The canid pest ejector challenge: controlling urban foxes while keeping domestic dogs safe

Abstract ContextIt is widely recognised that red foxes (Vulpes vulpes) are abundant within urban areas; however, it is difficult to apply lethal control measures using poison baits in cities because of concerns about the safety of domestic pets, particularly dogs (Canis familiaris). AimsWe tested canid pest ejectors (CPEs) as a potential method of fox control by measuring visitation and activation behaviour of foxes and other wildlife while assessing non-target risk to domestic dogs. MethodsWe compared eight urban and eight peri-urban sites in Sydney, with half of the sites having restricted access for domestic dogs. We allocated five camera traps and ejectors per site. Through generalised linear mixed models, we compared the probability of ejector activation between foxes and dogs. We also assessed the relationship between dog visitation and distance to habitation and dog restrictions as measures of dog safety. Key resultsBoth species of canids were equally likely to pull the ejector (P=0.26). As expected, dog visitation was significantly lower in sites with dog restrictions (P<0.001). However, it was not related to distance from habitation. Only two non-canid species were recorded pulling the ejector, suggesting high target-specificity for canids. ConclusionsIn sites with dog restrictions, the risk of dog casualties from CPEs is minimal. However, distance from habitation does not increase dog safety, at least within 250m. The ejector is highly specific for canids. ImplicationsWe provide specific recommendations for the design of a potential fox control program using CPEs in urban and peri-urban areas. The ejector may be a safe method for fox control in cities when deployed at places without domestic dogs.

Minimizing animal welfare harms associated with predation management in agro-ecosystems

The impacts of wild predators on livestock are a common source of human-wildlife conflict globally, and predators are subject to population control for this reason in many situations. Animal welfare is one of many important considerations affecting decisions about predation management. Recent studies discussing animal welfare in this context have presented arguments emphasizing the importance of avoiding intentional harm to predators, but they have not usually considered harms imposed by predators on livestock and other animals. Efforts to mitigate predation impacts (including 'no control' approaches) cause a variety of harms to predators, livestock and other wildlife. Successfully minimizing the overall frequency and magnitude of harms requires consideration of the direct, indirect, intentional and unintentional harms imposed on all animals inhabiting agricultural landscapes. We review the harms resulting from the management of dingoes and other wild dogs in the extensive beef cattle grazing systems of Australia to illustrate how these negative impacts can be minimized across both wild and domestic species present on a farm or in a free-ranging livestock grazing context. Similar to many other predator-livestock conflicts, wild dogs impose intermittent harms on beef cattle (especially calves) including fatal predation, non-fatal attack (mauling and biting), pathogen transmission, and fear- or stress-related effects. Wild dog control tools and strategies impose harms on dingoes and other wildlife including stress, pain and death as a consequence of both lethal and non-lethal control approaches. To balance these various sources of harm, we argue that the tactical use of lethal predator control approaches can result in harming the least number of individual animals, given certain conditions. This conclusion conflicts with both traditional (e.g. continuous or ongoing lethal control) and contemporary (e.g. predator-friendly or no-control) predation management approaches. The general and transferable issues, approaches and principles we describe have broad applicability to many other human-wildlife conflicts around the world.

Uptake of ‘Eradicat’ feral cat baits by non-target species on Kangaroo Island

Abstract ContextPredation by feral cats (Felis catus) threatens a range of vertebrate species across Australia, and cat-free islands increasingly act as safe havens for biodiversity. A feral cat eradication program has begun on Kangaroo Island (4405km2) in South Australia, and poison baiting is likely to be one of the main methods used. Aims Here, we trial a non-toxic version of a cat bait, ‘Eradicat’, on western Kangaroo Island, to examine its potential impact on non-target species. MethodsNon-toxic baits containing the biomarker Rhodamine B were deployed across four sites in early August and late November in 2018, with bait take and consumption assessed both by remote cameras and by the presence of Rhodamine B in mammalian whisker samples taken post-baiting. Key resultsCats encountered baits on very few occasions and took a bait on only one occasion in August (<1% of 576 baits deployed). Non-target species accounted for over 99% of identifiable bait takes. In both seasons, >60% of all baits laid was taken by either the common brushtail possum (Trichosurus vulpecula), bush rat (Rattus fuscipes) or Australian raven (Corvus coronoides). In November, Rosenberg’s goanna (Varanus rosenbergi) and southern brown bandicoot (south-eastern subspecies; Isoodon obesulus obesulus), listed nationally as Endangered, also took baits (3% and 1% respectively). The Kangaroo Island dunnart (Sminthopsis fuliginosus aitkeni), listed nationally as endangered, approached a bait on only one occasion, but did not consume it. Evidence of bait consumption was visible in the whiskers of captured common brushtail possums (100% of post-baiting captured individuals in August, 80% in November), bush rats (59% in August and 50% in November), house mice (Mus musculus) (45% in November) and western pygmy-possums (Cercartetus concinnus) (33% in November). ConclusionsAlthough feral cat baiting has the potential to significantly benefit wildlife on Kangaroo Island, impacts on non-target species (particularly the bush rat and common brushtail possum) may be high. ImplicationsAlternative cat baits, such as those containing a toxin to which native species have a higher tolerance or that are less readily consumed by native wildlife, will be more appropriate.

Para-aminopropiophenone (PAPP) in canid pest ejectors (CPEs) kills wild dogs and European red foxes quickly and humanely

Lethal control remains an important approach to mitigating the impacts of predators on livestock and threatened fauna. This occurs in Australia, where wild dogs (Canis familiaris) and European red foxes (Vulpes vulpes) are commonly subjected to broad-scale poisoning programs. Ongoing refinement of lethal tools has led to the recent development of manufactured poison baits containing para-aminopropiophenone (PAPP). Canid pest ejectors (CPEs) have also been recently registered for use and are a target-specific poison delivery device; yet, there has been no confirmation that PAPP delivered via ejectors will provide similar efficacy to PAPP delivered via manufactured baits. We tested the efficacy of PAPP in ejectors on wild dogs (1000-mg dose) and foxes (400-mg dose). Time-to-death, physical signs of poisoning and other related factors were assessed. Ten of 11 (91%) wild dogs used in controlled trials died within 3 h after PAPP administration; the mean time to unconsciousness was 65 min and the mean time to death was 84 min. Three of four (75%) foxes also died within 3 h after PAPP administration; their mean time to unconsciousness was 78 min, and their mean time to death was 121 min. Carcasses of eight deceased wild dogs and one fox were found during field trials, with distances between the nearest triggered ejector and the deceased animal ranging from 30 to 200 m. The presence of de-oxygenated blood in all necropsied carcasses and photographic evidence of triggered ejectors unequivocally demonstrated that using powdered PAPP in ejectors produces rapid anoxia and death in both wild dogs and foxes. Although anxiety and accompanying behaviours were observed in wild dogs (but not foxes), the use of PAPP offers a humane, additional option for the control of wild canids.