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Context. The ecology of cryptic animals is difficult to study without invasive tagging approaches or labour-intensive field surveys. Acoustic localisation provides an effective way to locate vocalising animals using acoustic recorders. Combining this with land cover classification gives new insight into wild animal behaviour using non-invasive tools.
Aims. This study aims to demonstrate how acoustic localisation – combined with high-resolution land cover classification – permits the study of the ecology of vocalising animals in the wild. We illustrate this technique by investigating the effect of land cover and distances to anthropogenic features on coyote and wolf vocal behaviour.
Methods. We collected recordings over 13 days in Wisconsin, USA, and triangulated vocalising animals’ locations using acoustic localisation. We then mapped these locations onto land cover using a high-resolution land cover map we produced for the area.
Key results. Neither coyotes nor wolves vocalised more in one habitat type over another. Coyotes vocalised significantly closer to all human features than expected by chance, whereas wolves vocalised significantly further away. When vocalising closer to human features, coyotes selected forests but wolves showed no habitat preference.
Conclusions. This novel combination of two sophisticated, autonomous sensing-driven tools permits us to examine animal land use and behavioural ecology using passive sensors, with the aim of drawing ecologically important conclusions.
Implications. We envisage that this method can be used at larger scales to aid monitoring of vocally active animals across landscapes. Firstly, it permits us to characterise habitat use while vocalising, which is an essential behaviour for many species. Furthermore, if combined with additional knowledge of how a species’ habitat selection while vocalising relates to its general habitat use, this method could permit the derivation of future conclusions on prevailing landscape use. In summary, this study demonstrates the potential of integrating acoustic localisation with land cover classification in ecological research.
Context. Interaction between predators and humans is a key driver of human–wildlife conflicts, and can underpin management of predator populations. Management of the impacts of dingoes on livestock and native species is a prime example of a persistent and contentious predator management issue with potential impacts on the integrity of dingo populations. To manage the potential impacts of dingoes and their control, it is imperative to understand the effects of control approaches on their populations in the short and long term. Hybridisation of dingoes with domestic dogs also threatens the genetic integrity of pure dingoes. It has been hypothesised that lethal control of dingoes can facilitate hybridisation through disrupting pack social structures leading to increased dingo–domestic dog interactions.
Aims. We aimed to to investigate how dingo population structure and genetic purity have changed, assessing dingo purity, individual relatedness, population clustering and gene flow, particularly across land use types and barrier fences, in the context of ongoing lethal control within the Murchison Regional Vermin Cell area in Western Australia (WA).
Methods. We tested dingo genetic samples from three distinct sampling periods (2009, 2014 and 2020) for changes in population summary statistics and dingo ancestry. Barriers and corridors to gene flow were also examined.
Key results. We identified three genetically distinct populations in the study area, consistent with previous genetic studies in WA. We did not find any evidence of change in dingo purity or population characteristics; however, barrier fencing may be influencing recent gene flow.
Conclusions. The metapopulation of dingoes in the southern rangelands of WA appears to be stable over the 11 years assessed.
Implications. Because we were unable to demonstrate that lethal control has accelerated hybridisation between dingoes and domestic dogs in the study area over the last 11 years, we have no evidence that lethal control to reduce losses to livestock production and for conservation of native wildlife in the southern rangelands of WA is putting dingo purity at risk. Fencing appears to be an effective management tool because there is some evidence it is congruent with reduced gene flow in areas where the fences are well maintained.
Context. Good body condition in juvenile marine mammals is crucial for survival and, therefore, population demography. Australian fur seals, endemic to Australia, recently established a breeding colony at the southern edge of their range, at The Needles, a small group of islands in south-west Tasmania (43.6614°S) and a significant distance from their core breeding range in Bass Strait.
Aims. We aimed to compare pup body condition at two breeding colonies, distinct in time since establishment and latitude. Specific aims were to: (1) establish the timing of peak pupping, to compare condition of known-age pups, and determine a baseline at The Needles; (2) investigate pup body condition over time at an established colony; and (3) gain insight into the effects of environmental conditions on pup body condition.
Methods. We conducted a colony comparison of pup body condition using condition indices at The Needles and an established breeding colony in Bass Strait, Tenth Island, for the 2019/20 and 2020/21 breeding seasons. Pup body condition was quantified at Tenth Island over 18 years (2003–2020) using a long-term morphometric dataset. To establish breeding phenology at these two colonies, we determined peak pupping date for the 2019/20 breeding season using daily pup counts. We assessed the effect of environmental parameters on body condition for the long-term dataset.
Key results. Pups from The Needles displayed significantly higher body condition than those from Tenth Island, despite similar peak pupping date. Breeding phenology was consistent with published timing for Australian fur seals. Pup body condition at Tenth Island over the 2-year colony comparison was comparable to the historical average. Environmental drivers that affect maternal foraging efficiency are linked to pup body condition.
Conclusions. Higher pup body condition at The Needles is likely underpinned by better foraging conditions resulting in increased pup provisioning levels. Our results indicate that south-west Tasmania is a region of foraging and emerging breeding importance for Australian fur seals.
Implications. Future research to monitor pup body condition, maternal foraging behaviour and ecosystem productivity at The Needles will help to provide greater understanding of likely population trajectories at this southernmost breeding site for Australian fur seals.
Context. Manned aerial surveys are an expensive endeavour, which is one of the core reasons for insufficient data coverage on wildlife monitoring in many regions. Unmanned aerial vehicles (UAVs) can be a valid, cost-efficient alternative, but the application of UAVs also comes with challenges.
Aims. In this explorative simulation study, our aim was to develop an efficient layout of UAV surveys that could potentially overcome challenges related to double counts of individuals and even area coverage, and that would minimise off-effort travel costs.
Methods. Based on different simulated survey layouts we developed hypothetically for the Katavi National Park in Tanzania, we quantified the advantages that UAVs might offer. We then compared these findings with manned aerial surveys.
Key results. The proposed new survey design and layout indicated an increase in survey efficiency of up to 21% when compared with conventional survey designs using parallel transect lines. Despite the complex flight pattern, the accuracy of the flight paths of the UAV outcompeted those of manned aerial surveys. The adapted survey layout enabled a team of two operators with a small battery-powered UAV to cover an area of up to 1000 km2 per day, without specific infrastructural requirements.
Conclusion Our calculations may serve as a vital spark for innovation for future UAV survey designs that may have to deal with large areas and complex topographies while reducing operational effort.
Implications. UAV applications, if well designed, provide useful complementation, if not replacement, for manned aerial surveys and other remotely sensed data collections. Our suggested survey design is transferable to other study regions, and may be useful for applying UAVs efficiently.
Context. The conservation of the Endangered African wild dog (Lycaon pictus) poses a major challenge to conservationists because outside the boundaries of protected areas, wild dogs are prone to conflict with farmers. Mitigation measures appropriate for game farmers are scarce, leaving them with limited options to reduce wild dog impact. As a result, targeted persecution is a common occurrence. However, wild dogs are subject to intraguild competition with dominant competitors, often resulting in their suppression and spatial displacement. Therefore, olfactory cues of lion presence may trigger an adverse reaction in wild dogs, and could be a means to manage wild dog movements across the landscape to prevent conflict with farmers.
Aims. We aimed to evaluate whether wild dogs can be deterred by simulating lion presence.
Methods. By using translocated scent cues in the form of lion scat deployed along the perimeter of plots, lion presence was simulated on game farms where lions were absent. The rate and duration of incursions by wild dogs, collared with GPS trackers, into control and treatment plots (‘group’) were evaluated.
Key results. Wild dog incursion rate dropped by 55.5%, and duration of incursion events dropped by 72.7%, after lion scat was deposited. Control and treatment plots were equally affected with no significant effect of the grouping on wild dog movement. The magnitude of the treatment effect differed between packs.
Conclusion. The significant decline of wild dog movement after implementation of treatment suggests a deterrence effect. The insignificant effect of group on wild dog movement indicates large-scale avoidance triggered by a change in the wild dogs’ risk perception across the landscape following treatment. The fact that the magnitude of the treatment effect differed between packs indicates that the response to predator cues is likely to be context-dependent.
Implications. The findings present a novel approach to managing free-roaming wild dogs by utilising biologically relevant cues, which may benefit wild dog conservation. There is a need for further research to develop the emerging field of scent studies to provide non-lethal solutions and progress towards evidence-based large carnivore management practices.
Context. Carrion is a high-energy and nutrient-rich resource that attracts a diverse group of vertebrate scavengers. However, despite the carrion pool being highly seasonal in its availability, there is little understanding of how scavengers utilise carcasses across all four seasons.
Aims. To assess how season influences carcass-detection times by vertebrate scavengers and their rates of scavenging.
Methods. We used remote cameras to monitor vertebrate scavenging at 15 eastern grey kangaroo (Macropus giganteus) carcasses in four consecutive seasons (summer, autumn, winter, and spring; total 58 carcasses) in the Australian Alps.
Key results. In total, 745 599 remote-camera images were captured, within which 34 vertebrate species were identified, nine of which were recorded to actively scavenge. Time to first detection of carcasses by vertebrate scavengers was 5.3 and 9.6 times longer during summer (average 144 h) than during spring (average 34 h) and winter (average 24 h) respectively. Rates of vertebrate scavenging were highest in winter and spring, with brushtail possums (Trichosurus vulpecula) accounting for 78% of all scavenging events during winter, and ravens (Corvus spp.) accounting for 73% during spring. High rates of carcass use by these mesoscavengers may reflect a scarcity of other food sources, the demands of their breeding season, or a relative absence of scavenging by larger dominant species such as dingoes (Canis dingo) and wedge-tailed eagles (Aquila audax).
Conclusions. These findings demonstrate the highly seasonal nature of vertebrate scavenging dynamics in an alpine ecosystem, and that mesoscavengers, not apex scavengers, can dominate the use of carcasses.
Implications. Accounting for the effects of season is integral to understanding the way animals utilise carcasses in alpine and other strongly seasonal environments; and for developing further our knowledge of ecosystem processes linked to decomposition.
Context. Animals can be taught new behaviours to mitigate threatening processes. However, it is yet to be confirmed if such teaching can be deployed in the field. Here we test this possibility using the invasion of cane toads because they are highly toxic novel prey items to many predators across northern Australia.
Aims. Research has shown that training predators to avoid toads, using conditioned taste aversion (CTA), significantly improves the survival rates of individuals. We sought to determine if deployment of CTA baits, in situ, could reduce cane toad impacts on a mammalian predator, the northern quoll (Dasyurus hallucatus).
Methods. The work was conducted in the Kimberley, Western Australia, where we treated three quoll populations with training baits from November 2015–November 2017, and kept four populations as controls. We used camera traps and Bayesian hierarchal modelling to estimate the population size of quolls on up to four occasions before, and two occasions after, cane toad arrival.
Key results. We observed a 65% reduction in quoll population size at control sites and a 94% reduction at treatment sites: a significant effect of aversion training, but in the direction opposite to that expected.
Conclusions. Two complexities – decay of aversion, and individual variation – together, may explain our result. Our trials indicate that most animals are no longer averse within 120 days post-training. Earlier studies indicating that aversion training lasts longer may have inadvertently observed innate (i.e. genetically based) aversion to cane toads. Another possibility is that our dose rate of thiabendazole within the CTA baits was, in fact, too low; or the result may be an artefact of the non-random assignment of treatment and control groups. Ultimately, there is no way of determining exactly why our outcome occurred without further laboratory/captive trails. Regardless, our study demonstrates a failure of CTA training to mitigate the impact of cane toads on northern quolls in this system.
Implications. Our result calls into question the value of this approach for conserving quoll populations, at least in its current form. More generally, our results point to the often-unexpected complexities encountered as ideas progress from captive trials to field deployment.
Context. The introduction of the cat (Felis catus) to Australia has been a key driver of the decline and extinction of the continent’s endemic mammals. Currently, there is no clear long-term solution to controlling feral populations of cats at a landscape scale. As such, understanding how environmental conditions and habitat attributes can mediate the coexistence between introduced predators and native mammals can improve management outcomes for threatened species.
Aims. We sought to compare the differences in habitat use by feral cats and a remnant population of the endangered northern quoll (Dasyurus hallucatus) to understand what environmental variables allow these two mesopredators to coexist in tropical savanna of Cape York Peninsula, Queensland.
Methods. We deployed grids of motion-activated cameras three times per year over a 3-year period, across Eucalyptus tetrodonta-dominated plateaux known to be inhabited by feral cats and northern quolls. We modelled the spatial variation in the frequencies of detection of feral cats and northern quolls (referred to as ‘habitat use’), as a function of biotic and abiotic environmental variables by using a generalised linear model for consistent variables and a generalised linear mixed-effect model for fluctuating variables.
Key results. Habitat use by feral cats was most frequent in areas with high fire frequencies and low tree basal area, whereas habitat use by northern quolls was most frequent in areas of high basal area of E. tetrodonta (a commonly used den tree species), topographic ruggedness, and long-unburnt savanna.
Conclusions. Frequent fires in tropical savanna promote habitat use by feral cats and can result in a reduction of critical habitat for northern quolls.
Implications. We postulate that remnant populations of northern quolls on Cape York Peninsula occur in less frequently burnt refugia, primarily on top of plateaux that support high-biomass tropical savanna dominated by E. tetrodonta. Our findings highlighted that threatened mammals can persist alongside introduced predators in tropical savanna but are dependent on the maintenance of structurally complex habitat.
Context. The assessment of suitable habitat for a species is often evaluated based merely on where the species is most abundant. However, a variety of environmental factors such as temperature, resources and human disturbances might force animals to avoid otherwise high-quality habitats. Additionally, individuals’ capacities to cope with such factors – as reflected in physiological stress responses – may also contribute to avoidance. Combining measures of stress response of individual animals with habitat suitability models may contribute essential insights to the development of species conservation plans.
Aims. We used a landscape-level approach to assess whether habitat quality, abiotic factors and human disturbance affect the physiological stress response of a forest specialist, the capercaillie (Tetrao urogallus), and to what extent these relationships are determined by variation between individuals.
Methods. We applied a non-invasive approach by collecting 1096 droppings across the entire species range in two adjacent national parks spanning the border between the Czech Republic and Germany. We measured faecal corticosterone metabolites (FCMs) to evaluate the physiological stress response. To test the influences of temperature, habitat quality, season and sex, as well as forest management and tourism intensity on FCM levels, we used generalised additive mixed effect models (GAMMs). The same models were applied for a reduced subset of randomly selected samples that were attributed to individuals via DNA profiling using 10 microsatellite loci. This approach allowed us to control for possible individual differences (through repeated measures within individual genotypes).
Key results. Both models revealed decreasing FCM levels with increasing habitat quality and showed no relationship between increasing forestry intensity and FCMs. When accounting for individual identity, we found a significant positive effect from increasing tourism intensity, although this relationship was not significant in the full dataset.
Conclusions. Our results highlight three conclusions for the conservation of capercaillie: (1) high-quality habitats reduce stress levels; (2) tourism-free refuge areas are important, and (3) individuality appears to be a strong determinant of response to environmental factors.
Implications. Generalising management recommendations from observations for single individuals to an entire population may be inappropriate.
Context. Understanding habitat suitability for feral animals across a landscape is important for conservation planning because the spatial and temporal availability of water provides critical limits to native biodiversity and the processes that threaten it. Previous attempts to support management actions on feral pig populations through predictions of population abundance, distribution and seasonal resource constraints have been confounded by a lack of knowledge, classification and mapping of waterholes – which are critical to their survival.
Aims. In this paper, we aimed to apply a waterhole classification scheme for feral pig management to address gaps in our understanding of water and food availability through space and time, at scales relevant to feral animal movement and resource use.
Methods. We utilise an attribute-based waterhole classification scheme for ecosystem-based management by defining a waterhole typology of feral pig habitat suitability and applying it spatially.
Key results. Five attributes (water permanence, predictability of inundation, oceanic influence, dominant vegetation and shading) reflect many of the critical requirements for feral pig habitat in northern Australia. The attributes directly relate to the environmental constraints that exert population and behavioural pressure on feral pigs. These attributes were applied spatially in a specific hierarchy to group waterholes into 21 types.
Conclusions. A waterhole typology that characterises within the context of their suitability for feral pig populations is foundational for systematic adaptive management and monitoring programs that aim to reduce the impact of threatening processes on freshwater ecosystems.
Implications. Refining the mapping of important feral pig habitat variables (water and food) will greatly improve modelling approaches that aim to support data-driven management approaches, such as connectivity analysis and estimating population dynamics to inform culling programs. Here we demonstrate a significant increase in overlap with known feral pig distributions using a much smaller mapped effective management area when compared with previous best available spatial products.
KEYWORDS: climate change, conservation, dispersal, eco-geographical variables, Ensemble of Small Model (ESM), reptile, Species Distribution Model (SDM), varanidae
Context. Human-induced changes in climate and land cover have altered the distribution of fauna around the globe. Some reptiles have been found to be vulnerable to these changes; therefore, studies to identify the impact of the changes on other groups of reptiles are necessary.
Aims. We aimed to study the impact of climate and land cover change on the yellow monitor (Varanus flavescens) in Nepal. We also aimed to identify the current distribution range and predict the potential distribution under multiple climate change, corresponding land cover change, and dispersion scenarios in the near- and mid-future.
Methods. We used available presence locations with a candidate set of the least-correlated environmental variables and an Ensemble of Small Models (ESM), a Species Distribution Model (SDM) approach suitable for species with small sample size. Additionally, dispersal scenarios of 1 km, 5 km, and 10 km were added to the model to determine the future distribution under the dispersal scenarios.
Key results. We found soil particle size, distance to forest, precipitation of wettest quarter, bulk density, and elevation were the five most important variables contributing to the distribution of the species. The Terai lowland and wide valleys in Outer Himalayas are currently suitable but are expected to experience a substantial decrease under most future climate projections and dispersal scenarios.
Conclusions. The distribution is mostly dependent on soil-related variables; however, climatic variables might have a greater impact on future suitability.
Implications. Limiting emissions contributing to climatic changes, conserving the soil outside the protected areas, and the potential areas where the species will not experience habitat loss might contribute to the conservation of the species.
KEYWORDS: damage, eradication, home range ecology, invasive mammalian herbivore, Macropodidae, movement behaviour, Notamacropus rufogriseus, pest Management, red-necked wallaby, resource selection, South Canterbury, sustained control
Context. Bennett’s wallaby (Notamacropus rufogriseus) was introduced into New Zealand in the late-1800s, and has subsequently become a significant pest to agriculture, silviculture, and native vegetation. Effective management of wallabies requires robust spatial and temporal ecological information, which can be used operationally to increase detection and kill rates.
Aims. To determine home range size and shape, resource (i.e. habitat and topography) selection, and daily movement patterns of three populations of Bennett’s wallaby in the South Island.
Methods. We attached GPS-collars to 38 adult wallabies (17 females, 21 males) between May 2018 and May 2019, and obtained usable location data from 30 individuals. We used kernel density estimators and resource selection functions to quantify seasonal home ranges and resource selection, respectively.
Key results. The mean seasonal home range sizes of males and females were similar (26.8 ha and 24.8 ha, respectively; combined range = 1.2–101.9 ha), although the largest home ranges belonged to large males. Resource selection was strongly influenced by distance to concealment cover, ridgelines and streams, i.e. wallabies selected to be closer to these features, though not necessarily at them. Wallabies selected areas close to concealment cover throughout 24-h periods, but most strongly during the day, which is when they bed in dense cover. Wallabies sampled outside of peak breeding moved most during dusk and dawn (median = ~50 m/h), whereas those sampled during peak breeding moved widely during day, dusk, and night (110–280 m/h), but not dawn (median = ~50 m/h).
Conclusions. The home range sizes of wallabies in New Zealand were highly variable, but on average were similar for males and females. Wallabies selected pasture close to areas with some cover, suggesting a trade-off between access to high-quality forage and concealment cover.
Implications. Our results provide robust data for modelling management strategies for wallabies, and contribute directly to operational planning by identifying habitats where wallabies are most likely to be found temporally. This information can be used to determine the appropriate survey methods and control tools to maximise detection rates and kill rates of wallabies, based on habitat.
Context. Wild pigs (Sus scrofa) are a non-native invasive species that causes millions of dollars in damage each year to agriculture in the United States of America, destroys native plant communities, and competes with native wildlife for seasonally available pulse resources such as acorns. Despite many anecdotal observations and diet studies suggesting wild pigs reduce acorn availability for other wildlife species, no studies have comparatively examined acorn consumption among species in a natural environment (i.e. competition).
Aims. Our objective was to estimate the consumption of acorns by wild pigs relative to that of other native wildlife species.
Methods We established 40 monitoring stations beneath acorn-producing trees in a 3406-ha study area in eastern Alabama with an approximate density of 9 pigs/km2. At each monitoring station, we placed five acorns on a 1-m × 1-m sand pad and positioned a game camera to record acorn fate during 2-week intervals once a month from September to February 2018–2019 and 2019–2020. Cameras were set to capture images once every minute continuously during the survey period. Additionally, we constructed acorn traps from 18.9-L plastic buckets to estimate the timing and relative amounts of acorns that were potentially available for consumption at each monitoring station.
Key results From approximately 7.3 million camera images, we observed 15 wildlife species consuming 707 acorns over the 2 years. Aside from animal consumption, acorn fate was categorised as lost due to flooding (n = 153), remaining on the sand pad at time of camera failure (n = 720), or not consumed during the sampling period (n = 536).
Key conclusions Top acorn consumers were squirrel (Sciurus spp.), white-tailed deer (Odocoileus virginianus), raccoon (Procyon lotor), and wild pig. In the 2018–2019 sampling period, wild pigs consumption accounted for 23.4% (n = 87) of the total consumed acorns. After wild pig removal efforts were initiated in the summer and autumn of 2019, wild pigs consumed only 7.2% (n = 24) of consumed acorns.
Implications Wild pigs consume a significant number of acorns and likely reduce the availability of this pulse resource for other native wildlife species and may potentially influence oak regeneration.
Context. River regulation, coupled with climate change, has caused significant declines in global freshwater biodiversity. In Australia, water extraction within the Murray–Darling Basin (MDB) has reduced the frequency, extent and duration with which floodplains are inundated, resulting in widespread declines in wetland-dependent biodiversity, including reptiles. The endangered Ngabi (Hemiaspis damelii) is associated with floodplain systems in the MDB, yet its distribution and ecological requirements are poorly understood, hampering conservation actions.
Aims. We sought to validate an assumption that Ngabi is associated with wetland vegetation communities before investigating factors affecting its probability of detection in the lower Murrumbidgee catchment in southern New South Wales. We predicted Ngabi occurrence patterns would relate to frog abundance, wetland hydrology, microhabitat attributes and meteorological variables.
Methods. We compared Ngabi observations from 16 paired wetland and dryland vegetation transects to evaluate associations with vegetation type. We then used generalised linear mixed models to relate snake presence and absence to prey (frog abundance), microhabitat (logs and ground cover), wetland hydrology (water depth and inundation frequency) and meteorological conditions, using 12 repeat surveys between September 2018 and March 2021.
Key results. Fifty-eight snakes were observed at five of eight wetlands during the study. Ngabi was exclusively recorded in river red gum/spike rush or lignum vegetation communities, and was absent from sandhill woodland or chenopod communities. The probability of detecting Ngabi increased with ambient temperature and weakly with wetland inundation frequency, but not frog abundance, microhabitat attributes or year.
Conclusions. Ngabi is strongly associated with floodplain vegetation communities and, to some extent, frequently inundated wetlands in southern NSW, suggesting water management agencies should incorporate threatened floodplain snake species into future wetland management plans. The use of environmental water to restore aspects of flow regimes, improve wetland health and aquatic diversity is likely to benefit other wetland-dependent snake populations across the MDB.
Implications. The positive relationship between Ngabi detections and ambient temperature will be important for designing an effective monitoring program for the species across the MDB. Furthermore, our findings provide insight into the benefits of using environmental water to create wetland refuges to maintain floodplain snake populations during droughts.
Context. Wildlife rescue and rehabilitation centres aid millions of species worldwide. The clinical databases from these wildlife rehabilitation centres are increasingly being recognised as valuable scientific resources that have the potential to yield information on animal biology and inform conservation efforts. Although orphaned koala joeys constitute a substantial proportion of wildlife rescues in Australia, the causes of morbidity and mortality, specifically in rescued young koalas, remain largely unexplored.
Aims. The primary aim of this study is to analyse the trends in causes and outcomes of koala joeys admitted for rehabilitation at the Adelaide Koala Wildlife Centre (AKWC).
Methods. We analysed the hospital records of koala joeys admitted to the AKWC over an 8-year period (2014–2021) to identify the major causes of morbidity and mortality, and analysed the trends in arrivals in terms of season, sex and release rate.
Key results. Our examination indicates that the top five major reasons for admission and mortality in koala joeys are as follows – renal disease, heat stress, chlamydiosis, animal attack and vehicle collision. A significant increase in the proportion of heat stress, renal disease and chlamydiosis cases can be observed over the study period. Of the major causes of mortality, the most distinctive feature is the exceptionally high mortality rate of koala joeys with renal disease. Over the study period, the overall positive outcome for all joeys increased up to two-fold, and the mortality rate also declined slightly.
Conclusion Despite the significant increase in positive outcome, it is evident that renal disease, chlamydiosis and heat stress are increasing at a rapid rate. Renal disease poses a major threat to rehabilitating koala joeys due to its severely high mortality rate.
Implication This is the first study identifying the key drivers of morbidity and mortality of rescued koala joeys, and the rapid increase of renal disease, chlamydiosis and heat stress warrant the attention of future conservation policy developers. Furthermore, the severely high mortality rate of koala joeys due to renal disease warrants improving treatment protocols and any measures that can help reduce the mortality rate of this disease in koala joeys.
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