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Enumerating a continental-scale threat: How many feral cats are in Australia?
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.
... In most countries, management of stray cats in urban and peri-urban areas is a longstanding and continuing challenge [1,2]. There are an estimated 0.7 million urban stray cats in Australia (plausible range: 0.07-2.56 million) [3] and, based on the human population at the time (2016) [4] this represents 29 cats per 1000 residents (range: 3-104 cats/1000 residents). Stray cats in urban and peri-urban areas of Australia are categorized by the Royal Society for the Prevention of Cruelty to Animals (RSPCA) as domestic cats [5]. ...
... Typical approaches to manage urban and peri-urban free-roaming cats in Australia include reactive 'trap, adopt or kill' methods and mandated cat containment, both of which have proven to be ineffective at reducing the number of free-roaming cats or alleviating associated issues in the medium and long-term [2,[31][32][33][34]. Current Australian data suggest that approximately 7% [2,3] of the urban stray cat population is killed in shelters and council pounds annually. This low-level ad hoc culling is insufficient to reduce the overall number of stray cats over time, due to the high cat reproductive rate, immigration of new cats into the area, and increased survival of juveniles [35,36]. ...
... This assumed that pet cats constituted 92% of the urban cat population. In Australia, based on the estimate in 2016 of 3.3 million pet cats and 0.7 million stray cats [3], pet cats would constitute 79% of all cats, with stray cats (semi-owned and unowned) being approximately 21%. The stray cat population in Australia does not appear to be decreasing, based on static or increasing numbers of cats recorded as being impounded by councils [2]. ...
Managing stray cats in urban areas is an ongoing challenge, and in Australia, many are euthanized. Most stray cats are from disadvantaged areas and are under 1 year of age. The Australian Pet Welfare Foundation intended to assess the impact of a free cat sterilization program in an area with high shelter intake of cats in the city of Ipswich, Queensland. The aims of this pre-intervention study were to undertake a situational analysis of cat ownership, semi-ownership and cat caring behaviours, and compare those in the same demographic with dog ownership and caring behaviours relating to sterilization rates, to provide a basis against which to assess the program’s effectiveness. In a sample of 343 participants from that area, 35% owned cats and 3% fed stray cats. Cats were predominantly obtained from family or friends (31%) and shelters (20%). More respondents owned dogs (53%), which were most often sourced from breeders (36%) and family acquaintances (24%). More owned cats than owned dogs were sterilized (91% versus 78%). However, only 74% of cats aged 4 to <12 months were sterilized. Cat containment practices varied, with 51% of owners containing their cat(s) at all times, and a further 18% doing so at night. These results suggest the need for community-based programs that focus on sterilizing owned and semi-owned cats, and assisting semi-owners in becoming full owners to reduce stray cat populations and associated negative impacts. This includes assistance with cat containment where vulnerable native species are present. Public understanding of the causes and effective solutions for free-roaming cats, alongside legislative changes, are required to facilitate these efforts. Assistive programs aligned with One Welfare principles are expected to benefit the wellbeing of animals, humans and their environments.
... We hypothesised that feral cat survival rates are higher for female cats (e.g., Danner et al. 2010;Kaeuffer et al. 2004;Schmidt et al. 2007) and are negatively influenced by the presence of foxes and/or dingoes due to antagonistic interactions or dominance from these larger predators (Kennedy et al. 2012;Molsher et al. 2017). Conversely, we hypothesised that introduced rabbits benefit cat survival , as does cat density (indirectly), as densities may reflect prey abundance (Legge et al. 2017;Read and Bowen 2001). Further, we hypothesised that cats survive better in more productive landscapes: cat home-ranges are larger in landscapes with lower productivity (Bengsen et al. 2015;Nottingham et al. 2022). ...
... We then derived the rainfall deviation for each cat as rainfall deviation = (rainfall in the last year -50 year rainfall average)/100. We included rainfall deviation as cat population densities can fluctuate with varying Ecological factors influencing invasive predator survival and movement: insights from a… rainfall conditions in different environments in Australia (Legge et al. 2017). ...
... Cat density estimates were obtained from field observations for each study where available (n = 7). When unavailable, we derived predicted densities from published studies in the same area (n = 2) or from Legge et al. (2017) (n = 20). We removed very small cats from the compiled dataset as this class was not adequately represented across different habitat types (n = 23). ...
Feral cats (Felis catus) pose a significant global threat to biodiversity, primarily through predation, disease and competition. A key gap in parameterizing models for improving management decisions for feral cat control relates to factors that drive feral cat survival and movement in the wild. Our study objective was to conduct the first continental-scale analysis of survival rates and displacement distances for feral cats. We collated data on 528 feral cats from telemetry studies in naturally-vegetated landscapes across Australia. Using Cox-proportional hazards models, we investigated the effects of sex, presence of larger predators (dingoes, Canis familiaris and introduced foxes, Vulpes vulpes), presence of introduced prey (rabbits, Oryctolagus cuniculus), body mass, landscape productivity and feral cat density on feral cat survival. We also analysed the effects of sex, body mass and landscape productivity on feral cat displacement using linear mixed model analysis. Feral cat survival was positively associated with presence of dingoes and increasing body mass, whereas there was no clear association between feral cat survival and sex, presence of rabbits, or cat density. Presence of foxes had a strong negative effect on feral cat survival, but the hazard ratio was associated with considerable uncertainty. Net displacement of male feral cats was nearly two times further than that of females, and the proportion of feral cats making long-distance movements was greater in landscapes with low productivity. Increasing body mass of feral cats was positively related to net displacement, with heavier cats moving further. Analysis of metadata from telemetry studies can provide valuable insights into wildlife survival rates and movement behaviour. Our findings will help inform the development of effective management strategies and improve feral cat management for biodiversity conservation.
... In many situations domestic cats are estimated to occur in much higher numbers than all species of wild cats combined (Hunter, 2015). As a relatively fecund species able to persist under varied climate, habitat, and resource conditions (Lowe et al., 2000;Legge et al., 2017), and which is also regularly given food subsidies by people (Toukhsati et al., 2007;Davey et al., 2019), the domestic cat has some advantage over native predators and prey. Domestic cats (hereafter "cats") impact wildlife via predation, fear effects, competition, and as a vector of diseases and parasites (Beckerman et al., 2007;Dubey and Jones, 2008;Medina et al., 2011;Doherty et al., 2016). ...
... Should the stressors outweigh the rewards then there can be fatal impacts (Fardell et al., 2020). Free-roaming pet and feral cats that are prevalent in urban environments (Legge et al., 2017(Legge et al., , 2020a, could exacerbate stress impacts on urban wildlife through influencing their activity and adversely affecting their health and reproduction capabilities (Preisser et al., 2005), as well as the more obvious direct predation impacts (Murphy et al., 2019). ...
... Offering evidence for the negative nonconsumptive effects of roaming cats could support the need for more consideration in management to be given to the fear and stress impacts that cat presence alone can have on wildlife populations. We, therefore, investigated the fear/stress impacts on wildlife imposed by cat roaming activity, at all hours, in a patchy urban environment in Australia, where pet and feral cats are prevalent across all areas (Legge et al., 2017(Legge et al., , 2020b, to determine if landscapes of fear were evident. To do so, we used infrared motion sensor cameras to observe rates and times of activity of native and introduced wildlife, compared to roaming cat activity within a 24-h period in both yard and green space edge habitats. ...
Roaming domestic cats (Felis catus) are recognised as a threat to wildlife globally. Yet management of pet cats in urbanised areas is not regularly mandated, and management of feral cats in urbanised areas is rarely implemented. Mounting evidence emphasises the value of urban environments as hot spots of wildlife activity, which as the human population continues to grow may become the best or only habitats available to some wildlife species. Wildlife in urban environments must navigate introduced stressors that can compound with natural stressors. Additional, often novel, predators such as free-roaming pet and feral cats that are prevalent in urban environments could have high nonconsumptive fear/stress impacts on urban wildlife that influence their activity and adversely affect their health and reproduction capabilities, possibly more so than direct predation effects do. Cat roaming activity, particularly that of pet cats, could be managed with the support of the community, though motivation needs to be ensured. Understanding if roaming cat activity influences urban wildlife activity via perceived fear/stress impacts will help to build community motivation for the need for domestic cat management in urbanised areas. Using infrared motion sensor cameras positioned in both yards and green space edge habitats, we observed whether the presence and times active of native and introduced small mammals, and native birds, were impacted by domestic cat activity within a 24-h period and by their activity in the prior-24-h period. We found evidence of cat roaming activity during the hours of most wildlife activity, and show that wildlife navigated “landscapes of fear” relative to cat activity, as wildlife observed across a 24-h period increased their activity in the absence of cats in the same 24-h period and in the previous 24-h period. We also tested if cat activity was relative to previous cat activity, or disturbances, and found that cats reduced activity in response to each, but were still consistently present. Our results provide justification for the need to increase management of domestic cats in urbanised areas and offer fear/stress impacts as a novel approach to engender community support of such management.
... This conclusion was based on the assumption that pet cats make up 92% of the urban cat population. In Australia, using 2016 estimates of 3.3 million pet cats and 0.7 million stray cats [60], pet cats represent about 79% of the total cat population, with stray cats (including semi-owned and unowned) accounting for approximately 21%. There are now a substantial number of reports in the literature documenting successful management of free-roaming cats by sterilization programs that target largely owned and semi-owned cats [6,61]. ...
... There are now a substantial number of reports in the literature documenting successful management of free-roaming cats by sterilization programs that target largely owned and semi-owned cats [6,61]. Due to the higher proportion of semi-owned stray cats in Australia, as well as in other countries such as the USA [1,21,54,60], sterilization programs must also focus on these populations. This is particularly important since most of these cats are not sterilized [23,62,63]. ...
Free-roaming cats in urban and peri-urban areas and in rural towns pose significant challenges due to their nuisance behaviors, threats to wildlife, and potential disease transmission. Traditional management methods often involve trapping and euthanizing many of these cats, which is not only costly but also distressing for the shelter staff involved, and have failed to reduce numbers of impounded cats or cat-related complaints. Our study aimed to evaluate the effectiveness of a Community Cat Program that provided free sterilization, microchipping, and preventative veterinary care for all owned, semi-owned, and unowned cats in a small rural town with high cat impoundments in Ipswich, Queensland. The program was instigated by the Australian Pet Welfare Foundation in collaboration with the Royal Society for the Prevention of Cruelty to Animals, Queensland and the Animal Welfare League, Queensland, and it was funded by various organizations including Fondation Brigitte Bardot. Data from 2017 to 2023 were analyzed to assess the impact of the program on cat intake and outcomes in local shelters. A total of 308 cats were sterilized, representing 94 cats per 1000 residents over 3.4 years, and in the third year, this was associated with a 60% decrease in cat intake, an 85% reduction in numbers euthanized and 39% fewer cat-related calls to the local council. These findings suggest that high-intensity, targeted sterilization programs significantly decrease shelter intake and euthanasia, and thus alleviate the psychological burden on staff. These programs are a humane and effective alternative to traditional cat management, and benefit animal welfare as well as community wellbeing. This is aligned with a One Welfare approach, which enhances the well-being of animals, humans, and their environments. Legislative changes are required to support these programs to effectively decrease the numbers of free-roaming cats in cities and towns and the issues they cause, while protecting human wellbeing.
... On the other hand, stray cats are unowned, but live freely in close proximity to human settlements, often in colonies in and around towns and cities, relying on anthropogenic resources including food and shelter (Crawford et al., 2020;Doherty et al., 2016). They may represent abandoned or lost domestic cats (Ogan and Jurek, 1997), and it is estimated that 0.7 million stray cats inhabit Australian urban areas (Legge et al., 2017). In contrast, feral cats live independently from humans and anthropogenic resources (Crawford et al., 2020;Nottingham et al., 2022). ...
... In contrast, feral cats live independently from humans and anthropogenic resources (Crawford et al., 2020;Nottingham et al., 2022). They are generally found in less modified or rural areas and are present across more than 99 % of the total Australian land area, with an estimated population of 1.4 -5.6 million (Legge et al., 2017). Understanding the epidemiology of T. gondii in free-roaming cats is crucial to understanding the infection risk to intermediate hosts. ...
... Sobre todo, hay poca información de lo que ocurre en las zonas urbanas y los hábitats naturales y agrícolas que los rodean, a pesar de la alta densidad que los gatos pueden alcanzar en estos sitios (Hernández-Cortazar et al., 2015;Orduña-Villaseñor, 2015;Ortega-Pacheco et al., 2007;Pacheco, 2003). Por la información existente para otros países podemos suponer que los gatos deben tener importantes efectos sobre diversas especies de reptiles, anfibios, aves y mamíferos (Baker et al., 2008;Barratt, 1997;Legge et al., 2017;Loyd et al., 2013). El impacto por depredación de los gatos en el México continental solo se ha estudiado con gatos domésticos con dueño de vida libre en la ciudad de Morelia, Michoacán (Orduña-Villaseñor, 2015) y Xalapa, Veracruz (Mella-Méndez, 2019). ...
... Dada la información existente, consideramos que gatos y perros deben de ser considerados dentro de planes de manejo a diferentes escalas geográficas para reducir sus efectos ambientales negativos, sobre todo en países megadiversos. Actualmente, ha sucedido solo en Australia (Bellard et al., 2016;Legge et al., 2017;Moseby et al., https://doi.org/10.22201/ib.20078706e.2023.94.4850 2015). En el caso de nuestro país, tanto la alta diversidad β, como el alto número de especies endémicas de diferentes grupos de vertebrados, nos vuelve más susceptibles a los efectos negativos por depredación de ambas especies y nos obliga a considerar acciones de manejo en el corto plazo. ...
Revista Mexicana de Biodiversidad 94 (2023): e944850 Artículo de revisión Tus mejores amigos pueden ser tus peores enemigos: impacto de los gatos y perros domésticos en países megadiversos Recibido: 12 noviembre 2021; aceptado: 23 septiembre 2022 Resumen Los gatos y perros domésticos son las mascotas preferidas del hombre, por lo que se han convertido en especies invasoras y los carnívoros más abundantes del planeta. A pesar de su buena relación con nuestra especie, tienen un impacto ecológico negativo con consecuencias para las políticas de conservación. Los efectos que estos animales tienen sobre la fauna silvestre han sido estudiados principalmente en países con baja biodiversidad de vertebrados (EUA, Nueva Zelanda y Europa), y salvo por algunos trabajos realizados en Australia, Brasil, y México, no contamos con información sobre sus efectos en países con alta biodiversidad. Los efectos negativos que ambas especies tienen sobre la biodiversidad incluyen la depredación y competencia con fauna nativa, su hibridación con especies filogenéticamente cercanas o poblaciones silvestres de su propia especie, y la transmisión de enfermedades a la fauna silvestre y a los humanos. La falta de información sobre los efectos de depredadores introducidos a nivel continental y la falsa idea de que los gatos y perros son ambientalmente inocuos, vuelve crucial aumentar la investigación sobre estas especies en países megadiversos para proponer estrategias de manejo que fomenten la conservación de fauna nativa.
... Feral cats are one of the most significant threats to native species in Australia with over 100 listed threatened species impacted by feral cats (Legge et al. 2017). Efforts to control feral cats have had mixed success with baiting practices having greater success in arid regions and much lower success rates in more temperate areas. ...
testing the target specificity and safety of the feral cat trap Felixer in the presence of Numbats, Myrmecobius fasciatus
... Domestic cats (Felis catus) were brought to Australia over 200 years ago (Koch, Algar, and Schwenk 2016), and now occupy over 99% of the continent (Legge et al. 2017). This species was domesticated from Felis lybica, the African wildcat (Driscoll et al. 2007), a felid with sandy-grey fur and vertical stripes (Werdelin and Olsson 1997) well suited for its grassy, There are several evolutionary advantages coat pattern and colour could provide. ...
Variations in coat morphology are well documented among felids and are theorised to aid in camouflage during stalk and ambush hunting. A diverse array of coat types has arisen in Felis catus (feral cats) through domestication and subsequent selective breeding. This species has successfully spread across Australia over the past 200 years, raising the question of whether any specific coat types offer an adaptive advantage. We used 24,657 camera‐trap images of feral cats in Tasmania, Australia, and assigned each cat observation a coat colour and pattern. We analysed these data to examine how different spatial features affect the modal coat type present at a site. We also tested if cats with differing coat types were active on different days in response to temporal features, including moon luminosity (full or new). Elevation was positively associated with the presence of orange (odds ratio = 2.5, 97.5% confidence interval = 1.5, 4.4) and tortoiseshell (odds ratio = 4.1, CI = 1.6, 10.5) cats, while blotched brown cats were negatively associated with elevation (odds ratio = 0.64, CI = 0.5, 0.9), relative to black cats. Brown mackerel cats were more common in eucalypt and rainforests (odds ratio = 1.9, CI = 1.1, 3.3), as well as sites with a higher FPAR (odds ratio = 1.3, CI = 1.1, 1.6). All coat types were 1.2–2 times more likely to be active on nights with a new moon, except for orange cats who were equally active regardless of moon luminosity (odds ratio = 0.94, CI = 0.62, 1.42). Our results indicate that coat types are equally successful across Tasmania, perhaps owing to naïve prey or limited predator competition. The high activity of orange cats irrespective of moon phase may be reflective of the male cat's tendency to patrol territory, as opposed to favouring dark nights for hunting. Future studies should consider comparing the coat types found in feral cats to adjacent domestic populations, and against a wider array of habitat types to further investigate the potential for selective pressure on feral cat coat types in Australia.
... There is strong evidence that cat over-population is a serious threat to biodiversity in many ecosystems, particularly in North America, Australasia, and islands where small wildcat species are not native fauna (e.g. Bellard et al. 2016;Doherty et al. 2016;Legge et al. 2017;Loss -Marra 2017;Medina et al. 2016). This has led to strategies aimed at reducing and controlling feline populations, namely 'feral' (unowned) cats. ...
The purpose of this paper is to review the international literature on the role of pets in the
family, with a particular focus on the differences that previous literature has found between
men and women in this regard. For this purpose, we use the scoping review method. In this
framework, we collected international journal articles published between 1980 and 2023 that
dealt with our chosen topic. Based on the results of the scoping review, we found 49 articles
that matched the focus of our research. After reviewing them, the following topics emerged:
the emergence of fictive kinship between humans and animals, the related flexible role of
pets within the family. In addition, some of the journal articles analysed the different types of
attachments between pets and their owners, and related to this, the issue of grief at the loss
of a companion animal is often at the centre of these studies. Finally, the focus is also on how
pet caregivers form partnerships and whether pets can be a substitute for children.
... There is strong evidence that cat over-population is a serious threat to biodiversity in many ecosystems, particularly in North America, Australasia, and islands where small wildcat species are not native fauna (e.g. Bellard et al. 2016;Doherty et al. 2016;Legge et al. 2017;Loss -Marra 2017;Medina et al. 2016). This has led to strategies aimed at reducing and controlling feline populations, namely 'feral' (unowned) cats. ...
Cat (Felis silvestris catus) abandonment in Saudi Arabia is a widespread phenomenon. While studies in ‘Western’1 countries have identified factors contributing to companion-animal relinquishment, the phenomenon in Saudi Arabia has not previously been examined. This study aims to bridge this gap through interviews, questionnaires, and social media analysis, delving into the effects of abandonment on cats in the region, as well as uncovering the reasons behind relinquishment and the broader factors influencing cat abandonment. Using grounded theory techniques and utilising the framework of The Five Animal Welfare Needs relating to all domestic morethanhuman animals, the research offers a comprehensive perspective on the reported impact on the affected cats. Results indicate that the Animal Welfare Needs of cats on the streets of Saudi Arabia are not met.
... There is strong evidence that cat over-population is a serious threat to biodiversity in many ecosystems, particularly in North America, Australasia, and islands where small wildcat species are not native fauna (e.g. Bellard et al. 2016;Doherty et al. 2016;Legge et al. 2017;Loss -Marra 2017;Medina et al. 2016). This has led to strategies aimed at reducing and controlling feline populations, namely 'feral' (unowned) cats. ...
Building upon the author’s doctoral research, this paper focuses on discourses surrounding roaming urban cats (Felis catus) and Foucauldian biopower over feline bodies. It demonstrates how a biopolitical framework can be applied to understand methods of control and power over other-than-human lives and serves as a means to understand cat-human relations. Whether to protect wildlife or the cats themselves, biopower is exerted over feline bodies via collars, microchips, desexing, and restrictions on roaming. The language of ‘domestication,’ ‘wild,’ and ‘feral’ are translated to different notions of ‘catness’ and beliefs about what is ‘best for cats’ and our role as guardians. This in turn shapes social expectations, pressures, and bylaws restricting the roaming of cats. Veterinarian and welfarist recommendations of desexing are instrumental in normalising neutering and spaying, which renders cats less prone to fight or spray urine, and more inclined to be docile companion animals. This essay argues that the desexed cats themselves become biopolitical agents by reinforcing notions of ‘catness’ and conforming to notions of ‘good’ companion animals or community members. The paper concludes by discussing how terms such as ‘community,’ rather than ‘feral’ or ‘street’ cats can help change the dialogue and foster more caring multispecies communities.
... This is a critical omission considering invasive species are recognised as one of the most pervasive threats to global biodiversity, especially on islands (Doherty et al. 2016). Invasive predators and herbivores often occur at extremely high densities on islands (Terborgh et al. 2001;Legge et al., 2017). They are responsible for numerous extinctions and continue to threaten many island species via predation, competition and habitat destruction (Kier et al., 2009;Medina et al., 2011;Courchamp et al 2014;Spatz et al., 2014). ...
Australia is a world leader in invasive species eradications on islands. Over 220 eradications of invasive vertebrates have been undertaken on Australian islands. At least 170 Australian islands have had invasive vertebrates successfully eradicated. To date, most island eradications have focused on ungulates and rodents. The number of rodent and ungulate eradications have increased in recent years. 96 islands have had two or more invasive vertebrate species successfully eradicated. Bigger, more complex and multi-species island eradications are more likely to occur in the future as many of the small, single species island eradications have been undertaken. Very few eradication plans (or supporting documents) have clear, defined objectives beyond removal of the targeted invasive species. The identification of intended outcomes is essential for informing future management. Monitoring the ecosystem response to eradication is becoming more important for large, and more complex islands. Monitoring should be considered and funded as part of an eradication. Several island eradications in Australia present novel opportunities for informing the likelihood of trophic cascades. Biosecurity planning would benefit from being integrated within eradication plans. Updating and maintaining databases of invasive species on Australian islands should be a priority.
... However, monitoring invasive predators, such as the feral cat, can be challenging (Christensen & Burrows, 1995;Jansen et al., 2021;Risbey et al., 2000). Additionally, predator densities are not always indicative of predation impact as predation rates are also dependent on the abundance of alternative prey, seasonal conditions and demography (Evans et al., 2021;Legge et al., 2017;Moseby, McGregor, & Read, 2021;Robinson et al., 2020). An alternative method of determining the effectiveness of predator management is to monitor the response of in situ native species. ...
In Australia, most threatened species translocations conducted into areas where feral predators are present fail to establish viable, self‐sustaining populations despite intensive predator control. These translocations are occurring amidst a lack of understanding regarding the conditions required for native species to survive, including predator densities. This study investigated whether population trends of in situ common species could be used as bioindicators to determine the effectiveness of predator management for threatened species protection. We compared changes in capture rates of four small mammals and four reptile species inside and outside a predator‐proof reserve for 11 years after cat and fox removal to identify which species responded to cat and fox eradication at various time scales. We only used sites inside the reserve where threatened species had not yet been reintroduced to isolate the effects of cat and fox removal. The effectiveness of these bioindicators was then tested at an unfenced reserve where predators were controlled using baiting, trapping, and shooting. There was a significant increase in the abundance of native rodents (spinifex hopping mouse and Bolam's mouse) inside the fenced reserve compared to outside, however, these differences were not detected in the unfenced reserve possibly due to inadequate predator control or insufficient time for in situ species to recover with sustained predator control. Captures of the introduced house mouse were higher at sites inside the fenced reserve in some years, but the difference was not consistent. Native dunnarts and all four reptile species did not respond consistently over the 11‐year time frame at either reserve. Native rodent abundance was the best indicator of effective feral predator control and may provide a useful bioindicator for threatened species management, such as reintroductions.
... It is also estimated that there are approximately 470 million pet dogs and 370 million pet cats in the world. To achieve the effective management of stray animals in an environment, it is necessary to understand the relationship between the population of stray animals and their effects on different dimensions of the environment and to know how their relationships are influenced by other factors (threatening and environmental factors such as weather) (Legge et al., 2017). It is necessary to create a long-term and sustainable approach to deal effectively with the population of stray animals. ...
Stray animals such as cats and dogs, mainly have an independent life, are homeless, have uncontrollable reproduction, and have a large population in the environment and the city. These animals have become a concern for public health in cities and the environment. With the spread of deadly diseases such as rabies, they are considered a threat to human life and health, and their number is increasing day by day in Tehran City. Therefore, it is necessary to provide basic solutions to control and reduce the population of stray animals in Tehran City. Based on reviewing the laws of successful developed and developing countries and expert interviews with 40 people in different fields, suitable solutions for the basic collection, control, and management of stray animals in Tehran City were obtained according to the existing conditions. The results showed that the best solutions include neutering (19%), education and awareness in society (16%), collecting and transfer to shelters (15%), fines for people who violate the rules and prohibition of food to stray animals (13%), euthanasia (10%), using efficient experts and waste management (9%), registration in the system, birth certification, and microchipping of the animal (8%), amending existing laws (6%), and amending municipal contracts (4%). Therefore, it is necessary to control the population of stray animals in Tehran City with solutions such as neutering, educating informing people, and collecting stray animals to be transferred to the shelter.
... Hunting by domestic cats can pose a significant risk to prey population persistence and biodiversity (Kays et al., 2020;van Heezik et al., 2010), leading conservationists to call for greater control and regulation of cats (Legge et al., 2017;Loss et al., 2013). Cat owners are critical stakeholders central to reducing their cats' hunting (Crowley et al., 2019Kikillus et al., 2017;MacDonald, 2015), yet most efforts to change cat owner behavior have been styled in the traditional "command and control" or knowledge-deficit approaches . ...
Solutions to the cats‐hunting‐wildlife environmental conflict could benefit from social science approaches. Our Theory of Planned Behavior questionnaire—informed by an elicitation survey of cat owners at veterinary clinics about their attitudes, norms, and beliefs regarding bringing their cats inside at night—surveyed 158 cat owners across 20 veterinarian clinics in four cities. It revealed that wildlife conservation was not influential on cat owner intention but veterinarians, cat safety, peers, and household members were. Thus, we designed a social marketing campaign with two treatments: (1) a veterinarian/cat safety message or (2) social/family norm message. Thirty‐four veterinary clinics received one of the two campaign posters or served as the control group. Customers (n = 510) received a “cat welfare” survey and then a pamphlet with the advocated message, and a follow‐up survey by email or telephone 3–6 weeks later (69% response rate). Campaign messaging significantly increased the number of cat owners who reported bringing their cats inside at night compared to the control group. The social/family norm message was most effective. Although rudimentary, the campaign generated measurable changes in cat owner intention and behavior. Conservation campaigns informed by co‐benefits for cat owners may reduce cats' hunting and be conciliatory ways of transcending environmental conflict.
... "Many stray cats wander the streets and are occasionally found in restaurants, campuses, places of worship, and landfills hunting for food" [11]. "Old dogs and cats typically live alone, produce offspring uncontrollably, fill up the environment, and frequently cause difficulties and global issues for public health and environmental safety" [5]. ...
Overpopulation of stray animals is a significant public health and animal welfare issue in India. Neglected zoonotic illnesses spread through stray animals and humans, especially in low- and middle-income nations. Stray animals often breed uncontrolled because they do not rely on humans for food or shelter. Uncontrolled stray animal breeding increases their population, increasing the risk of predation, road traffic accidents, and the transfer of zoonotic diseases, making them vectors for certain diseases. Stray animal population management strategies vary based on the situation and type of animals. These methods include contraception, trap-neuter-return, poisoning, euthanasia, and gun firing, among others. To properly monitor and control the stray animal population, it's vital to educate the community about the challenges that free-roaming animals cause and provide methods to alleviate them.
... For example, although some species may occur in cities, low survival could indicate that these populations are not self-sustained but driven by dispersal of juveniles into cities (Withey & Marzluff, 2005). Survival of birds in urban areas may be low because they suffer immediate lethal consequences from fatal collisions with buildings (Elmore et al., 2021) or from feral predators, which occur at high density in urban areas (Loss, Will, & Marra, 2013;Legge et al., 2017; but see Fischer et al., 2012). On the other hand, 'natural' predators might avoid cities, resulting in lower predation rates (E€ otv€ os, Magura, & L€ ovei, 2018). ...
Urbanization forms one of the most drastic alterations of the environment and poses a major threat to wildlife. The human–induced modifications of the landscape may affect individual's fitness resulting in population declines. Research on how urbanization affects fitness traits has shown mixed results. However, studies typically contrasted data from a single species from few urban and non‐urban sites collected over short timeframes. Examining multiple species across a broad urbanization gradient enables a more robust comparison and understanding of how different species are impacted by urbanization‐knowledge crucial for generating population predictions, which are essential for conservation management. Here, we use data from a nation‐wide citizen science project to examine variation in survival and relative body mass and size (wing length) of common passerine birds, collected along an urbanization gradient in the Netherlands over an 8‐year period. Urbanization was measured as the distance from the city's border and the proportion of impervious surface area. Although the overall association between urbanization and survival was slightly negative, there was support for lower survival closer to the city in three species (chiffchaff Phylloscopus collybita, European robin Erithacus rubecula, European greenfinch Chloris chloris) and higher survival closer to the city in two (great tit Parus major and house sparrow Passer domesticus) of the 11 species examined. The contrasting survival successes among species suggest that ongoing urbanization may lead to shifts in community structure and loss of biodiversity. Impacts of urbanization on relative mass and size also exhibited varying effects, albeit less pronounced, and these effects were not correlated with the effects on survival. This implies that body mass and size cannot be used as indicators for urban‐associated patterns of survival. Our results further imply that effective conservation management targeting bird communities should involve a range of diverse actions, as focusing on single measures is unlikely to simultaneously impact multiple species due to the variation in responses to urbanization.
... Feral cats (Felis catus) are recognised as a significant predation threat to wildlife and have contributed to severe declines and extinctions in native birds, mammals and reptiles across Australia (Lepczyk et al. 2004;Medina et al. 2011;Doherty et al. 2017;Legge et al. 2017;Woolley et al. 2019). Predation by feral cats is recognised as a key threatening process under the Australian Commonwealth Government's Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act) and threatens the survival of over 100 native species in Australia (Department of Climate Change, Energy, the Environment and Water 2023a). ...
Feral cat predation is recognised as a significant threat to Australian wildlife that has contributed to population declines and extinctions. Cat predation of bats worldwide is a growing concern, though there are few studies focusing on Australian species. We consolidated empirical evidence of cat predation on the threatened Pilbara leaf-nosed bat (Rhinonicteris aurantia) in the Pilbara region of Western Australia. Observations in video and camera trap datasets demonstrated repeated predation of R. aurantia by several individual cats at three significant roosts. Between 2020 and 2023, we documented 183–200 bat kills at these sites. We recommend feral cat predation be formally recognised as a key threat to this species. To prevent declines at key colonies that would contribute to a population reduction, ongoing monitoring and proactive control of cats at known R. aurantia roosts should be prioritised. As demonstrated herein, camera trap monitoring is a valid method for quantifying the impact of feral cats at roost sites. Because relatively few individual cats at just a few sites can have a large impact, and most of the larger roost sites of R. aurantia have been discovered, there is potential for amelioration of this threat with multiple established and emerging methods deployed concurrently.
... were the most studied non-native species, accounting for 34.7% and 16.3%, respectively, of the urban studies researching non-native species. While domesticated animals might not be considered wildlife, we included these studies because feral populations of such animals often interact with their surrounding ecosystems in a detrimental fashion, such as disease transmission and predation of native species (Baker et al., 2018;Davis et al., 2018;Legge et al., 2017). ...
The threat to biodiversity posed by urban expansion is well researched and supported. Since the late 1990s, the field of urban ecology has been expanding along with the developed landscapes it studies. Past reviews have shown unequal publication rates in urban ecology literature for taxonomic groups and research locations. Herein, we explore differences in the publication rate of urban studies by vertebrate groups, but also expand on previous investigations by broadening the scope of the literature searched, exploring trends in subtopics within the urban wildlife literature, identifying geographic patterns of such publications, and comparing the rate at which non‐native and threatened and endangered species are studied in urban settings. We used linear and segmented regression to assess publication rates and Fisher's exact tests for comparisons between groups. All vertebrate groups show an increasing proportion of urban studies through time, with urban avian studies accelerating most sharply and herpetofauna appearing to be understudied. Non‐native mammals are more studied than non‐native birds, and threatened and endangered herpetofauna and mammals are more likely to be studied than threatened and endangered birds in urban areas. The plurality of urban wildlife studies are found in North America, while there is a dearth of studies from Africa, Asia, and South America. Our results can help inform decisions of urban ecologists on how to better fill in knowledge gaps and bring a greater degree of equity into the field.
... Although these techniques can be successful, they are not without limitations, including intensive labour and associated costs, their indiscriminate nature, welfare concerns (such as the humaneness of poison baiting (Johnston et al. 2020)) and wariness of remnant individuals Legge et al. 2017). Cat eradication programs can take years to complete, with remnant individuals often proving difficult to remove, thus the need for new additional efficient management techniques (Nogales et al. 2004;Ratcliffe et al. 2010;Algar et al. 2011;Robinson and Copson 2014;Dickman et al. 2019;Algar et al. 2020). ...
Context. Feral cats are a significant threat to wildlife in Australia and globally. Current feral cat management techniques have limitations that can result in wary, remnant individuals persisting in the landscape and reducing overall pest control efficacy, thus there is a need for additional innovative management techniques. Aims. This research aimed to identify whether the Mata Hari Judas technique could be applied to female cats (queens) in situ as a means of attracting and assisting the capture of feral cats. Methods. Three queens were induced into prolonged oestrus and contained in enclosures (vennels) in situ with traps attached to capture attracted feral cats. Two vennel treatments were trialled, one housing a Mata Hari Judas queen (queen vennel) and another using auditory and olfactory lures from a Mata Hari Judas queen (faux queen vennel) to compare the attractiveness of the two treatments at three study sites. Camera traps and soil plots were used to monitor and compare cat activity surrounding the vennels prior to, during and after the presence of a Mata Hari Judas queen or her lures. Key results. Both vennel treatments attracted multiple feral cats of both sexes, and each trapped one male cat, demonstrating proof of concept for this technique. The queen vennel was significantly more attractive than the faux queen vennel, as demonstrated by higher frequency of cat detections and the duration of time feral cats spent at this vennel. Comparisons between monitoring periods and when the vennels were active showed significant differences in the frequency of cats attracted to the area, further supporting that both the queen and her lures were attractive to cats. Conclusions. This research is the first instance where Mata Hari Judas queens have been successfully used in situ to attract and capture feral cats. Future studies should aim to assess this technique in a controlled area with a known cat population to allow for a direct comparison of efficacy with more traditional feral cat management methods. Implications. With further refinement, the use of Mata Hari Judas queens in situ could provide an efficient technique for removing remnant cats.
... Estimates of the world dog population vary widely but is generally believed to be upwards of between 500-600 million [2,3]; approximately 75% (~480 million animals) of which are considered to be free-ranging or strays [4]. Additionally, the feral cat population is estimated to be at least 100 million, including 60 million in the USA and up to 12 million in Australia alone [5,6]. These numbers highlight the magnitude of the worldwide problem posed by free-roaming domestic dogs and cats, which impacts not only human health but also imposes significant economic and environmental costs. ...
The surgical sterilization of cats and dogs has been used to prevent their unwanted breeding for decades. However, this is an expensive and invasive procedure, and often impractical in wider contexts, for example the control of feral populations. A sterilization agent that could be administered in a single injection, would not only eliminate the risks imposed by surgery but also be a much more cost-effective solution to this worldwide problem. In this study, we sought to develop a targeting peptide that would selectively bind to Leydig cells of the testes. Subsequently, after covalently attaching a cell ablation agent, Auristatin, to this peptide we aimed to apply this conjugated product (LH2Auristatin) to adult male mice in vivo, both alone and together with a previously developed Sertoli cell targeting peptide (FSH2Menadione). The application of LH2Auristatin alone resulted in an increase in sperm DNA damage, reduced mean testes weights and mean seminiferous tubule size, along with extensive germ cell apoptosis and a reduction in litter sizes. Together with FSH2Menadione there was also an increase in embryo resorptions. These promising results were observed in around a third of all treated animals. Given this variability, we discuss how these reagents might be modified in order to increase target cell ablation and improve their efficacy as sterilization agents.
... Because many stray cats are consistently taken care of by humans and some owned cats are permitted to go outdoors (free-ranging ownership), the free-ranging cat population is continuously replenished worldwide ( Figure 1). Approximately 1.4−5.6 million feral cats subsist outside in Australia (Legge et al., 2017). In Ottawa, Canada, the average free-ranging cat density is 130 cats/km 2 (Perkins et al., 2021), and in the United Kingdom, the median unowned cat density is 9 cats/km 2 in urban areas (McDonald & Skillings, 2021). ...
Because global anthropogenic activities cause vast biodiversity loss, human dimensions research is essential to forming management plans applicable to biodiversity conservation outside wilderness areas. Engaging public participation is crucial in this context to achieve social and environmental benefits. However, knowledge gaps remain in understanding how a balance between conservation and public demands can be reached and how complicated sociocultural contexts in the Anthropocene can be incorporated in conservation planning. We examined China's nationwide conflict between free‐ranging cats (owned cats that are allowed to go outdoors or homeless cats living outdoors) and wildlife to examine how a consensus between compassion and biodiversity conservation can help in decision‐making. We surveyed a random sample of people in China online. Over 9000 questionnaires were completed (44.2% response). In aggregate, respondents reported approximately 29 million free‐ranging owned cats and that over 5 million domestic cats per year become feral in mainland China. Respondents who were cat owners, female, and religious were more likely to deny the negative impacts of cats on wildlife and ongoing management strategies and more supportive of stray cat shelters, adoption, and community‐based fund raising than nonowners, male, and nonreligious respondents (p < 0.05). Free‐ranging cat ownership and abandonment occurred less with owners with more knowledge of biodiversity and invasive species than with respondents with less knowledge of these subjects (p < 0.05). We recommend that cat enthusiasts and wildlife conservationists participate in community‐based initiatives, such as campaigns to keep cats indoors. Our study provides a substantially useful framework for other regions where free‐ranging cats are undergoing rapid expansion.
... 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. ...
... It was recently estimated that there are between 2 and 6 million feral cats in Australia (Legge et al. 2017). Approximately, half of the studies included in this review used camera traps to estimate the abundance of feral cats. ...
Feral cats (Felis catus) are difficult to manage and harder to detect. For 20 years, we have been using an annual aerial baiting program to suppress feral cat numbers on the Matuwa National Park in Western Australia. The efficacy of this management is monitored via pre-bait and post-bait surveys of feral cat activity on sandy tracks, and at least 120 camera-traps. In 2021, we detected cats on only five occasions, despite using 130 camera-traps with an olfactory lure known as Catastrophic. In this study, we measured the detectability of feral cats at three camera-traps arrangements on Matuwa: passive cameras (n = 57), camera with the Catastrophic lure (n = 120), and cameras with a Magnum Scrape-Dripper® (n = 63) dispersing cat urine. All 120 sites had two cameras, one with Catastrophic for comparison with data from prior surveys, plus a camera that was either passive or had a dripper. Camera-traps were active for an average of 57 days (range 55–60 days). Cats were detected by cameras with drippers 29 times more than passive cameras and six times more than Catastrophic cameras. Further, cats spent on average 2.6 s in front of passive cameras, 8.5 s in front of Catastrophic cameras, and 65.5 s in front of drippers. The ability to detect feral cats affects the magnitude and accuracy of abundance or occupancy estimates for cats. Therefore, our research highlights a severe weakness in current feral cat survey methodologies and any management decisions derived from that data.
... 9,[17][18][19] The semi-owned and unowned domestic cat population in Australia has been estimated at 0.7-2 million, or 60-100 cats per 1000 human residents, depending on location. [1][2][20][21][22] Many, even most, unowned domestic cats are provided with some care (food, shelter, veterinary treatment) by people who do not consider they own them. 2,7,9 This semi-owned population are generally sexually intact with a high reproductive rate owing to supplementary feeding and hence their offspring contribute to animal shelter intakes and swell the feral and owned pet cat populations ( Figure 1). ...
Objectives
Unowned ‘stray’ domestic cats threaten wildlife, as well as create a community nuisance and contribute to high rates of euthanasia in animal shelters. These cats can experience poor welfare, contribute to the pet cat population and compromise attempts to control feral cats. However, many unowned domestic cats are cared for by semi-owners who do not consider they own these cats; therefore, semi-owners are a potentially important target population for human behaviour change interventions. The present study aimed to describe the characteristics of cat semi-owners and compare these with the general population of cat owners and non-cat owners to inform future cat management interventions.
Methods
An online questionnaire open to all residents of New South Wales, Australia was developed and advertised. Respondents were asked ‘do you care for other free-roaming or stray cats (not including the cats you own)?’, whether they owned cats, about characteristics of their home and their agreement with 15 capability, social opportunity and motivation (COM) items relating to cat containment.
Results
Questionnaire responses were received from 8708 people, including 588 semi-owners (7%). Semi-owners were significantly more likely to be female, live in urban areas, live in lower socioeconomic areas and rent their home. Most semi-owners also owned their own cats and owned more cats than non-semi-owners.
Conclusions and relevance
Semi-owners of unowned ‘stray’ cats are a valuable potential target audience for human behaviour change interventions. Understanding that these semi-owners often have their own cats, might already be overwhelmed with cat-caring responsibilities and are disproportionately from lower socioeconomic backgrounds should guide intervention design. A nuanced approach is needed that prioritises the wellbeing of cats and semi-owners for semi-owners to ‘buy in’. Any intervention should also recognise that semi-owners often face multiple, complex barriers to neutering or claiming ownership of the cats they care for, especially cost, and trust in the authorities.
... Most dogs are considered strays due to abandonment by their owners for a number of reasons, including family migration, disease, and intolerable physiological behavior in pets with no means of treatment or feeding ( (Lyu, 2015)). Many stray cats roam on the streets and are sometimes seen in restaurants, campuses, places of worship, and in landfills looking for food (Legge et al., 2017). Old dogs and cats mostly live alone, reproduce uncontrollably, overpopulate the environment and often become a source of difficulties and global problems for public health and environmental safety (Voslarova and Passantino, 2012). ...
Stray animals are unowned free roaming, homeless, abandoned, street or sheltered animals, particularly dogs, cats and cattle. They could act as carrier of several zoonotic pathogens such as rabies virus, Mycobacterium and Brucella species. However, comprehensive information on the prevalence of zoonotic pathogens in stray animals is very limited. We conducted a systematic review as per Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) 2020 guidelines to estimate the prevalence of brucellosis in stray dogs, cats and cattle. Eligibility criteria for the study were determined using the PECOS classification (population, exposure, comparison, outcome, study design) as a tool to guide the research and adjust the search strategy. Major bibliographic databases [Web of Science, Medline, Scopus, ScienceDirect, Google Scholar and PubMed] were searched using predefined keywords for published epidemiological studies on brucellosis in stray animals (dogs, cats and cattle). Systematic assessments of all the studies since 1990-2022 were conducted and those reporting the prevalence of brucellosis in stray dogs, cats and cattle using appropriate diagnostic tests (culture, molecular, serological) were included. Studies reporting prevalence of brucellosis (Brucella infection or exposure) in kennel dogs, dairy herds, livestock farms, humans or marine species were excluded. The apparent individual test- wise prevalence along with 95% confidence intervals (CI) was estimated using Epitools. Out of 2689 studies, 37 met the inclusion criteria and were included in the systematic review. Of 37 studies, 28 (75.7%) were conducted in stray dogs, 7 (18.9%) in cattle and 2 (5.4%) in cats. Furthermore, only 21.62% studies (8/37) used probabilistic random sampling approaches and 13.51% studies (5/37) explained and justified the study sample size using appropriate methods for estimation of disease prevalence in the study populations. Higher sero-prevalence in stray dogs has been reported in studies conducted in Jordan (38.0% (95% CI: 24.0-54.0) and Pakistan (38.0% (95% CI: 31.0-45.0) whereas no sero-positivity was recorded in the studies conducted in Brazil, North Colombia, Cyprus, South Korea and USA. All studies on brucellosis (n = 7) in stray cattle were from India; conducted in stray cattle reared in cow-shelters. Sero-prevalence in the range of 4.3%- 64.3% was reported in stray cattle. Differences in diagnostic tests and host species, as well as limited number and non-randomized studies and high statistical heterogeneity did not allow us to determine combined meta-analysed prevalence estimates. Stray animals are likely to pose a zoonotic and disease spillover risk to human and livestock populations.
... GI is easy to calculate and can be used to monitor variations in feral cat population as an alternative to harder-to-calculate indicators, such as estimated feral cat absolute density (spatially explicit capture-recapture, SECR; Efford 2015). It has been shown to be robust on relative abundance, leading to conclusions that are consistent with those based on other indices (Bengsen et al. 2012;Legge et al. 2017;Palmas et al. 2020a). The GI estimates feral cat activity (relative abundance approximation) by measuring mean camera capture events per camera and per occasion, following the equation of Engeman (2005): ...
Context Invasive feral cats strongly threaten native fauna on islands worldwide. The impact of feral cat populations is assumed to be higher in the presence of introduced rodents and may also vary according to an island’s rodent species assemblage. Aims This study assessed feral cat impacts on island biodiversity in French Polynesian islands harbouring differing assemblages of rat species, by investigating their abundance and trophic ecology. Methods We focused on the following six human-inhabited islands of three archipelagos in French Polynesia (South Pacific) with differing rat species assemblages: Tahiti and Moorea, Ua Huka and Tahuata, Rurutu and Rimatara. We studied (1) cat abundance, by setting up camera traps during 15 consecutive days to provide an abundance index, the general index (GI) or mean number of virtual captures per camera per occasion, and (2) cat diet, by performing macroscopic analyses of scat samples to determine the frequency of occurrence (FO) of prey categories. Key results Our study showed previously unreported patterns of cat-abundance index for the Society archipelago, with a GI of 0.30 ± 0.12 in Tahiti and 0.02 ± 0.02 in Moorea; for the Marquesas, with a GI of 0.75 ± 0.20 in Ua Huka and 0.20 ± 0.06 in Tahuata; and for the Austral, with a GI of 0.06 ± 0.04 in Rurutu and 0.19 ± 0.05 in Rimatara. Feral cats are shown to prey strongly on introduced rodents (FO = 91.3%), arthropods (37.8%), squamates (18.6%) and birds (13.3%) in our study sites. FO of birds are particularly high in Rimatara (31.9%) and Ua Huka (16.8%). Conclusions We demonstrated that feral cats represent a serious threat to biodiversity in French Polynesian islands, with 15 species preyed on, including eight endemic birds, four of them being considered threatened by the IUCN Red List. Surprisingly, relative abundances of feral cats were higher both on islands harbouring only one rat species (Ua Huka, with only Rattus exulans) and on islands free of black rats. This finding raises questions regarding the ‘hyperpredation’ hypothesis for multi-invaded island ecosystems. Implications This study on islands with differing assemblages of introduced rodents demonstrated the need for invasive predator studies in multi-invaded ecosystems, so as to improve bird conservation and guide management strategies and site prioritisation.
... Habitat protection and community engagement to curb overhunting are the primary conservation responses in New Guinea, the Solomons, and Indonesia (Woinarski and Fisher 2023). In Australia, habitat protection is essential but insufficient for preventing declines and extinction in marsupials, mainly because introduced predators occur across all tenures (Legge et al. 2017). ...
... It is also likely that the region supported elevated cat densities following high rainfall during the 2010-11 La Niña event (Wardle et al. 2013;Legge et al. 2017). In this context, with high cat densities and crashing rodent populations triggering cats to seek alternative prey (Letnic and Dickman 2010). ...
Australia’s recent mammal declines have been most severe in the arid regions, with at least 14 species extinctions occurring therein. The common brushtail possum (Trichosurus vulpecula) is a semi-arboreal marsupial that historically occurred widely across arid Australia but has disappeared from much of this region. We surveyed the last known sites for the species in central Australia. In 2012, we detected possum scats from 3 of 19 sites in Tjoritja National Park in the Northern Territory. Presence sites were separated by <4 km and characterised by extreme ruggedness. Further scat surveys in 2016–17, and 10 499 camera-trap nights of targeted survey in 2020–21, resulted in no possum detections. Moreover, no possums were detected during >60 000 camera-trap nights at nearby monitoring sites targeting other species in 2016–22. The contraction of common brushtail possums to rugged refuges by 2012 is consistent with a decline driven by mammalian predators. The possible extirpation also coincided with or followed record years of high temperatures. The culturally significant common brushtail possum is a priority candidate species for reintroduction to parts of central Australia. Reintroduction attempts must manage mammalian predators and consider the suitability of source populations and translocation sites in the face of a rapidly warming climate.
... Cats are putatively the primary threat to savanna mammals in northern Australia (Johnson, 2006;Frank et al., 2014;Ziembicki et al., 2015;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. ...
... Higher density cat populations are typically seen in and around urban environments [4]. In Australia, there are approximately 4.09 million owned cats in 30% of households, and approximately 2.8 million feral cats, covering more than 99.8% of Australia's surface area [5][6][7][8]. ...
Free-roaming cats pose a risk to their own health and welfare, as well as to the health and welfare of wildlife and humans. This study aimed to monitor and quantify area-specific free-roaming cat movement. Two local government areas (LGAs) in Greater Sydney were included, Campbelltown (CT) and the Blue Mountains (BM). Motion-capture cameras were installed on 100 volunteer properties (50 per LGA) to indirectly capture animal movements over two months. Transect drives were completed eight times (four per LGA) to directly observe roaming cats in residential areas. The cameras and transects both identified higher free-roaming cat numbers in CT (density of 0.31 cats per ha, resulting in an estimated abundance of 361 cats in the 1604 ha of residential area) than the BM (density of 0.21 cats per ha, resulting in an estimated abundance of 3365 cats in the 10,000 ha of residential area). More wildlife events were captured in the BM (total = 5580) than CT (total = 2697). However, there was no significant difference between CT and the BM for cat events (p = 0.11) or wildlife events (p = 0.32) observed via the cameras. Temporally, cats were observed via the cameras throughout the entire day with peaks at 9:30 am and 8:00 pm in the BM, and 7:00 am and 12:00 pm in CT. Overlaps in activity times were recorded for free-roaming cats with bandicoots (BM), possums (BM), and small mammals (BM and CT). This study demonstrates that camera monitoring on private property and transect drives are useful methods to quantify free-roaming cat abundance to inform cat management interventions.
... The impacts of each invasive mammalian predator species can vary with their abundance and behaviour, and with the tolerance of the prey species present, all of which may be dynamic across habitats, landscapes, or seasons. Invasive predators may cause detriment, or may provide ecological benefits, such as controlling potentially damaging native or invasive species (Rayner et al. 2007;Bergstrom et al. 2009;Dowding et al. 2009;Ritchie and Johnson 2009;Glen et al. 2013;Legge et al. 2017;Springer 2018;Ortega et al. 2021), providing food for native species (Carlsson et al. 2009;Travers et al. 2021), or pollination and dispersal for native plants or fungi (Vernes and McGrath 2009;Pattemore and Wilcove 2012;O'Rourke et al. 2020). Given these complexities, understanding the ecological role of invasive predators is critical for informing the need, priority and likely benefits of invasive species management. ...
Context Invasive mammalian predators are a primary cause of extinctions, especially on islands. Baseline data on the impact of invasive mammalian predators are critical for deciding whether their eradication or control should be attempted, and for monitoring ecosystem changes over time if control does occur. Christmas Island is a tropical island with multiple invasive species, including two mammalian predators (black rats, Rattus rattus and feral cats, Felis catus). Black rats are known to prey upon island bird species (including their nests) elsewhere, but the severity of their impacts on Christmas Island birds is unclear. Describing these impacts would help managers decide whether rat control is warranted, especially as a cat eradication program underway on the island could conceivably result in increased rat density. Aims In this study, we quantify the impacts of rats on Christmas Island bird abundance and nesting success. Methods The abundance of four endemic forest bird species/subspecies (Christmas Island imperial pigeon, Ducula whartoni, emerald dove, Chalcophaps indica natalis, thrush, Turdus poliocephalus erythropleurus and white-eye, Zosterops natalis) was measured using transect surveys. Nest success was measured using remote sensing camera surveillance for one forest bird species (thrush) and one seabird species (red-tailed tropicbird, Phaethon rubicaudra westralis). We explored whether these measures were related to spatial variation in rat density and activity (measured by trapping and inkcards), the presence of other invasive species, habitat and seasonal variables. Key results Neither rat density nor activity explained the abundance of any forest bird species. Instead, seasonal and habitat features were more consistent predictors of bird abundance. White-eyes were more abundant near yellow crazy ant (Anoplolepis gracilipes) supercolonies. Nest success for thrushes and red-tailed tropicbirds was either not, or only very weakly, influenced by rats. Conclusions Black rats currently have little effect on the population sizes and nesting success of Christmas Island birds. Implications This study suggests that rat control is not currently a management priority, but ongoing monitoring of rat density, activity, and impacts is needed to ensure management can respond promptly if rat density or impacts change as cat control progresses towards eradication.
... Across Australia, the predation impacts of feral cats are thought to be greatest in areas with sparse groundlayer vegetation cover (Lawes et al., 2015). This may be in part because (1) cats are more abundant in these areas (Legge et al., 2017) and/or (2) cats potentially hunt most effectively in open habitats as there may be less cover for prey, making them easier to detect and capture (McGregor, . Therefore, the removal of vegetative cover by fire may advantage feral cats, even if some cats are killed by fire, and even if there is a lower abundance of prey species post-fire. ...
Predation by feral cats ( Felis catus ) has caused the extinction of many native species in Australia and globally. There is growing evidence that the impacts of feral cats can be amplified in post‐fire environments, as cats are drawn to hunt in or around recently burnt areas and are also more effective hunters in open habitats. In 2018–2019, we established arrays of camera traps to estimate the abundance of feral cats on Kangaroo Island, South Australia. Much of the island (including five of our seven survey sites) was subsequently burnt in a severe wildfire (December 2019–February 2020). We re‐sampled the sites 3–8 months post‐fire (seven sites) and 11–12 months post‐fire (three sites). At two unburnt sites sampled post‐fire, it was possible to produce density estimates of cats using a spatially explicit capture–recapture approach. Where estimating density was not possible (due to low detections or individual cats not being distinguishable), the number of individuals and percentage of trap nights with detections was compared between the sampling periods. Some low‐level cat control occurred within 2 km of three of the seven arrays (all within the burn scar) within 3 months of the fire. Across the five burnt sites, there was a decline in cat detections post‐fire (including those without post‐fire cat control). At 3–8 months post‐fire, there was, on average, a 57% reduction in the number of individual cats, and a 65% reduction in the number of nights with cat detections, relative to pre‐fire levels. Although cat detections declined following the fire, reduced population sizes of prey species and reduced cover as a result of the fire might still mean that cat predation is a threat to some surviving prey species. Management that reduces feral cat predation pressure on wildlife following wildfire should enhance the likelihood of post‐fire wildlife persistence and recovery.
... These numbers highlight how little we know about the real magnitude of the predation pressure exerted by domestic cats upon wildlife in Brazil. This becomes even clearer if we consider that the conservative estimate of the cat population in Brazil is 14 million individuals [40], approximately four times larger than the cat population estimated in Australia [41]. Therefore, the low number of species impacted by domestic cats in Brazil is likely due to the lack of systematic studies including long term observations (of this feline and its prey) encompassing different habitats [see 42,43,44]. ...
Domestic cats (Felis catus Linnaeus, 1758) can interact with and cause several negative impacts upon wildlife if unconstrained by their owners. These impacts occur especially because of their innate predatory behavior and, usually the lack of any natural predators, as well as due to their high abundances relative to native carnivores. Although these impacts are well studied in temperate countries, there are but a few records of species used as prey by these carnivores in Brazil. Here, we expand the knowledge of native species preyed upon by domestic cats in Brazil by presenting new records of this predator-prey interaction and reviewing records in the literature. Predation events were recorded through opportunistic encounters between 2016 and 2022. We recorded the predation of 14 native terrestrial vertebrate species (reptiles, amphibians, birds, and mammals) from the Cerrado and Atlantic Forest biomes. Our literature review recovered predation events by cats in the two aforementioned biomes plus in the Amazonia. Our results increase to 48 the number of wild species preyed upon by domestic cats in Brazil, which is probably an underestimation, as this number is much higher in other countries of comparable land size and species diversity. We suggest that cat population control measures should be carried out, especially in protected areas.
Context Predation by feral cats continues to place substantial pressure on native Australian wildlife, contributing to significant population declines and localised extirpations of susceptible species. In Western Australia (WA), the registration of the poison bait Eradicat® provides a tool to help manage these introduced predators, but only in areas where the risk to non-target species is considered acceptable. The red-tailed phascogale (Phascogale calura), a small carnivorous marsupial now restricted to vegetation remnants in the highly fragmented agricultural zone of south-western WA (i.e. the Wheatbelt), is one species that may be vulnerable to lethal ingestion. Aim To investigate the impact of repeated Eradicat® baiting, to control feral cats, on the activity levels of the red-tailed phascogale, focusing on populations in two Wheatbelt conservation reserves. Methods We established a novel approach to monitoring red-tailed phascogales by using tree-mounted camera trap arrays in an area with feral cat management using ground-delivered Eradicat® baits, and two control zones with no feral cat management. We examined changes in activity levels (detection rate and occupancy) based on camera trap detections, before and after Eradicat® application, across two autumn and two spring baiting events. We also investigated non-target bait uptake using camera traps. Key results Although a small number of baits (7/60) was removed by red-tailed phascogales from the field of view of a camera, our results showed no overall impact of Eradicat® on their activity levels within the study area. Tree-mounted camera traps proved to be highly effective and efficient at detecting red-tailed phascogales. To maximise camera detections, the optimal time for monitoring red-tailed phascogales is during autumn, prior to male die-off. Conclusions Our results suggested that the risk posed to red-tailed phascogale populations from the repeated use of Eradicat® baits is likely to be low. Implications Integrating the application of Eradicat® to control feral cats with existing fox control in conservation reserves that support populations of red-tailed phascogales is likely to pose minimal risk to the species.
Most cats entering animal shelters in Australia are less than 12 months old and emanate from low socioeconomic areas. Many are unidentified and may be either owned or semi-owned cats (cats cared for by someone who does not consider themselves the owner). In Australia, approximately 33% of cats entering shelters and pounds are euthanized annually, adversely affecting the mental health of staff involved. Our study investigated cat ownership and caregiving behaviors of cats enrolled in the Australian Pet Welfare Foundation’s Community Cat Program, which included free sterilization, microchipping, and preventive healthcare. The suburbs targeted in Ipswich, Australia had a high per capita cat intake into animal shelters. We surveyed 1094 cat owners and semi-owners. Most cats were under 12 months old (79%), primarily domestic short-haired (69%), and acquired through informal channels such as friends, family, or as strays. Veterinary care was limited, with only 15% of cats having visited a veterinarian and 28% being vaccinated. Prior to hearing about the free sterilization program, 88.5% of participants identified as owners, while 11.5% were semi-owners. Before completing the survey, these semi-owners transitioned from an informal caregiving relationship to becoming owner of the cat/s. Of the semi-owners, 93% indicated that their transition to ownership was driven by feelings of responsibility, emotional attachment, and access to free sterilization services. These findings suggest that targeted interventions, such as accessible veterinary care and sterilization programs, are crucial in encouraging semi-owners to take full ownership of cats, improving cat welfare, and reducing unplanned breeding. Supporting this transition helps curb overpopulation and fosters improved caregiving, benefiting both cats and communities.
Introduction
Feline calicivirus (FCV) commonly causes upper respiratory tract, oral and ocular infections in species of the family Felidae, with high prevalence amongst domestic cat ( Felis catus ) populations worldwide. Detection of FCV‐specific antibodies in serum provides evidence of previous infection with FCV and an indication of whether a cat may be protected against clinical FCV disease. This study describes the most extensive sampling for anti‐FCV antibodies in feral and stray cat populations in Australia, and examines variation in prevalence associated with cat age, sex and location.
Methods
Blood samples were opportunistically collected from 669 feral, stray or Indigenous community cats from the Northern Territory, South Australia, Victoria, south‐east Tasmania and south‐west New South Wales. The sera were harvested and tested for antibodies capable of neutralising the FCV vaccine strain F9 by serum‐virus neutralisation assay.
Results
Of the 669 cats tested, 69.7% had detectable FCV‐F9‐neutralising antibodies (titres ≥5). Maturity was significantly associated with higher seroprevalence and higher antibody titres, with adult cats being more than twice as likely to have detectable FCV‐neutralising antibodies than subadults. Male cats had a higher seroprevalence and slightly higher antibody titres than females. Cats living in closer proximity to humans had significantly higher seroprevalences and higher FCV‐neutralising antibody titres than feral cats from more remote regions of Australia.
Conclusion
Australian feral and stray cats have a high risk of natural exposure to and infection with FCV, with the prevalence and levels of pre‐existing immunity to FCV being highest amongst adult cats living in highly modified urban, peri‐urban and agricultural environments.
Context. Feral cats are responsible for the decline and extinction of species globally. Predation by feral cats is identified in Australian legislation as a key threatening process. However, clear guidance to local land managers on feral cat management techniques and their impacts, limitations and potential costs can be difficult to find. Aims. In this study, feral cat management experts from around Australia identified available management techniques and their average environmental, social, and economic impact for different ecoregions and land-use types. Methods. We convened a 1-day structured elicitation workshop with 19 experts and five facilitators. Experts identified the techniques used for feral cat management; the effectiveness, impact, and cost of each method; and the key knowledge gaps associated with feral cat management. Facilitators aided in the design and format of the workshop, led the discussion at each stage and collated the results. Key results. Experts identified the following 10 techniques currently used in Australia: aerial baiting; ground baiting; leghold trapping; cage trapping; shooting; tracking with detector dogs; tracking by Indigenous Rangers; habitat modification; resource modification; and exclusion fencing. In general, experts highlighted that permits, legislation and scale of application constrained many of these techniques. Aerial baiting was considered the most effective technique for reducing feral cat populations in natural and production systems. Cage trapping, shooting, or tracking with detector dogs were considered more effective in residential areas. For all techniques, efficacy estimates varied according to the following three broad vegetation structural regions: (1) deserts and xeric shrublands; (2) forests and woodlands; and (3) grasslands, savannas and shrublands. Techniques considered to have the lowest social tolerance and highest impact to non-target native species included aerial baiting, ground baiting and leghold trapping. Techniques considered to have high social tolerance and low impact on non-target species included tracking by Rangers, tracking with detector dogs, and habitat and resource modification. Conclusions. Estimates of management action efficacy differ among land-use types and at least three vegetation structural regions. However, social licence, logistic and legislative constraints are the key drivers of the availability of methods for these areas. Implications. Feral cat management programs should consider how program strategy can be prioritised on the basis of technique availability, region of use and expected impact.
Context The deleterious impacts of cat predation on wildlife have been well documented. Additionally, unowned cats may act as reservoirs of disease important to public and companion animal health and their proclivity for roaming and fighting enables effective disease transmission. Urban environments support the highest human populations and companion animal densities, increasing the potential for disease transmission from unowned cats to people and pets. However, there is little data on the prevalence of pathogens in unowned cat populations. Aims This aim of this research was to establish baseline prevalence data for priority pathogens in an urban population of unowned cats. Methods One hundred unowned cat cadavers were collected from the Brisbane City Council region, Queensland, Australia. Blood and additional organ or tissue samples were collected post-mortem. Diagnostic methods for pathogen detection included use of real-time polymerase-chain reaction, commercially available rapid enzyme-linked-immunosorbent assay, lavage and faecal flotation. Key results Pathogen carriage was found in 79% (95% CI 71, 87%) of sampled cats. In total, 62% (95% CI 52, 72%) of cats showed evidence of co-carriage of two or more pathogenic organisms. The overall prevalence found for pathogens and parasites investigated were: Toxoplasma gondii, 7% (95% CI 2, 12%); Coxiella burnetii, 0.0% (95% CI 0, 0%); feline immunodeficiency virus, 12% (95% CI 6, 18%); feline leukaemia virus, 0.0% (95% CI 0, 0%); and gastrointestinal parasites, 76.8% (95% CI 68, 85%). Conclusions This study reports contemporary prevalence data for these pathogens that have not previously been available for unowned cats of south-east Queensland. High rates of gastrointestinal parasitism observed throughout the study population prompt concerns of a general increase in pathogenic prevalence, especially in comparison with that of owned domestic cats, as per previously published literature. The presence of signs of fighting is an important risk factor for increased likelihood of infection. Implications Data produced from this study contribute to informing cat management efforts throughout urban regions. Continued and expanded investigations, considering prevalence and risk factors of pathogens important to human and companion animal health, are recommended for the south-east Queensland area and beyond.
Worldwide predation by feral cats has caused severe declines in many animal species. Prior to extinction, threatening processes typically alter species behaviour, habitat use, survival and reproductive rates. By monitoring these parameters, we may be able to determine if feral cats are a significant threatening process to a species prior to extinction. We aimed to test whether feral cats are negatively affecting the population size, morphometrics and movement patterns of mulgaras (Dasycercus blythi) on the Matuwa Indigenous Protected Area, in the arid rangelands of Western Australia. We hypothesised that mulgaras, which inhabit a cat-free environment, would have a larger home range and denser population, and be in better condition than those that inhabited an adjacent area with a suppressed density of feral cats. We trapped (n = 64), and radio-tracked (n = 19) mulgara inside and outside an 1100 ha cat-free fenced enclosure on five occasions in 2012. Treatment (i.e. inside or outside the cat-free enclosure) was a significant variable for explaining variation in mulgara density. There was no significant difference in morphometrics or the home ranges of mulgara between the sexes or treatments. Head length, pes length and weight, as well as tail width and length, were significantly different between sexes and over time, suggesting that seasonal variation influences mulgara populations more than low levels of cat predation.
Eastern barred bandicoots (Perameles gunnii) are thought to be highly susceptible to disease caused by infection with the protozoan parasite Toxoplasma gondii. This study followed a population of 67 P. gunnii introduced onto the Summerland Peninsula, Phillip Island, Australia, where the prevalence of T. gondii infection in the feral cat population was known to be very high. Prior to release, bandicoots were tested for serologic exposure to T. gondii using the modified agglutination test. A subset of bandicoots was tested on four occasions after release onto the peninsula. No seroconversion was detected at any time point. A subset of bandicoots was radiotracked after release and at two additional trapping sessions to help monitor survival. Toxoplasma gondii DNA was not detected by PCR in eight carcasses recovered for necropsy. Fourteen founder bandicoots (21% of founders) were known to be alive at 500 d postrelease. A total of 29 unmarked bandicoots were trapped over the study period, confirming that the bandicoots were successfully reproducing on the island. Body weight, packed cell volume, and total plasma protein were used as measures of individual animal health; population health was inferred from these data. Body weight was significantly associated with trip number, with a general trend of increasing weight after release onto the island. This study showed that eastern barred bandicoots were able to establish a new population despite a probably high environmental load of T. gondii.
Control of invasive predators is a priority to protect island biodiversity. Understanding the responses of other species in multi-species invaded food webs is important to avoid unintended consequences. We use an intensive 2-year cat-trapping program in the vicinity of seabird colonies on Bruny Island, Tasmania, to investigate its effectiveness in reducing feral cat density and whether cat control influenced the behaviour and abundance of native and invasive mammal species. Cat density before control was extremely high around this seasonally rich food resource, much higher than on mainlands. Cat density was reduced 5.4-fold by control showing that trapping is effective in reducing cat density in this focussed landscape context. We found no direct effect of cat reduction on the abundance or behaviour of native or invasive mammalian prey species. Recruitment of invasive black rats and native swamp rats increased on the seabird colonies after the shearwater breeding season, and cats responded by increasing their presence on the colonies relative to surrounding areas. This suggests cascading bottom-up effects from a lagged productivity pulse provided by breeding seabirds which would require nutrient sampling to confirm. Our results highlight the complexity of subsequent effects of an invasive predator control on the broader ecosystem.
Australia's biota is species rich, with high rates of endemism. This natural legacy has rapidly diminished since European colonization. The impacts of invasive species, habitat loss, altered fire regimes, and changed water flows are now compounded by climate change, particularly through extreme drought, heat, wildfire, and flooding. Extinction rates, already far exceeding the global average for mammals, are predicted to escalate across all taxa, and ecosystems are collapsing. These losses are symptomatic of shortcomings in resourcing, law, policy, and management. Informed by examples of advances in conservation practice from invasive species control, Indigenous land management, and citizen science, we describe interventions needed to enhance future resilience. Many characteristics of Australian biodiversity loss are globally relevant, with recovery requiring society to reframe its relationship with the environment.
This report reviews valuation methods with potential to include the non-market values associated with alien invasive species in benefit-cost analysis. It illustrates non-market impacts using the examples of the feral cat (Felix catus) and buffel grass (Cenchrus ciliaris). It then summarises the results of a survey of environmental managers that provides insights into factors influencing the use of non-market valuation methods. The report concludes with practical strategies that decision makers can use to improve the consideration of non-market values when managing AIS.
An evidence-based approach to the conservation management of a species requires knowledge of that species' status, distribution, ecology, and threats. Coupled with budgets for specific conservation strategies, this knowledge allows prioritisation of funding toward activities that maximise benefit for the species. However, many threatened species are poorly known, and determining which conservation strategies will achieve this is difficult. Such cases require approaches that allow decision-making under uncertainty. Here we used structured expert elicitation to estimate the likely benefit of potential management strategies for the Critically Endangered and, until recently, poorly known Night Parrot (Pezoporus occidentalis). Experts considered cat management the single most effective management strategy for the Night Parrot. However, a combination of protecting and actively managing existing intact Night Parrot habitat through management of grazing, controlling feral cats, and managing fire specifically to maintain Night Parrot habitat was thought to result in the greatest conservation gains. The most cost-effective strategies were thought to be fire management to maintain Night Parrot habitat, and intensive cat management using control methods that exploit local knowledge of cat movements and ecology. Protecting and restoring potentially suitable, but degraded, Night Parrot habitat was considered the least effective and least cost-effective strategy. These expert judgements provide an informed starting point for land managers implementing on-ground programs targeting the Night Parrot, and those developing policy aimed at the species' longer-term conservation. As a set of hypotheses, they should be implemented, assessed, and improved within an adaptive management framework that also considers the likely co-benefits of these strategies for other species and ecosystems. The broader methodology is applicable 1 3 Biodiversity and Conservation to conservation planning for the management and conservation of other poorly known threatened species.
Despite the importance of safeguarding forests and woodlands for achieving global climate and biodiversity agendas, logging continues across most forested countries. Forestry advocates often claim logging has minimal impacts, but rarely consider the cumulative threat deforestation and degradation has had, and continue to have, on species. Using New South Wales (Australia) as a case study, we quantify the extent of deforestation and degradation from 1750 – current. Using these estimates of overall loss as a baseline, we then quantify the relative extent of contemporary (2000 – 2022) logging and the condition of the remaining native forest and woodland (quantified by measuring the similarity of a current ecosystem to a historical reference state with high ecological integrity). Using these data, we measure the impacts on distinct vegetation types and on 484 terrestrial forest-dependent now-threatened species. We show that more than half (29 million ha) of pre-1750 (pre-European colonization of Australia) native forest and woodland vegetation in NSW has been lost. Of the remaining 25 million ha, 9 million ha is degraded. We found contemporary degradation from logging affected 244 forest-dependent now-threatened species that had already been affected by this historical deforestation and degradation, but the impacts varied across species and vegetation types. We found that 70 now-threatened species that were impacted by historical deforestation and degradation and continue to be impacted by logging, now have ≤50% of their pre-1750 extent remaining that is intact (with three species now having <20%). By quantifying the historical impacts of deforestation and degradation, our research sets the impact of contemporary degradation from logging in perspective and highlights shortfalls in current environmental assessments that fail to consider appropriate baselines when reporting on overall impact. Future land management decisions need to consider not only the extent of remaining habitat based on pre-1750 extents, but also its condition.
Article impact statement
The impact of logging needs to be placed in perspective by considering past losses and degradation due to human land use decisions.
The Australian marsupial fauna has been devastated in the past 250 years, mainly due to impacts from invasive mammalian predators (cats and foxes), although other threats such as invasive herbivores, habitat loss and fragmentation, changes to fire regimes, and now climate change have played a role. The profound and ongoing impact of invasive predators has driven substantial research and management innovation. Australia has been at the forefront of developing approaches to reduce the density and impacts of introduced predators and implementing novel and ambitious species conservation programs. A large and growing network of islands and mainland fenced areas, free of introduced predators (“havens”), has been critical for avoiding further species extinctions. Outside these havens, advances in toxin presentation and deployment have enabled cat and fox densities to be reduced over large areas. Substantial research and field trials have been carried out to understand how predator-prey interactions, and habitat quality management, can be used to reduce predation impacts on susceptible native species. Synthetic biology offers new opportunities to manage introduced predators, including potentially by using gene drives. Finally, the attenuation of the formerly large continuous ranges of many species to small, isolated population remnants (because of predation or other reasons) has also driven research and improvements in genetic and metapopulation management that will increase the chance of population persistence in the longer term. However, unless Australia continues to invest in research and innovative conservation actions, the plight of its priceless marsupial fauna will remain perilous.
The 'Compassionate Conservation' movement is gaining momentum through its promotion of 'ethical' conservation practices based on self-proclaimed principles of 'first-do-no-harm' and 'individuals matter'. We argue that the tenets of 'Compassionate Conservation' are ideological-that is, they are not scientifically proven to improve conservation outcomes, yet are critical of the current methods that do. In this paper we envision a future with 'Compassionate Conservation' and predict how this might affect global biodiversity conservation. Taken
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
Predation by house cats (Felis catus) is one of the largest human-related sources of mortality for wild birds in the United States and elsewhere, and has been implicated in extinctions and population declines of several species. However, relatively little is known about this topic in Canada. The objectives of this study were to provide plausible estimates for the number of birds killed by house cats in Canada, identify information that would help improve those estimates, and identify species potentially vulnerable to population impacts.
In total, cats are estimated to kill between 100 and 350 million birds per year in Canada (> 95% of estimates were in this range), with the majority likely to be killed by feral cats. This range of estimates is based on surveys indicating that Canadians own about 8.5 million pet cats, a rough approximation of 1.4 to 4.2 million feral cats, and literature values of predation rates from studies conducted elsewhere. Reliability of the total kill estimate would be improved most by better knowledge of feral cat numbers and diet in Canada, though any data on birds killed by cats in Canada would be helpful.
These estimates suggest that 2-7% of birds in southern Canada are killed by cats per year. Even at the low end, predation by house cats is probably the largest human-related source of bird mortality in Canada. Many species of birds are potentially vulnerable to at least local population impacts in southern Canada, by virtue of nesting or feeding on or near ground level, and habitat choices that bring them into contact with human-dominated landscapes where cats are abundant. Because cat predation is likely to remain a primary source of bird mortality in Canada for some time, this issue needs more scientific attention in Canada.
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.
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.
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
Significance
The island continent of Australia harbors much of the world’s most distinctive biodiversity, but this review describes an extent of recent and ongoing loss of its mammal fauna that is exceptionally high and appreciably greater than previously recognized. The causes of loss are dissimilar to those responsible for most biodiversity decline elsewhere in the world.
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.
Feral cats (Felis catus) have a wide global distribution and cause significant damage to native fauna. Reducing their impacts requires an understanding of how they use habitat and which parts of the landscape should be the focus of management. We reviewed 27 experimental and observational studies conducted around the world over the last 35 years that aimed to examine habitat use by feral and unowned cats. Our aims were to: (1) summarise the current body of literature on habitat use by feral cats, in the context of existing ecological theory (i.e. habitat selection, foraging theory); (2) develop testable hypotheses to help fill important knowledge gaps in the current body of knowledge on this topic; and (3) build a conceptual framework that will guide the activities of researchers and managers in reducing feral cat impacts. We found that feral cats exploit a diverse range of habitats including arid deserts, shrublands and grasslands, fragmented agricultural landscapes, urban areas, glacial valleys, equatorial to sub-Antarctic islands and a range of forest and woodland types. Factors invoked to explain cat habitat use included prey availability, predation/competition, shelter availability and human resource subsidies, but the strength of evidence used to support these assertions was low, with most studies being observational or correlative. We therefore provide a list of key directions that will assist conservation managers and researchers in better understanding and ameliorating the impact of feral cats at a scale appropriate for useful management and research. Future studies will benefit from employing an experimental approach and collecting data on the relative abundance and activity of prey and other predators. This might include landscape-scale experiments where the densities of predators, prey or competitors are manipulated and then the response in cat habitat use is measured. Effective management of feral cat populations could target high-use areas, such as linear features and structurally complex habitat. Since our review shows often-divergent outcomes in the use of the same habitat components and vegetation types worldwide, local knowledge and active monitoring of management actions is essential when deciding on control programs.
We studied the response of vegetation and vertebrate assemblages to fire and grazing, and their interacting effects, in Eucalyptus woodland in north-eastern Australia. In this vegetation type, many pastures remain free of cattle grazing due to the occurrence of a native shrub poisonous to livestock. Vegetation (floristic data and 22 habitat variables) and vertebrate fauna (birds, mammals, reptiles) were sampled in 29 standardized 50 × 50-m quadrats in the 2001 wet season, representing four treatments: sites burnt recently (within 2 y) and grazed by cattle (423%, fire in ungrazed sites 68–39%) and increased the cover of forbs (8% in burnt and grazed sites, 3% if ungrazed) and tussock grasses (20% in grazed and unburnt sites and 5% when ungrazed). Grazing caused a shift in floristic composition from the perennial hummock grass Triodapungens to tussock grasses (e.g. Aristida spp., Enneapogon spp.), forbs (e.g. Phyllanthus spp.) and shrubs (e.g. Acacia spp.). Of the vertebrate groups, birds responded more to fire effects (9 species), reptiles to grazing effects (6 species) and mammals to the interaction (2 species). Species reacted to increases in bare ground (e.g. crested pigeon Ocyphapslophotes, hooded robin Melanodryascucullatus, Ctenophorusnuchalis) and to the dominant ground cover (e.g. Ctenotuspantherinus) or change in vegetation architecture (e.g. singing honeyeater Lichenostomusvirescens, variegated fairy-wren Maluruslamberti). The clearest example of an interacting effect was the cycle of complementary dominance between the rodents Pseudomysdelicatulus and P.desertor, the latter's post-fire recovery becoming more muted in sites where cattle grazed (modelled time for population recovery twice as long as in ungrazed sites).
Intensification of fires and grazing by large herbivores has caused population declines in small vertebrates in many ecosystems worldwide. Impacts are rarely direct, and usually appear driven via indirect pathways, such as changes to predator-prey dynamics. Fire events and grazing may improve habitat and/or hunting success for the predators of small mammals, however, such impacts have not been documented. To test for such an interaction, we investigated fine-scale habitat selection by feral cats in relation to fire, grazing and small-mammal abundance. Our study was conducted in north-western Australia, where small mammal populations are sensitive to changes in fire and grazing management. We deployed GPS collars on 32 cats in landscapes with contrasting fire and grazing treatments. Fine-scale habitat selection was determined using discrete choice modelling of cat movements. We found that cats selected areas with open grass cover, including heavily-grazed areas. They strongly selected for areas recently burnt by intense fires, but only in habitats that typically support high abundance of small mammals. Intense fires and grazing by introduced herbivores created conditions that are favoured by cats, probably because their hunting success is improved. This mechanism could explain why, in northern Australia, impacts of feral cats on small mammals might have increased. Our results suggest the impact of feral cats could be reduced in most ecosystems by maximising grass cover, minimising the incidence of intense fires, and reducing grazing by large herbivores.
Two models to predict the food of predators are proposed. They assume that prey size and prey abundance are the only availability factors of importance to predators. One model assumes that the predator consumes prey as they are encountered and the other that predators feed to maximize their energy intake. Previous work, principally from aquatic
situations is examined to test the models. It is concluded that many invertebrates and larval vertebrates eat prey as they are encountered while adult vertebrates feed as energy maximizers. The limitations of the models are discussed and their relation to models of optimal diet examined.
Animals commonly choose among habitats that differ both in foraging return and mortality hazard. However, no experimental study has attempted to predict the level of increase in resources, or the decrease in mortality hazard, which will induce a forager to shift from a safer to a more hazardous (but richer) foraging area. Here we present and test a model that specifies the choice of foraging areas ("habitats") that would minimize total mortality risk while allowing collection of some arbitrary net energy gain. We tested the model with juvenile creek chubs (Semotilus atromaculatus) in an experimental field stream in which the foragers could utilize a foodless refuge and choose between two foraging areas that differed in experimentally manipulated resource densities (Tubifex spp. worms in sediments) and mortality hazard (adult creek chubs). For the case tested, the model specified a simple rule: "use the refuge plus the site with the lowest ratio of mortality rate (μ) to gross foraging rat (f)," i.e., "minimize μ./f." Independent prior measurements of mortality hazard (as a function of predator density) and gross foraging rate (as a function of resource density) allowed us to predict the resource level in the more hazardous foraging site that should induce a shift from the safer to the more hazardous site. The chubs' preferences in subsequent choice experiments agreed well with the theoretical predictions. The "minimize μ/f" rule (deaths per unit energy), perhaps in modified form, provides a simple alternative to the "maximize f" (energy per unit time) criterion that applies to long-term rate maximization when predation hazard does not differ among choices.
Small mammal species are declining across northern Australia. Predation by feral cats Felis sylvestris catus is one hypothesised cause. Most evidence of cat impacts on native prey comes from islands, where cat densities are often high, but cats typically occur at low densities on mainland Australia.
We conducted a field experiment to measure the effect of predation by low‐density cat populations on the demography of a native small mammal. We established two 12·5‐ha enclosures in tropical savanna in the Northern Territory. Each enclosure was divided in half, with cats allowed access to one half but not the other. We introduced about 20 individuals of a native rodent, Rattus villosissimus, into each of the four compartments (two enclosures × two predator‐access treatments). We monitored rat demography by mark‐recapture analysis and radiotracking, and predator incursions by camera surveillance and track and scat searches.
Rat populations persisted over the duration of the study (18 months) in the predator‐proof treatment, where we detected no predator incursions, but declined to extinction in both predator‐accessible compartments. In one case, cat incursions were frequently detected and the rat population was rapidly extirpated (<3 months); in the other, cat incursions were infrequent, and the population declined more gradually ( c . 16 months) due to low recruitment. We detected no incursions by dingoes Canis dingo , the other mammalian predator in the area.
Synthesis and applications . This is the first study to provide direct evidence that cats are capable of extirpating small mammals in a continental setting, in spite of their low population densities. This finding supports the hypothesis that predation by feral cats is contributing to declines of small mammals in northern Australia. The conservation management of native small mammals in northern Australia may require intensive control of cat populations, including large cat‐free enclosures.
The domestic cat Felis catus is distributed worldwide and has had a long historical relationship with humans. In some regions, such as Australia, it has become feral and a significant predator of native wildlife. A key component of quantifying and managing the conservation threat of introduced predators is an understanding of exactly what size and taxa of prey species are consumed, and whether there is a high degree of selectivity in the diet. A total of 169 cat stomachs were collected from north‐eastern Australia, and their contents examined in relation to prey size, the body size of cats and selectivity using Jacob's index. I found that F. catus contains a large amount of prey per cat (∼200 g), mammals are the dominant prey item by mass, and feral cats predation was selective of small mammals (Australia that are declining are within the size range that is highly selected by feral cats; the relationship between smaller cat size in the tropics and smaller prey size has correspondence to the fact that the declining mammals in this region are smaller than those that went extinct in southern Australia. There is an urgent need to find a conservation solution to reducing feral cat predation on wildlife, and this should include landscape scale reduction in fire extent and frequency, and removal of cattle in key sites, in order to maintain ground cover, thus reducing the predation success of feral cats.