects of increasing development of urban areas, agriculture, energy production, mining, transportation and service corridors, resulting in pollution, invasive species, human intrusions and disturbance, biological resource overuse and in general, natural system modifications. In addition, climate change together with social underdevelopment of many desert-range countries places the mitigation of threat factors in a large and complex web of global-local societal challenges. Conservation actions targeting land/ water and species protection and management, as well as education, awareness, capacity building, and legislation measures to increase livelihood development, are being developed. Additional research efforts are need to enhance biodiversity conservation planning, monitoring biodiversity and land-degradation status (based on Essential Biodiversity Variables), and quantification of socioeconomic factors associated with sustainable use of natural resources and human development. Sahara-Sahel wetlands are important life-support systems for both humans and vertebrates, the last vulnerable to listed global threats. They offer framework scenario to revert current environmental and societal challenges in deserts. Long-term conservation of desert vertebrate biodiversity requires appropriate policy instruments to promote sustainable use of natural resources. Raising environmental alertness within local communities of uniqueness of desert biodiversity is needed to promote policy change.
Article
Full-text available
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. Methods In 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. Conclusions These 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.
Article
en • Cats Felis catus, in all their forms (domestic, free‐roaming/stray and feral), have been identified as a major global threat to biodiversity, especially birds and small mammals. However, there has been little previous consideration of the extent and impact of predation of bats by cats, or of whether specific characteristics make certain species of bats particularly vulnerable to predation by cats. • We reviewed the impact of cats on bats, based on a collation of scientific literature and the International Union for Conservation of Nature (IUCN) Red List database. Our aim was to produce a synthesis of the extent to which cats prey upon and threaten bats. We also collated available data on cat diet, which provide information on predation rates of bats by cats. • Few studies (n = 44) have identified bat species preyed upon or threatened by cats, with a disproportionate number of studies from islands. In these studies, 86 bat species (about 7% of the global extant tally) are reported as preyed upon or threatened by cats, and about one quarter of these species are listed as Near Threatened or threatened (IUCN categories Critically Endangered, Endangered, or Vulnerable). In IUCN Red List assessments, cats are more frequently mentioned as a threat to threatened or Near Threatened bat species than to non‐threatened species (IUCN category Least Concern). • In studies reporting on the incidence of bats in cat dietary samples (scats, stomachs and guts), the frequency of occurrence of bats in samples averaged 0.7 ± 2.1% (mean ± standard deviation; n = 102). Many studies had sample sizes that were too small to be likely to detect bats. • All forms of cat are reported to kill bats, and such predation has been reported in all major terrestrial habitats. We conclude that predation by cats is an under‐appreciated threat to the world’s bat species. Abstract fr RESUMÉ EN FRANÇAIS • Les chats Felis catus, sous toutes leurs formes (domestiques, errants ou harets), ont été identifiés comme une menace mondiale majeure pour la biodiversité, en particulier pour les oiseaux et les petits mammifères. Cependant, l'ampleur de ce phénomène et l'impact de la prédation exercée sur les chauves‐souris par les chats n'ont guère été pris en compte jusqu'à présent. En particulier la question de savoir si des caractéristiques spécifiques rendent certaines espèces de chauves‐souris particulièrement vulnérables à la prédation par les chats reste en suspens. • Nous avons examiné l'impact des chats sur les chauves‐souris, en croisant les informations issues de la littérature scientifique sur le sujet et celles disponibles dans la base de données de la liste rouge de l'Union Internationale pour la Conservation de la Nature (UICN). Notre objectif était de produire une synthèse mondiale visant à estimer dans quelle mesure les chats s'attaquent aux chauves‐souris et constituent une menace. Nous avons également rassemblé les données disponibles sur le régime alimentaire des chats, qui fournissent des informations sur les taux de prédation des chauves‐souris par les chats. • Peu d'études (n = 44) ont permis d’identifier des espèces de chauves‐souris prédatées et/ou menacées par les chats, un nombre disproportionné d’entre elles concernent les écosystèmes insulaires. Ces études ont permis d’identifier 86 espèces de chauves‐souris (environ 7 % des espèces mondiales) représentant des proies ou étant directement menacées par les chats ; environ un quart de ces espèces sont classées comme "quasi menacées" ou "menacées" (catégories de l'UICN : En danger critique d'extinction, En danger ou Vulnérable). Dans les évaluations de la Liste rouge de l'UICN, les chats sont plus fréquemment mentionnés comme une menace pour les espèces de chauves‐souris menacées ou quasi menacées que pour les espèces non menacées (catégorie de l'UICN "Préoccupation mineure"). • Dans les études analysant le régime alimentaire des chats (excréments, estomacs et tubes digestifs) la fréquence d'occurrence des chauves‐souris dans les échantillons était en moyenne de 0.7 ± 2.1 % (moyenne ± écart‐type ; n = 102). Dans de nombreux travaux, la taille des échantillons était trop petite pour permettre de détecter la prédation sur des chauves‐souris. • Toutes les formes de chats s'attaquent aux chauves‐souris, et cette prédation a été signalée dans tous les principaux habitats terrestres. En conclusion, la prédation des chauves‐souris par les chats apparait être une menace sous‐estimée au niveau mondial.
Article
Full-text available
Predation is a key factor contributing to the failure of reintroductions of vertebrates but there is variation in predation risk between individuals. Understanding the traits that render some animals less susceptible to predation, and selecting for these traits, may help improve reintroduction success. Here, we test whether prior exposure to predators or specific morphological and/or behavioural attributes explained variation in post‐reintroduction survival in a moderate and low predator density environment. We exposed a population of the threatened burrowing bettong (Bettongia lesueur) to controlled densities of feral cats (Felis catus) for ≥3 years. We then conducted two translocations of cat‐exposed and control populations that had no exposure to predators to a new site where cats were present at moderate, then low density. Variation in survival of burrowing bettongs was not explained by prior predator exposure to predators or measured individual traits at moderate cat density. At lower cat densities, males died sooner and burrowing bettongs with larger hind feet survived longer. Although prior cat‐exposure did not confer a survival advantage at low cat densities, the cat‐exposed burrowing bettong population had larger hind feet (n = 44) compared to the control population (n = 45) suggesting that trait divergence between cat‐exposed and non‐cat‐exposed burrowing bettongs may not yet be sufficient for improved survival. Alternatively, prior predator exposure may not confer a survival advantage because they are “outgunned” by evolutionarily novel cats. Predation is a major problem thwarting successful reintroductions world‐wide. Exposing populations to predators over longer time periods and periodically testing survival will be required to determine whether pre‐release predator exposure prepares animals for life with novel predators. Our study highlights the importance of reducing predator activity at release sites prior to reintroduction to enable any benefits from intraspecific variation in survival traits to be realised. We tested whether prior exposure to predators or specific morphological attributes explained variation in post‐reintroduction survival of burrowing bettongs in a moderate and low predator density environment. Variation in survival was not explained by prior exposure to predators or measured individual traits at moderate cat density, but at lower cat densities males died sooner and burrowing bettongs with larger hind feet survived longer. Predation is a major problem thwarting successful reintroductions world‐wide, and exposing populations to predators over longer time periods and periodically testing survival is required to determine whether pre‐release predator exposure prepares animals for life with novel predators.
Article
Residential gardens can provide essential opportunities for native wildlife and represent a valuable way of creating new habitats. Bandicoots (marsupial family Peramelidae) are medium-sized digging mammals that play a valuable role in maintaining ecosystem health; retaining these important ecosystem engineers across urban landscapes, including in private gardens, can have enormous conservation benefits. Urbanisation is a significant threat for some bandicoot species, and therefore understanding the factors associated with their activity can help guide urban landscape and garden design. To identify key features associated with the activity of a local endemic bandicoot species, the quenda (Isoodon fusciventer), we carried out a camera trap survey of front and back yards for 65 residential properties in the City of Mandurah, Western Australia. We compared quenda activity with biotic and abiotic factors that could indicate potential predation risk (activity of domestic dogs Canis familiaris and cats Felis catus, and the presence of artificial or natural protective cover), food availability (including deliberate or inadvertent supplementary feeding, provision of water, and diggable surfaces) and garden accessibility (distance to bushland, permeability of boundary fencing, and garden position). Supplementary feeding was strongly associated with quenda activity. Quenda were also more active in back yards, and in gardens where there was greater vegetation cover. Of concern, quenda activity was positively associated with cat activity, which could reflect that straying pet cats are attracted to gardens that harbour wildlife populations, including quenda. Furthermore, almost half of the gardens showed cat activity despite only a small sample of the surveyed residents owning a pet cat. Results of this study can help guide the design of residential gardens to increase useful habitat for these important digging mammals. Vegetation, wood mulch and semi-permeable fencing can provide valuable resources needed to support the persistence of quendas across the rapidly changing urban landscape mosaic, where natural and managed (e.g., gardens and parks) green spaces are becoming less common and more isolated.
Article
Full-text available
The domestic cat (Felis catus) is an invasive exotic in many locations around the world and is thought to be a key factor driving recent mammal declines across northern Australia. Many mammal species native to this region now persist only in areas with high topographic complexity, provided by features such as gorges or escarpments. Do mammals persist in these habitats because cats occupy them less, or despite high cat occupancy? We show that occupancy of feral cats was lower in mammal-rich habitats of high topographic complexity. These results support the idea that predation pressure by feral cats is a factor contributing to the collapse of mammal communities across northern Australia. Managing impacts of feral cats is a global conservation challenge. Conservation actions such as choosing sites for small mammal reintroductions may be more successful if variation in cat occupancy with landscape features is taken into account.
Book
Full-text available
Felis catus, the domestic cat, occurs throughout the Australian mainland as well as on more than 40 islands off the Australian coast. Cats exploit diverse habitats, including deserts, forests, woodlands, grasslands, towns and cities, and occur from sea level to altitudes above 2000 m. The classification of cats as domestic, stray or feral (Moodie 1995) reflects the varied ecology of cats and their dichotomous status in Australia — as both a valued pet species and an introduced feral predator. Impacts Feral cats are carnivorous hunters that depredate animals up to 2 kg, but more often take prey under 200 g. The feral cat is linked to the early continental extinctions of up to seven species of mammals. They are also linked to island and regional extinctions of native mammals and birds and have caused the failure of reintroduction attempts aimed at re-establishing threatened species. Today, 35 vulnerable and endangered bird species, 36 mammal species, seven reptile species and three amphibian species are thought to be adversely affected by feral cats. Other species are potentially affected by infectious diseases transmitted by cats. The true environmental and economic impact of feral cats has not been calculated. Legislation In most Australian states and territories, legislation has been introduced to restrict the reproductive and predation potential of owned domestic cats. Many local government areas have introduced cat-specific legislation, with restrictions including the banning of cats as pets in some communities, compulsory neutering, individual identification, and containment of pet cats. Predation by feral cats was listed as a Key Threatening Process under the Federal Endangered Species Protection Act 1992 (now incorporated in the Environment Protection and Biodiversity Conservation Act 1999). A Threat Abatement Plan for Predation by Feral Cats was produced in 1999 and amended in 2008 to promote the recovery of vulnerable and endangered native species and threatened ecological communities (Environment Australia 1999 and DEWHA 2008). Estimating abundance The three most common techniques for estimating cat abundance in Australia are spotlighting, counting tracks, and bait uptake estimates. The accuracy of spotlighting is dependent upon the density of vegetative cover and cat behaviour; the accuracy of track counts depends upon where track pads are set and the competence of the operative in recognising tracks; and most bait uptake studies provide data on cat activity rather than relative abundance or densities. All three techniques are best suited to open, dry habitats with low vegetative cover. In wetter, more closed and productive habitats with high vegetative cover, techniques such as remote photography and the analysis of DNA extracted from scats or hairs provide alternatives for estimating abundance or density. Such estimates are a necessary prerequisite for the implementation of control or eradication programs to avoid over- or under-commitment of labour, time and money, and are also necessary to measure the efficacy of management programs. Techniques for control or eradication A nationally co-ordinated program of feral cat control across Australia is not feasible, as it is with other introduced species, and control efforts are best targeted at protecting threatened species or habitats. All successful cat eradication programs in Australia have been conducted on islands or within areas bounded by predator-proof fencing, and most have required the use of more than one control method. Successful techniques for the control or eradication of cats on islands have proved largely impractical on the mainland. Hunting, trapping and shooting are time and labour intensive and not economically viable over large areas. Trap-neuter-return is unsuccessful in open populations and not practical over large areas. The introduction of disease (e.g. panleucopaenia) is restricted by the probable impact on owned domestic cats and the low transmission rate amongst widely dispersed feral cats. Toxins presently registered for cat baiting may have unacceptable environmental impacts on many habitats. Research into more felid-specific toxins, cat attracting baits and lures and cat-specific toxin delivery systems may lead to the adoption of poisoning as the most widely used technique for the control or eradication of feral cats. Management at the regional and local level Management of feral cats requires reliable data on the density or relative abundance of cats in targeted areas, and analysis of the cost effectiveness and efficacy of the various control measures that may be implemented. At the regional and local level, eradication of cat colonies and the management of resource-rich artificial habitats to discourage colonisation by cats should be an adjunct to any feral cat control program. Implementation of companion animal legislation that requires firmer controls on the owned, domestic cat population is also an important consideration for the longer-term reduction of the feral cat population in Australia. Factors limiting effective management Although adequate legislation is in place in some jurisdictions, the problems associated with cat control programs in Australia include: the time, cost and social impacts associated with enforcing companion animal legislation; the acceptance in some states of cats as pest control agents; variable cat densities between habitats; relatively low bait acceptance by feral cats; a lack of programs aimed specifically at stray cat colonies exploiting highly modified habitats; little data on the impact of cat removal on populations of introduced rodents and rabbits; and few accurate estimates of the density or relative abundance of feral cats. Research is needed to define the most successful methods for gaining public acceptance of the importance of maintaining effective companion animal legislation; estimating densities of cats in various habitats; the cost effectiveness of control techniques including broadscale baiting; assessing the impact of the removal of colony-forming cats in resource-rich artificial habitats on the broader feral cat population; and assessing the impact of cat removal on both native and introduced small mammal populations and the further indirect effects of removal on other components of the biota.
Book
Full-text available
This report provides an overview of the impact of feral cats Felis catus on native fauna of the Pacific region, with particular reference to Australia and its island territories. In Australia, cats take a wide variety of native species of mammals, birds and reptiles, but show evident preference for young rabbits or small marsupials where these are available. Reptiles are taken primarily in arid habitats, while birds often feature predominantly in the diet of cats on islands. Despite their catholic diet, population-level impacts of feral cats on native fauna have been poorly documented. There is considerable potential for competition to occur between cats and carnivorous species such as quolls and raptors, but no critical evidence has yet been adduced. There is also potential for amensal impacts to occur, either via transmission of the pseudophyllidean tapeworm Spirometra erinacei or of the protozoan parasite Toxoplasma gondii, but evidence for deleterious effects in free-living animals is not compelling. Direct predatory impacts have been inferred from anecdotal and historical evidence, more strongly from failed attempts to reintroduce native species to their former ranges, and most critically from the decimation of island faunas and responses of prey species following experimental removal of cats or reduction of cat numbers. Attributes of the biology of feral cats and their prey species derived from the literature review were used to develop a rank-scoring system to assess the susceptibility of native species to cat predation. Species listed federally as endangered or vulnerable were designated as being at zero, low or high risk of impact from cats according to their attribute scores, and their distributions mapped from primary sources and actual locality data. Based on the number of threatened species they contain, localities and regions within Australia were placed in order of priority for future research to clarify the precise impacts of feral cats. Although difficult and expensive to carry out, controlled and replicated field removal experiments are recommended to elucidate cat impacts in all mainland areas. Removal of cats should take place also on offshore islands and island territories, but only if pilot studies show that this will not release populations of alternative predator species such as introduced rats. If release appears likely, cats should be removed only as a component of an integrated control program that targets all relevant predators.
Article
Full-text available
As evidence mounts that the feral Cat (Felis catus) is a significant threat to endemic Australian biodiversity and impedes reintroduction attempts, uncertainty remains about the impact a residual population of cats following control will have on a mammal reintroduction programme. Also, behavioural interactions between cats and their prey continue to be an area of interest. Within the framework of an ecosystem restoration project, we tested the hypotheses that successful reintroductions of some medium-sized mammals are possible in locations where feral cats are controlled (but not eradicated) in the absence of European Red Fox (Vulpes vulpes), and that hare-wallabies that dispersed from their release area are more vulnerable to cat predation compared with those that remain at the release site. We used radiotelemetry to monitor the survivorship and dispersal of 16 Rufous Hare-wallabies (Lagorchestes hirsutus spp.) and 18 Banded Hare-wallabies (Lagostrophus fasciatus fasciatus) reintroduced to four sites within Shark Bay, Western Australia. Nearly all foxes were removed and feral cats were subject to ongoing control that kept their indices low relative to prerelease levels. All monitored hare-wallabies were killed by cats within eight and 10 months following release. Significant predation by feral cats was not immediate: most kills occurred in clusters, with periods of several months where no mortalities occurred. Once a hare-wallaby was killed, however, predation continued until each population was eliminated. Animals remaining near their release site survived longer than those that dispersed. The aetiology of predation events observed offers new insights into patterns of feral cat behaviour and mammal releases. We propose a hypothesis that these intense per capita predation events may reflect a targeted hunting behaviour in individual feral cats. Even where feral cats are controlled, the outcome from consistent predation events will result in reintroduction failures. Managers considering the reintroduction of medium-sized mammals in the presence of feral cats should, irrespective of concurrent cat control, consider the low probability of success. We advocate alternative approaches to cat-baiting alone for the recovery of cat-vulnerable mammals such as hare-wallabies.
Article
Full-text available
Invasive mammalian predators are major drivers of species extinctions globally. To protect native prey, lethal control is often used with the aim of reducing or exterminating invasive predator populations. The efficacy of this practice, however, is often not considered despite multiple practical and ecological factors that can limit success. Here, we summarize contemporary knowledge regarding the use and challenges of both lethal control and alternative approaches for reducing invasive predator impacts. As the prevailing management approach, we outline four key issues that can compromise the effectiveness of lethal control: release of herbivore and mesopredator populations, disruption of predator social systems, compensatory predator immigration, and ethical concerns. We then discuss the relative merits and limitations of four alternative approaches that may enhance conservation practitioner's ability to effectively manage invasive predators: top-predator conservation or reintroduction, maintaining habitat complexity, exclusion fencing, and behavioral and evolutionary ecology. Considerable uncertainty remains regarding the effectiveness of management approaches in different environmental contexts. We propose that the deficiencies and uncertainties outlined here can be addressed through a combination of adaptive management, expert elicitation, and cost-benefit analyses. Improved management of invasive predators requires greater consideration and assessment of the full range of management approaches available.
Article
Full-text available
Feral cats are normally territorial in Australia’s tropical savannahs, and hunt intensively with home-ranges only two to three kilometres across. Here we report that they also undertake expeditions of up to 12.5 km from their home ranges to hunt for short periods over recently burned areas. Cats are especially likely to travel to areas burned at high intensity, probably in response to vulnerability of prey soon after such fires. The movements of journeying cats are highly directed to specific destinations. We argue that the effect of this behaviour is to increase the aggregate impact of cats on vulnerable prey. This has profound implications for conservation, considering the ubiquity of feral cats and global trends of intensified fire regimes.
Article
Full-text available
The ecology of a feral cat population in an intensively cultivated region of northern Italy was studied. The study area is a land accretion territory, reclaimed in the early 1970s, characterised by the absence of any food source of human origin (e.g. garbage dumps, farms, houses) and surrounded by a continuous irrigation channel that is likely to limit immigration/emigration of cats. The cat population was censused for two successive years using the sighting-resighting method; spacing patterns were studied by means of radio-telemetry; hunting behaviour was assessed by observation. Feral cats avoided any direct contact with humans, and reproduced in the wild. The density of the population remained stable throughout the study period. Turnover appeared very high, and was remarkably higher than that of cats regularly fed by humans. Very low densities, large home range sizes, solitary habits, territorial patterns similar to those of the wildcat, seasonal parturition, and prevalence of hunting activity were found. We speculate that these patterns are related to the peculiar conditions of resource availability and dispersion in the study area. Our results indicate that feral cats, even in agricultural areas and in the absence of any food provided by humans, have solitary habits and low densities, thus confirming a key role of resource availability and dispersion on the ecology of carnivores.
Article
Full-text available
Context Feral cats are a major cause of mammal declines and extinctions in Australia. However, cats are elusive and obtaining reliable ecological data is challenging. Although camera traps are increasingly being used to study feral cats, their successful use in northern Australia has been limited. Aims We evaluated the efficacy of camera-trap sampling designs for detecting cats in the tropical savanna of northern Australia. We aimed to develop a camera-trapping method that would yield detection probabilities adequate for precise occupancy estimates. Methods First, we assessed the influence of two micro-habitat placements and three lure types on camera-trap detection rates of feral cats. Second, using multiple camera traps at each site, we examined the relationship between sampling effort and detection probability by using a multi-method occupancy model. Key results We found no significant difference in detection rates of feral cats using a variety of lures and micro-habitat placement. The mean probability of detecting a cat on one camera during one week of sampling was very low (p≤0.15) and had high uncertainty. However, the probability of detecting a cat on at least one of five cameras deployed concurrently on a site was 48% higher (p≤0.22) and had a greater precision. Conclusions The sampling effort required to achieve detection rates adequate to infer occupancy of feral cats by camera trap is considerably higher in northern Australia than has been observed elsewhere in Australia. Adequate detection of feral cats in the tropical savanna of northern Australia will necessitate inclusion of more camera traps and a longer survey duration. Implications Sampling designs using camera traps need to be rigorously trialled and assessed to optimise detection of the target species for different Australian biomes. A standard approach is suggested for detecting feral cats in northern Australian savannas.
Article
Full-text available
One of the key gaps in understanding the impacts of predation by small mammalian predators on prey is how habitat structure affects the hunting success of small predators, such as feral cats. These effects are poorly understood due to the difficulty of observing actual hunting behaviours. We attached collar-mounted video cameras to feral cats living in a tropical savanna environment in northern Australia, and measured variation in hunting success among different microhabitats (open areas, dense grass and complex rocks). From 89 hours of footage, we recorded 101 hunting events, of which 32 were successful. Of these kills, 28% were not eaten. Hunting success was highly dependent on microhabitat structure surrounding prey, increasing from 17% in habitats with dense grass or complex rocks to 70% in open areas. This research shows that habitat structure has a profound influence on the impacts of small predators on their prey. This has broad implications for management of vegetation and disturbance processes (like fire and grazing) in areas where feral cats threaten native fauna. Maintaining complex vegetation cover can reduce predation rates of small prey species from feral cat predation.
Article
Full-text available
Introduced predators have been implicated in the decline of many fauna populations around the world and are the main factor responsible for the failure of numerous fauna reintroduction programs. As a result, control of introduced predators is a significant management action implemented in wildlife protection programs, particularly in Australia, New Zealand and on islands. Individual predators are seldom targeted in conservation programs, which usually conduct broad-scale, non-specific predator control based on the assumption that the removal of each individual predator is equally important. In contrast, predator management programs initiated by human–wildlife conflict typically use profiling or specific control techniques to target ‘problem’ predators.
Article
Full-text available
A quantitative review was conducted of the effects of cattle grazing in arid systems on 16 response variables ranging from soil bulk density to total vegetative cover to rodent species diversity. Various studies from North American arid environments that used similar measures for assessing grazing effects on the same response variables were used for the review; each study was assigned to serve as a single data point in paired comparisons of grazed versus ungrazed sites. All analyses tested the 1-tailed null hypothesis that grazing has no effect on the measured variable. Eleven of 16 analyses (69%) revealed significant detrimental effects of cattle grazing, suggesting that cattle can have a negative impact on North American xeric ecosystems. Soil-related variables were most negatively impacted by grazing (3 of 4 categories tested were significantly impacted), followed by litter cover and biomass (2 of 2 categories tested), and rodent diversity and richness (2 of 2 categories tested). Vegetative variables showed more variability in terms of quantifiable grazing effects, with 4 of 8 categories testing significantly. Overall, these findings could shed light on which suites of variables may be effectively used by land managers to measure ecosystem integrity and rangeland health in grazed systems.
Article
Full-text available
Context Feral cats (Felis catus) pose a significant threat to biodiversity in Australia, and are implicated in current declines of small mammals in the savannas of northern Australia. Basic information on population density and ranging behaviour is essential to understand and manage threats from feral cats. Aims In this study, we provide robust estimates of density and home range of feral cats in the central Kimberley region of north-western Australia, and we test whether population density is affected by livestock grazing, small mammal abundance and other environmental factors. Methods Densities were measured at six transects sampled between 2011 and 2013 using arrays of infrared cameras. Cats were individually identified, and densities estimated using spatially explicit capture-recapture analysis. Home range was measured from GPS tracking of 32 cats. Key results Densities were similar across all transects and deployments, with a mean of 0.18 cats km-2 (range≤0.09-0.34km-2). We found no evidence that population density was related to livestock grazing or abundance of small mammals. Home ranges of males were, on average, 855ha (±156ha (95% CI), n≤25), and those of females were half the size at 397ha (±275ha (95% CI), n≤7). There was little overlap in ranges of cats of the same sex. Conclusions Compared with elsewhere in Australia outside of semiarid regions, feral cats occur at low density and have large home ranges in the central Kimberley. However, other evidence shows that despite this low density, cats are contributing to declines of small mammal populations across northern Australia. Implications It will be very difficult to reduce these already-sparse populations by direct control. Instead, land-management practices that reduce the impacts of cats on prey should be investigated.
Article
Full-text available
The number of individuals in a wildlife population is often estimated and the estimates used for wildlife management. The scientific basis of published continental-scale estimates of individuals in Australia of feral cats and feral pigs is reviewed and contrasted with estimation of red kangaroo abundance and the usage of the estimates. We reviewed all papers on feral cats, feral pigs and red kangaroos found in a Web of Science search and in Australian Wildlife Research and Wildlife Research, and related Australian and overseas scientific and 'grey' literature. The estimated number of feral cats in Australia has often been repeated without rigorous evaluation of the origin of the estimate. We propose an origin. The number of feral pigs in Australia was estimated and since then has sometimes been quoted correctly and sometimes misquoted. In contrast, red kangaroo numbers in Australia have been estimated by more rigorous methods and the relevant literature demonstrates active refining and reviewing of estimation procedures and management usage. We propose four criteria for acceptable use of wildlife abundance estimates in wildlife management. The criteria are: use of appropriate statistical or mathematical analysis; precision estimated; original source cited; and age (current or out-of-date) of an estimate evaluated. The criteria are then used here to assess the strength of evidence of the abundance estimates and each has at least one deficiency (being out-of-date). We do know feral cats, feral pigs and red kangaroos occur in Australia but we do not know currently how many feral cats or feral pigs are in Australia. Our knowledge of red kangaroo abundance is stronger at the state than the continental scale, and is also out-of-date at the continental scale. We recommend greater consideration be given to whether abundance estimates at the continental scale are needed and to their use, and not misuse, in wildlife management.
Article
Full-text available
Introduction: Recent studies at sites in northern Australia have reported severe and rapid decline of several native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic groups of mammals in northern Australia have some species for which their conservation status has been assessed as threatened, with 53 % of dasyurid, 47 % of macropod and potoroid, 33 % of bandicoot and bilby, 33 % of possum, 30 % of rodent, and 24 % of bat species being assessed as extinct, threatened or near threatened. However, the geographical extent and timing of declines, and their causes, remain poorly resolved, limiting the application of remedial management actions.
Article
Full-text available
Introduction: Recent studies at sites in northern Australia have reported severe and rapid decline of several native mammal species, notwithstanding an environmental context (small human population size, limited habitat loss, substantial reservation extent) that should provide relative conservation security. All of the more speciose taxonomic groups of mammals in northern Australia have some species for which their conservation status has been assessed as threatened, with 53 % of dasyurid, 47 % of macropod and potoroid, 33 % of bandicoot and bilby, 33 % of possum, 30 % of rodent, and 24 % of bat species being assessed as extinct, threatened or near threatened. However, the geographical extent and timing of declines, and their causes, remain poorly resolved, limiting the application of remedial management actions. Material and methods: Focusing on the tropical savannas of northern Australia, this paper reviews disparate recent and ongoing studies that provide information on population trends across a broader geographic scope than the previously reported sites, and examines the conservation status and trends for mammal groups (bats, macropods) not well sampled in previous monitoring studies. It describes some diverse approaches of studies seeking to document conservation status and trends, and of the factors that may be contributing to observed patterns of decline. Results and Discussion: Current trends and potential causal factors for declines. The studies reported demonstrate that the extent and timing of impacts and threats have been variable across the region, although there is a general gradational pattern of earlier and more severe decline from inland lower rainfall areas to higher rainfall coastal regions. Some small isolated areas appear to have retained their mammal species, as have many islands which remain critical refuges. There is now some compelling evidence that predation by feral cats is implicated in the observed decline, with those impacts likely to be exacerbated by prevailing fire regimes (frequent, extensive and intense fire), by reduction in ground vegetation cover due to livestock and, in some areas, by ‘control’ of dingoes. However the impacts of dingoes may be complex, and are not yet well resolved in this area. The relative impacts of these individual factors vary spatially (with most severe impacts in higher rainfall and more rugged areas) and between different mammal species, with some species responding idiosyncratically: the most notable example is the rapid decline of the northern quoll (Dasyurus hallucatus) due to poisoning by the introduced cane toad (Rhinella marina), which continues to spread extensively across northern Australia. The impact of disease, if any, remains unresolved. Conservation Management Responses. Recovery of the native mammal fauna may be impossible in some areas. However, there are now examples of rapid recovery following threat management. Priority conservation actions include: enhanced biosecurity for important islands, establishment of a network of feral predator exclosures, intensive fire management (aimed at increasing the extent of longer-unburnt habitat and in delivering fine scale patch burning), reduction in feral stock in conservation reserves, and acquisition
Article
Full-text available
The highly distinctive and mostly endemic Australian land mammal fauna has suffered an extraordinary rate of extinction (>10% of the 273 endemic terrestrial species) over the last ∼200 y: in comparison, only one native land mammal from continental North America became extinct since European settlement. A further 21% of Australian endemic land mammal species are now assessed to be threatened, indicating that the rate of loss (of one to two extinctions per decade) is likely to continue. Australia's marine mammals have fared better overall, but status assessment for them is seriously impeded by lack of information. Much of the loss of Australian land mammal fauna (particularly in the vast deserts and tropical savannas) has been in areas that are remote from human population centers and recognized as relatively unmodified at global scale. In contrast to general patterns of extinction on other continents where the main cause is habitat loss, hunting, and impacts of human development, particularly in areas of high and increasing human population pressures, the loss of Australian land mammals is most likely due primarily to predation by introduced species, particularly the feral cat, Felis catus, and European red fox, Vulpes vulpes, and changed fire regimes.
Article
Full-text available
Understanding the impact of habitat fragmentation, roads, and other anthropogenic influences on cougars (Puma concolor) requires quantitative assessment of habitat selection at multiple scales. We calculated annual and multiyear home ranges using a fixed-kernel (FK) estimator of home range for 13 adult female and 2 adult male radiotagged cougars that were monitored October 1986 through December 1992 in the Santa Ana Mountain Range of southern California, USA. Using compositional analysis, we assessed diurnal use of vegetation types and areas near roads at 2 orders of selection (second- and third-order; Johnson 1980). Mean annual and multiyear 85% FK home ranges for males were larger than those reported by previous studies in California. Mean wet-season 85% FK home ranges were significantly larger than those of the dry season. At both scales of selection and across seasons, cougars preferred riparian habitats and avoided human-dominated habitats. Grasslands were the most avoided natural vegetation type at both scales of selection. Although cougar home ranges tended to be located away from high- and low-speed 2-lane paved roads (second-order avoidance), cougars did not avoid roads within their home range, especially when roads were in preferred riparian areas. Protection of habitat mosaics that include unroaded riparian areas is critical to the conservation of this cougar population.