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Inappropriate fire regimes and predation by introduced species each pose a major threat to Australia’s native mammals. They also potentially interact, an issue that is likely to be contributing to the ongoing collapse of native mammal communities across Australia. In the present review, I first describe the mechanisms through which fire could create predation pinch points, exacerbating the impacts of predators, including red foxes, Vulpes vulpes, and feral cats, Felis catus, on their native mammalian prey. These mechanisms include a localised increase in predator activity (a numerically mediated pathway) and higher predator hunting success after fire (a functionally moderated pathway), which could both increase native mammal mortality and limit population recovery in fire-affected landscapes. Evidence for such interactions is growing, although largely based on unreplicated experiments. Improving native mammal resilience to fire in predator-invaded landscapes requires addressing two key questions: how can the impacts of introduced predators on native mammals in fire-affected areas be reduced; and, does a reduction in predation by introduced species result in higher native mammal survival and population recovery after fire? I then examine potential management options for reducing predator impacts post-fire. The most feasible are landscape-scale predator control and the manipulation of fire regimes to create patchy fire scars. However, robust field experiments with adequate statistical power are required to assess the effectiveness of these approaches and preclude null (e.g. compensatory mortality) or adverse (e.g. mesopredator or competitor release) outcomes. Ongoing predator management and prescribed burning programs provide an opportunity to learn through replicated natural experiments as well as experimental manipulations. Standardised reporting protocols and cross-jurisdiction monitoring programs would help achieve necessary spatial and environmental replication, while multi-trophic, spatially explicit simulation models could help synthesise findings from disparate study designs, predict management outcomes and generate new hypotheses. Such approaches will be key to improving management of the complex mechanisms that drive threatened native mammal populations in Australia’s predator-invaded, fire-prone landscapes.
Context. Human activity in wildlands can influence wildlife populations by decreasing or degrading habitat, decreasing survival, or through displacement. For bighorn sheep (Ovis canadensis), some human activities are detrimental and may result in physiological stress, altered activity budgets, or habitat abandonment. From 1979 to 2000, human recreation increased over 300% in areas occupied by desert bighorn sheep (O. c.nelsoni) in south-eastern Utah. Concurrently, the population of desert bighorn sheep occupying the Potash Bighorn Sheep Management Unit of south-eastern Utah was in steep decline.
Aims. We investigated behavioural responses of desert bighorn sheep to different levels of human activity in this area from 2002 to 2003.
Methods. We divided the study population into two areas on the basis of the level of human use, i.e. low and high. We observed desert bighorn sheep at seven sites within these areas, including three with a high level of human use and four areas of a low level of human use.
Key results. Desert bighorn sheep spent significantly less time grazing and more time vigilant in areas of a high level of human use than in areas of a low level of human use.
Conclusions. Human recreational use of desert bighorn sheep habitat has the potential to negatively affect foraging by desert bighorn sheep.
Implications. We raise a cautionary flag because recreational use in bighorn sheep habitat near Moab, Utah, continues to increase and bighorn numbers continue to decline. When managers consider proposals to increase areas or trails for human recreation, they should incorporate ways to minimise impacts and reduce stressors to bighorn sheep.
Context. Introduced rats (Rattus spp.) can pose a serious threat to native flora and fauna, especially on islands where most species have evolved in the absence of terrestrial predators. Effective detection and eradication methods for introduced rats are essential to the maintenance of insular ecosystem integrity. Thus, it is important to better understand the behaviour of rats when they first arrive in a new setting.
Aims. To determine whether rats would find some novel stimuli to be significantly more attractive than other novel stimuli.
Methods. An eight-arm radial maze was used to study the behaviour of three species of Rattus finding themselves in a novel environment with various familiar and unfamiliar stimuli.
Key results. Although there were some differences in responses by species and by sex, most rats sought out and spent considerable time in the den box, suggesting an immediate need for security when in an unfamiliar setting. Rats also sought out faeces of conspecifics, suggesting the need for social contact or reproduction. The rats, which had not been food deprived, did not seem interested in food sources, although there was some attraction to the water source.
Implications. The management implications of the present study’s results are two-fold. First, appears that detection of newly arriving rats on islands would be aided by strategic placement of den boxes that are highly acceptable to rats. Managers could then inspect the den boxes periodically (or use a remote sensing system) for evidence of rat presence. Second, the den boxes could be scented with the faeces of other rats to further attract invading rats to the den boxes. This protocol might also hold the rats near the invasion site for a longer period of time before they begin seeking other shelter, food sources or mates. These protocols could give managers increased opportunities to detect any newly invading rats, and potentially increase the available time to deploy a rapid response to the invasion, before the animals begin to widely disperse. Of course, the rats will ultimately seek a source of palatable food, so placing durable, yet palatable, rodenticide bait in the den boxes might further decrease the probability of the invaders establishing a self-sustaining population.
Context. Wildlife tourism has been shown to increase stress in a variety of species and can negatively affect survival, reproduction, welfare, and behaviour of individuals. In African elephants, Loxodonta africana, increased physiological stress has been linked to use of refugia, rapid movement through corridors, and heightened aggression towards humans. However, we are unaware of any studies assessing the impact of tourism pressure (tourist numbers) on physiological stress in elephants.
Aims. We used faecal glucocorticoid metabolite (fGCM) concentrations to investigate whether tourist numbers in Madikwe Game Reserve, South Africa, were related to changes in physiological stress in elephants.
Methods. We repeatedly collected dung samples (n = 43) from 13 individually identified elephants over 15 months. Using a generalised linear mixed model and a Kenward–Roger approximation, we assessed the impact of monthly tourist numbers, season, age, and sex on elephant fGCM concentrations.
Key results. High tourist numbers were significantly related to elevated fGCM concentrations. Overall, fGCM concentrations increased by 112% (from 0.26 to 0.55 µg g−1 dry weight) in the months with the highest tourist pressure, compared to months with the lowest tourist pressure.
Conclusions. Managers of fenced reserves should consider providing potential alleviation measures for elephants during high tourist pressure, for example, by ensuring that refuge areas are available. This may be of even higher importance if elephant populations have had traumatic experiences with humans in the past, such as poaching or translocation. Such management action will improve elephant welfare and increase tourist safety.
Implications. Although tourism can generate substantial revenue to support conservation action, careful monitoring of its impact on wildlife is required to manage potential negative effects.
Context. Examining land cover’s influences on roadkills at single predetermined scales is more common than evaluating multiple scales, but examining land cover at the appropriate scale may be necessary for efficient design of mitigation measures, and that appropriate scale may be difficult to discern a priori. In addition, the taxonomic rank at which data is analysed may influence results and subsequent conclusions concerning mitigation.
Aims. The objective of the present study was to assess the influence of variation in spatial scales of land cover explanatory variables and taxonomic rank of response variables in models of wildlife–vehicle collisions (WVCs). Research questions include: (1) do the scales of land cover measurement that produce the highest quality models differ among species; (2) do the factors that influence roadkill events differ within species at different scales of measurement and among species overall; and (3) does the taxonomic rank at which data is analysed influence the selection of explanatory variables?
Methods. Four frequent WVC species representing diverse taxonomic classes, i.e. two mammals (Cerdocyon thous and Hydrochaeris hydrochaeris), one reptile (Caiman yacare) and one bird (Caracara plancus), were examined. WVCs were buffered, land cover classes from classified satellite imagery at three buffer radii were extracted, and logistic regression model selection was used.
Key results. The scale of land cover variables selected for the highest quality models (and the selected variables themselves) may vary among wild fauna. The same explanatory variables and formulae are not always included in the candidate models in all compared scales for a given species. Explanatory variables may differ among taxonomically similar species, e.g. mammals, and pooling species at higher taxonomic ranks can result in models that do not correspond with species-level models of all pooled species.
Conclusions. The most accurate analyses of WVCs will likely be found when species are analysed individually and multiple scales of predictor variable collection are evaluated.
Implications. Mitigating the effects of roadways on wildlife population declines for both common and rare species is resource intensive. Resources spent optimising models for spatially targeting management actions may reduce the amount of resources used and increase the effectiveness of these actions.
Context. Australia has a high diversity of endemic vertebrate fauna. Yet, transnational human activities continue to increase the rate of transportation, introduction and establishment of new alien vertebrates in Australia, to the detriment of environmental and socioeconomic services. Eradication of invasive vertebrates is often costly and without guarantee of success; therefore, methods for detecting, intercepting and preventing the transport of alien species earlier in the invasion pathway provide substantial benefit.
Aim. To anticipate emergent threats to Australian biosecurity posed by the transport and introduction of new alien vertebrates over time.
Methods. We collated vertebrate interception data from various mainland Australian State, Territory and Commonwealth government reporting agencies, including data from a previously published study, at both pre-border and post-border stages from 1999 to 2016. Using generalised linear and generalised additive modelling, we predicted trends in interception frequency using predictors such as vertebrate taxa, detection category and alien status.
Key results. Interception frequency increased over time for all vertebrate classes, for pre-border stowaways and for post-border captive and at-large interceptions, with no saturation in the accumulation of new species over time. Five species were responsible for almost half of all incidents, of which red-eared sliders (Trachemys scripta elegans), boa constrictors (Boa constrictor) and corn snakes (Pantherophis guttatus) are prominent in Australia’s illegal alien pet trade. Rose-ringed parakeets (Psittacula krameri) are prominent in the legal alien cage-bird trade, which remains poorly regulated. Asian common toads (Duttaphrynus melanostictus) were frequently detected as stowaways, and most stowaway incidents originated from Southeast Asia, particularly Indonesia, via shipping. Data deficiency for pre-border incidents increased rapidly in 2015 and 2016.
Conclusions. Australia is subject to a persistent and increasing risk of alien vertebrate introductions and incursions over time, owing partly to emergent trends in the alien pet trade as well as increased global trade and tourism.
Implications. The future of Australia’s biosecurity remains dependent on stringent border security to prevent the arrival of novel species, but our findings also highlight the importance of ongoing management and control of high-risk species already present, often illegally, within Australia.
Context. Understanding the factors that determine the distribution and abundance of species is an important aim of ecology and prerequisite for conservation. The Andean cat (Leopardus jacobita) and the pampas cat (L. colocolo) are two of the least studied felids. Both are threatened, of similar size and live sympatrically in the Andes of Argentina, Bolivia, Chile, and Perú.
Aims. We aimed at estimating the population densities of the Andean cat and pampas cat in two continuous areas and to analyse the activity patterns of these two species and that of mountain vizcacha (Lagidium viscacia), the main prey of the Andean cat.
Methods. We used camera traps to evaluate the density of both felid species using the space explicit capture recapture (SECR) framework and the overlap in their activity patterns with that of mountain vizcacha, using the kernel-density estimator in two contiguous areas in the Bolivian Altiplano, at Muro-Amaya and at Micani, both within the Ciudad de Piedra region.
Key results. Andean cat density was estimated at 6.45 individuals per 100 km2 in Muro-Amaya and 6.91 individuals per 100 km2 in Micani, whereas the density of the pampas cat was 5.31 individuals per 100 km2 and 8.99 individuals per 100 km2 respectively. The Andean cat was mainly nocturnal, whereas the pampas cat was cathemeral. The activity of the mountain vizcacha overlapped less with that of its specialised predator, the Andean cat, than with that of the pampas cat.
Conclusions. In line with our predictions, the Andean cat, considered a more specialised nocturnal hunter, particularly of mountain vizcacha, had lower population densities than did the more generalist pampas cat.
Implications. Low population densities, as compared with theoretical expectations, pose an additional conservation problem for these felids, in an area such as the high Andes.
Context. Bobcats (Lynx rufus) were extirpated from Ohio, USA, during the mid-1800s. Genetic evidence indicates that they recolonised from neighbouring states. Initial re-establishment occurred almost simultaneously in two spatially distinct areas of a coal-mined landscape in the 1980s. Relative population growth was apparently higher in the eastern than in the southern area.
Aims. Understanding the reasons for the disparity in population dynamics and sustainability is essential for proper bobcat management. It also addresses substantial knowledge gaps in vertebrate carnivore ecology on mined land. We hypothesised that the characteristics of mined land in the eastern Ohio area provided bobcats with greater resources, enabling a more rapid recovery.
Methods. We trapped bobcats and took body measurements and weights to determine condition indices. We attached GPS radio-collars and used locations to determine annual home-range and core-area sizes, home-range and core-area overlap, and habitat selection using remotely sensed land cover data and mine permit records. We compared factors between the two bobcat population areas.
Key results. Body condition indices were higher, and home ranges and core areas of males and females were smaller, for eastern Ohio bobcats. Home-range overlap did not differ for any dyad type. Selection of mined land by habitat type differed at the home-range level, with eastern bobcats selecting more mined habitats and southern bobcats showing an opposite tendency.
Conclusions. An interaction may exist between landscape features of former surface mines and bobcat recovery. Results suggest more favourable habitat conditions in the eastern area, which featured more mined land and more older, less regulated mines, than in the southern area. These conditions may support a higher bobcat reproductive success.
Implications. The first bobcat harvest season in Ohio is under development by authorities. We recommend the regulation of eastern and southern Ohio as separate bobcat management units; the southern population should remain protected, and the eastern population should be managed conservatively as a source population to further colonise southern Ohio. Our data suggest that surface-mined land can be conducive to the restoration and conservation of species.
Context. Each year, millions of reptile skins are commercially exported from Southeast Asia for exotic leathers. Quotas are commonly used to regulate this trade, but quotas are sometimes exceeded and do little to ensure harvest sustainability.
Aims. To explore the relationship between the size of live pythons and their skins, and to assess whether skin measurements can be used to enforce the application of limits on the size of harvested snakes.
Methods. We measured the body size of three heavily harvested python species (Malayopython reticulatus, Python breitensteini and Python brongersmai) in Indonesia and Malaysia and examined the relationship with skin length, skin width, the size of the ventral scale and its adjacent dorsal scale.
Key results. Measurements of 2261 pythons showed strong relationships between the size of live pythons and measurements made on their skins. Skins can be stretched 30% longer than the body length of snakes from which they came and inter-facility and country differences in stretching technique result in different relationships between the sizes of live snakes and the measurements made on their skins. Male and female Malayopython reticulatus differed in their skin dimensions relative to the size of the live snake, but these differences were minor.
Conclusions. Despite variations in stretching techniques, in functional terms, this variation is minor (maximum 3.5% relative to each mean measurement) and does not limit application of skin sizes for regulating trade within an acceptable level of error. However, differences in the stretched length of Indonesian and Malaysian skins were much greater (5.9% of the mean length of skins), and, thus, each country should apply its own limits and predictive tools.
Implications. The strong relationship between the skin size and the size of the live snake offers great potential for regulating trade by using skin-size limits. Inspection of the size of skins can be used to enforce harvest-size limits and focus harvesting away from sexes and life stages most critical for population persistence. This management tool has numerous advantages over current regulatory practices (quotas) and should be considered for management of trade in Asian reptile skins.
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