Toxic Trojans: can feral cat predation be mitigated by making their prey poisonous?

Predation, along with competition and disease transmission from feral domestic cats (Felis catus), poses the key threat to many in situ and reintroduced populations of threatened species globally. Feral cats are more challenging to control than pest canids because cats seldom consume poison baits or enter baited traps when live prey are readily available. Novel strategies for sustainably protecting threatened wildlife from feral cats are urgently required. Emerging evidence suggests that once they have successfully killed a challenging species, individual feral cats can systematically eradicate threatened prey populations. Here we propose to exploit this selective predation through three targeted strategies to improve the efficacy of feral cat control. Toxic collars and toxic implants, fitted or inserted during monitoring or reintroduction programs for threatened species, could poison the offending cat before it can effect multiple kills of the target species. A third strategy is informed by evidence that consumption of prey species that are relatively tolerant to natural plant toxins, can be lethal to more sensitive cats. Within key habitats of wildlife species susceptible to cat predation, we advocate increasing the accessibility of these toxins in the food chain, provided negative risks can be mediated. Deliberate poisoning using live and unaffected ‘toxic Trojan prey’ enables ethical feral cat management that takes advantage of cats’ physiological and behavioural predilection for hunting live prey while minimising risks to many non-targets, compared with conventional baiting.

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Evidence of significantly higher island feral cat abundance compared with the adjacent mainland

Wildlife Research ◽

10.1071/wr18118 ◽

2019 ◽

Vol 46 (5) ◽

pp. 378 ◽

Cited By ~ 9

Author(s):

Patrick L. Taggart ◽

Bronwyn A. Fancourt ◽

Andrew J. Bengsen ◽

David E. Peacock ◽

Patrick Hodgens ◽

...

Keyword(s):

Relative Abundance ◽

Spatial Model ◽

Native Species ◽

Prey Species ◽

South Australia ◽

Camera Trap ◽

Feral Cat ◽

Feral Cats ◽

Continental Scale ◽

Scale Models

Context Feral cats (Felis catus) impact the health and welfare of wildlife, livestock and humans worldwide. They are particularly damaging where they have been introduced into island countries such as Australia and New Zealand, where native prey species evolved without feline predators. Kangaroo Island, in South Australia, is Australia’s third largest island and supports several threatened and endemic species. Cat densities on Kangaroo Island are thought to be greater than those on the adjacent South Australian mainland, based on one cat density estimate on the island that is higher than most estimates from the mainland. The prevalence of cat-borne disease in cats and sheep is also higher on Kangaroo Island than the mainland, suggesting higher cat densities. A recent continental-scale spatial model of cat density predicted that cat density on Kangaroo Island should be about double that of the adjacent mainland. However, although cats are believed to have severe impacts on some native species on the island, other species that are generally considered vulnerable to cat predation have relatively secure populations on the island compared with the mainland. Aims The present study aimed to compare feral cat abundance between Kangaroo Island and the adjacent South Australian mainland using simultaneous standardised methods. Based on previous findings, we predicted that the relative abundance of feral cats on Kangaroo Island would be approximately double that on the South Australian mainland. Methods Standardised camera trap surveys were used to simultaneously estimate the relative abundance of feral cats on Kangaroo Island and the adjacent South Australian mainland. Survey data were analysed using the Royle–Nichols abundance-induced heterogeneity model to estimate feral cat relative abundance at each site. Key results Cat abundance on the island was estimated to be over 10 times greater than that on the adjacent mainland. Conclusions Consistent with predictions, cat abundance on the island was greater than on the adjacent mainland. However, the magnitude of this difference was much greater than expected. Implications The findings show that the actual densities of cats at local sites can vary substantially from predictions generated by continental-scale models. The study also demonstrates the value of estimating abundance or density simultaneously across sites using standardised methods.

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Understanding Australia’s national feral cat control effort

Wildlife Research ◽

10.1071/wr19216 ◽

2020 ◽

Vol 47 (8) ◽

pp. 698

Author(s):

Georgia E. Garrard ◽

Alexander M. Kusmanoff ◽

Richard Faulkner ◽

Chathuri L. Samarasekara ◽

Ascelin Gordon ◽

...

Keyword(s):

Threatened Species ◽

Native Species ◽

Control Effort ◽

Data Repositories ◽

Feral Cat ◽

Feral Cats ◽

Mixed Methods Approach ◽

Qualitative Responses ◽

The Impact ◽

Combining Estimates

Abstract Context. Feral cats (Felis catus) pose a significant threat to Australia’s native species and feral cat control is, therefore, an important component of threatened species management and policy. Australia’s Threatened Species Strategy articulates defined targets for feral cat control. Yet, currently, little is known about who is engaged in feral cat control in Australia, what motivates them, and at what rate they are removing feral cats from the environment. Aims. We aim to document who is engaging in feral cat control in Australia, how many cats they remove and to estimate the number of feral cats killed in a single year. Furthermore, we seek to better understand attitudes towards feral cat control in Australia. Methods. We used a mixed methods approach combining quantitative and qualitative techniques. Feral cat control data were obtained from existing data repositories and via surveys targeting relevant organisations and individuals. A bounded national estimate of the number of feral cats killed was produced by combining estimates obtained from data repositories and surveys with modelled predictions for key audience segments. Attitudes towards feral cat control were assessed by exploring qualitative responses to relevant survey questions. Key results. We received information on feral cat control from three central repositories, 134 organisations and 2618 individuals, together removing more than 35000 feral cats per year. When including projections to national populations of key groups, the estimated number of feral cats removed from the environment in the 2017–2018 financial year was 316030 (95% CI: 297742–334318). Conclusions. Individuals and organisations make a significant, and largely unrecorded, contribution to feral cat control. Among individuals, there is a strong awareness of the impact of feral cats on Australia’s biodiversity. Opposition to feral cat control focussed largely on ethical concerns and doubts about its efficacy. Implications. There is significant interest in, and commitment to, feral cat control among some groups of Australian society, beyond the traditional conservation community. Yet more information is needed about control methods and their effectiveness to better understand how these efforts are linked to threatened species outcomes.

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Acute Toxicity of Sodium Monofluoroacetate (1080) Baits to Feral Cats.

Wildlife Research ◽

10.1071/wr9910445 ◽

1991 ◽

Vol 18 (4) ◽

pp. 445 ◽

Cited By ~ 16

Author(s):

CT Eason ◽

CM Frampton

Keyword(s):

Body Weight ◽

Acute Toxicity ◽

Lethal Dose ◽

Predator Control ◽

Confidence Limits ◽

Feral Cat ◽

Feral Cats ◽

Wildlife Species ◽

Higher Doses

Feral cat populations have a devastating effect on many native wildlife species. As part of a programme to evaluate improved predator control, feral cats were observed after they had ingested a polymer bait loaded with sodium monofluoroacetate (1080) 0.4-1.6 mg/g bait, equivalent to doses of 0.1-1.3 mg/kg body weight. Deaths occurred with 0.6 mg/g bait and all higher doses. With the highest dose all animals died within 24 h. An approximate oral LD50 of 0.28 mg/kg (0.07-0.49) and LD90 of 0.35 mg/kg (0.14-0.56) were calculated (with 95% confidence limits). Main symptoms were disorientation and lethargy, followed by death. A dose of 2 mg/g bait is recommended as a humane and lethal dose of 1080 for feral cats.

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Feral cat diet and predation on endangered endemic mammals on a biodiversity hot spot (Amami–Ohshima Island, Japan)

Wildlife Research ◽

10.1071/wr14161 ◽

2015 ◽

Vol 42 (4) ◽

pp. 343 ◽

Cited By ~ 12

Author(s):

Kazumi Shionosaki ◽

Fumio Yamada ◽

Takuya Ishikawa ◽

Shozo Shibata

Keyword(s):

Prey Item ◽

Prey Species ◽

Hot Spot ◽

Rattus Rattus ◽

Active Management ◽

Term Survival ◽

Scat Analysis ◽

Feral Cat ◽

Feral Cats ◽

Main Prey

Context There has been concern that feral cats have negative impacts on the endangered endemic mammals of Amami-Ohshima Island, Japan, including the Amami rabbit, Pentalagus furnessi, Ryukyu long-tailed giant rat, Diplothrix legata, and Amami spiny rat, Tokudaia osimensis. However, no diet study of feral cat has been conducted to support the necessity of an urgent feasible feral-cat management for the island. Aims The aims of the present study were to analyse feral-cat diet on Amami-Ohshima Island by using scat analysis and estimate the potential predation impact of feral cats on endangered mammals on the island. Methods The diet of feral cats was studied using scat analysis. We estimated the number of prey, percentage of prey, frequency of occurrence (the percentage of scats in a sample containing a particular prey item), percentage of biomass (biomass of the same prey item divided by the total consumed biomass ×100) and daily consumed biomass (DCB). Key results Three endangered endemic mammals were the main prey species of the feral cat diet (65% of total DCB). The percentage contributions of these species on DCB were long-tailed giant rat (34.7%), Amami spiny rat (21.9%) and Amami rabbit (12%). Conclusions Mammals, especially endangered endemic mammals, were main prey species of feral cat on Amami Island. In Amami Island, where native and invasive rodents coexisted, feral cats consumed more native (56.6%) than invasive (22.2% for Rattus rattus) species. Implications Feral cats are likely to be having a significant impact on endangered endemic mammals on the island. To ensure the long-term survival of these endemic species, active management of the feral-cat population should be considered.

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Predation by feral cats key to the failure of a long-term reintroduction of the western barred bandicoot (Perameles bougainville)

Wildlife Research ◽

10.1071/wr15070 ◽

2016 ◽

Vol 43 (1) ◽

pp. 38 ◽

Cited By ~ 16

Author(s):

Jeff Short

Keyword(s):

Prey Species ◽

Local Extinction ◽

Contributing Factors ◽

Feral Cats ◽

European Rabbits ◽

Threatening Processes ◽

The Impact ◽

Methods Of Control

Context Reintroduction of endangered species potentially places them back in contact with putative factors of historical decline, inadvertently providing the opportunity to evaluate their impact. Aims To monitor the long-term progress of a population of western barred bandicoot reintroduced to mainland Australia and to assess factors involved in its eventual local extinction. Methods Bandicoots were reintroduced from offshore Dorre Island to the nearby mainland peninsula of Heirisson Prong in 1995. The narrow neck of the peninsula was fenced to exclude foxes and feral cats from a 1200 ha area, but the area was subject to periodic incursions. There was parallel management of a confined but unsupported population in an in situ 17-ha predator refuge. Bandicoots were assessed for abundance, body condition and reproduction two to four times annually between 1995 and 2010. In addition, perceived threatening processes (drought, disease and the abundance of cats, foxes and rabbits) were monitored. Key results Bandicoots became well established at the site, spreading to all available habitat. Numbers fluctuated strongly, peaking at ~250 in 1999 and then declining to apparent local extinction (with subsequent re-establishment from the refuge), and at ~470 animals in 2006, followed again by extinction. Conclusions Predation by feral cats was implicated as the primary cause of both free-range extinctions and the eventual elimination of all bandicoots from the predator refuge. Other contributing factors in one or more of the declines were a reduction in reproduction and recruitment in bandicoots during a one-in-100-year drought, the impact of overabundant European rabbits on vegetation used by bandicoots for nesting shelter and brief fox incursions at key times. Implications Existing methods of control of feral cats are rendered ineffective in the presence of abundant and diverse native fauna and abundant exotic species (particularly European rabbits). In addition, episodic drought in arid Australia intensifies the impact of predation by restricting reproduction of prey species. These factors hamper the attempts of conservation managers to re-establish vulnerable species at sites other than those with the infrastructure and/or management intensity to largely exclude exotic predators (and preferably European rabbits) over the long-term.

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The diet of feral house cats (Felis catus) at a regional rubbish tip, Victoria

Wildlife Research ◽

10.1071/wr99067 ◽

2003 ◽

Vol 30 (1) ◽

pp. 103 ◽

Cited By ~ 21

Author(s):

Susan Hutchings

Keyword(s):

Native Species ◽

Prey Species ◽

Felis Catus ◽

Control Measures ◽

Live Prey ◽

Feral Cats ◽

Dietary Breadth ◽

Bone Fragments ◽

Dietary Components ◽

Potential Impact

The diet of feral cats (Felis catus) inhabiting a regional rubbish tip (dump) in Victoria was studied to determine whether cats utilised garbage or live prey from the surrounding heathlands for food. Between 30 and 50 cat scats were collected from the tip over two years in each of four sampling periods: spring 1997, autumn 1998, spring 1998 and autumn 1999. The scats were analysed to determine major dietary components, dietary breadth and seasonal overlap of diet. Bone fragments from meat scraps were the most frequent dietary item detected in the scats. Vertebrate prey species occurred less often in the cats' diet but a variety of both introduced and native species were represented. Analysis of dietary breadth confirmed that cats selected mainly meat and chicken scraps from the garbage but indicated that vertebrates were hunted opportunistically. Control measures are suggested to reduce cat numbers at regional rubbish tips to relieve potential impact on native wildlife.

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Control of Feral Cats for Nature Conservation. II. Population Reduction by Poisoning

Wildlife Research ◽

10.1071/wr96071 ◽

1997 ◽

Vol 24 (6) ◽

pp. 703 ◽

Cited By ~ 59

Author(s):

Jeff Short ◽

Bruce Turner ◽

Danielle A. Risbey ◽

Reg Carnamah

Keyword(s):

Prey Species ◽

Control Programme ◽

Laboratory Mice ◽

Timing Control ◽

Feral Cat ◽

Feral Cats ◽

Track System ◽

Population Reduction ◽

Before And After ◽

Semi Arid

A feral cat population was substantially reduced by poisoning at a semi-arid site in Western Australia. The control programme was designed to protect two species of endangered native mammals that had recently been reintroduced to the site. Feral cats were poisoned with carcasses of laboratory mice, each impregnated with 4.5 mg of sodium monofluoroacetate (1080). Baits were placed at 100-m intervals along the track system each night for four consecutive nights. Kill rates were assessed by monitoring survival of radio- collared cats and by spotlight counts of cats before and after baiting. All radio-collared cats were killed and there was a 74% reduction in spotlight counts of cats after baiting. Bait removal varied with the abundance of rabbits, the primary prey item for cats in this area. Effectiveness of control operations against feral cats is maximised by baiting at times of low prey abundance. Monitoring the changing abundance of the primary prey species provides important information for timing control operations against feral cats.

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Management of invasive mesopredators in the Flinders Ranges, South Australia: effectiveness and implications

Wildlife Research ◽

10.1071/wr19237 ◽

2020 ◽

Vol 47 (8) ◽

pp. 720

Author(s):

Alyson M. Stobo-Wilson ◽

Robert Brandle ◽

Christopher N. Johnson ◽

Menna E. Jones

Keyword(s):

Prey Species ◽

South Australia ◽

Short Time Period ◽

Short Term ◽

Feral Cat ◽

Feral Cats ◽

Flinders Ranges ◽

Time Period ◽

Short Time ◽

The Impact

Abstract ContextSignificant resources have been devoted to the control of introduced mesopredators in Australia. However, the control or removal of one pest species, such as, for example, the red fox (Vulpes vulpes), may inadvertently benefit other invasive species, namely feral cats (Felis catus) and rabbits (Oryctolagus cuniculus), potentially jeopardising native-species recovery. AimsTo (1) investigate the impact of a large-scale, long-term fox-baiting program on the abundance of foxes, feral cats and introduced and native prey species in the Flinders Ranges, South Australia, and (2) determine the effectiveness of a short time period of cat removal in immediately reducing feral cat abundance where foxes are absent. MethodsWe conducted an initial camera-trap survey in fox-baited and unbaited sites in the Flinders Ranges, to quantify the impact of fox baiting on the relative abundance of foxes, feral cats and their prey. We then conducted a secondary survey in sites where foxes were absent, following an intensive, but short, time period of cat removal, in which 40 cats were shot and killed. Key resultsNo foxes were detected within baited sites, but were frequently detected in unbaited sites. We found a corresponding and significant increase in several native prey species in fox-baited sites where foxes were absent. Feral cats and rabbits were also more frequently detected within baited sites, but fox baiting did not singularly predict the abundance of either species. Rather, feral cats were less abundant in open habitat where foxes were present (unbaited), and rabbits were more abundant within one predominantly open-habitat site, where foxes were absent (fox-baited). We found no effect of short-term cat removal in reducing the local abundance of feral cats. In both camera-trap surveys, feral cat detections were positively associated with rabbits. ConclusionsLong-term fox baiting was effective in fox removal and was associated with a greater abundance of native and introduced prey species in the Flinders Ranges. To continue to recover and conserve regional biodiversity, effective cat control is required. ImplicationsOur study showed fox removal has likely resulted in the local release of rabbits and an associated increase in cats. Because feral cat abundance seemingly fluctuated with rabbits, we suggest rabbit control may provide an alternative and more effective means to reduce local feral cat populations than short-term removal programs.

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A trial reintroduction of the western quoll to a fenced conservation reserve: implications of returning native predators

Australian Mammalogy ◽

10.1071/am19041 ◽

2020 ◽

Vol 42 (3) ◽

pp. 257 ◽

Cited By ~ 2

Author(s):

R. S. West ◽

L. Tilley ◽

K. E. Moseby

Keyword(s):

Threatened Species ◽

Carrying Capacity ◽

Potential Role ◽

Prey Species ◽

Close Monitoring ◽

Dietary Analysis ◽

Feral Cats ◽

Nocturnal Foraging ◽

Threat Management ◽

Foraging Ranges

While fenced reserves provide sanctuary for many threatened prey species, few projects have reintroduced native threatened predators, despite their potential role in regulating prey, addressing prey naivety, trophic regulation, and predator conservation. We aimed to investigate a set of issues unique to predator reintroduction into fenced reserves: how to contain predators that are naturally wide roaming, how to estimate carrying capacity, and will native predators impact resident threatened species? We conducted a trial reintroduction of four western quolls (Dasyurus geoffroii) (two males, two females) into a fenced reserve where four threatened prey species had been reintroduced and feral cats and foxes excluded. We monitored quoll survival, diet, movement and reproduction. Nocturnal foraging ranges measured over a fortnight were 3–17km2, favouring burrows in dune habitat for shelter. Dietary analysis indicated a preference for reintroduced bettongs and western barred bandicoots, and resident hopping mice. Successful breeding was recorded but the two male quolls eventually escaped the reserve by climbing over the external fence and did not return. Results suggest that quoll reintroductions to fenced reserves will require fence designs that enable quolls to climb back into the reserve, threat management outside the reserve, and close monitoring of prey species.

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Framing of visual content shown on popular social media may affect viewers’ attitudes to threatened species

Scientific Reports ◽

10.1038/s41598-021-92815-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Fernando Ballejo ◽

Pablo Ignacio Plaza ◽

Sergio Agustín Lambertucci

Keyword(s):

Social Media ◽

Threatened Species ◽

Social Medium ◽

Visual Content ◽

Wildlife Species ◽

Mammalian Predators ◽

Negative Comments ◽

Over Time ◽

The Way

AbstractContent published on social media may affect user’s attitudes toward wildlife species. We evaluated viewers’ responses to videos published on a popular social medium, focusing particularly on how the content was framed (i.e., the way an issue is conveyed to transmit a certain meaning). We analyzed videos posted on YouTube that showed vultures interacting with livestock. The videos were negatively or positively framed, and we evaluated viewers’ opinions of these birds through the comments posted. We also analyzed negatively framed videos of mammalian predators interacting with livestock, to evaluate whether comments on this content were similar to those on vultures. We found that the framing of the information influenced the tone of the comments. Videos showing farmers talking about their livestock losses were more likely to provoke negative comments than videos not including farmer testimonies. The probability of negative comments being posted on videos about vultures was higher than for mammalian predators. Finally, negatively framed videos on vultures had more views over time than positive ones. Our results call for caution in the presentation of wildlife species online, and highlight the need for regulations to prevent the spread of misinformed videos that could magnify existing human-wildlife conflicts.

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