In situ predator conditioning of naive prey prior to reintroduction

Sustained predation pressure may prevent the loss of anti-predator traits from havened populations

Conservation havens free of invasive predators are increasingly relied upon for fauna conservation, although havened populations can lose anti-predator traits, likely making them less suitable for life 'beyond the fence'. Sustaining low levels of mammalian predator pressure inside havens may prevent the loss of anti-predator traits from havened populations. We opportunistically compared behavioural and morphological anti-predator traits between four woylie (Bettongia penicillata ogilbyi) populations- one haven isolated from all mammalian predators, one haven containing a native mammalian predator (chuditch; Dasyurus geoffroii), and their respective non-havened counterparts (each containing both chuditch and invasive predators). Havened woylies existing without mammalian predators were smaller (shorter hindfeet, smaller body weight) and less reactive (consumed more food from fox-treated and control feeding stations, less agitated during human handling) than a non-havened reference population. However, in the haven containing chuditch, we found no difference in behaviour or morphology compared to the adjacent non-havened population. Across populations, anti-predator responses tended to appear stronger at sites with higher predator activity, suggestive of an adaptive response across a gradient of predation pressure. Our findings suggest that maintaining mammalian predation pressure in conservation havens could be effective for preventing or slowing the loss of anti-predator traits from these populations.

Acquired predator recognition via epidermal alarm cues but not dietary alarm cues by isolated pupfish

We tested whether Shoshone pupfish Cyprinodon nevadensis shoshone and Amargosa River pupfish C. n. amargosae respond behaviourally to conspecific chemical alarm cues released when epidermal tissue is damaged by a predator. We found that both subspecies reduced activity and vertical position in the water column in response to alarm cues. We then tested if pupfish can use alarm cue to acquire recognition of a novel predator. We trained pupfish with (1) water + odour of largemouth bass fed a diet of earthworms, (2) alarm cues from skin extract (epidermal alarm cues) + odour of bass fed a diet of earthworms, or (3) water + odour of bass fed a diet of pupfish (dietary alarm cues). Pupfish responded to epidermal alarm cues but not to dietary alarm cues. Pupfish were retested with the odour of bass that were fed an earthworm diet. Pupfish that had previously received epidermal alarm cues reduced vertical position and activity relative to the other two treatments. This is the first demonstration of acquired recognition of a novel predator by a pupfish, the first report of partial predator naiveté, and opens the possibility of predator-recognition training as a tool for management and conservation of endangered desert fishes.

Improving the success of reinforcement programs: effects of a two-week confinement in a field enclosure on the anti-predator behaviour of captive-bred European hamsters

Captive breeding programs are an important pillar in biodiversity conservation, aiming to prevent the extinction of threatened species. However, the establishment of self-sustaining populations in the wild through the release of captive-bred animals is often hampered by a high mortality upon release. In this study, we investigated how a 2-week confinement period within a large field enclosure affected the anti-predator behaviour of 'naive' captive-bred hamsters and how potential modifications persisted over time. During three consecutive tests, hamsters were confronted with a moving predator model (a red fox mount, Vulpes vulpes) and their behaviour was filmed. After the initial round of confrontation with the predator model, one group of hamsters (field group) was released into a field enclosure protected from predators, while the other group (control) remained in their individual laboratory cages. After 2 weeks, hamsters from the field group were recaptured and individuals of both groups underwent a second confrontation test. A total of 1 month after their return from the field enclosure, field hamsters were subjected to a last confrontation test. Video analysis, investigating four behavioural variables, revealed that field hamsters significantly modified their behavioural response following the 2 weeks confinement in the enclosure, while this was not the case for control hamsters. In addition, most behavioural modifications in field hamsters persisted over 1 month, while others started to revert. We suggest that an appropriate pre-release period inside a field enclosure will enable naive (captive-bred) hamsters to develop an adequate anti-predator behaviour that will increase their immediate survival probability upon release into the wild. We believe that such measure will be of great importance for hamster conservation programs.

Identifying the most effective behavioural assays and predator cues for quantifying anti-predator responses in mammals: a systematic review

BACKGROUND

Mammals, globally, are facing population declines. Protecting and breeding threatened populations inside predator-free havens and translocating them back to the wild is commonly viewed as a solution. These approaches can expose predator-naïve animals to predators they have never encountered and as a result, many conservation projects have failed due to the predation of individuals that lacked appropriate anti-predator responses. Hence, robust ways to measure anti-predator responses are urgently needed to help identify naïve populations at risk, to select appropriate animals for translocation, and to monitor managed populations for changes in anti-predator traits. Here, we undertake a systematic review that collates existing behavioural assays of anti-predator responses and identifies assay types and predator cues that provoke the greatest behavioural responses.

METHODS

We retrieved articles from academic bibliographic databases and grey literature sources (such as government and conservation management reports), using a Boolean search string. Each article was screened against eligibility criteria determined using the PICO (Population-Intervention-Comparator-Outcome) framework. Using data extracted from each article, we mapped all known behavioural assays for quantifying anti-predator responses in mammals and examined the context in which each assay has been implemented (e.g., species tested, predator cue characteristics). Finally, with mixed effects modelling, we determined which of these assays and predator cue types elicit the greatest behavioural responses based on standardised difference in response between treatment and control groups.

REVIEW FINDINGS

We reviewed 5168 articles, 211 of which were eligible, constituting 1016 studies on 126 mammal species, a quarter of which are threatened by invasive species. We identified six major types of behavioural assays: behavioural focals, capture probability, feeding station, flight initiation distance, giving-up density, and stimulus presentations. Across studies, there were five primary behaviours measured: activity, escape, exploration, foraging, and vigilance. These behaviours yielded similar effect sizes across studies. With regard to study design, however, studies that used natural olfactory cues tended to report larger effect sizes than those that used artificial cues. Effect sizes were larger in studies that analysed sexes individually, rather than combining males and females. Studies that used 'blank' control treatments (the absence of a stimulus) rather than a treatment with a control stimulus had higher effect sizes. Although many studies involved repeat measures of known individuals, only 15.4% of these used their data to calculate measures of individual repeatability.

CONCLUSIONS

Our review highlights important aspects of experimental design and reporting that should be considered. Where possible, studies of anti-predator behaviour should use appropriate control treatments, analyse males and females separately, and choose organic predator cues. Studies should also look to report the individual repeatability of behavioural traits, and to correctly identify measures of uncertainty (error bars). The review highlights robust methodology, reveals promising techniques on which to focus future assay development, and collates relevant information for conservation managers.

Addressing prey naivety in native mammals by accelerating selection for antipredator traits

Harnessing natural selection to improve conservation outcomes is a recent concept in ecology and evolutionary biology and a potentially powerful tool in species conservation. One possible application is the use of natural selection to improve antipredator responses of mammal species that are threatened by predation from novel predators. We investigated whether long-term exposure of an evolutionary naïve prey species to a novel predator would lead to phenotypic changes in a suite of physical and behavioral traits. We exposed a founder population of 353 burrowing bettongs (Bettongia lesueur) to feral cats (Felis catus) over 5 years and compared the physical and behavioral traits of this population (including offspring) to a control (non-predator exposed) population. We used selection analysis to investigate whether changes in the traits of bettongs were likely due to phenotypic plasticity or natural selection. We also quantified selection in both populations before and during major population crashes caused by drought (control) and high predation pressure (predator-exposed). Results showed that predator-exposed bettongs had longer flight initiation distances, larger hind feet, and larger heads than control bettongs. Trait divergence began soon after exposure and continued to intensify over time for flight initiation distance and hind foot length relative to control bettongs. Selection analysis found indicators of selection for larger hind feet and longer head length in predator-exposed populations. Results of a common garden experiment showed that the progeny of predator-exposed bettongs had larger feet than control bettongs. Results suggest that long-term, low-level exposure of naïve prey to novel predators can drive phenotypic changes that may assist with future conservation efforts.

Mini Safe Havens for population recovery and reintroductions 'beyond-the-fence'

In response to the ongoing decline of fauna worldwide, there has been growing interest in the rewilding of whole ecosystems outside of fenced sanctuaries or offshore islands. This interest will inevitably result in attempts to restore species where eliminating threats from predators and competitors is extremely challenging or impossible, or reintroductions of predators that will increase predation risk for extant prey (i.e., coexistence conservation). We propose 'Mini Safe Havens' (MSHs) as a potential tool for managing these threats. Mini Safe Havens are refuges that are permanently permeable to the focal species; allowing the emigration of individuals while maintaining gene flow through the boundary. Crucial to the effectiveness of the approach is the ongoing maintenance and monitoring required to preserve a low-to-zero risk of key threats within the MSH; facilitating in-situ learning and adaptation by focal species to these threats, at a rate and intensity of exposure determined by the animals themselves. We trialled the MSH approach for a pilot reintroduction of the Australian native New Holland mouse (Pseudomys novaehollandiae), in the context of a trophic rewilding project to address potential naïveté to a reintroduced native mammalian predator. We found that mice released into a MSH maintained their weight and continued to use the release site beyond 17 months (525 days) post-release. In contrast, individuals in temporary soft-release enclosures tended to lose weight and became undetectable approximately 1-month post-release. We discuss the broad applicability of MSHs for population recovery and reintroductions 'beyond-the-fence' and recommend avenues for further refinement of the approach.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s10531-022-02495-6.

Can native predators be used as a stepping stone to reduce prey naivety to novel predators?

Predator naivety negatively affects reintroduction success, and this threat is exacerbated when prey encounters predators with which they have had no evolutionary experience. While methods have been developed to inculcate fear into such predator-naïve individuals, none have been uniformly successful. Exposing ontogenetically- and evolutionary-naïve individuals first to native predators may be an effective stepping stone to improved responses to evolutionarily novel predators. We focused on greater bilbies (Macrotis lagotis) and capitalized on a multi-year mammalian recovery experiment whereby western quolls (Dasyurus geoffroii) were reintroduced into parts of a large fenced reserve that contained a population of naïve bilbies. We quantified a suite of anti-predator behaviors and measures of general wariness across quoll-exposed and quoll-naive bilby populations. We then translocated both quoll-exposed and quoll-naïve individuals into a large enclosure that contained feral cats (Felis catus) and monitored several behaviors. We found that bilbies can respond appropriately to quolls but found only limited support that experience with quolls better-prepared bilbies to respond to cats. Both populations of bilbies rapidly modified their behavior in a similar manner after their reintroduction to a novel environment. These results may have emerged due to insufficient prior exposure to quolls, inappropriate behavioral tests, or insufficient predation risk during cat exposure. Alternatively, quolls and cats are only distantly related and may not share sufficient similarities in their predatory cues or behavior to support such a learning transfer. Testing this stepping stone hypothesis with more closely related predator species and under higher predation risk would be informative.

Revisiting the 4 R’s: Improving post-release outcomes for rescued mammalian wildlife by fostering behavioral competence during rehabilitation

Rescue, rehabilitation, and release (‘rescue-rehab-release’) of wildlife is an increasingly widespread practice across ecosystems, largely driven by habitat loss, wildlife exploitation and a changing climate. Despite this, its conservation value has not been realized, in part due to the scarcity of what has been termed “the 4th R”, research. Similar to conservation breeding and headstarting, rescue and rehabilitation entails close association of humans and the wildlife in their care over impressionable and extended periods. However, unlike these interventions, rescue and rehabilitation require an initial, and sometimes sustained, focus on crisis management and veterinary needs which can impede the development of natural behaviors and promote habituation to humans, both of which can compromise post-release survival and recruitment. In this perspective, we discuss the pathways toward, and implications of, behavioral incompetence and highlight opportunities for testable interventions to curtail negative outcomes post-release, without compromising the health or welfare of rescued individuals. We propose that practitioners ‘switch gears’ from triage to fostering behavioral competence as early in the rehabilitation process as is possible, and that research be implemented in order to develop an evidence-base for best practices that can be shared amongst practitioners. We focus on four mammalian species to illustrate specific contexts and considerations for fostering behavioral competence by building on research in the conservation translocation literature. Finally, we discuss a way forward that calls for greater cross-pollination among translocation scenarios involving extended time under human care during developmentally sensitive periods.

When ancestry haunts – can evolutionary links to ancestors affect vulnerability of Australian prey to introduced predators? A preliminary study

The high extinction risk of Australian marsupials has been attributed to their failure to recognise novel predators, the application of inappropriate antipredator responses, and advanced hunting strategies of novel predators. This study is a preliminary attempt to explore whether the Lumholtz’ tree-kangaroo (Dendrolagus lumholtzi) (a) is able to recognise odour cues from different predators as threats, and (b) possesses predator-archetype specific antipredator responses. A small number of available captive tree-kangaroos were exposed to faecal odours from two extant predators of different archetypes (python, dingo), a regionally extinct predator which closely matches past terrestrial predators (Tasmanian devil), and a novel predator (domestic dog). Lavender oil was used as non-predator novel odour and water as control. Results suggest that all subjects associated the presented odours with a threat, albeit to different degrees, but did not display predator-archetype specific responses. It appears that this species applies an ancestral antipredator response of flight-on-the ground when encountering predators, including novel predators. Although the results need to be confirmed with more animals, further studies on the vulnerability of Australian prey to novel predators should take the ancestral history of Australian prey species into account.

History of canids in Chile and impacts on prey adaptations

Artiodactyl prey species of Chile, especially guanacos (Lama guanicoe), are reported to be very susceptible to predation by pack-hunting feral dogs. It has been previously suggested that guanacos and endemic South American deer may have evolved in the absence of pack-hunting cursorial predators. However, the paleoecology of canid presence in southern South America and Chile is unclear. Here, we review the literature on South American and Chilean canids, their distributions, ecologies, and hunting behavior. We consider both wild and domestic canids, including Canis familiaris breeds. We establish two known antipredator defense behaviors of guanacos: predator inspection of ambush predators, for example, Puma concolor, and rushing at and kicking smaller cursorial predators, for example, Lycalopex culpaeus. We propose that since the late Pleistocene extinction of hypercarnivorous group-hunting canids east of the Andes, there were no native species creating group-hunting predation pressures on guanacos. Endemic deer of Chile may have never experienced group-hunting selection pressure from native predators. Even hunting dogs (or other canids) used by indigenous groups in the far north and extreme south of Chile (and presumably the center as well) appear to have been used primarily within ambush hunting strategies. This may account for the susceptibility of guanacos and other prey species to feral dog attacks. We detail seven separate hypotheses that require further investigation in order to assess how best to respond to the threat posed by feral dogs to the conservation of native deer and camelids in Chile and other parts of South America.

Mismatch Between Risk and Response May Amplify Lethal and Non-lethal Effects of Humans on Wild Animal Populations

Human activity has rapidly transformed the planet, leading to declines of animal populations around the world through a range of direct and indirect pathways. Humans have strong numerical effects on wild animal populations, as highly efficient hunters and through unintentional impacts of human activity and development. Human disturbance also induces costly non-lethal effects by changing the behavior of risk-averse animals. Here, we suggest that the unique strength of these lethal and non-lethal effects is amplified by mismatches between the nature of risk associated with anthropogenic stimuli and the corresponding response by wild animals. We discuss the unique characteristics of cues associated with anthropogenic stimuli in the context of animal ecology and evolutionary history to explore why and when animals fail to appropriately (a) detect, (b) assess, and (c) respond to both benign and lethal stimuli. We then explore the costs of over-response to a benign stimulus (Type I error) and under-response to a lethal stimulus (Type II error), which can scale up to affect individual fitness and ultimately drive population dynamics and shape ecological interactions. Finally, we highlight avenues for future research and discuss conservation measures that can better align animal perception and response with risk to mitigate unintended consequences of human disturbance.

A Cause for Alarm: Increasing Translocation Success of Captive Individuals Through Alarm Communication

Translocation programmes implying the movement of animals from one place to another aim to sustain endangered populations in the wild. However, their success varies greatly, with predation being a major contributing factor. This is particularly prevalent in released captive-raised individuals which have a reduced or lost awareness of predators. Alarm calls are an immediate response made toward a predator, mostly studied in highly predated, social vertebrates. These warning vocalizations are a vital part of a prey species' anti-predator behavior, enhancing the individuals' and surrounding listeners' survival. To date, most translocation programmes have not considered this behavior for release success. Here we review the literature summarizing alarm communication systems of wild and captive vertebrates, aiming to establish recommendations and actions which could encourage alarm communication behavior in captive vertebrate species. Observations of wild animals show that alarm-call understanding is gained through the experience of predation pressure from a young age, amongst conspecific and heterospecific social groups, which captive individuals can lack. This information, combined with consideration of a programme's accessible resources and captive individual's developmental history, is pivotal to efficiently guide appropriate actions. Focusing on preserving behaviors in captivity, we provide a list of recommendations and actions to guide the reinforcement of alarm communication throughout the translocation process. Ensuring predator awareness and the maintenance of alarm communication in translocated individuals may greatly improve the likelihood of release success.

Evolutionary dynamics in the Anthropocene: Life history and intensity of human contact shape antipredator responses

Humans profoundly impact landscapes, ecosystems, and animal behavior. In many cases, animals living near humans become tolerant of them and reduce antipredator responses. Yet, we still lack an understanding of the underlying evolutionary dynamics behind these shifts in traits that affect animal survival. Here, we used a phylogenetic meta-analysis to determine how the mean and variability in antipredator responses change as a function of the number of generations spent in contact with humans under 3 different contexts: urbanization, captivity, and domestication. We found that any contact with humans leads to a rapid reduction in mean antipredator responses as expected. Notably, the variance among individuals over time observed a short-term increase followed by a gradual decrease, significant for domesticated animals. This implies that intense human contact immediately releases animals from predation pressure and then imposes strong anthropogenic selection on traits. In addition, our results reveal that the loss of antipredator traits due to urbanization is similar to that of domestication but occurs 3 times more slowly. Furthermore, the rapid disappearance of antipredator traits was associated with 2 main life-history traits: foraging guild and whether the species was solitary or gregarious (i.e., group-living). For domesticated animals, this decrease in antipredator behavior was stronger for herbivores than for omnivores or carnivores and for solitary than for gregarious species. By contrast, the decrease in antipredator traits was stronger for gregarious, urbanized species, although this result is based mostly on birds. Our study offers 2 major insights on evolution in the Anthropocene: (1) changes in traits occur rapidly even under unintentional human “interventions” (i.e., urbanization) and (2) there are similarities between the selection pressures exerted by domestication and by urbanization. In all, such changes could affect animal survival in a predator-rich world, but through understanding evolutionary dynamics, we can better predict when and how exposure to humans modify these fitness-related traits.

This study reveals that the evolutionary dynamics of antipredator responses of urbanized animals are similar to those of domestication but at a rate 3 times slower. Hence, contact with humans has profound impacts on the capacity of populations to respond to predation. Both foraging guilds and social level of species have an impact on the speed of the decrease of fear-related traits over time.

Applied Functional Biology: Linking Ecological Morphology to Conservation and Management

Many researchers work at the interface of organisms and environment. Too often, the insights that organismal, or functional, biologists can bring to the understanding of natural history, ecology, and conservation of species are overlooked. Likewise, natural resource managers are frequently focused on the management of populations and communities, while ignoring key functional traits that might explain variation in abundance and shifts in species composition at these ecological levels. Our intention for this symposium is two-fold: (1) to bring to light current and future research in functional and ecological morphology applicable to concerns and goals of wildlife management and conservation and (2) to show how such studies can result in measurable benchmarks useful to regulatory agencies. Symposium topics reveal past, present, and future collaborations between functional morphologists/biomechanists and conservation/wildlife biologists. During the SICB 2020 Annual Meeting, symposium participants demonstrated how data gathered to address fundamental questions regarding the causes and consequences of organismal form and function can also help address issues of conservation and wildlife management. Here we review how these, and other, studies of functional morphology, biomechanics, ecological development morphology and performance can inform wildlife conservation and management, principally by identifying candidate functional traits that have clear fitness consequences and population level implications.

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.

A comparative study of survival, recruitment and population growth in two translocated populations of the threatened greater bilby (Macrotis lagotis)

Abstract Context Translocations have been widely used to re-establish populations of threatened Australian mammalian species. However, they are limited by the availability of sites where key threats can be effectively minimised or eliminated. Outside of ‘safe havens’, threats such as exotic predators, introduced herbivores and habitat degradation are often unable to be completely eliminated. Understanding how different threats affect Australian mammal populations can assist in prioritising threat-management actions outside of safe havens. AimsWe sought to determine whether translocations of the greater bilby to two sites in the temperate zone of South Australia could be successful when human-induced threats, such as prior habitat clearance, historic grazing, the presence of feral cats and European rabbits, could not be completely eliminated. Methods Greater bilbies were regularly cage trapped at two translocation sites and a capture–mark–recapture study was used to determine survival, recruitment and population growth at both sites. Key results Our study showed that bilbies were successfully translocated to an offshore island with a previous history of grazing and habitat clearance, but which was free of exotic predators. At a second site, a mainland exclosure with feral cats and European rabbits present, the bilby population declined over time. Adult bilbies had similar survival rates in both populations; however, the mainland bilby population had low recruitment rates and low numbers of subadults despite high adult female fecundity. ConclusionsThe results indicated that past grazing and habitat clearance did not prevent the bilby population on the offshore island establishing and reaching a high population density. In the mainland exclosure, the low recruitment is probably due to feral cats predating on subadult bilbies following pouch emergence. Implications The results demonstrated that the bilby, an ecologically flexible Australian marsupial, can be successfully translocated to sites with a history of habitat degradation if exotic predators are absent. At the mainland exclosure site, threat mitigation for bilbies should focus on control or eradication of the feral cats. The control of European rabbits without control of feral cats could lead to prey-switching by feral cats, further increasing predation pressure on the small bilby population.

Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation

The impact of environmental change on the reproduction and survival of wildlife is often behaviourally mediated, placing behavioural ecology in a central position to quantify population- and community-level consequences of anthropogenic threats to biodiversity. This theme issue demonstrates how recent conceptual and methodological advances in the discipline are applied to inform conservation. The issue highlights how the focus in behavioural ecology on understanding variation in behaviour between individuals, rather than just measuring the population mean, is critical to explaining demographic stochasticity and thereby reducing fuzziness of population models. The contributions also show the importance of knowing the mechanisms by which behaviour is achieved, i.e. the role of learning, reasoning and instincts, in order to understand how behaviours change in human-modified environments, where their function is less likely to be adaptive. More recent work has thus abandoned the 'adaptationist' paradigm of early behavioural ecology and increasingly measures evolutionary processes directly by quantifying selection gradients and phenotypic plasticity. To support quantitative predictions at the population and community levels, a rich arsenal of modelling techniques has developed, and interdisciplinary approaches show promising prospects for predicting the effectiveness of alternative management options, with the social sciences, movement ecology and epidemiology particularly pertinent. The theme issue furthermore explores the relevance of behaviour for global threat assessment, and practical advice is given as to how behavioural ecologists can augment their conservation impact by carefully selecting and promoting their study systems, and increasing their engagement with local communities, natural resource managers and policy-makers. Its aim to uncover the nuts and bolts of how natural systems work positions behavioural ecology squarely in the heart of conservation biology, where its perspective offers an all-important complement to more descriptive 'big-picture' approaches to priority setting. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.

Animal learning may contribute to both problems and solutions for wildlife-train collisions

Transportation infrastructure can cause an ecological trap if it attracts wildlife for foraging and travel opportunities, while increasing the risk of mortality from collisions. This situation occurs for a vulnerable population of grizzly bears (Ursus arctos) in Banff National Park, Canada, where train strikes have become a leading cause of mortality. We explored this problem with analyses of rail-associated food attractants, habitat use of GPS-collared bears and patterns of past mortality. Bears appeared to be attracted to grain spilled from rail cars, enhanced growth of adjacent vegetation and train-killed ungulates with rail use that increased in spring and autumn, and in areas where trains slowed, topography was rugged, and human density was low. However, areas with higher grain deposits or greater use by bears did not predict sites of past mortality. The onset of reported train strikes occurred amid several other interacting changes in this landscape, including the cessation of lethal bear management, changes in the distribution and abundance of ungulates, increasing human use and new anthropogenic features. We posit that rapid learning by bears is critical to their persistence in this landscape and that this capacity might be enhanced to prevent train strikes in future with simple warning devices, such as the one we invented, that signal approaching trains. This article is part of the theme issue 'Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation'.