Koala Phascolarctos Cinereus Research Articles

Immediate impacts of fire on koala movement in a fragmented landscape

Hazard reduction burns could pose a significant conservation challenge to threatened habitat specialists, such as koalas Phascolarctos cinereus. This study examines the immediate effects of a medium to hot hazard reduction burn on a small number of koalas occupying a fragmented agricultural area. Three koalas being monitored using GPS telemetry were inadvertently exposed to fire in a small strip of roadside vegetation in an agricultural landscape, providing an unexpected opportunity to assess their immediate responses to the fire. Nearly 81% of available trees were burnt to some degree, with 31% of tree foliage scorched up to 10.2m above the ground. The koalas reduced their home range sizes by 20–54% post-fire, where two avoided burnt areas while one remained within them. These findings highlight the importance of maintaining unburnt patches and corridors in fragmented landscapes and developing comprehensive conservation plans to mitigate the adverse effects of fire on koalas and other arboreal fauna.

Broad-scale acoustic monitoring of koala populations suggests metapopulation stability, but varying bellow rate, in the face of major disturbances and climate extremes.

Population trends are lacking for most threatened species, especially those that are cryptic and difficult to survey. Recent developments in passive acoustics and semi-automated call recognition provide a cost-effective option to systematically monitor populations of vocal species. We assessed recent trends for the koala Phascolarctos cinereus, an iconic marsupial, based on 7 years of acoustic monitoring across 224 forested sites. The study period overlapped with a severe drought and extensive megafires in 2019 followed by 2 years of extremely high rainfall. Dynamic occupancy modelling with a range of covariates at multiple landscape scales found that initial occupancy was related to elevation (-ve), NDVI (+ve) and previous selective harvesting (16-30-year age class; weakly +ve). Extinction probability increased with the extent of high-severity fire. Colonisation probability was related to a range of factors, with the top model showing a decrease with increasing lagged annual rainfall. However, the null model was also supported, suggesting weak associations for colonisation. Using these relationships, koala occupancy was found to be high and stable over the study period. Fire did not influence regional trends because koalas often persisted with low- to moderate-severity fire and because high-severity fire was limited to 11% of their habitat. In contrast, bellow rate varied across years, being initially low and declining immediately after the 2019 fires, with the driver of these changes unclear. Neither timber harvesting nor low-severity fire influenced koala occupancy or bellow rate. Given the extensive area of koala habitat in the region, our results point to the presence of a large population in these public forests, and in recent years, stable occupancy (albeit with site-scale reductions in density with high-severity fire). Ongoing monitoring is crucial for tracking future changes, especially with predictions of more frequent, severe forest fires due to climate change.

GPS tracking reveals koalas Phascolarctos cinereus use mosaics of different forest ages after environmentally regulated timber harvesting

AbstractAn accurate picture of an animal's home range is fundamental for quantifying habitat quality and response to disturbance. When combined with remote sensing of vegetation attributes, there is potential to assess habitat selection at high resolution. We used a high‐quality GPS‐collaring data set (> 12 500 fixes) from 10 koalas Phascolarctos cinereus and a canopy height model derived from LiDAR in multiple‐use forests harvested for timber 5–10 years previously. Our aim was to assess how individual koalas use the forest mosaic created by timber harvesting by quantifying home ranges and habitat selection of different forest age/height classes created by past harvesting. We found that koalas maintained a stable home range over the average of 7 months of tracking. On average, there was 95% overlap for individuals among seasons, illustrating high site fidelity in the regenerating forest. Also, there were no apparent shifts during the intense drought of spring 2019. Male home ranges (64 ha) were three times the size of females (21 ha). Core areas were considerably smaller, ranging from 15 (male) to 6 ha (female). Three forest age/height classes were defined from LiDAR: (i) harvest – regeneration <14 m, (ii) harvest – retained trees ≥14 m and (iii) harvest – exclusion trees ≥14 m (zones excluded from harvesting for environmental protection). Home ranges covered the mosaic of forest classes and mixed models revealed no selection of forest class based on use versus availability. High site fidelity with no clear selection for forest age/height class (i.e. harvested and non‐harvested patches) confirms that resource quality in the home range remained sufficient for breeding koalas in the post‐harvest landscape. Ongoing monitoring of koalas is required to ensure that environmental protections are effective in maintaining koala populations in the face of additional disturbances from fire and climate change.

Trends in the rescue and fate of koalas in New South Wales (1973-2020), with a focus on disease and trauma

ABSTRACT In line with the objectives of both the 2022 National Recovery Plan for the Koala Phascolarctos cinereus and 2022 NSW Koala Strategy, our study aimed to draw on the long-term records of koala rescue in NSW from 1973 to 2020 to describe trends in admissions across NSW. A total of 18,039 koala admission records were collated from 1973 to 2020. Koalas were rescued due to disease, motor vehicle collision, dog attacks, unsuitable environment, bushfire, orphaning, and other reasons. However, the reasons for rescue were not evenly distributed among the rehabilitation groups. Across all rehabilitation groups and all years (1973-2020), the release rate of all admitted koalas was 47.6%. The NSW Koala Strategy identifies an action of “supporting koala rehabilitators” (Pillar 3 Improving the safety and health of koalas), and strong partnerships, including with koala rehabilitators, are “critical to achieving success”. Our study has confirmed that strong partnerships are possible and identified the prevalence of disease and trauma in rescued koalas. While it is not possible to assess the scale of the threats from disease and trauma to koala populations from rehabilitation records alone, we can use the trends in admissions to inform the efficient distribution of resources to rescue and rehabilitation efforts.

Performance of habitat offsets for species conservation in dynamic human‐modified landscapes

Abstract Biodiversity offsets are a popular policy tool for mitigating the impact of development on biodiversity, but the ecological success of offsets arise from complex interactions among socio‐economic, ecological and policy processes, making outcomes challenging to assess. Many offset policies use habitat surrogates to determine offset requirements, rather than using direct measures of impacted biota, and this can lead to poor outcomes for species. One potential solution to this is for offsets to be delivered by a public agency (agency‐led) rather than by developers (developer‐led). This is because agencies may be able to strategically choose offset sites that maximise outcomes for species (e.g. abundance), while there may be little reason for developers to act strategically in this way when offset requirements are based purely on habitat surrogates. Yet, the success of a strategic agency‐led approach is likely to depend on patterns of development and offset site availability. To examine this, we developed a novel integrated spatially explicit model of land‐use change, habitat, species abundance and offset regulation. We apply the model to the Queensland Government's Environmental Offsets Policy for koalas Phascolarctos cinereus in South East Queensland, Australia, and test how patterns of development and offset site availability influence the performance of agency‐led versus developer‐led offsets. When potential offset sites were plentiful, agency‐led offsets tended to outperform developer‐led offset delivery for maximising koala abundance while achieving similar or better outcomes for habitat area. Yet, when potential offset sites were rare, the relative performance of agency‐led offset was often poor, and offset requirements for habitat area were less likely to be met. Different spatial patterns of development had little effect on the relative performance of agency‐led versus developer‐led offsets. Our analysis shows that agency‐led offsets with strategic choices of offset sites can improve species' outcomes for habitat‐based offsets but can also risk failing to meet habitat area requirements when the availability of offset sites is low. Importantly, our integrated spatial model provides a holistic approach to assessing policy options for biodiversity offsets in dynamic human‐modified landscapes. Read the free Plain Language Summary for this article on the Journal blog.

Comparative Study of Brain Size Ontogeny: Marsupials and Placental Mammals.

Simple SummaryThis study examined brain/body ontogenetic growth in marsupials and compared it with placental mammals. While marsupials display morphology and cerebral organization diverse from placentals, their neocortical arrangement and cellular composition is unclear. Unfortunately, knowledge of marsupial ontogenetic brain/body size allometry is limited. Since marsupial brain structure and volume differ when compared with those of placentals, marsupials are considered to possess simple behavioural patterns. This is misleading, since even at a basic observation, Australian marsupials display many of the same mental capacities as other mammals. Consequently, the study findings support further investigation into the intellectual abilities of marsupials.There exists a negative allometry between vertebrate brain size and body size. It has been well studied among placental mammals but less is known regarding marsupials. Consequently, this study explores brain/body ontogenetic growth in marsupials and compares it with placental mammals. Pouch young samples of 43 koalas (Phascolarctos cinereus), 28 possums (Trichosurus vulpecula), and 36 tammar wallabies (Macropus eugenii) preserved in a solution of 10% buffered formalin, as well as fresh juveniles and adults of 43 koalas and 40 possums, were studied. Their brain size/body size allometry was compared to that among humans, rhesus monkeys, dogs, cats, rats, guinea pigs, rabbits, wild pigs, and mice. Two patterns of allometric curves were found: a logarithmic one (marsupials, rabbits, wild pigs, and guinea pigs) and a logistic one (the rest of mammals).

Chlamydiosis and Cystic Dilatation of the Ovarian Bursa in Female Koalas (Phascolarctos cinereus): Novel Insights into the Pathogenesis and Mechanisms of Formation

Chlamydiosis and Cystic Dilatation of the Ovarian Bursa in Female Koalas (Phascolarctos cinereus): Novel Insights into the Pathogenesis and Mechanisms of Formation

Predicting the optimal amount of time to spend learning before designating protected habitat for threatened species

Abstract Deciding when to protect threatened species habitat when complete knowledge about the habitat extent is uncertain is a common problem in conservation. More accurate habitat mapping improves conservation outcomes once that habitat is protected. However, delaying protection to improve accuracy can lead to species decline or, at worst, local extinction when threats to that habitat continue unabated before protection is implemented. Hence, there is a trade‐off between gaining knowledge and taking conservation action. We quantified this trade‐off and determined the optimal time to spend learning about a species' habitat before protecting that habitat. We used a range of hypothetical learning curves to model improvements in the accuracy of predicted habitat over time, and receiver operating characteristic (ROC) curves to model the corresponding increase in the proportion of habitat protected. We used rates of habitat loss to model the impact of delaying habitat protection and derived analytical solutions to the problem for different types of learning curves. We illustrate our approach using two threatened species, the koala Phascolarctos cinereus in Australia and northern abalone Haliotis kamtschatkana in Canada. Our approach confirms that when impacts of threatening processes are incurred rapidly, the need for timely protection is high, and the optimal time to spend learning is short for all learning curves. When the rate of habitat loss is low, we benefit from better habitat identification, and the optimal time to protect is sensitive to assumptions about how we learn and the proportion of non‐habitat we are willing to protect unnecessarily. Navigating the trade‐off between information gain and timely action is a common problem in conservation. By optimizing the trade‐off between the benefits of improving mapping accuracy and the costs of delaying protection, we provide guidelines on the effective allocation of resources between habitat identification and habitat protection. Importantly, by explicitly modelling this trade‐off with a range of learning curves and estimates of the rates of habitat loss or other threatening processes, we can predict the optimal time to spend learning even when relatively little is known about a species and its habitat.

TESTIS ABNORMALITIES IN A POPULATION OF SOUTH AUSTRALIAN KOALAS (PHASCOLARCTOS CINEREUS).

Testis asymmetry, in which the testes in an individual differ in size, has recently been reported in koalas (Phascolarctos cinereus) in the Mount Lofty Ranges population of South Australia. We describe the morphology and histology of both testes from affected individuals in this population (n=56) and the parameters of koalas with normal-sized testes based on age and breeding season (n=56). Morphologic measurements included testis weight, length, width, and volume; histologic parameters included seminiferous tubule diameter, seminiferous epithelial height, and seminiferous tubule (interstitial tissue ratio and presence or absence of spermatozoa). Of the 56 koalas with intraindividual variation in testes size, 47 were classified as asymmetric and nine as microtestes. For koalas with asymmetric testes, all morphologic parameters were significantly decreased in the smaller testes compared with normal-sized testes, but for the histologic parameters, only seminiferous tubule diameter was significantly less. Histopathologic examination of the asymmetric testes showed 38 with normal parenchyma histologically indistinguishable between intraindividual testes, four with degeneration and atrophy, and three with hypoplasia, whereas examination of microtestes showed degeneration and atrophy in seven, hypoplasia in one, and aplasia in one. No association of testis size difference with Chlamydia pecorum infection was found in a subset of animals. For the 56 koalas with normal-sized testes, morphologic parameters were found to increase with age, and juvenile and young adults were found to have smaller seminiferous tubule diameters than adults. No differences were found between testes of koalas in the breeding and nonbreeding season. Overall, these findings indicate that testis asymmetry in koalas from the Mount Lofty Ranges population is common but not associated with decreased function, except where testis malformations such as hypoplasia or aplasia occur or when parenchyma has been disrupted by acquired disease.

WildWID: An open‐source active RFID system for wildlife research

Abstract Radio‐frequency identification (RFID) tags represent some of the smallest animal‐borne technologies available. They are frequently used for understanding fine‐scale associations between animals and their environments. However, currently available devices are often prohibitively expensive or difficult to customise. We present ‘WildWID’, an open‐source radio‐frequency identification system that can be used for detecting encounters between tags and loggers and/or integrated into more advanced experimental set‐ups for triggering audio or visual playbacks following the detection of RFID tag codes. WildWID systems can be made using commercially available components (costing ~$20 USD for tags and ~$60 for loggers) and can be customised to fit project and species‐specific needs. WildWID tags have been deployed on a range of species including koalas Phascolarctos cinereus, lions Panthera leo and shy albatross Thalassarche cauta for a range of research topics, including the assessment of road‐crossing structures and species' responses to intraspecific competitors. WildWID is a cost‐effective RFID system that can increase the accessibility of this technology for a wider range of researchers and study questions. Its use provides researchers with opportunities to mitigate ethical concerns, for example, by customising systems for species‐specific conditions, and its customisability extends the range of applications where RFID systems can be used by field biologists.

Retroviral integrations contribute to elevated host cancer rates during germline invasion

Repeated retroviral infections of vertebrate germlines have made endogenous retroviruses ubiquitous features of mammalian genomes. However, millions of years of evolution obscure many of the immediate repercussions of retroviral endogenisation on host health. Here we examine retroviral endogenisation during its earliest stages in the koala (Phascolarctos cinereus), a species undergoing germline invasion by koala retrovirus (KoRV) and affected by high cancer prevalence. We characterise KoRV integration sites (IS) in tumour and healthy tissues from 10 koalas, detecting 1002 unique IS, with hotspots of integration occurring in the vicinity of known cancer genes. We find that tumours accumulate novel IS, with proximate genes over-represented for cancer associations. We detect dysregulation of genes containing IS and identify a highly-expressed transduced oncogene. Our data provide insights into the tremendous mutational load suffered by the host during active retroviral germline invasion, a process repeatedly experienced and overcome during the evolution of vertebrate lineages.

Pulmonary Actinomycosis in South Australian Koalas (Phascolarctos cinereus).

Pneumonia has been reported in both free-ranging and captive koalas and a number of causative agents have been described. Between 2016 and 2019, 16 free-ranging and 1 captive koala (Phascolarctos cinereus) from the Mount Lofty Ranges of South Australia were identified with pyogranulomatous lobar pneumonia, which involved the left caudal lobe in 14/17 (82%) cases. Within lesions, numerous gram-positive or gram-variable, non-acid-fast filamentous bacteria were observed in association with Splendore-Hoeppli phenomenon. Culture yielded growth of anaerobic bacteria, which were unidentifiable by MALDI-TOF-MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) analysis in 5/5 cases. Sequencing of the bacterial 16S rRNA gene identified a novel Actinomyces species in 4 samples, confirming a diagnosis of pulmonary actinomycosis. Concurrent examination of resin lung casts from healthy koalas suggested greater laminar flow of air to the left caudal lung lobe in koalas. Actinomyces spp. have been reported as commensals of the oral microbiome in other species, and an association with similar pulmonary lesions in other species. Considering the predilection for involvement of the left caudal lung lobe, aspiration is suggested as the likely cause in some cases of pulmonary actinomycosis in koalas. Pulmonary actinomycosis has not been previously described in koalas and further work needs to be undertaken in order to classify this organism within the Actinomyces genus.

Are physiological and behavioural responses to stressors displayed concordantly by wild urban rodents?

Understanding wild animal responses to stressors underpins effective wildlife management. In order for responses to stressors to be correctly interpreted, it is critical that measurements are taken on wild animals using minimally invasive techniques. Studies investigating wild animal responses to stressors often measure either a single physiological or behavioural variable, but whether such responses are comparable and concordant remains uncertain. We investigated this question in a pilot study that measured responses of wild-caught urban brown and black rats (Rattus norvegicus, Rattus rattus) to fur-based olfactory cues from a predator, the domestic cat (Felis catus); a novel herbivore, the koala (Phascolarctos cinereus); and a familiar herbivore and competitor, the common brushtail possum (Trichosurus vulpecula). Physiological responses, measured by assaying faecal glucocorticoid metabolites, were compared to behavioural responses observed via video recordings. We found that physiological and behavioural responses to stressors were expressed concordantly. There was no sizeable physiological response observed, and the behavioural response when considered across the night was negligible. However, the behavioural response to the predator and competitor cues changed across the observation period, with activity increasing with increasing hours of exposure. Our results indicate that responses of wild rodents to cues are nuanced, with stress responses modulated by behaviour changes that vary over time according to the severity of the perceived threat as animals gather further information. If the physiological response alone had been assessed, this moderated response may not have been evident, and in terms of wildlife management, vital information would have been lost.

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

AbstractHabitat 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.

A proposed roadmap for the control of infections in wildlife using Chlamydia vaccine development in koalas Phascolarctos cinereus as a template

Vaccination strategies provide a crucial tool for managements of disease risks in wildlife, but have been utilized mostly for domestic species. However, a significant body of work has now been published describing the successful development of an anti-chlamydial vaccine for the koala Phascolarctos cinereus, Goldfuss, 1817. As such, vaccinations against these infections in the koala, can provide important insights into the use of vaccines for wildlife. Chlamydia infections in the koala have been intensively studied for over 30 years. Infections cause severe disease states, such as kerato-conjunctivitis (blindness) and reproductive tract disease (infertility), and/or mortality; and are contributing significantly to population declines. We aim to use the plethora of data available from koala chlamydial studies as a template to propose a roadmap for the development of vaccines for other wildlife species, especially in this era of antibiotic resistance. As such we have outlined the important steps that have led to significant milestones resulting in the successful development of a vaccine against an infectious disease in a non-domestic species. We hope to thus provide, not only a timely review on Chlamydia vaccines in koalas, but also an important conservation and management roadmap to help guide future researchers that are considering the development of a vaccine for a wild species.

CHANGES IN ANTIOXIDANT CAPACITY OF KOALAS (PHASCOLARCTOS CINEREUS) BASED ON HEALTH STATUS AND MEASUREMENT OF THE ANTIOXIDANT ASCORBATE IN EUCALYPT LEAVES.

Antioxidants have a crucial role in protecting the body from oxidative stress, which would otherwise result in cellular damage and possibly predispose animals to disease. The antioxidant capacity of koalas (Phascolarctos cinereus) and its association with health or disease status is currently unknown. Ascorbate, a dietary antioxidant, has previously been identified in a few eucalypt species eaten by koalas. This study aimed to determine 1) differences between the antioxidant capacity of healthy and diseased koalas, and 2) concentration of the antioxidant ascorbate in Eucalyptus spp. leaves eaten by koalas. To determine differences in antioxidant capacity of koalas, plasma samples from clinically healthy koalas in Kangaroo Island, South Australia (SA) (n = 23), euthanized koalas with oxalate nephrosis from Mount Lofty Ranges, SA (n = 11), and euthanized koalas with chlamydiosis from Moggill, Queensland (n = 11) were analyzed for the three antioxidants α-tocopherol, ascorbate, and retinol and for two measures of antioxidant capacity, ferric reducing ability of plasma (FRAP), and trolox equivalent antioxidant capacity (TEAC). The thiobarbituric acid reactive substance (TBARS) measured formation of oxidants, and an oxidative stress index (OSI) was calculated by TBARS/(TEAC + FRAP). Ascorbate concentration was measured in dietary eucalypt leaves from Mount Lofty Ranges and Moggill. Results showed that in diseased Mount Lofty Ranges and Moggill koalas, plasma α-tocopherol concentrations were significantly lower, and ascorbate, TBARS, and OSI was significantly higher compared with clinically healthy koalas from Kangaroo Island. Ascorbate was high in eucalypt leaves, particularly young leaves from the Mount Lofty Ranges. This study showed that disease was associated with some measures of poor antioxidant capacity in koalas and also found that ascorbate is high in the dietary eucalypts of koalas.

Sniffing out solutions to enhance conservation: How detection dogs can maximise research and management outcomes, through the example of koalas

In conservation, consistent and extensive under-funding has necessitated creative thinking to address conservation issues on a low budget, and innovations are burgeoning as a result. One example is the use of dogs that, thanks to their heightened olfactory abilities and bond with humans, are trained to detect odours of interest to conservationists. Conservation dogs have proven to repeatedly outperform alternative survey methods in terms of accuracy, efficiency and/or cost. They have now been used for the detection of endangered and invasive species, fauna and flora, direct and indirect (e.g. scat) targets, on land and at sea, across every continent and most taxa from fire ants to whales. Here, we emphasise the versatility of detection dogs through their multiple uses applied to one species, the koala Phascolarctos cinereus . We selected, trained, tested and deployed five dogs; two for koala habitat (koala scats), one for genetic sampling (fresh scats only), one for the koala itself and one for koala disease ( Chlamydia spp. ) detection. Dogs enabled both large-scale and fine-scale survey design, with 2370 surveys performed, and 1479 genetic samples collected to date. Detection dogs are subject to similar (although sometimes much lower) limitations in terms of survey biases (e.g. individual or environmental conditions) and, importantly, detection dog/handler teams need to be tested regularly for accuracy. Nonetheless, detection dogs can, and are, helping researchers and land managers to collect more robust datasets and better inform conservation decisions. Alliances with unexpected partners in conservation (such as with police forces), citizen science, and timeshare use of dogs might improve the democratisation of their use and enable conservation detection dogs to fulfil their astonishing potential.

Attitudes towards wildlife conservation

People's attitudes towards the conservation of Australian wildlife is of particular importance as the types of attitudes people hold can have a significant impact on conservation solutions. We investigated attitudes held towards Australian wildlife and conservation solutions. A sample of 312 residents participated in an online questionnaire. An ‘ecoscientistic’ attitude was the most commonly held attitude, highlighting that wildlife are appreciated for the role they play within our ecosystem. There was a significant association between age and attitude towards Koala Phascolarctos cinereus and Crownof-thorns starfish Acanthaster planci conservation and a significant association between socio-economic status and attitude towards Brush-turkey Alectura lathami conservation. Most participants agreed that action should be taken towards wildlife conservation in the future. Conservation managers and other key stakeholders need to capitalise on this information to increase public support for Australian wildlife, and encourage conservation action. Significant associations between attitude and some sociodemographic characteristics were observed, however more research between attitude and sociodemographic associations is recommended, including in other regions of Australia and internationally.

Using Passive Acoustic Recording and Automated Call Identification to Survey Koalas in the Southern Forests of New South Wales

Cost-effective surveys of low density koala populations are challenging, but technological developments in the acoustics field offer great potential for landscape-scale surveys and monitoring. We assessed passive acoustic recording coupled with automated call identification as a survey method for koalas Phascolarctos cinereus . Surveys targeted areas of previously known koala activity based on scat surveys in southern forests of New South Wales where a low density of koalas is suspected. We set 24 Song Meters to record at night over a two week period (~3,696 hours) in the koala breeding season (October/November) in Murrah Flora Reserve. Recordings were scanned by a koala call recogniser and “matches” were manually verified. Across the 24 sites, 522 validated koala bellows were recorded at 21 sites (87.5 % detection rate). Three environmental variables had most influence on detection probability of koalas, including nightly rainfall (-ve), nightly temperature (-ve) and topographic position (lower on ridges). Calling activity peaked at midnight. Sustained site occupancy, at least in the short-term, was apparent as under optimal conditions (no rain) koalas were recorded, on average, for > 50 % of survey nights rather than for just a few nights. We suggest that only a modest survey effort (4–5 nights) in the breeding season, on nights with < 3 mm of rain, is required to achieve 90–95 % probability of koala call detection in an area of low koala density. Comparison with scat surveys at the same sites revealed that detection rates were more than three times greater with acoustic surveys. Technological advances will continue to provide improvements for wildlife survey, and perhaps most importantly, for collecting much needed long-term data to assess trends in occupancy or other population attributes over time.

No Evidence of Toxoplasma Gondii Exposure in South Australian Koalas (Phascolarctos cinereus)

Infection with the cat-borne parasite Toxoplasma gondii has been detected in numerous Australian marsupials and can lead to severe disease (toxoplasmosis) in some cases. The seroprevalence of Toxoplasma on Kangaroo Island, South Australia has been reported to be higher than the South Australian mainland in macropods, cats, and sheep, suggesting an increased risk of infection on this island. However, Toxoplasma seroprevalence in small- and medium-sized terrestrial mammals was almost zero on the island and did not differ from that on the mainland. We surveyed Toxoplasma seroprevalence in koala (Phascolarctos cinereus) populations on the island and on the mainland and assessed their risk of infection and their role in the life cycle of Toxoplasma. All screened koalas from the island (n = 94) and the mainland (n = 63) were seronegative. This represents the largest Toxoplasma seroprevalence survey in this species and provided sufficient evidence to confidently demonstrate freedom from parasite exposure in both island and mainland populations at the time of the survey. Because koalas are extensively arboreal and predominately consume tree foliage, they appear to be at negligible risk of Toxoplasma infection. Furthermore, as koalas are rarely consumed by cats, we suggest that they have a minor role in the parasite's life cycle.