Context . Fertility control is seen as an attractive alternative to lethal methods for control of population size and genetic diversity in managed animal populations. Immunocontraceptive vaccines have emerged as the most promising agents for inducing long-term infertility in individual animals. However, after over 20 years of scientific testing of immunocontraceptive vaccines in the horse, the scientific consensus is that their application as a sole management approach for reducing population size is not an effective strategy.

Aims . The purpose of this review is to evaluate currently available non-lethal fertility-control methods that have been tested for their contraceptive efficacy in Equidae, and to assess their suitability for effective management of wild (feral) horses in an Australian setting.

Key results . (1) Fertility-control agents, particularly injectable immunocontraceptive vaccines based on porcine zona pellucida (PZP) or gonadotrophin-releasing hormone (GnRH), can induce multi-year infertility (up to 3 years) in the horse. Some formulations require annual or biennial booster treatments. Remote dart delivery (on foot) to horses is possible, although the efficacy of this approach when applied to large numbers of animals is yet to be determined. (2) The proportion of females that must be treated with a fertility-control agent, as well as the frequency of treatment required to achieve defined management outcomes (i.e. halting population growth in the short term and reducing population size in the long term) is likely to be >50% per annum. In national parks, treatment of a large number of wild horses over such a broad area would be challenging and impractical. (3) Fertility control for wild horses could be beneficial, but only if employed in conjunction with other broad-scale population-control practices to achieve population reduction and to minimise environmental impacts.

Conclusions . In Australia, most populations of wild horses are large, dispersed over varied and difficult-to-access terrain, are timid to approach and open to immigration and introductions. These factors make accessing and effectively managing animals logistically difficult. If application of fertility control could be achieved in more than 50% of the females, it could be used to slow the rate of increase in a population to zero (2–5 years), but it will take more than 10–20 years before population size will begin to decline without further intervention. Thus, use of fertility control as the sole technique for halting population growth is not feasible in Australia.

Context . Identification of key threats to endangered species is vital for devising effective management strategies, but may be hindered when relevant data is limited. A population viability approach may overcome this problem.

Aims . We aimed to determine the population viability of endangered northern bettongs (Bettongia tropica) in north-eastern Australia. We also assessed the key threats to the population resilience and how the population viability responds to increases in mortality rates and changes in fire and drought frequency.

Methods . Using population viability analysis (PVA) we modelled survival probability of B. tropica populations under likely scenarios, including: (1) increased predation; (2) changes in drought and fire frequency predicted with anthropogenic climate change; and (3) synergistic effects of predation, fire and drought.

Key results . Population viability models suggest that populations are highly vulnerable to increases in predation by feral cats (Felis catus), and potentially red fox (Vulpes vulpes) should they colonise the area, as juvenile mortality is the main age class driving population viability. If B. tropica become more vulnerable to predators during post-fire vegetation recovery, more frequent fires could exacerbate effects of low-level cat predation. In contrast, it was predicted that populations would be resilient to the greater frequency of droughts expected as a result of climate change, with high probabilities of extinctions only predicted under the unprecedented and unlikely scenario of four drought years in 10. However, since drought and fire are interlinked, the impacts of predation could be more severe with climate change should predation and fire interact to increase B. tropica mortality risk.

Conclusion . Like other Potoroids, B. tropica appear highly vulnerable to predation by introduced mammalian predators such as feral cats.

Implications . Managers need information allowing them to recognise scenarios when populations are most vulnerable to potential threats, such as drought, fire and predation. PVA modelling can assess scenarios and allow pro-active management based on predicted responses rather than requiring collection of extensive field data before management actions. Our analysis suggests that assessing and controlling predator populations and thereby minimising predation, particularly of juveniles, should assist in maintaining stability of populations of the northern bettong.

Context . Global climatic changes are increasingly producing observable shifts in species distributions. It is widely believed that the northern distribution of white-tailed deer (Odocoileus virginianus) in North America is limited by cold winter temperatures and deep snow. Under all climate change scenarios, it is likely that the adverse effects of winter will diminish, which may result in a northward expansion of the distribution of white-tailed deer.

Aims . The goal of this project was to quantify the drivers of white-tailed deer distribution identified from a set of climate and land cover variables. We wanted to forecast changes to the northern limit on white-tailed deer distribution under several climate change scenarios.

Methods . We used an occupancy-modelling approach to identify the variables or combination of variables that best estimated the occupancy of white-tailed deer across a 140-site camera-observation network operating from 2013 to 2015. We validated our model using data from a mammal atlas from 1993. We used available data from climate change scenarios to predict and map changes to the northern limit of white-tailed deer distribution for three time horizons up to 2100.

Key results . Our models indicated that both climate and land cover had a determining influence on the northern limit of white-tailed deer distribution in our study area. Variables describing winter climate, in particular temperature and snow depth, were most closely associated with the northern edge of white-tailed deer distribution, and land cover variables added explanatory power. Our predictions suggested that white-tailed deer distribution will expand northward, given the retreat of severe winters.

Conclusions . White-tailed deer distribution is controlled by land-based habitat indicators and limited at a northern boundary by the severity of winter climate. Current CO₂ emission scenarios indicate that winter conditions will no longer limit the northern distribution of white-tailed deer in our study area by the year 2100.

Implications . Under all climate change scenarios, the influx of white-tailed deer to new northern environments will likely impact the dynamics of other wildlife populations. The management of species such as moose (Alces alces) and caribou (Rangifer tarandus caribou) in these regions must anticipate the disruptive potential of white-tailed deer.

Context . Wood bison (Bison bison athabascae) have been absent from Alaska for over 170 years. In the spring and summer of 2015, however, 130 animals were reintroduced to the state. These wood bison were restored through a consensus-based planning process, but it remains unknown how the animals will be managed.

Aims . To survey urban and rural Alaska residents to understand the effect of proximity to the resource on residents’ preferences for management of wood bison in different scenarios.

Methods . Data were collected in urban areas using a mail-back questionnaire (n = 515) and by on-site interviews with rural residents (n = 31), between June and September 2015. Respondents were asked to state their preferred wood bison management strategies under specific situations of potential human–bison conflict.

Key results . Residents from urban and rural study areas differed in their preference of bison management, particularly in more severe situations (i.e. damage to property, causing injury to people).

Conclusions . Urban and rural residents were reluctant to use lethal management of wood bison, even under situations that threaten human property.

Implications . Backlash from urban residents could occur if managers use lethal management. Rural residents, however, favour lethal management when human injury occurs.

Context . Livestock depredation is a major conservation challenge around the world, causing considerable economical losses to pastoral communities and often result in retaliatory killing. In Mongolia, livestock depredation rates are thought to be increasing due to changes in pastoral practices and the transformation of wild habitats into pasture lands. Few studies have examined the interactions between humans and carnivores and even fewer have considered how recent changes in pastoral practices may affect depredation rates.

Aim . This study aimed to assess the influence of herding practices on self-reported livestock losses to snow leopards and wolves in two communities in South Gobi, Mongolia.

Methods . In total, 144 herder households were interviewed and an information-theoretic approach was used to analyse the factors influencing self-reported livestock losses to snow leopards and wolves.

Key results . The majority of self-reported losses to both snow leopards and wolves occurred when herds were left unattended in the pastures. The economic loss associated with livestock losses to snow leopards and wolves amounted to an average loss of US$825 per herder and year. The number of livestock owned by a household and the frequency of shifting campsite had the strongest influence on livestock losses to snow leopards and wolves. Other determinants of livestock losses included frequency of visiting the soum (county) centre.

Implications . On the basis of the findings, we make recommendations for mitigating the conflict with large carnivores, with focus on guiding future herding practices.

Context . Feral cats (Felis catus) are a threat to biodiversity globally, but their impacts upon continental reptile faunas have been poorly resolved.

Aims . To estimate the number of reptiles killed annually in Australia by cats and to list Australian reptile species known to be killed by cats.

Methods . We used (1) data from >80 Australian studies of cat diet (collectively >10 000 samples), and (2) estimates of the feral cat population size, to model and map the number of reptiles killed by feral cats.

Key results . Feral cats in Australia’s natural environments kill 466 million reptiles yr^–1 (95% CI; 271–1006 million). The tally varies substantially among years, depending on changes in the cat population driven by rainfall in inland Australia. The number of reptiles killed by cats is highest in arid regions. On average, feral cats kill 61 reptiles km^–2 year^–1, and an individual feral cat kills 225 reptiles year^–1. The take of reptiles per cat is higher than reported for other continents. Reptiles occur at a higher incidence in cat diet than in the diet of Australia’s other main introduced predator, the European red fox (Vulpes vulpes). Based on a smaller sample size, we estimate 130 million reptiles year^–1 are killed by feral cats in highly modified landscapes, and 53 million reptiles year^–1 by pet cats, summing to 649 million reptiles year^–1 killed by all cats. Predation by cats is reported for 258 Australian reptile species (about one-quarter of described species), including 11 threatened species.

Conclusions . Cat predation exerts a considerable ongoing toll on Australian reptiles. However, it remains challenging to interpret the impact of this predation in terms of population viability or conservation concern for Australian reptiles, because population size is unknown for most Australian reptile species, mortality rates due to cats will vary across reptile species and because there is likely to be marked variation among reptile species in their capability to sustain any particular predation rate.

Implications . This study provides a well grounded estimate of the numbers of reptiles killed by cats, but intensive studies of individual reptile species are required to contextualise the conservation consequences of such predation.

Context . European rabbits evolved in Spain and Portugal and are adapted to winter-rainfall Mediterranean habitats. On introduction into Australia in 1859, wild rabbits quickly colonised similar habitats across the southern two-thirds of the continent. However, over the past 40 years, they have spread further into monsoonal savanna habitats in northern Queensland.

Aims. To explain this, we considered adaptive responses of wild rabbits to hot conditions, particularly potential mechanisms for reducing the heat load of lactation, which has been identified as a likely limiting factor.

Methods . We analysed data from captive wild rabbits to identify mechanisms that could potentially reduce lactational heat load, and obtained data from shot samples of wild rabbits from northern Queensland to determine which of these might be most important in the field.

Key results . Rabbits spread food intake evenly across the 20-day lactation period and under hot conditions, captive wild individuals used body reserves to meet energy requirements for lactation, which is more energy efficient than converting digestible foods to milk.

Conclusions . This strategy reduces the heat load of lactation, enabling rabbits to suckle young successfully under hot conditions, but it comes at a cost. Rabbits need extra body reserves before breeding and need to regain those reserves between litters.

Implications . The slow spread of rabbits into Australia’s monsoonal savannas is likely to continue, given the rabbit’s reproductive flexibility and further natural selection for breeding in this environment.

Context . Several studies have estimated cougar (Puma concolor) abundance using remote camera trapping in conjunction with capture–mark–recapture (CMR) type analyses. However, this methodology (photo-CMR) requires that photo-captured individuals are individually recognisable (photo identification). Photo identification is generally achieved using naturally occurring marks (e.g. stripes or spots) that are unique to each individual. Cougars, however, are uniformly pelaged, and photo identification must be based on subtler attributes such as scars, ear nicks or body morphology. There is some debate as to whether these types of features are sufficient for photo-CMR, but there is little research directly evaluating its feasibility with cougars.

Aim . We aimed to examine researchers’ ability to reliably identify individual cougars in photographs taken from a camera-trapping survey, in order to evaluate the appropriateness of photo-CMR for estimating cougar abundance or CMR-derived parameters.

Methods . We collected cougar photo detections using a grid of 55 remote camera traps in north-west Wyoming, USA. The photo detections were distributed to professional biologists working in cougar research, who independently attempted to identify individuals in a pairwise matching process. We assessed the level to which their results agreed, using simple percentage agreement and Fleiss’s kappa. We also generated and compared spatially explicit capture–recapture (SECR) density estimates using their resultant detection histories.

Key results . There were no cases where participants were in full agreement on a cougar’s ID. Agreement in photo identification among participants was low (n = 7; simple agreement = 46.7%; Fleiss’s kappa = 0.183). The resultant SECR density estimates ranged from 0.7 to 13.5 cougars per 100 km² (n = 4; s.d. = 6.11).

Conclusion . We were unable to produce reliable estimates of cougar density using photo-CMR, due to our inability to accurately photo-tag detected individuals. Abundance estimators that do not require complete photo-tagging (i.e. mark–resight) were also infeasible, given the lack of agreement on any single cougar’s ID.

Implications . This research suggested that there are substantial problems with the application of photo-CMR to estimate the size of cougar populations. Although improvements in camera technology or field methods may resolve these issues, researchers attempting to use this method on cougars should be cautious.

Context . On airports, birds often exhibit escape behaviour in response to aircraft. Avian escape behaviours can enable birds to effectively avoid collisions with aircraft, although some are maladaptive and may increase the risk of collision (e.g. erratic flying). Habituation and habituation-like processes among birds potentially mediate the likelihood of aircraft-bird collisions. Moreover, because managers exploit avian escape behaviour to reduce bird–aircraft collision risks, habituation may decrease the efficiency of bird-hazard management.

Aims . Our aim was to better understand avian behavioural responses to approaching aircraft, which may inform bird-hazard management.

Methods . We examined the response of Australian magpie, Cracticus tibicen, a species commonly involved in collisions with aircraft, to the noise associated with take-off and landing in three areas: airside, on airport but not airside, and off airport.

Key results . Magpies responded to aircraft noise in a nuanced way. Take-off produced more responses, and more intense responses, than did landing; both resulted in more frequent, and more intense, responses than did a ‘silent’ control. Responses were least likely, and response latencies were longer, airside, followed by on airport but not airside, and off airport. Intensity of responses was similar across these areas.

Conclusions . Magpies on the airside were least responsive, and this might influence their strike risk.

Implications . Given that most wildlife collisions occur during take-off and landing and at low altitudes, and that take-off has greatest overall strike risk, the lack of responsiveness of airside-inhabiting magpies may contribute to collision risk.