Article

Aerial baiting and wild dog mortality in south-eastern Australia

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Abstract

ContextWild dogs, including dingoes and dingo cross-breeds, are vertebrate pests when they cause financial losses and emotional costs by harming livestock or pets, threaten human safety or endanger native fauna. Tools for lethal management of these animals currently include aerial baiting with poisoned baits. In New South Wales (NSW), Australia, aerial baiting was previously permitted at a rate of 40 baits km−1 but a maximum rate of 10 baits km−1 was subsequently prescribed by the Australian Pesticides and Veterinary Medicines Authority. The efficacy of these baiting rates has not been quantified in eastern Australia, undermining the value of the policy and rendering adaptive management efforts difficult, at best. AimTo quantify the mortality rate of wild dogs exposed to aerial baiting at historic and currently approved rates, i.e. 40 baits per kilometre and 10 baits per kilometre, respectively. Methods Wild dog mortality rates were measured at sites in mesic north-eastern NSW, where aerial baiting was applied to control wild dogs and contrasted with sites and individuals where no baiting was undertaken. In total, 132 wild dogs were trapped and fitted with GPS-VHF telemetry collars before annual aerial baiting programs. Collars were used to locate animals after aerial baiting and to determine the fates of individuals. Key results90.6% of collared wild dogs exposed to aerial baiting at 40 baits km−1 died, whereas only 55.3% of those exposed to 10 baits km−1 died (Welsh’s t=4.478, P=0.004, v=6.95). All wild dogs that were not exposed to toxic baits survived during the same periods. Conclusion Managers using aerial baiting to maximise wild dog mortality in mesic south-eastern Australia should use 40 baits km−1 rather than 10 baits km−1. ImplicationsWild dog population reduction for mitigation of livestock and faunal predation requires the application of efficacious control. The currently prescribed maximum aerial baiting rate of 10 baits km−1 is inadequate for controlling wild dog populations in mesic forest environments in NSW.

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... To reduce the threat that wildlife poses to human safety and their resources, humans have controlled populations of species considered harmful or pests (Reynolds and Tapper 1996;Treves and Bruskotter 2014), especially predators. Baiting has been extensively used worldwide for reducing populations of animal species considered harmful, eradicating invasive species, vaccination, contraception or producing conditioned aversion (Bradley et al. 1999;Díez-Delgado et al. 2018;Ballard et al. 2020;Tobajas et al. 2020a). ...
... Baits are often used with poisons, for example sodium fluoroacetate (1080) and 4'-para-aminopropiophenone (PAPP), both of which are widely employed to control invasive species in Australia and New Zealand Eason et al. 2017;Philip 2020) and are considered a costeffective method to control invasive and harmful species (Thomson et al. 2000;Eason et al. 2017;Ballard et al. 2020). Baiting programs are also used in contraceptive or vaccination campaigns of several animal species, to regulate fertility or reduce the incidence of diseases that potentially could affect humans or their economy (Bradley et al. 1999;Díez-Delgado et al. 2018). ...
... The low detectability or probability of encountering the baits by the target species forces the use of extensive methods to deliver the baits Ballard et al. 2020). Increasing the number of baits deployed means increased cost, but also increases the risk of bait intake by non-target species (Dundas et al. 2014;Hohnen et al. 2020;Smith et al. in press). ...
Article
Context. The use of baits for reducing the populations of harmful animal species, eradicating invasive species, vaccination, contraceptive or producing conditioned aversion, is widespread worldwide. However, baiting programs are often not successful enough and affect non-target species, requiring new approaches for baiting methods. Aims. Here, we evaluate two attractants used in carnivore studies to improve bait intake probability by red foxes while minimizing bait intake by non-target species. Methods. Non-toxic baits were distributed across 1000 ha, with bait intake monitored by camera-traps during three-weeks trials. Baits were assigned to two treatments with lures (lynx urine and Fatty Acid Scent - FAS) and one control. Data of bait intake by red foxes and non-target species were analysed using GLMM and Kaplan-Meier survival analyses. Key results. Lynx urine increased significantly the bait intake by red foxes (58.8%) compared to control (5.7%) and FAS (16.7%) treatment. However, FAS did not significantly increase the bait intake by red foxes compared to control. Bait intake by non-target species differed significantly between treatments, with lower intake in lynx urine (23.5%) treatment than control (54.7%), but not regarding FAS (36.7%), and neither between FAS and control. The probability of bait persistence after the three-weeks trial period differed significantly between treatments, being lower in lynx urine treatment (0.18) than FAS (0.50) and control (0.43). All baits taken by foxes with lynx urine treatment (58.8%) occurred within the first 10 days whereas intake by non-target species (23.5%) stopped after the day 7. Conclusions. The use of lynx urine lure increased the proportion of baits consumed by red fox while reduced the bait intake by non-target species. Implications: Lures can serve to optimize bait delivery methods for red foxes in their different applications, such as conditioned aversion studies, vaccination, live trapping or predator control while minimizing risks to non-target species and reducing the costs and application time up to 10 days.
... The impact of 1080 baiting on dingo populations is variable, ranging between 22 and 100% (Ballard et al., 2020;Fleming, 1996;McIlroy et al., 1986a;Thomson, 1986). To sustain a reduction in dingo density, 75% or greater of the population needs to be removed annually (Ballard et al., 2020;Hone et al., 2010;Pacioni et al., 2020a). ...
... The impact of 1080 baiting on dingo populations is variable, ranging between 22 and 100% (Ballard et al., 2020;Fleming, 1996;McIlroy et al., 1986a;Thomson, 1986). To sustain a reduction in dingo density, 75% or greater of the population needs to be removed annually (Ballard et al., 2020;Hone et al., 2010;Pacioni et al., 2020a). The effectiveness of baiting can be influenced by environmental factors such as season, prey availability, activity of target and non-target species, and the age and social status of target species (Kreplins et al., 2018;McIlroy et al., 1986b;Thomson, 1986). ...
... The effectiveness of baiting can be influenced by environmental factors such as season, prey availability, activity of target and non-target species, and the age and social status of target species (Kreplins et al., 2018;McIlroy et al., 1986b;Thomson, 1986). Additionally, variables in baiting programs such as bait type Thomson, 1986), rate of bait lay (Ballard et al., 2020) and bait placement can influence the availability, attractiveness, palatability and lethality of baits (Allsop et al., 2017;Fancourt et al., 2020;Saunders and McLeod, 2007). ...
Article
Carnivores are important drivers of ecological processes around the world. However, medium-large carnivores are often the focus of human-wildlife conflicts and are subject to control efforts. Determining the effectiveness of predator control efforts in reducing predator abundance or impact is critical to ensuring control is achieving its intended aims. This information is also vital to understanding any impacts of control efforts on the ecological functions of carnivores. In this study, we deployed camera traps on two properties in the southern rangelands of Western Australia to examine the effectiveness of repeated rounds of landscape-scale toxicant baiting in reducing dingo populations. Biannual baiting at each property was temporally offset from the other to provide a comparison of short-term changes in dingo activity and density over 16 months' monitoring. While there were significant differences in dingo density between properties, there was no significant differences between months categorised as ‘month of baiting’, ‘month immediately post-baiting’ or ‘between baiting’. Further, there was no overall decline in dingo density on either property over the duration of the study and survival of dingoes exceeded 84% on each site. Neither individual nor sequential rounds of baiting therefore resulted in a reduction in dingo density approaching 75%, which is necessary for dingo population control in this environment. Several factors are likely to have contributed to the limited effect of baiting, including bait uptake by non-target species, low encounter rate with baits and aversive responses to baits. Consideration of baiting practices, including bait rate, frequency and attractiveness, as well as evaluation of the net returns of baiting should be addressed in future work to ensure dingo control achieves its intended aims to reduce dingo abundance and/or impacts.
... Although baiting, either via aerial (Ballard et al. 2020) or on-ground (Thomson and Algar 2000;Marlow et al. 2015) deployment, is a commonly used technique, it does have some shortcomings. These include consumption or removal of baits by non-target species before the target species, which can reduce baiting effectiveness (Dundas et al. 2014;Kreplins et al. 2018). ...
... baiting, trapping, fencing and shooting) can be challenging, and where these tools have been evaluated, the outcomes can vary considerably (e.g. McIlroy et al. 1986a;Thomson 1986;Fleming et al. 1996;Ballard et al. 2020). There are several factors that can contribute to this variation, including environmental factors such as season, prey availability, and behaviour of wild dogs and non-target species (McIlroy et al. 1986b;Thomson 1986;Kreplins et al. 2018). ...
... The declines and suppression of dingoes at Morven and Tambo also highlight the value of the exclusion fencing erected at our sites (see also [78][79][80][81]. Multiple previous studies have demonstrated that even though dingo populations can be temporarily supressed by substantial amounts up to 100% in open or unfenced systems 22,63,77 , they typically recover to pre-control levels within a few months or by the next annual breeding season due to immigration by dispersing dingoes looking for a new home range 82,83 . That dingo populations at Morven were knocked down and then held down inside the fence while dingo populations were increasing outside the fence (Fig. 3) is a powerful demonstration of the utility of cluster fences at excluding dingoes, much like other types of fences exclude other species 79 . ...
... 2) did indeed cause a demonstrable reduction in dingoes there, confirming a treatment effect. This does not often occur outside fences75,76 , but can occur in such open systems when control is particularly intensive22,77 . ...
Article
Full-text available
Removal or loss of top-predators has been predicted to cause cascading negative effects for ecosystems, including mesopredator release. However, reliable evidence for these processes in terrestrial systems has been mixed and equivocal due, in large part, to the systemic and continued use of low-inference study designs to investigate this issue. Even previous large-scale manipulative experiments of strong inferential value have been limited by experimental design features (i.e. failure to prevent migration between treatments) that constrain possible inferences about the presence or absence of mesopredator release effects. Here, we build on these previous strong-inference experiments and report the outcomes of additional large-scale manipulative experiments to eradicate Australian dingoes from two fenced areas where dingo migration was restricted and where theory would predict an increase in extant European red foxes, feral cats and goannas. We demonstrate the removal and suppression of dingoes to undetectable levels over 4–5 years with no corresponding increases in mesopredator relative abundances, which remained low and stable throughout the experiment at both sites. We further demonstrate widespread absence of negative relationships between predators, indicating that the mechanism underpinning predicted mesopredator releases was not present. Our results are consistent with all previous large-scale manipulative experiments and long-term mensurative studies which collectively demonstrate that (1) dingoes do not suppress red foxes, feral cats or goannas at the population level, (2) repeated, temporary suppression of dingoes in open systems does not create mesopredator release effects, and (3) removal and sustained suppression of dingoes to undetectable levels in closed systems does not create mesopredator release effects either. Our experiments add to similar reports from North America, Asia, Europe and southern Africa which indicate that not only is there a widespread absence of reliable evidence for these processes, but there is also a large and continually growing body of experimental evidence of absence for these processes in many terrestrial systems. We conclude that although sympatric predators may interact negatively with each other on smaller spatiotemporal scales, that these negative interactions do not always scale-up to the population level, nor are they always strong enough to create mesopredator suppression or release effects.
... In Australia, baiting is currently considered the most cost-effective tool for the landscape-scale control of wild dogs and foxes (Burrows et al., 2003;Fleming et al., 2014), however it is generally not considered as effective for feral cats. Many factors can potentially contribute to the success or failure of control programs, including local environmental conditions and prey availability (Algar et al., 2007;Christensen et al., 2013), predator behaviour (Allsop et al., 2017), target-specificity of the control tool (Young, 2016), spatial or temporal mismatches between control and predator activity (Fleming and Korn, 1989;Mosnier et al., 2008), baiting densities (Ballard et al., 2020) and interference from non-target species (Dundas et al., 2014). While some studies have investigated variables that might influence the uptake of baits by feral cats (Algar et al., 2007;Christensen et al., 2013;, many of these studies have only been undertaken in western or central Australia, and so the broader applicability of their findings beyond those regions is currently unknown. ...
... Burying baits can reduce removal by some non-target species in introduced canid baiting programs (Allen et al., 1989;, however bait uptake by target canids can also decrease , and cats are far less likely to dig up and consume buried baits than dogs and foxes . Ballard et al. (2020) found that increasing baiting densities from 10 baits km − 1 to 40 baits km − 1 significantly increased wild dog mortality and suggested that the higher bait rates might have overcome reduced bait availability at lower bait rates; however the results are less clear for feral cats. Angus et al. (2002) found no significant increase in bait uptake rates by feral cats by increasing baiting densities between 25 and 100 baits km − 1 , suggesting that higher baiting rates may not yield linear increases in baiting efficacy for feral cats. ...
Article
Reducing the impacts of invasive predators is a key objective for conservation managers, livestock producers and human health agencies globally. The efficacy of invasive predator control programs, however, is highly variable. To improve control efficacy, managers require a fundamental understanding of the factors that contribute to the success or failure of a control program. Using a predator baiting program as a case study, we measured the efficacy of baiting as a control tool to significantly reduce feral cat (Felis catus) populations. We used camera traps and cat-borne GPS collars to monitor changes in feral cat populations at a baited site and an unbaited site, using a Before-After, Control-Impact (BACI) design. We also identified five key elements required for a successful baiting program (bait encounter rate, availability, attractiveness, palatability and lethality) and simultaneously measured these to identify areas for potential improvement. Baiting was ineffective at reducing feral cat populations; collared cat mortality was only 11% (1/9), with camera traps revealing negligible reductions in the number of cat detection events (9%), naïve occupancy (15%), and no significant change in the relative abundance of feral cats (F1,54 = 0.8641, P = 0.357). Several factors contributed to the poor control efficacy. Bait encounter rates were low, with cats active along tracks (where baits were laid) <4% of the time. Cats encountered only 14% (7/50) of monitored baits, but none were eaten. Initially, baits appeared attractive to cats; however meat ants and desiccation rapidly decreased bait palatability. Bait availability to cats declined rapidly, with 36% of monitored baits (18/50) removed by non-target species within the first 48 hours. The mortality of one collared cat and chemical assays confirmed that, on average, each bait contained sufficient 1080 to kill a large (>5 kg) feral cat. Our findings suggest that altering bait deployment patterns, increasing bait densities and improving bait palatability could potentially improve the efficacy of baiting programs to reduce feral cat populations. Our study provides a framework to measure and evaluate the key elements that contribute to efficacy of pest control programs, and to identify opportunities for improving outcomes of future control programs.
... Dingo control in Australia can result in reductions in dingo populations of 22-100%, depending on a range of factors, including the history of baiting program, density of baiting, season and location (Ballard et al., 2020;Fleming, 1996;Thomson, 1986). Where dingo control programs cause significant population reductions (e.g. ...
... Where dingo control programs cause significant population reductions (e.g. Ballard et al., 2020;Thomson, 1986), this could potentially affect trophic interactions with feral cats (hypothesized with correlative data in Brook et al., 2012), foxes (hypothesized with correlative data in Colman et al., 2014) and their prey. We took advantage of a dingo control program carried out across two large pastoral properties in WA, where ongoing control has occurred at varying intensity for the last~40 years, to investigate whether the density of feral cats and their temporal activity changed in response to dingo control (red foxes are absent at these study sites). ...
Article
The mesopredator release hypothesis proposes that when top-down suppression by a larger predator (e.g. dingoes, Canis familiaris) is removed, smaller mesopredators (e.g. feral cats, Felis catus) increase in abundance. Lethal control of dingoes could therefore potentially exacerbate predation pressure by feral cats on smaller prey species. We monitored the activity of dingoes and feral cats (in the absence of red foxes) in two dingo-baited areas over 16 months using 182 camera traps. First, we estimated population densities across each property and found that dingo and feral cat density were unrelated. Second, we compared daily capture rate of dingo and feral cats and found that both predators' capture rates were weakly related to environmental factors and the baiting program. Third, we analysed temporal overlap in activity of these two predators. Although both predators were nocturnal and showed 78.7% overlap in temporal activity patterns, there was a significant difference in activity peaks. Finally, while both predators were distributed across the whole study site, there was strong temporal separation within 1, 12 and 24 h periods at each individual camera. In conclusion, there was no indication of suppression of feral cat population by dingoes. The large and growing body of similar evidence suggests that calls to restrict dingo control on grounds that it will cause mesopredator releases are unsupported and highly unlikely to yield the biodiversity benefits often hoped for by proponents.
... dominated forest ecosystems of New South Wales, south-eastern Australia ( Fig. 1) (Keith 2004). The main technique used by land management authorities to suppress dingo populations is the distribution of poisoned meat baits containing 6 mg of the toxin sodium fluoroacetate (compound 1080) (Ballard et al. 2020). Baiting at our study sites was targeted at dingoes. ...
Article
Full-text available
The mesopredator release hypothesis predicts that abundance of smaller predators should increase in the absence of larger predators due to release from direct killing and competition. However, top predators’ effects on mesopredators are unlikely to operate in isolation but interact with other factors such as primary productivity of the landscape and human activities. We investigate factors influencing activity indices of a top predator (dingo) and an introduced mesopredator (red fox) in forests of south-eastern Australia. We used generalised linear models to investigate the effects that net primary productivity, proximity to freehold land and poison baiting campaigns directed at dingoes had on fox and dingo activity. Baiting was the best predictor of activity for both dingoes and foxes. Dingo activity was variable but typically lower at baited sites. Fox activity varied within a lower range at a majority of sites compared to the dingo but was typically higher at the baited sites. Positive responses of foxes to dingo control are consistent with the mesopredator release hypothesis and suggest in this region dingoes may have greater suppressive effect on fox populations than poisoning campaigns directed towards dingoes. Our results suggest that removal of dingoes may be counter-productive for biodiversity conservation because it may lead to higher activity of foxes.
... The naïve occupancy of the dingo was 0.14 whilst that of the red fox was 0.55. The relatively low occupancy of dingoes may reflect ongoing control of populations over much of the study region (Colman et al. 2014;Ballard et al. 2020). Consistent with the idea that there is limited spatial overlap between dingoes and foxes, a previous study which deployed cameras at 298 sites across nine forested conservation reserves in NSW detected dingoes at 18% of sites but detected foxes at just 2% of sites (McHugh et al. 2019). ...
Article
Full-text available
Invasive predators, land clearing and altered fire regimes have been implicated in species decline and extinction worldwide. Enhanced knowledge of how these factors interact and influence medium-sized mammals is warranted. We tested three hypotheses using occupancy data for a diverse mammal assemblage including three threatened species, five common species, two introduced mesopredators and an apex predator in eastern Australia. We hypothesised that occupancy of mammal species within the assemblage would be influenced by (i) the physical environment (rainfall, vegetation type and elevation), (ii) habitat disturbance (number of fires and habitat fragmentation) and (iii) mesopredator release, whereby occupancy and/or detection of medium-sized mammals are influenced by mesopredators, the feral cat ( Felis catus ) and the red fox ( Vulpes vulpes ), which are influenced by an apex predator, the dingo ( Canis familiaris ). We utilised camera-trapping data from 173 sites (692 camera locations) across a north–south gradient spanning ~ 1500 km in eastern Australia. Although hypotheses i (physical environment) and ii (habitat disturbance) are not mutually exclusive, we show that the variables considered in each were only weakly correlated. We conducted occupancy modelling to investigate the physical environment and habitat disturbance hypotheses. We conducted co-occurrence modelling to investigate interactions between species. The physical environment hypothesis best supported occupancy models for six mammal species: red-necked pademelon ( Thylogale thetis ), bandicoots ( Isoodon macrourus and Perameles nasuta ), swamp wallaby ( Wallabia bicolor ), red-necked wallaby ( Macropus rufogriseus ), eastern grey kangaroo ( Macropus giganteus ) and feral cat. The disturbance hypothesis best supported occupancy models for four mammal species: long-nosed potoroo ( Potorous tridactylus ), red-necked pademelon and both mesopredators. Support for the mesopredator release hypothesis was equivocal. Large macropods showed site avoidance towards the red fox. Four species showed higher detection at sites where mesopredators were not detected. The fox showed a negative detection interaction to the dingo and the cat did not. Our study highlights how factors such as rainfall, land clearing, elevation and number of fires influence the occupancy of species within a diverse mammal assemblage at the macroecological scale. Our findings have implications for the conservation of threatened species in managed landscapes and suggestions for further research following the recent 2019–2020 wildfires.
... The ecological role of the dingo is understood as essential to ecosystem health in the majority of biological and environmental studies Emmott 2020;Letnic et al. 2012;Wallach et al. 2017). The only school of thought that argues this point are the agricultural scientists (Allen et al. 2011(Allen et al. , 2013Ballard et al 2020;Fleming and Ballard 2014), under whose guidance the 82-million-hectare marginal grazing zone region has become one of the world's worst examples of land degradation and species extinction. ...
Article
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The longest environmental barrier in the world is Australia's 5614 km Dingo Barrier Fence. The structure was completed in the 1950s, designed to facilitate the eradication of the country's apex predator and cultural keystone species the dingo ( Canis dingo ) from sheep ( Ovis aries ) grazing areas to the south-east of the continent. The fence and its support systems now present an immense obstacle to ecological restoration in Australia's arid zone, preventing traditional management practices, and are hazardous to all terrestrial wildlife in the immediate vicinity. The barrier presents a worst-case scenario for animal-generated seed dispersal patterns over the wider region and limits genetic transfer. Plummeting biodiversity inside the fence line and increasing pressures of climate change have left this region highly vulnerable to ecological collapse. Concurrently, sheep numbers have contracted over 75% in the arid zone since 1991, due to market forces and climate change, while demand for ethically produced goods such as predator-friendly meat production and organic produce is increasing. Decommissioning the Dingo Barrier Fence, moving the stock protection zone south and diversifying land use would not impact significantly on the current livestock production. It offers a sound economic alternative for the region, with the potential for regeneration of 82 million hectares of land, a scale encouraged for inclusion in the global initiative the United Nations Decade for Ecosystem Reconstruction (2021–2030). This would restore connectivity across the region, including vital access to the waters of the Murray Darling Basin. This would provide mitigation for the effects of climate change, new markets in organic and sustainable industries, and support ecological and cultural renewal.
... Appropriate monitoring and research are needed to understand what works in protecting livestock from dingoes in different habitats , what role dingoes play in livestock production systems, and what role dingoes play in suppressing wild herbivores and introduced predators (Figure 1). This means shifting research efforts from focusing on the efficacy of lethal control in terms of its ability to control the target population (e.g., Ballard, Fleming, Meek, & Doak, 2020) to research that quantifies livestock losses in relation to dingo management interventions while simultaneously evaluating the environmental and agricultural costs and benefits of maintaining dingoes in the landscape. The findings of this research should form the foundation for identifying appropriate locations for coexistence with dingoes, combined with tools that predict the likelihood that targeted communities will adopt the desired management behaviors (Kuehne et al., 2017). ...
Article
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Achieving conservation goals, such as coexistence between wildlife and humans, requires an evidence-based understanding of the factors that shape conservation contexts. For addressing conflict between humans and wildlife, this means understanding the barriers and opportunities to changing human behaviors toward wildlife. Here, we develop a Theory of Change (ToC) to promote coexistence between livestock producers and dingoes in Australia. The ToC is based on behavior change principles and interdisciplinary research identifying four key stakeholder groups who may influence dingo management. It employs four overlapping strategies to address these barriers: (a) a media campaign to promote public awareness of dingo management practices, which may result in pressure upon governments to restrict lethal control; (b) promoting more inclusive decision-making processes, specifically including Aboriginal Australians; (c) monitoring and evaluation of the effects of dingo management on livestock and ecosystems to identify opportunities for non-lethal dingo management; (d) campaign to encourage adoption of nonlethal management methods by livestock producers based on an understanding of sociopsychological factors that shape behaviors. The framework is a tool for conservation advocates and policymakers to implement and monitor change that facilitates both wildlife conservation and thriving rural communities. K E Y W O R D S human dimensions of wildlife, human-wildlife conflict, Theory of Change
... alleviate local impacts and broad-scale programs focussed on general population reduction (Fleming et al. 2001). Furthermore, foot-hold trapping is a crucial component of Australian predator research; (Meek et al. 1995(Meek et al. , 2019aShort et al. 2002;Marks et al. 2004;Doherty and Algar 2015;Ballard et al. 2020). ...
Article
ContextImproving the welfare outcomes for captured animals is critically important and should underpin ‘best-practice’ trapping. Most Australian States and Territories have regulations and guidelines that form a legal framework for the maximum number of hours an animal can be restrained in a trap. Because servicing all traps within preferred time frames (less than 24h) can be logistically difficult or is considered undesirable for efficacy reasons, some jurisdictions have adopted relatively long trap-checking intervals (up to 72 h). AimsWe developed and tested the signal transmission and alert efficacy of a foot hold-trap alert system, based on Celium technology, so as to advise trappers of the activation of individual foot-hold traps, even in remote locations. Methods We refined the Celium trap-alert system and designed a below-ground wireless node that transmits a message via satellite or by using the cellular system when a foot-hold trap is sprung. We tested signal transmission and alert efficacy in three locations, with a focus in Australia. Key resultsTransmission of signals from nodes to hubs and to a smart-phone application were used to resolve interference problems and to identify signal limitations and strengths. During the capture of 34 dingoes, 91% of captures resulted in an alert being received. False negatives were attributed to technical issues with nearby transmitters swamping signals, and software problems that have since been resolved. In 40 captures of dogs and foxes, only one trap-alert transmitter (mole) was uncovered by a target animal and no devices were damaged by animals post-capture. Conclusions This cable-less trap-alert system successfully uses both cellular and satellite networks to transmit messages from desert and coastal locations to trappers, in Australia. We confirmed that this trap-alert system is not detected by target predators in the areas tested and can be effectively used to alert trappers when traps have been sprung. ImplicationsThis trap-alert system provides a tool to improve welfare outcomes for trapped target and non-target animals through Australia and New Zealand and wherever trapping occurs. It, furthermore, provides a solution to checking traps daily when the distance to and between traps cannot be covered within an appropriate time frame. Although trap alerts can never replace the value of daily trap checking by the trapper, they provide a solution to a management problem, namely, one of accessibility to sites.
... Importantly, the potential flow-on effects to lower trophic levels from non-target poisoning are not well understood. Because dingoes (Canis dingo) coexist with feral cats over most of their range and are susceptible to poison baiting (Ballard et al. 2020), broadcast applications of feral cat poison baits may also reduce and disrupt dingo populations (Wallach et al. 2009). As the largest terrestrial apex predator in Australia, aside from humans, the dingo is known to affect prey and mesopredator populations and behaviour (Brook et al. 2012;Letnic et al. 2012). ...
Article
ContextTo understand the ecological consequences of predator management, reliable and accurate methods are needed to survey and detect predators and the species with which they interact. Recently, poison baits have been developed specifically for lethal and broad-scale control of feral cats in Australia. However, the potential non-target effects of these baits on other predators, including native apex predators (dingoes), and, in turn, cascading effects on lower trophic levels (large herbivores), are poorly understood. AimsWe examined the effect that variation in camera trapping-survey design has on detecting dingoes, feral cats and macropodids, and how different habitat types affect species occurrences. We then examined how a feral cat poison baiting event influences the occupancy of these sympatric species. Methods We deployed 80 remotely triggered camera traps over the 2410-km2 Matuwa Indigenous Protected Area, in the semiarid rangelands of Western Australia, and used single-season site-occupancy models to calculate detection probabilities and occupancy for our target species before and after baiting. Key resultsCameras placed on roads were ~60 times more likely to detect dingoes and feral cats than were off-road cameras, whereas audio lures designed to attract feral cats had only a slight positive effect on detection for all target species. Habitat was a significant factor affecting the occupancy of dingoes and macropodids, but not feral cats, with both species being positively associated with open woodlands. Poison baiting to control feral cats did not significantly reduce their occupancy but did so for dingoes, whereas macropodid occupancy increased following baiting and reduced dingo occupancy. Conclusions Camera traps on roads greatly increase the detection probabilities for predators, whereas audio lures appear to add little or no value to increasing detection for any of the species we targeted. Poison baiting of an invasive mesopredator appeared to negatively affect a non-target, native apex predator, and, in turn, may have resulted in increased activity of large herbivores. ImplicationsManagement and monitoring of predators must pay careful attention to survey design, and lethal control of invasive mesopredators should be approached cautiously so as to avoid potential unintended negative ecological consequences (apex-predator suppression and herbivore release).
Article
Feral Cat (Felis catus) (cat) is a predator of the Bridled Nail‐Tailed Wallaby (BNTW) (Onychogalea frenata) living at Taunton National Park (Scientific) (Taunton). The aim of this study was to determine if traps and poison baits could be used to control feral cats without impacting non‐target species at Taunton. The techniques trialled included poison fresh meat baits and several types of traps presented in different ways and with various lures. Thirty‐one percent of fresh meat baits was taken during bait uptake trials; corvids removed 40% of these and dogs removed 16%. Cats were not detected, on camera traps, taking a bait. The elevated soft‐jaw traps (81 trap nights/cat) and single‐entry cage traps (98 trap nights/cat) were found to be the most successful of all the trap types trialled and had low amounts of by‐catch. Other trap types trialled took more than 166 trap nights to catch a cat. The elevated soft‐jaw trap configurations had the lowest amount of by‐catch (avg. 0.33%), and the log trap had the highest amount of by‐catch (1%). Ground‐set traps successfully trapped cats (305 trap nights/cat) but caught more by‐catch (0.9%) compared to the elevated soft‐jaw trap types and most wallabies caught in these traps had to be euthanised.
Article
ContextOutside its breeding season, the marsupial carnivore the spotted-tailed quoll (Dasyurus maculatus) is apparently largely unaffected by aerial baiting for dingoes and other wild dogs (Canis familiaris). However, the potential impact of aerial baiting during spring on female spotted-tailed quolls carrying and weaning young remains unquantified. Aim The survivorship of female quolls and their pouch young was investigated after aerial baiting at two sites representing the northern and southern part of their New South Wales range. The null hypothesis was that aerial baiting would not lead to direct mortality of any adult females or higher pouch young mortality over that reported in the published literature under normal conditions. Methods In total, nine female quolls with pouch young and eight male quolls were trapped, fitted with GPS/VHF collars containing mortality sensors and released at their point of capture. After trapping ceased, meat baits nominally containing 6mg of 1080 and 50mg of the biomarker rhodamine B were deployed by helicopter at both sites at the maximal permissible rate of 40 baits km−1. We monitored collared quolls daily for 4–5 weeks for mortality then retrapped animals and sampled whiskers for evidence of the biomarker. The fate of pouch young was also followed throughout our study by examining pouches of adult females and camera trapping at maternal den sites. Key Results No collared quolls died. After the daily monitoring period, 10 quolls, including all six collared female quolls, were trapped at the southern site, and whisker samples taken and assayed for Rhodamine B. Seven (4 females and 3 males) tested positive for rhodamine B, indicating consumption of baits. Separate bands of the biomarker in whisker samples indicated that most animals that tested positive had been exposed to multiple baits. At the northern site, four quolls (including two females and two males) tested positive for rhodamine B from the nine sampled. Post-baiting inspection of pouches of all trapped adult female animals, together with camera trapping at den sites, showed that the development of pouch young was unaffected by the baiting. Camera trapping arrays set across both sites continued to record the animals that were exposed to baits well beyond the baiting events, including evidence of breeding in a subsequent season. Conclusion Our aerial baiting programs had no observable impact on the collared female quolls, or their ability to raise and wean young. These findings are consistent with results from all previous field-based experimental studies, which show no population-level impacts of 1080 baits on spotted-tailed quolls. Implications Land managers should not be concerned about impacts of aerial baiting for wild dogs on spotted-tailed quolls, either in autumn or in spring during the breeding season.
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Australia has two introduced canid species — European red foxes (Vulpes vulpes) and wild dogs (which include dingoes, Canis lupus dingo, feral domestic dogs C. l. familiaris and their hybrids). Foxes were introduced into mainland Australia in the 1860s and quickly spread (Rolls, 1984; Jarman 1986). This dispersal and establishment is believed linked with the introduction and spread of European wild rabbits (Oryctolagus cunniculus) (Saunders et al., 1995). Except in Tasmania, where previous introductions appear to have been unsuccessful, and in northern Australia, where the climate is unsuitable and rabbits are essentially absent, foxes have become established throughout in virtually all habitats including urban and residential environments (Saunders et al., 1995). Within decades of their introduction, legislation was enacted proclaiming them as pests to agriculture, and more recently, as a key threatening process to endangered small mammals (NSW National Parks & Wildlife Service, 2001). This status has been enshrined in subsequent legislation and strengthened by virtue of foxes being an introduced pest species rather than a native animal. Dingoes are thought to have arrived in Australia from Southeast Asia about 5000 years before present (Corbett, 1995a). A number of reports have reviewed the origins, ecological significance of dingos, and their morphological and genetic relationship to domestic dogs. Interested readers are referred to Newsome et al. (1980) as one example. Like foxes they are also found in virtually every habitat across the Australian continent and are absent from Tasmania (Fleming et al., 2001). However, because of their longer association with Australia, they are often regarded as a “native” species (Davis, 2001). Wild domestic dogs have been present since the first European settlement in 1788 (Fleming et al., 2001) and hybridization with dingoes has been occurring ever since (Corbett, 1995a, 2001). Despite the native status of dingoes, all wild dogs and foxes are regarded and managed as pests on agricultural lands, i.e. outside of conservation areas. Pure dingoes alone are afforded legislative protection in areas set aside for conservation (Fleming et al., 2001; Davis and Leys, 2001) yet feral dogs and hybrids effectively enjoy the same legislative protection in conservation areas as dingoes, because they cannot be managed separately.
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In many parts of the world, livestock guardian dogs (LGDs) are a relatively new and increasingly popular method for controlling the impact of wild predators on livestock. On large grazing properties in Australia, LGDs are often allowed to range freely over large areas, with minimal supervision by their owners. How they behave in this situation is mostly unknown. We fitted free-ranging Maremma sheepdogs with GPS tracking collars on three properties in Victoria, Australia; on two properties, four sheep were also fitted with GPS collars. We investigated how much time the Maremmas spent with their livestock, how far they moved outside the ranges of their stock, and tested whether they use their ranges sequentially, which is an effective way of maintaining a presence over a large area. The 95% kernel isopleth of the Maremmas ranged between 31 and 1161 ha, the 50% kernel isopleth ranged between 4 and 252 ha. Maremmas spent on average 90% of their time in sheep paddocks. Movements away from sheep occurred mostly at night, and were characterised by high-speed travel on relatively straight paths, similar to the change in activity at the edge of their range. Maremmas used different parts of their range sequentially, similar to sheep, and had a distinct early morning and late afternoon peak in activity. Our results show that while free-ranging LGDs spend the majority of their time with livestock, movements away from stock do occur. These movements could be important in allowing the dogs to maintain large territories, and could increase the effectiveness of livestock protection. Allowing LGDs to range freely can therefore be a useful management decision, but property size has to be large enough to accommodate the large areas that the dogs use.
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Top-predators contribute to ecosystem resilience, yet individuals or populations are often subject to lethal control to protect livestock, managed game or humans from predation. Such management actions sometimes attract concern that lethal control might affect top-predator function in ways ultimately detrimental to biodiversity conservation. The primary function of a predator is predation, which is often investigated by assessing their diet. We therefore use data on prey remains found in 4,298 Australian dingo scats systematically collected from three arid sites over a four year period to experimentally assess the effects of repeated broad-scale poison-baiting programs on dingo diet. Indices of dingo dietary diversity and similarity were either identical or near-identical in baited and adjacent unbaited treatment areas in each case, demonstrating no control-induced change to dingo diets. Associated studies on dingoes' movement behaviour and interactions with sympatric mesopredators were similarly unaffected by poison-baiting. These results indicate that mid-sized top-predators with flexible and generalist diets (such as dingoes) may be resilient to ongoing and moderate levels of population control without substantial alteration of their diets and other related aspects of their ecological function.
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An experiment that held the density of feral pigs constant while varying the effective density of aerially distributed baits was conducted at three sites in north-western New South Wales. Meat baits, containing one of the biomarkers iophenoxic acid, tetracycline or rhodamine B, were distributed at different intensities over each site, and a sample of pigs was shot from a helicopter at each site to determine bait uptake. Serum and tissue samples taken from each pig were analysed for the occurrence of the biomarkers; the proportions of pigs exhibiting biomarkers represented the proportions of the feral pig populations that had consumed baits at different baiting intensities (expressed as baits per unit of pig density). The maximum percentage of sampled pigs that had eaten baits varied from 31% to 72% across the three sites. Bait uptake was regressed against baiting intensity. For two of the trials, the quantity of bait hypothetically required to eliminate a population of feral pigs was extrapolated to be 1577 baits per unit of pig density, while for the third trial 1874 baits per unit of pig density would have been required. Bait-uptake by non-target animals was substantial, posing potential hazards to birds and reducing the availability of baits to feral pigs. Most likely, seasonal conditions affected bait-uptake by feral pigs. We discuss the implications of these results for exotic disease contingency planning.
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There has been much recent debate in Australia over whether lethal control of dingoes incurs environmental costs, particularly by allowing increase of populations of mesopredators such as red foxes and feral cats. Allen et al. FIZ 10:39, 2013 claim to show in their recent study that suppression of dingo activity by poison baiting does not lead to mesopredator release, because mesopredators are also suppressed by poisoning. We show that this claim is not supported by the data and analysis reported in Allen et al.'s paper.
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Top-predators have been reported to have an important role in structuring food webs and maintaining ecological processes for the benefit of biodiversity at lower trophic levels. This is thought to be achieved through their suppressive effects on sympatric mesopredators and prey. Great scientific and public interest surrounds the potential use of top-predators as biodiversity conservation tools, and it can often be difficult to separate what we think we know and what we really know about their ecological utility. Not all the claims made about the ecological roles of top-predators can be substantiated by current evidence. We review the methodology underpinning empirical data on the ecological roles of Australian dingoes (Canis lupus dingo and hybrids) to provide a comprehensive and objective benchmark for knowledge of the ecological roles of Australia’s largest terrestrial predator. From a wide variety of methodological flaws, sampling bias, and experimental design constraints inherent to 38 of the 40 field studies we assessed, we demonstrate that there is presently unreliable and inconclusive evidence for dingoes’ role as a biodiversity regulator. We also discuss the widespread (both taxonomically and geographically) and direct negative effects of dingoes to native fauna, and the few robust studies investigating their positive roles. In light of the highly variable and context-specific impacts of dingoes on faunal biodiversity and the inconclusive state of the literature, we strongly caution against the positive management of dingoes in the absence of a supporting evidence-base for such action.
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1. The maximum annual population growth rate (r m ) is a critical parameter in many models of wildlife dynamics and management. An important application of r m is the estimation of the maximum proportion of a population that can be removed to stop population growth (p). 2. When r m cannot be estimated in the field, one option is to estimate it from demographic data. We evaluate the use of the relationship between r m and female age at first reproduction (α), which is independent of phylogeny, to estimate r m . We first demonstrate that the relationship between field and demographic estimates of r m is unbiased. We then show that the relationship provides an unbiased and simple method to estimate r m using data for 64 mammal species. We also show that p declines exponentially as α increases. 3. We use the fitted relationship to estimate annual r m and p for 55 mammal species in Australia and New Zealand for which there are no field estimates of r m . The estimates differ by species but have low precision (wide 95% credible intervals CIs). Our estimate of r m for the Tasmanian devil Sarcophilus harrisii is high (0·6, 95% CI: 0·05-2·39) and suggests devils would become extinct if >0·34 of the population is removed annually (e.g. by facial tumour disease). Our estimate of r m (0·77, 95% CI: 0·71-1·05) for brushtail possum Trichosurus vulpecula is much greater than published estimates and highlights the need for further field estimates of r m for the species in New Zealand. 4. Synthesis and applications. Since r m has not been estimated in the field for the majority of mammal species, our approach enables estimates with credible intervals for this important parameter to be obtained for any species for which female age at first reproduction is known. However, the estimates have wide 95% CIs. The estimated r m , and associated uncertainty can then be used in population and management models, perhaps most importantly to estimate the proportion that if removed annually would drive the population to extinction. Our approach can be used for taxa other than mammals.
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Abundance indices for wild dogs (Canis familiaris familiaris and C. familiaris dingo) were calculated from their visitation to stations containing non-toxic baits before and after a replacement-baiting programme (conducted in January-February 1993). The programme, where 1080 (sodium fluoroacetate)-impregnated baits removed by target animals were replaced each day, achieved a mean reduction of 76.1% in the index of dog abundance. The replacement-baiting strategy removed all resident animals that would accept baits and the probable reductions in the populations of dogs were greater than the reductions reported in previous studies. The indices of the abundance of sympatric red foxes (Vulpes vulpes) were also reduced (90.8%) by the replacement-baiting programme. Minimum numbers of dogs and foxes using roads and tracks in the study area were estimated by index-manipulation-index methodology. The risk of this replacement-baiting programme to populations of non-target animals was insubstantial. The effects of the manipulation of canid populations on the management of populations of non-target animals are discussed.
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Factory-prepared beef crackle cubes and fresh meat baits are routinely used with the poison 1080 to prevent or reduce predation by wild dogs, Canis familiaris. Four field trials totalling 674 bait nights per bait type were conducted in southern Queensland to assess the relative attractiveness and palatability of the two baits to wild dogs and non-target animals. Buried meat and surface-laid meat baits were also compared to assess the effect that bait presentation can have on control programme efficiency and non-target hazard. Fresh meat was found to be significantly more palatable to wild dogs than factory baits. Factory baits, despite being equally attractive to wild dogs as fresh meat, had significantly more visits by wild dogs where baits were not eaten. Fresh meat was significantly more attractive and palatable to non-target species than factory baits. Buried baits were equally attractive and palatable to wild dogs compared with surface-laid meat baits, yet had greatly reduced non-target bait take. The significance of the results is discussed with regard to the potential 1080 hazard to birds and reptiles (which removed 28% and 10% of baits, respectively) and the influence that non-target removal of baits may have on the efficiency and design of wild-dog control programmes. Extra keywords: Compound 1080, poison, SEA, sodium fluoroacetate.
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The short-term impact of 1080 aerial baiting for wild dogs ( Canis lupus dingo, Canis lupus familiaris and hybrids of the two) on spotted-tailed quolls (Dasyurus maculatus) was investigated at a rainshadow woodland site in southern New South Wales, Australia. Sixteen quolls were trapped and fitted with radio-transmitters containing mortality sensors. Three feral cats were also opportunistically trapped and radio-collared. One week after trapping ceased, meat baits nominally containing 6 mg of 1080 poison and 50 mg of the biomarker rhodamine B were deployed aerially over a 10-km transect across the study area. Following bait deployment, collared quolls and cats were monitored daily over four weeks for evidence of mortality. During this time, one quoll and two cats died. The quoll did not die from 1080 but both cats showed clear signs of poisoning. Whisker samples were obtained from trapped quolls 5-8 weeks after baiting to determine whether they had been exposed to baits. Of the 15 remaining collared quolls, 12 were retrapped. Four of these tested positive for rhodamine B. Three individuals originally collared were not retrapped but confirmed alive at least seven weeks after bait deployment. A further six non-collared quolls were also trapped, with two of these positive for rhodamine B. Of the 19 quolls from which whisker samples were tested for rhodamine B then, 13 (68%) were negative and six (32%) were positive. Aerial baiting had no observable impact on the local radio-collared quoll population, a finding consistent with results from a similar study recently conducted in northern New South Wales.
Book
The types of damage caused by wildlife are many and varied, and can be costly and far-reaching. Until now, there has been little effort to identify and evaluate generalities across that broad range of species, methods and topics. Wildlife Damage Control promotes principle-based thinking about managing impact. It documents and discusses the key principles underlying wildlife damage and its control, and demonstrates their application to real-life topics – how they have been used in management actions or how they could be tested in the future. It synthesises the wide but diffuse literature dealing with the impacts of vertebrate pests and encourages readers to adopt a more theoretical framework for thinking about pest impacts and ways to manage them. The book is organised around key principles that apply across species, rather than looking at individual species, and is damage-based not pest animal-based. Within each chapter there are exercises designed to help readers learn and evaluate key principles. Conservation biologists, ecologists and others involved in wildlife management will find the sections covering principles in biodiversity conservation, of production such as agriculture, and in human and animal health of real value.
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Beef cattle production is the major agricultural pursuit in the arid rangelands of Australia. Dingo predation is often considered a significant threat to production in rangeland beef herds, but there is a need for improved understanding of the effects of dingo baiting on reproductive wastage. We experimentally compared fetal/calf loss on baited and non-baited treatment areas within three northern South Australian beef herds over a 2-4-year period. At re-musters, lactation was used to determine the outcomes of known pregnancies. Potential explanatory factors for fetal/calf loss (dingo baiting, dingo activity, summer heat, cow age, seasonal conditions, activity of dingo prey and selected livestock diseases) were investigated. From 3145 tracked pregnancies, fetal/calf loss averaged 18.6%, with no overall significant effect of baiting. Fetal/calf loss averaged 27.3% for primiparous (first pregnancy) heifers and 16.8% for multiparous (2nd or later calf) cows. On average, dingo-activity indices were 59.3% lower in baited treatments than in controls, although background site differences in habitat, weather and previous dingo control could have contributed to these lower indices. The overall scale and timing of fetal/calf loss was not correlated with dingo activity, time of year, a satellite-derived measure of landscape greenness (normalised difference vegetation index), or activity of alternative dingo prey. Limited blood testing suggested that successful pregnancy outcomes, especially in primiparous heifers, may have been reduced by the livestock diseases pestivirus and leptospirosis. The percentage occurrence of cattle hair in dingo scats was higher when seasonal conditions were poorer and alternative prey less common, but lack of association between fetal/calf loss and normalised difference vegetation index suggests that carrion feeding, rather than calf predation, was the more likely cause. Nevertheless, during the fair to excellent prevailing seasons, there were direct observations of calf predation. It is likely that ground baiting, as applied, was ineffective in protecting calves, or that site effects, variable cow age and disease confounded our results.
Article
Fresh meat baits containing sodium fluoroacetate (1080) are widely used for controlling feral pigs in Queensland, but there is a potential poisoning risk to non-target species. This study investigated the non-target species interactions with meat bait by comparing the time until first approach, investigation, sample and consumption, and whether dying bait green would reduce interactions. A trial assessing species interactions with undyed bait was completed at Culgoa Floodplain National Park, Queensland. Meat baits were monitored for 79 consecutive days with camera traps. Of 40 baits, 100% were approached, 35% investigated (moved) and 25% sampled, and 25% consumed. Monitors approached (P<0.05) and investigated (P<0.05) the bait more rapidly than pigs or birds, but the median time until first sampling was not significantly different (P>0.05), and did not consume any entire bait. A trial was conducted at Whetstone State Forest, southern Queensland, with green-dyed and undyed baits monitored for eight consecutive days with cameras. Of 60 baits, 92% were approached and also investigated by one or more non-target species. Most (85%) were sampled and 57% were consumed, with monitors having slightly more interaction with undyed baits than with green-dyed baits. Mean time until first approach and sample differed significantly between species groups (P≤0.038 and 0.007 respectively) with birds approaching sooner (P<0.05) and monitors sampling later (P<0.05) than other (unknown) species (P>0.05). Undyed bait was sampled earlier (mean 2.19 days) than green-dyed bait (2.7 days) (P≤0.003). Data from the two trials demonstrate that many non-target species regularly visit and sample baits. The use of green-dyed baits may help reduce non-target uptake, but testing is required to determine the effect on attractiveness to feral pigs. Further research is recommended to quantify the benefits of potential strategies to reduce the non-target uptake of meat baits to help improve the availability of bait to feral pigs.
Article
In Australia many animals are classed as vermin because of their deleterious effects on livestock or crops. A major method used to limit agricultural damage is the erection of fences to exclude vermin from areas of pastoral or crop production. Such exclusion fencing has been important in Australia since the beginning of the rabbit menace in the mid-nineteenth century. A special kind of exclusion fence is the continuous barrier fence, which is designed to bar one or more species from a large area. More than 6500 miles of barrier fencing are currently maintained in Australia. They were originally planned to stem the spread of rabbits, but now are useful primarily to exclude dingoes, kangaroos, and emus. This method of vermin control is almost exclusively Australian and has a number of shortcomings, but under certain circumstances it has been peculiarly effective and will undoubtedly continue to be a notable element in the Australian rural scene.
Article
Sodium fluoroacetate (1080) is a vertebrate poison commonly used for the control of vertebrate pests in Australia. Long-term environmental persistence of 1080 from baiting operations has likely nontarget species and environmental impacts and is a matter of public concern. Defluorinating micro-organisms have been detected in soils of Western and central Australia, and Queensland, but not in south-eastern Australia. The presence or absence of defluorinating micro-organisms in soils from south-eastern Australia will assist in determining whether long-term environmental persistence of 1080 is or is not occurring. Soils from the Central West Slopes and Plains and Central Tablelands of New South Wales were sampled to investigate the presence and capability of 1080 defluorinating soil micro-organisms. Thirty-one species of micro-organisms were isolated from soils from each site after 10 days incubation in a 20 mM 1080 solution. Of these, 13 isolates showed measurable defluorinating ability when grown in a 1080 and sterile soil suspension. Two species, the bacteria Micromonospora, and the actinomycete Streptosporangium, have not been previously reported for their defluorinating ability. These results indicate that defluorinating micro-organisms are present in soils in south-eastern Australia, which adds weight to other studies that found that 1080 is subject to microbiological degradative processes following removal from the bait substrate. Soil micro-organism defluorination, in combination with physical breakdown and uptake by plants, indicates that fluoroacetate in soils and natural water ways is unlikely to persist. This has implications for the better informed use of 1080 in pest animal management programmes in south-eastern Australia.
Article
Using a biomarker, we assessed the propensity of spotted-tailed quolls (Dasyurus maculatus) to encounter and consume non-toxic meat baits, ordinarily laced with the poison 1080 (sodium monofluoroacetate) and deployed for control of wild dogs (Canis lupus dingo, Canis familiaris and hybrids of the two) in southern Australia. In the first experiment, 60 unpoisoned meat baits injected with Rhodamine B were placed on the surface of the ground at 250-m intervals along two separate transects crossing an open woodland study area. One week after placement, a range of animals, including quolls, had removed all baits. Microscopic assay of whisker samples collected from live-captured quolls later revealed that 6 of 10 (60%) animals were positive for the biomarker, indicating that they had encountered and consumed baits. In the second experiment, conducted at the same site one year later, 150 similarly prepared meat baits were delivered aerially from a helicopter along the same transects, at a rate of one bait every 100 m. Eight of 17 quolls (47%) were found to have encountered and consumed at least one and up to five baits. Combined with previous studies, our results reaffirm that surface or aerial baiting operations for wild dogs may place local quoll populations at risk. However, further research is necessary to establish the relationship between this risk and actual mortality levels during such baiting operations since there are a number of factors that may influence the toxicity of baits for spotted-tailed quolls in a field situation as well as the danger those baits may pose.
Article
In eastern Australia, the spotted-tailed quoll (Dasyurus maculatus) is the species thought to be most likely at risk from aerial baiting with compound 1080 to control wild dogs (Canis lupus familiaris and C. l. dingo). Although it is known that quolls occasionally die of 1080 poisoning, the broader impact on populations remains unresolved. We therefore assessed the impact of a regular aerial baiting campaign on a population of spotted-tailed quolls. Baiting with 1080 meat baits was conducted by the local Wild Dog Control Association and followed the same procedure as in previous years with the exception that the biomarker, rhodamine B, was added to the baits. Prior to the baiting, 36 quolls were trapped and fitted with mortality radio-collars; 31 of these collars were still functional at the time of baiting. Quolls were monitored from a helicopter and on the ground until retrapped 5-9 weeks after baiting. Transmitters were then removed and a sample of vibrissae was taken for rhodamine B analysis. Carcasses found were analysed for 1080. Predator numbers were assessed before and after baiting using track pads across trails. Among the initial 36 radio-collared quolls, nine mortalities were recorded during the course of the study (seven after baiting). Only one of the nine deaths could be directly attributed to 1080 poisoning. In addition, vibrissae from five of the 35 individuals sampled after baiting were marked with rhodamine B, indicating that these individuals had consumed bait, and survived. Consequently, mortality attributable to this particular aerial baiting campaign was low, apparently because few quolls ate bait and most of those that did survived. Track counts for predators indicated a significant decrease in dog and fox numbers after baiting. Cat activity remained unchanged and the number of quoll tracks increased.
Article
To further investigate the non-target impact of baiting using sodium monofluoroacetate (compound 1080) to control wild dogs, a population of radio-collared spotted-tailed quolls was subject to an experimental aerial baiting exercise. The trial was conducted at a site on the New England Tablelands, New South Wales, without a recent history of that practice. Sixteen quolls were trapped and radio-collared before baiting. Fresh meat baits were delivered from a helicopter at a rate of 10-40 baits km-1. In addition to 1080 (4.2 mg), each bait contained the bait marker rhodamine B (50 mg), which becomes incorporated into growing hair if an animal survives bait consumption. Two quoll mortalities were recorded following aerial baiting. Both quolls died 3-5 weeks after baiting when baits, on average, retained little 1080. None of the carcasses contained traces of 1080, but the test result is less reliable for the quoll that was found 19 days after its death although tissue was well preserved because of the cool weather. Nevertheless, given that this animal died 34 days after bait delivery, it appears likely that none of the radio-collared quolls succumbed to baiting. In contrast, vibrissae samples collected from 19 quolls captured after the baiting showed that 68% had eaten baits and survived. Furthermore, multiple bait takes were common, with up to six baits consumed by one female. The results demonstrate that most, if not all, quolls survived the baiting trial, including those that consumed dog baits. Hence bait consumption figures per se are not indicative of mortality rates attributable to poisoning.
Article
Three trials were conducted to compare the effectiveness of four 1080 dingo baits (two non-refined meat baits and two highly processed manufactured baits) in reducing dingo activity in the Northern Territory. Baits were laid at water points and dingo activity was estimated from track counts along a circular path cleared around each water point before baiting, immediately after and 10 months after baiting. Significant reductions in dingo activity were observed only at water points baited with non-refined meat baits. Highly processed manufactured baits did not significantly affect dingo activity. Data for non-target and dingo prey species were also recorded, but were generally insufficient to identify any effects of baiting on these species, or any relationships between the effectiveness of bait and the availability of prey. It is recommended that non-refined meat baits be used in preference to highly processed manufactured baits for the control of dingoes in the Northern Territory.
Article
The efficacy of aerial baiting with 1080 poison (sodium fluoroacetate) for the control of wild dogs (Canis familiaris familiaris and C. familiaris dingo) in the temperate rangelands of north-eastern New South Wales was studied. In each year from 1991 to 1993, 2 indices of the abundance of dogs, one a raw count of sets of footprints per km of transect (SF) and the other an ln-transformed frequency corrected for sightability of signs (CI), were used to quantify the changes in abundance caused by aerial baiting. Abundance of dogs at a nil-treatment site was estimated concurrently. The SF index found the 1991 baiting to be efficacious. Both measures of abundance showed baiting to be efficacious in 1992 and 1993. Reductions of 66.3-84.5% in the abundance of dogs at the treatment site were found for the CI measure. The SF measure displayed abundance changes of 76.1-91.1%. The indices of abundance measured prior to the annual baiting in 1992 and 1993 were similar, indicating that populations returned to their initial abundance within 1 year.
Article
Radiotracking was used to evaluate the effectiveness of aerial baiting in controlling populations of wild dingoes, Cams familiaris dingo. Four baitings were carried out in the West Pilbara region of Western Australia, using fresh-meat baits or factory-produced baits, poisoned with compound 1080. In one trial fresh-meat baits killed all 18 radio-collared dingoes; in another, factory baits killed 63% of radio-collared dingoes; _ in a third, 62% were killed by factory and fresh-meat baits. The factors considered to be most important in influencing the results of these trials included the number and distribution of baits dropped, bait type, and the age and social status of dingoes. Aerial baiting was shown to be an efficient and cost-effective dingo control technique under the conditions existing during the study. The long-term effects on the dingo population are discussed.
Article
In Australia, baiting with 1080 (sodium fluoroacetate) is widely used to reduce predation of native wildlife by the red fox. However, such control programs may place some native carnivores at risk, particularly the spotted-tailed quoll in eastern Australia. We measured the mortality in a total of 57 quolls fitted with mortality radio-transmitters during four experimental fox baitings with Foxoff® 1080 baits containing Rhodamine B in north-east New South Wales. In all experiments quolls visited bait stations regularly and removed a total of 20 baits. All but one of these baits was found in the vicinity of the bait station, indicating that quolls did not ingest baits. This was confirmed by the absence of Rhodamine B in the vibrissae of all quolls retrapped after baiting. The only quoll that may have died from a bait had eaten a cached bait some six weeks after baiting concluded. Thus, baiting did not threaten any of the quoll populations sampled. Therefore it appears that most restrictions imposed to protect spotted-tailed quolls during fox baiting are unnecessary as long as this bait type is used.
Article
On flat terrain no differences between aircraft were recorded except for the reduced accuracy of the fixed-wing aircraft at 300 ft (92 m), the highest altitude tested. The helicopter was more accurate in rugged terrain and is therefore the preferred aircraft for aerial baiting in tablelands and escarpment environments. Fixed-wing aircraft are recommended for flatter terrain, such as the Western Division of New South Wales, because of lower hire costs. -from Authors
Article
Birds in Australia vary greatly in their sensitivity to 1080 poison (sodium monofluoroacetate). Median lethal doses (LD*50s) range from 0.63 mg kg-1 for red-browed firetails, Emblema temporalis, to approximately 278 mg kg-' for the emu, Dromaius novaehollandiae. Significant differences occur between the sensitivity of different groups of birds and may be related to differences in their metabolic rates. A few species may also have developed a tolerance to 1080 from being exposed to indigenous plants that contain fluoroacetate, or to insects and other animals which have fed on such plants. The most common signs of 1080 poisoning among birds are depression, fluffed feathers, a reluctance to move, and convulsions. Signs of poisoning first appeared among the species tested at 1-60 h after dosing, and deaths follow between 1 h to almost 11 days after dosing. The susceptibility of 48 species of birds in Australia to 1080 poisoning is discussed in relation to typical baits and poison concentrations used against vertebrate pests. Theoretically, fewer types of birds are likely to be at risk from dingo-poisoning than pig-poisoning campaigns that also use meat baits but higher concentrations of 1080. Individuals of 39 out of the 48 species could be at risk from rabbit and other pig-poisoning campaigns. The impact on bird populations will depend, among other factors, on the amount of bait individuals eat and on the poisoning methods employed.
Article
Aerial baitjng for the management of wild dogs in north-eastern New South Wales is carried out in nine Rural Lands Protection Board districts covering coastal and tablelands environments. A survey of participants in the 1988 aerial baiting programme costed the total operation at $106,152. Labour ($36,418) and helicopter hiring charges ($35,693) accounted for over 70 per cent of the costs borne by local and regional control authorities. A total of 24,285 kg of meat (approx. 105,500 baits) valued at $21,018 was used. The average cost of the programme was $4.21 per kg of bait used. Total baiting costs can be accurately predicted from bait quantity. The cost, to individual producers, of aerial baiting for wild dogs, when compared with expected livestock losses without this form of management, suggests that aerial baiting is cost-beneficial.
Article
Three methods of preparing meat baits for 1080-poisoning were compared: tumble-mixing where baits were sprayed with 1080 solution; tumble-mixing where baits were sprinkled with 1080 solution; and injection. The tumble-mixing techniques produced baits which averaged 91% retention of the nominated (3.3 mg) dose, and contained 1.3-6.1 and 1.2-5.3 mg 1080, respectively. Two lots of injected baits retained averages of 90% and 97% of the nominated (6 mg) dose, with ranges 3.4-6.8 and 4.5-6.6 mg of 1080, respectively. Both tumble-mixing (either sprinkled or sprayed) and injection can give good average retention of 1080 in meat baits, but tumble-mixing appears to produce baits with a wider range in 1080 content than does injection. The latter method does not require bulky equipment and is quick and convenient, except when one person has to prepare very large quantities of meat baits (e.g. 2-3 tonne). Possible reasons for variation in 1080 content of single-lethal-dose baits prepared by these methods are discussed.
Article
Eutherian carnivores tested were more sensitive to 1080 poison than marsupial carnivores. Both groups of animals displayed similar symptoms but there was wide intra- and interspecific variation in the time to onset, the sequence of occurrence and duration of the symptoms. The risks that individual carnivores face from primary and secondary poisoning have been assessed. Theoretically, dingoes probably face the greatest risk amongst the species studied, followed by members of the smaller dasyurids and feral cats. Members of the larger dasyurids and long-nosed bandicoots probably face the least risk. Factors likely to influence the actual effect of 1080-poisoning campaigns on carnivore populations are dis- cussed.
Managing the impacts of dingoes and other wild dogs
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