Out of the frying pan: Reintroduction of toad-smart northern quolls to southern Kakadu National Park

Affordable RFID loggers for monitoring animal movement, activity, and behaviour

Effective conservation management strategies require accurate information on the movement patterns and behaviour of wild animals. To collect these data, researchers are increasingly turning to remote sensing technology such as radio-frequency identification (RFID). RFID technology is a powerful tool that has been widely implemented in ecological research to identify and monitor unique individuals, but it bears a substantial price tag, restricting this technology to generously-funded disciplines and projects. To overcome this price hurdle, we provide detailed step-by-step instructions to source the components for, and construct portable RFID loggers in house, at a fraction of the cost (~5%) of commercial RFID units. Here, we assess the performance of these RFID loggers in the field and describe their application in two studies of Australian mammal species; monitoring nest-box use in the Northern quolls (Dasyurus hallucatus) and observing the foraging habits of quenda (Isoodon fusciventer) at feeding stations. The RFID loggers performed well, identifying quenda in >80% of visits, and facilitating the collection of individual-level behavioural data including common metrics such as emergence time, latency to approach, and foraging effort. While the technology itself is not novel, by lowering the cost per unit, our loggers enabled greater sample sizes, increasing statistical power from 0.09 to 0.75 in the quoll study. Further, we outline and provide solutions to the limitations of this design. Our RFID loggers proved an innovative method for collecting accurate behavioural and movement data. With their ability to successfully identify individuals, the RFID loggers described here can act as an alternative or complementary tool to camera traps. These RFID loggers can also be applied in a wide variety of projects which range from monitoring animal welfare or demographic traits to studies of anti-predator responses and animal personality, making them a valuable addition to the modern ecologists’ toolkit.

Clair CC, Tobajas J. Conditioned Taste Aversion as a Tool for Mitigating Human-Wildlife Conflicts

Modern wildlife management has dual mandates to reduce human-wildlife conflict (HWC) for burgeoning populations of people while supporting conservation of biodiversity and the ecosystem functions it affords. These opposing goals can sometimes be achieved with non-lethal intervention tools that promote coexistence between people and wildlife. One such tool is conditioned taste aversion (CTA), the application of an evolutionary relevant learning paradigm in which an animal associates a transitory illness to the taste, odor or other characteristic of a particular food item, resulting in a long-term change in its perception of palatability. Despite extensive support for the power of CTA in laboratory studies, field studies have exhibited mixed results, which erodes manager confidence in using this tool. Here we review the literature on CTA in the context of wildlife conservation and management and discuss how success could be increased with more use of learning theory related to CTA, particularly selective association, stimulus salience, stimulus generalization, and extinction of behavior. We apply learning theory to the chronological stages of CTA application in the field and illustrate them by synthesizing and reviewing past applications of CTA in HWC situations. Specifically, we discuss (1) when CTA is suitable, (2) how aversion can be most effectively (and safely) established, (3) how generalization of aversion from treated to untreated food can be stimulated and (4) how extinction of aversion can be avoided. For each question, we offer specific implementation suggestions and methods for achieving them, which we summarize in a decision-support table that might be used by managers to guide their use of CTA across a range of contexts. Additionally, we highlight promising ideas that may further improve the effectiveness of CTA field applications in the future. With this review, we aspire to demonstrate the diverse past applications of CTA as a non-lethal tool in wildlife management and conservation and facilitate greater application and efficacy in the future.

Effects of learning and adaptation on population viability

Cultural adaptation is one means by which conservationists may help populations adapt to threats. A learned behavior may protect an individual from a threat, and the behavior can be transmitted horizontally (within generations) and vertically (between generations), rapidly conferring population-level protection. Although possible in theory, it remains unclear whether such manipulations work in a conservation setting; what conditions are required for them to work; and how they might affect the evolutionary process. We examined models in which a population can adapt through both genetic and cultural mechanisms. Our work was motivated by the invasion of highly toxic cane toads (Rhinella marina) across northern Australia and the resultant declines of endangered northern quolls (Dasyurus hallucatus), which attack and are fatally poisoned by the toxic toads. We examined whether a novel management strategy in which wild quolls are trained to avoid toads can reduce extinction probability. We used a simulation model tailored to quoll life history. Within simulations, individuals were trained and a continuous evolving trait determined innate tendency to attack toads. We applied this model in a population viability setting. The strategy reduced extinction probability only when heritability of innate aversion was low (<20%) and when trained mothers trained >70% of their young to avoid toads. When these conditions were met, genetic adaptation was slower, but rapid cultural adaptation kept the population extant while genetic adaptation was completed. To gain insight into the evolutionary dynamics (in which we saw a transitory peak in cultural adaptation over time), we also developed a simple analytical model of evolutionary dynamics. This model showed that the strength of natural selection declined as the cultural transmission rate increased and that adaptation proceeded only when the rate of cultural transmission was below a critical value determined by the relative levels of protection conferred by genetic versus cultural mechanisms. Together, our models showed that cultural adaptation can play a powerful role in preventing extinction, but that rates of cultural transmission need to be high for this to occur.

Measuring, evaluating and improving the effectiveness of invasive predator control programs: Feral cat baiting as a case study

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 (F_1,54 = 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 h. 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.

The effectiveness of conditioned aversion in wolves: Insights from experimental tests

It has been suggested that conditioned food aversion (CFA) could be a potential non-lethal intervention by which to deter attacks on livestock by large carnivores. CFA occurs when an animal associates the characteristics of a food with an illness, thus rejecting that food in subsequent encounters. CFA can be associated with an artificial odour during conditioning. Despite the debate surrounding the use of this intervention, more studies evaluating the effectiveness of CFA are necessary. We experimentally evaluated the potential of microgranulated levamisole + a vanilla odour cue to induce CFA in captive Iberian wolves (Canis lupus signatus). Four out of the five wolves treated showed an aversion to the meat for a minimum of one month after conditioning. The microgranulated presentation masked the flavour and smell of the levamisole but increased its volume, which may have facilitated its detection by the wolves. We also observed that the strength of the odour played an important role in the aversion extinction. The use of microgranulated levamisole + an odour cue has the potential to be used as an intervention by which to induce aversive conditioning in wolves in the wild, although rigorous field tests are required. We discuss the potential of CFA to deter attacks on livestock by large carnivores.

Training fails to elicit behavioral change in a marsupial suffering evolutionary loss of antipredator behaviors

Attempts to reintroduce threatened species from ex situ populations (zoos or predator-free sanctuaries) regularly fail because of predation. When removed from their natural predators, animals may lose their ability to recognize predators and thus fail to adopt appropriate antipredator behaviors. Recently, northern quolls (Dasyurus hallucatus; Dasyuromorpha: Dasyuridae) conserved on a predator-free “island ark” for 13 generations were found to have no recognition of dingoes, a natural predator with which they had coevolved on mainland Australia for about 8,000 years. A subsequent reintroduction attempt using quolls acquired from this island ark failed due to predation by dingoes. In this study, we tested whether instrumental conditioning could be used to improve predator recognition in captive quolls sourced from a predator-free “island ark.” We used a previously successful scent-recognition assay (a giving-up density experiment) to compare predator-scent recognition of captive-born island animals before and after antipredator training. Our training was delivered by pairing live predators (dingo and domestic dog) with an electrified cage floor in repeat trials such that, when the predators were present, foraging animals would receive a shock. Our training methodology did not result in any discernible change in the ability of quolls to recognize and avoid dingo scent after training. We conclude either that our particular training method was ineffective (though ethically permissible); or that because these quolls appear unable to recognize natural predators, predator recognition may be extremely difficult to impart in a captive setting given ethical constraints. Our results point to the difficulty of reinstating lost behaviors, and to the value of maintaining antipredator behaviors in conservation populations before they are lost.

Demography and spatial requirements of the endangered northern quoll on Groote Eylandt

Abstract ContextAustralia has experienced the highest number of mammal extinctions of any continent over the past two centuries. Understanding the demography and spatial requirements of populations before declines occur is fundamental to confirm species trajectory, elucidate causes of decline and develop effective management strategies. AimsWe evaluated the demography and spatial requirements of a northern quoll, Dasyurus hallucatus, population on Groote Eylandt, Northern Territory. Groote Eylandt is considered a refuge for the species because key threatening processes are absent or limited; cane toads and introduced ungulates are absent, feral cats are infrequently detected and the fire regime is benign compared with mainland Northern Territory. MethodsWe conducted a 4-year capture–mark–recapture study to monitor growth, reproduction and survival of northern quolls within a 128-ha area, and we evaluated spatial requirements by attaching GPS units to both sexes. To assess the status of the Groote Eylandt population, we compared the demographics with existing data from mainland populations. Key resultsThe average density of northern quolls was 0.33ha−1. However, there was a 58% decline in female density, primarily between 2012 and 2013, corresponding with a decrease in female body mass. Females survived and bred in up to 3 years and adult survival rates did not vary among years, suggesting that juvenile recruitment drives population fluctuations. Male quolls were semelparous, with die-off occurring in the months following breeding. The median female and male home ranges were 15.7ha and 128.6ha respectively, and male ranges increased significantly during breeding, with 1616ha being the largest recorded. ConclusionsThe northern quoll population on Groote Eylandt had a higher density, female survival and reproductive success than has been previously recorded on the mainland. However, a marked decline was recorded corresponding with a decrease in female mass, indicating below-average rainfall as the likely cause. ImplicationsGroote Eylandt remains a refuge for the endangered northern quoll. However, even in the absence of key threatening processes, the population has declined markedly, highlighting the impact of environmental fluctuations. Maintaining the ecological integrity of Groote Eylandt is imperative for population recovery, and managing threats on the mainland over appropriate spatial scales is necessary to increase population resilience.

The perils of paradise: an endangered species conserved on an island loses antipredator behaviours within 13 generations

When imperilled by a threatening process, the choice is often made to conserve threatened species on offshore islands that typically lack the full suite of mainland predators. While keeping the species extant, this releases the conserved population from predator-driven natural selection. Antipredator traits are no longer maintained by natural selection and may be lost. It is implicitly assumed that such trait loss will happen slowly, but there are few empirical tests. In Australia, northern quolls (Dasyurus hallucatus) were moved onto a predator-free offshore island in 2003 to protect the species from the arrival of invasive cane toads on the mainland. We compared the antipredator behaviours of wild-caught quolls from the predator-rich mainland with those from this predator-free island. We compared the responses of both wild-caught animals and their captive-born offspring, to olfactory cues of two of their major predators (feral cats and dingoes). Wild-caught, mainland quolls recognized and avoided predator scents, as did their captive-born offspring. Island quolls, isolated from these predators for only 13 generations, showed no recognition or aversion to these predators. This study suggests that predator aversion behaviours can be lost very rapidly, and that this may make a population unsuitable for reintroduction to a predator-rich mainland.

Targeted gene flow and rapid adaptation in an endangered marsupial

Targeted gene flow is an emerging conservation strategy. It involves translocating individuals with favorable genes to areas where they will have a conservation benefit. The applications for targeted gene flow are wide-ranging but include preadapting native species to the arrival of invasive species. The endangered carnivorous marsupial, the northern quoll (Dasyurus hallucatus), has declined rapidly since the introduction of the cane toad (Rhinella marina), which fatally poisons quolls that attack them. There are, however, a few remaining toad-invaded quoll populations in which the quolls survive because they know not to eat cane toads. It is this toad-smart behavior we hope to promote through targeted gene flow. For targeted gene flow to be feasible, however, toad-smart behavior must have a genetic basis. To assess this, we used a common garden experiment, comparing offspring from toad-exposed and toad-naïve parents raised in identical environments, to determine whether toad-smart behavior is heritable. Offspring from toad-exposed populations were substantially less likely to eat toads than those with toad-naïve parents. Hybrid offspring showed similar responses to quolls with 2 toad-exposed parents, indicating the trait may be dominant. Together, these results suggest a heritable trait and rapid adaptive response in a small number of toad-exposed populations. Although questions remain about outbreeding depression, our results are encouraging for targeted gene flow. It should be possible to introduce toad-smart behavior into soon to be affected quoll populations.

Cloacal and Ocular Microbiota of the Endangered Australian Northern Quoll

The Australian northern quoll is an important predatory marsupial carnivore that is currently endangered due to inappropriate fire regimes, predation, and the spread of invasive cane toads. The microbiota of Australian marsupials has not been extensively studied, but is thought to play a role in their health. This study provides an initial characterization of the cloacal microbiota of the northern quoll, as well as other marsupials including possums and kangaroos which were opportunistically sampled. The northern quoll cloaca microbiota was dominated by Enterococcus and Lactobacillus and had a relatively high proportion of members of the Proteobacteria phylum, which has been observed in other carnivorous marsupials. The diversity and structure of the microbiota was not influenced by presence of Chlamydiales which are intracellular bacteria and potential pathogens. The microbiota of the other marsupials was quite varied, which may be related to their health status. Characterization of the northern quoll microbiota will help to better understand the biology of this endangered animal.