Physiological and behavioural responses of Australian and exotic prey to the scent of native and introduced predators

This study examined the physiological and behavioural effects of a stress-inducing stimulus (predator odour) on potential prey species (Australian native and exotic). The aim was to determine if differences in the response of prey were related to the scent of evolutionary known predators compared to unfamiliar or short-term introduced ones. In laboratory experiments, responses were always restricted to changes in respiratory variables, with brushtail possums (Trichosurus vulpecula), rabbits (Oryctolagus cuniculus) and tammar wallabies (Macropus eugenii) showing no variation in metabolic rate after exposure to predator odours.Brushtail possums showed strong changes in ventilatory rate only when faced with the scent of an historical predator, increasing respiratory frequency (ratio after/before exposure = 4.55 ± 1.007) and decreasing tidal volume (ratio after/before exposure = 0.38 ± 0.113 ) in response to stale dingo urine. The changes were short-lived, lasting for only one minute of exposure. For this reason, it is unclear if the response observed could be considered as a fear reaction. However, there was no habituation after three exposures and this may indicate that possums were initially displaying an investigative approach to a predator scent and then relaxing once assessment was completed.The effect of predator and novel odours on the ventilation of rabbits appeared to be in general mediated by anxiety, as shown by the responses elicited by both predator and control scents. However, stronger reactions were observed in response to feral cat and quoll odours for both respiratory frequency (ratio after/before exposure to feral cat = 4.39 ± 0.721 and to quoll = 3.75 ± 0.486) and tidal volume (ratio after/before exposure to feral cat = 0.47 ± 0.065 and to quoll = 0.64 ± 0.129). This could be due to different intensity of the olfactory stimuli. Nevertheless, the effects of noxious odours on rabbits clearly demonstrate that they become highly vigilant at any sudden change in their environment.Tammar wallabies appeared to possess a mechanism for the recognition of predator odours as ventilatory responses were restricted to particular predator scents. After investigation, fox and cat odour provoked a stronger and more prolonged change in respiratory frequency (ratio after/before exposure to fox = 3.58 ± 0.918 and to feral cat = 2.44 ± 0.272) and tidal volume (ratio after/before exposure to fox = 0.84 ± 0.110 and to feral cat = 0.98 ± 0.155) compared to the other scents, suggesting that wallabies may have perceived these species as more immediate threats.For wild, free-living brushtail possums and southern brown bandicoots (Isodoon obesulus), there was no pattern of avoidance of historical or introduced predator odours, with no difference in number of animals captured in predator and control scented traps. This may indicate that predator odour avoidance has not evolved in these species and that they have poor possibilities of escaping potential predators. However it may also be explained by the long-term predator-free environment in which the study was conducted, and suggests loss of anti-predator behaviour in populations without predation risk.Wild, free-ranging western grey kangaroos (Macropus fuliginosus) reacted to the odour of both historical (dingo) and novel (fox) predators by reducing number of feeding events (5.2±2.08 for fox and 5.9±1.33 for dingo) and time spent foraging (17.7±7.2 sec for fox and 22.2±4.6 sec for dingo) when predator scents were present and by escaping areas tainted with predator odours (41.4±17.5 sec for fox and 33.8±13 sec for dingo). Clearly these results suggest that kangaroos are scared of predator odours. However, a close investigation of predator scents was necessary before a response could be elicited and feeding areas were not completely abandoned.It is still unclear if small Australian prey, such as southern brown bandicoots and brushtail possums, respond to olfactory cue of predation in the wild, as different results were obtained in the studies conducted in the laboratory and in free populations. However, this research showed that medium and large-sized macropods respond to both native, long-term and introduced predator odours. This indicates that at least some Australian prey species can recognise the odour of potential predators, although responses usually occur after a period of investigation, and do not always result in avoidance behaviour. Differential responses appear to be based on the perceived risk. Use of predator odour is unlikely to be an effective mechanism of deterring herbivores from preferred feeding locations

Ventilatory frequency as a measure of the response of tammar wallabies (Macropus eugenii) to the odour of potential predators

This study uses changes in ventilatory frequency to quantify the physiological response of an Australian terrestrial herbivore, the tammar wallaby (Macropus eugenii), to olfactory cues suggesting the presence of potential predators. Ventilatory frequency proved to be a quantifiable measure to assess the response of this macropod marsupial to olfactory cues. Ventilatory frequency increased from mean resting levels of 45 ± 5.1 breaths min–1 to 137 ± 11.2 breaths min–1 during the first minute of exposure to all odours. These physiological responses diminished over time, with ventilatory frequency in the first minute after introduction of the scents greater than that during the subsequent four, suggesting that the initial reaction was due to disturbance and was investigative in nature. However, the ratio of ventilatory frequency in the remaining 4 min after introduction of the odours compared with before was greater for fox (3.58 ± 0.918) and cat (2.44 ± 0.272) odours than for snake (2.27 ± 0.370), distilled water (1.81 ± 0.463) and quoll (1.71 ± 0.245) odours, suggesting that fox and cat odour provoked a greater response. However, the wallabies’ response to the odour of these introduced predators and to horse odour (2.40 ± 0.492) did not differ. Our study indicates that a long period of co-history with particular predators is not a prerequisite for detection of potentially threatening species. We do not find any support for the hypothesis that an inability to interpret olfactory cues to detect and respond to potential predation by introduced predators is responsible for the decline of these macropod marsupials

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Foxes in trees: a threat for Australian arboreal fauna?

We document the first evidence of tree climbing by red foxes (Vulpes vulpes) in Australia. Camera traps recorded foxes in trees on the Liverpool Plains, New South Wales. This finding prompts a reassessment of the impact that this invasive predator has on Australian fauna: from purely terrestrial to also potentially arboreal

Habitat fragmentation affects movement and space use of a specialist folivore, the koala

Habitat fragmentation changes landscape patterns and can disrupt many important ecological processes. Movement allows individuals to find resource patches to maintain their fitness and habitat fragmentation can disrupt this process. We explored the ecological impact of habitat fragmentation on movement and space use of a specialist folivore, the koala Phascolarctos cinereus. We GPS tracked koala movements within a fragmented agricultural landscape. We calculated the total distance moved across four months and the number of core patches by each koala. We used four metrics (proximity, functional connectivity, clumpiness, perimeter-to-area fractal dimension) to quantify landscape fragmentation within koala home ranges and determine its effects on movement and space use. Functional connectivity had the greatest effect on individual movement and space use. Decreasing connectivity led to longer and more direct movements by koalas and more core patches within an individual home range. Our study provides insight into the effects of habitat fragmentation on animal movement and space use, which can be used by wildlife managers to plan and manage landscapes more effectively.We conclude that restoring or protecting resource patches to promote greater functional connectivity will reduce the costs associated with the isolation of resource patches for species occupying fragmented landscapes. By providing a quantitative relationship between habitat connectivity and movement and space use costs, our results enable managers to set restoration targets, by identifying the most effective way to provide the functional connectivity minimizing the negative impact on focal species

Factors influencing the success of hand-reared juvenile brushtail possums (Trichosurus vulpecula) released into the wild

Context: Wildlife is ubiquitous in urban environments, resulting in frequent interactions with humans and human infrastructure. The result of these interactions is often negative, in the form of road injury, orphaning of dependent young or eviction from natural home ranges. Wildlife rehabilitation programmes are devised to counter these negative interactions. However, the success of current management strategies is rarely assessed. Aims: We aimed to determine whether short-term survival of juvenile hand-reared common brushtail possums (Trichosurus vulpecula) released in the wild was a function of (1) intrinsic factors such as sex, individual personality and level of human habituation, and (2) extrinsic factors such as release practice (soft vs hard-release) or location (urban vs rural). We also evaluated the relationship between habituation to humans and time spent in care by possums, if presence of conspecifics during the rehabilitation process influenced the development of individual personality, and if this differed in hand-raised animals compared with wild individuals. Methods: We radio-tracked and monitored 20 hand-reared juvenile possums (10 females and 10 males) for up to 40 days after release in the wild. Key results: Eight possums (40%) survived until the end of the study, nine possums (45%) were killed by foxes or had to be returned into care and three possums (15%) had unknown fates (i.e. lost VHF signal). We found that more exploratory individuals and those less human-habituated were more likely to be successful in the wild in both rural and urban areas, whether or not they were hard or soft released. Conclusions: Our results suggest that personality is a key criterion to consider when evaluating the success of rehabilitation programmes. Behavioural traits of hand-reared brushtail possums differed significantly from those of wild individuals, showing that captive conditions can affect the development of personality. Hand-reared possums that spent more time in care were also more likely to display highly human-habituated behaviours. Implications: By demonstrating which factors influence success of hand-reared wildlife after release in the wild, our results help in evaluating current rearing and release practices, and improve the evidence base for developing best practice wildlife rehabilitation guidelines

Needing a drink: Rainfall and temperature drive the use of free water by a threatened arboreal folivore.

Arboreal folivores are particularly vulnerable to the impacts of extreme climate change-driven heatwaves and droughts as they rely on leaf moisture to maintain hydration. During these increasingly frequent and intense weather events, leaf water content may not be enough to meet their moisture requirements, potentially leading to large-scale mortality due to dehydration. Water supplementation could be critical for the conservation of these animals. We tested artificial water stations for a threatened arboreal folivore, the koala (Phascolarctos cinereus), as a potential mitigation measure during hot and dry weather in New South Wales, Australia. We provided ground and tree drinkers to koalas and investigated changes in use with season, environmental conditions and foliar moisture. Our study provides first evidence of the regular use of free water by koalas. Koalas used supplemented water extensively throughout the year, even during cooler months. Time spent drinking varied with season and depended on days since last rain and temperature. The more days without rain, the more time koalas spent drinking. When temperature was high, visits to water stations were more frequent, indicating that in hot weather koalas need regular access to free water. Our results suggest that future changes in rainfall regimes and temperature in Australia have the potential to critically affect koala populations. Our conclusions can be applied to many other arboreal folivorous mammals worldwide which rely on leaves for their nutritional and water requirements. Artificial water stations may facilitate the resilience of vulnerable arboreal folivores during heat and drought events and may help mitigate the effects of climate change

A Practical guide to avoid giving up on giving-up densities

The giving-up density (GUD) framework provides a powerful experimental approach with a strong theoretical underpinning to quantify foraging outcomes in heterogeneous landscapes. Since its inception, the GUD approach has been applied successfully to a vast range of foraging species and foraging scenarios. However, its application is not simple, as anyone who has tried to use it for the first time might attest. Limitations of the technique were noted at its conception, yet only the artificiality of the patches, the appropriateness of the food resource, and the possibility of multiple visiting foragers were identified. Here we show the current uses of GUD and outline the practical benefits as well as the often overlooked limitations of the technique. We define seven major points that need to be addressed when applying this methodology: (1) the curvilinearity between harvest rate and energy, (2) the energetic state of the forager, (3) the effect of group foraging, (4) food quality and substrate properties, (5) the predictability of the patch, (6) behavioral traits of the forager, and (7) nontarget species. We also suggest how GUD experiments can be enhanced by incorporating complementary methods (such as cameras) to better understand the foraging processes involved in the GUD itself. We conclude that the benefits of using GUD outweigh the costs, but that its limitations should not be ignored. Incorporating new methods when using GUD can potentially offer novel and important insights into the study of foraging behavior.13 page(s

Efficacy of a synthetic peptide Chlamydia pecorum major outer membrane protein vaccine in a wild koala (Phascolarctos cinereus) population

Abstract Chlamydiosis is a significant disease affecting Eastern Australian koala (Phascolarctos cinereus) populations, impacting individual animal welfare and fecundity and therefore influencing population dynamics. The aim of this study was to investigate the effect of a synthetic peptide vaccine based on 4 components of the Chlamydia pecorum major outer membrane protein (MOMP), over an 18-month period in a koala population severely impacted by chlamydiosis. Wild koalas were recruited into a vaccination or a placebo treatment group on a random allocation, then followed through a period of 18 months, with recapture at 6 monthly intervals. Vaccination did not alter clinical disease expression or chlamydial shedding from the ocular or urogenital sites. Vaccination did not stimulate a significant plasma anti-MOMP IgG response, when compared to the placebo group. There was no significant effect of vaccination on IFN-γ and IL-17A mRNA expression of peripheral blood lymphocytes when stimulated with rMOMP. We have demonstrated that a synthetic peptide vaccination against chlamydiosis is not an effective management tool in a koala population with a high prevalence of C. pecorum infection and related disease. The lack of antigenic response found in this study suggests that further research utilising a larger, full-length antigen is an avenue worth investigation if we are to consider vaccination as a part of a management strategy in diseased koala populations