Semi-aquatic freshwater mammals are a heterogeneous global group that are subject to a range of anthropogenic disturbances, with many species now being recognised as threatened and some viewed as indicators of freshwater ecosystem health. The platypus (Ornithorhynchus anatinus) is one such species where concern has been raised about declining populations. Population monitoring is required, but the most effective way to do this is yet to be determined. We used data from 20 years of mark–recapture in two pools in the Upper Shoalhaven River, New South Wales, to demonstrate an approach to describe population trajectory over time. Modelling of capture data for adult females, juvenile females and males showed that only the adult female data produced reliable estimates of annual abundance, which ranged from 5.9 (95%CI, 5.1–11) to 17.7 (15.7–26.0) individuals. Population growth estimated from these values suggests that the population increased over the 20-year period, which encompassed a severe drought. In adult females the probability of initial capture was 0.61 (95%CI 0.45–0.75), but that of recapture was 0.35 (95%CI 0.23–0.48), suggesting a negative response to initial capture. Males showed no difference, with the probability being estimated at 0.19 (95%CI 0.08–0.41) per occasion. Our study employed two capture sessions per year, which could be increased, here and elsewhere, to improve the precision of parameter estimates. Given that platypuses are long-lived, annual capture surveys are not required to index a population. This study provides an example of how a platypus population can be monitored to guide future conservation efforts.
Arid Australia is home to a diverse array of marsupial predators (Dasyuridae) that play important ecological roles. We studied the population dynamics, demography, burrow use, movements, diet, and seasonal and diel activity of the brush-tailed mulgara Dasycercus blythi (hereafter ‘mulgara’) in central Western Australia, representing a south-western part of its range. Working at two properties (Matuwa and Jundee), we collected data at 20 survey sites in spinifex grasslands through pitfall trapping, radio-tracking, camera trapping and scat collection. Mulgara population density at Matuwa was 0.08 to 0.40 individuals ha−1 per session and abundance was approximately twice as high at Matuwa compared to Jundee, most likely due to long-term feral cat control. Capture rates overall were higher in autumn compared to spring, particularly for males, which had lower survival probabilities than females. Activity of mulgaras on camera traps was highest in summer and autumn and lowest in winter and spring. Mulgaras showed seasonal differences in nightly activity, with activity in the coldest months peaking just after sunset and then declining, whereas activity in the warmer months was more consistent throughout the night. The mean distance between denning burrows on consecutive days was 105 m, with males moving further and more frequently than females. Mulgara diets were dominated by invertebrates, particularly ants/termites, with vertebrates being uncommon, possibly due to multiple years of below average rainfall. Our study provides new insights into the ecology of the brush-tailed mulgara, while also adding further depth to existing knowledge of mulgara population dynamics, behaviour and diet.
Extant ‘tree-rats’ in the genera Mesembriomys and Conilurus are declining in the Australian wet–dry tropics. Paucity of information on their life histories makes it challenging to assess some population parameters and long-term threats. This study of a laboratory colony of up to 117 brush-tailed rabbit-rats (Conilurus penicillatus) was conducted during 1982–1986. Data were obtained using vaginal smears, changes in external vaginal appearance, matings and birth of young. Males matured at about 18–20 weeks. Vaginal opening occurred at 11 weeks (6–19 weeks) with oestrus up to 2 days later. Mean oestrous cycle length was 10.7 days (range 7–21), with oestrus lasting 1–2 days. Non-lactational gestation length was 35–38 days (x̄ = 35.8, n = 11) and that associated with lactation was longer (x̄ = 43.0 days, 39–48). Postpartum oestrus occurred within 1 day of parturition and if this did not result in conception, oestrus resumed about 50 days later. Mean litter size was 2.5 (range 1–4). Births in the laboratory occurred throughout the year, with a reduction in pregnancies during January/February. The reproductive characteristics of C. penicillatus are similar to those of other species in the phylogenetic ‘Conilurus division’ (Conilurus, Leporillus, Mesembriomys).
The northern quoll (Dasyurus hallucatus) is an endangered dasyurid found in four genetically disjunct populations from Western Australia (WA) to Queensland. Fauna surveys conducted in WA recorded new localities for the northern quoll, one in the Gascoyne region and two in Gulali (Collier Range) National Park, equating to a southerly range extension of 140 km. These are the first northern quoll records for Gulali National Park and the most southerly records of the species for WA. This population may serve as an important residual population based on regulatory guidance and requires further surveys to determine the full extent of its distribution.
Recent catastrophic climate events in Australia that have affected millions of animals across a range of landscapes have initiated a need for planned and coordinated rescue responses. The platypus (Ornithorhynchus anatinus) is one of Australia’s most iconic and biologically significant species. At a workshop held at Healesville Sanctuary, Victoria, Australia, in 2023, species experts discussed the greatest threats, scenarios where intervention may be required and the types of intervention option that may be suitable for platypuses. We consider drought to be the most concerning event for the species, along with the impact of cumulative events on their habitat over time. Here, we discuss how intervention criteria should consider the degree of habitat impact, the recovery time frame, the genetic importance and local extinction risk of a population, risks to animal welfare, and the capacity requirements and feasibility of resourcing any action. Suitable interventions are weighed against potential risks and include the rescue and rehabilitation of displaced individuals, in situ habitat support, and translocation to either temporary ex situ care or inter or intra catchment. Further research is required to address how the platypus responds during and after different climate events, and to different interventions, and to determine which populations are most at risk. The outcomes discussed here and the framework provided should aid in management response decision-making after natural disasters that may impact platypus populations.
The control of invasive predators such as the red fox (Vulpes vulpes) and feral cat (Felis catus) is a key conservation strategy used to protect native wildlife in Australia. In the Northern Jarrah Forest of south-western Australia, predator control has been implemented for decades through broadscale aerial and ground baiting with sodium fluoroacetate (1080). However, its effectiveness is likely to vary regionally and temporally, and requires ongoing evaluation. We assessed predator presence in relation to baiting using paired camera traps at 180 sites surveyed over two consecutive spring seasons. Foxes were detected at 18.3% of sites, with 88% of detections occurring outside baited areas. Detection probability increased strongly with distance from baited zones; foxes were more than twice as likely to be detected 1 km outside baited areas than 1 km inside, and >25 times more likely 5 km outside than 5 km inside. Feral cats were detected at only 10 sites, precluding further analysis. These results indicate that broadscale baiting likely remains effective in suppressing fox presence in the Northern Jarrah Forest, with a clear spatial gradient extending beyond baited boundaries. However, additional survey effort is required to determine its effectiveness for feral cats.
Much of the southern hairy-nosed wombat (SHNW; Lasiorhinus latifrons) population has been functionally isolated from its only major predator, the dingo (Canis familiaris), for over 80 years. In the absence of predators, prey species can lose the ability to recognise or respond appropriately to predation risk, which may be detrimental if re-exposed. This study investigated whether SHNWs show different behavioural responses to predator scent cues in dingo-exposed versus dingo-absent areas of their distribution. Camera traps were deployed at SHNW burrows in both locations and assigned one of the following three olfactory treatments: dingo faeces (predator), rabbit faeces (neutral), or no scent (control). An ethogram of SHNW behaviours was established, with behaviours divided into active, inactive, vigilant, investigation, scent investigation and grooming. A beta regression model was applied to analyse the proportion of time spent in various behaviours, while logistic and gamma models assessed the likelihood and duration of scent cue investigation. Our results showed similar response patterns between both study locations, where SHNWs were more likely to investigate dingo scent than rabbit scent. However, dingo-exposed SHNWs were significantly more likely to investigate scent in general, suggesting they may be more attentive to environmental change and potential threat cues than were dingo-absent SHNWs. Although not a direct anti-predator response, investigation of novel scent cues is the essential first stage of threat assessment to determine whether a behavioural response is necessary. This research offers foundational insight into experience-based predator responses in SHNWs, thereby improving our understanding of prey naivety.
A small, dark form of Chalinolobus gouldii (Gould's wattled bat) has been recognised in the 'Top End' of the Northern Territory (i.e. north of similar to 18 degrees S), Australia, for some time, but its taxonomic identity has remained uncertain. Re-examination of museum specimens showed several individuals differing from both C. gouldii and C. nigrogriseus (hoary wattled bat) in external morphology and dentition, notably by the combined presence of an enlarged pendent skin lobe at the base of the ear and an incipient secondary cusp on the upper first incisor, which are diagnostic traits of Chalinolobus orarius (coastal wattled bat), a species recently described from Papua New Guinea. Comparative analyses of cranial measurements and external features show close agreement between Northern Territory specimens and the type series of C. orarius, supporting their identification as C. orarius. All confirmed Northern Territory records occur within 5 km of the coast, below 100 m elevation, in mangrove and adjacent Eucalyptus open forest habitats. Current data suggest that the species is uncommon and possibly rare in northern Australia. The recognition of C. orarius in northern Australia represents an addition to the Australian bat fauna and highlights the need for targeted surveys across northern Australia to determine the species' distribution, abundance, taxonomic status and conservation status. It also necessitates revised species identifications for all Chalinolobus specimens from northern Australia held in museum collections worldwide.
The 2019-2020 wildfires in south-eastern Australia were the most extensive and severe of any recorded since European settlement, and the impacts of these fires on biodiversity are expected to be devastating. By using walked spotlighting transects, we investigated the impact of these fires on two forest-dependent species, the greater glider and yellow-bellied glider, across a range of sites in both north-eastern and south-eastern New South Wales (NSW), where one or both species were known to be present before the fires. In 2020-2021, in north-eastern NSW, greater gliders were observed at 57 (76%) of the 75 sites where they had been recorded previously, and at an additional three sites where they had not been recorded. Yellow-bellied gliders were observed at 11 (23%) of the 48 sites where they had been recorded previously. In 2021, in south-eastern NSW, greater gliders were still present at all nine long-term sites, but in greatly reduced numbers on the burnt sites. The yellow-bellied glider was also reduced in abundance on the burnt sites. We found no significant relationship between glider presence for both species and fire severity in the local landscape in both regions; however, greater glider counts were reduced on most severely burnt sites. Other factors, including elevation and logging history (indicators of habitat quality), appeared to condition fire effects. The decline in populations of both species at low-moderate elevations, regardless of fire severity, is of concern and requires further investigation. Climate change and the associated impacts of prolonged droughts, extended heatwaves, and more frequent wildfires could largely be responsible for some of these changes in glider occupancy.
The northern hairy-nosed wombat (Lasiorhinus krefftii, NHNW) is critically endangered following major range and population declines during the 20th century, resulting in a population bottleneck of similar to 30 individuals in the 1980s. Understanding the population history, impact of extirpations, range contraction and the bottleneck in this species is critical to contextualising ongoing efforts to understand and manage surviving genetic diversity. We generated mtDNA genomes from contemporary and historical samples of the NHNW from the extant and two extirpated populations and compared mtDNA diversity and phylogeography to the closely related southern hairy-nosed wombat (L. latifrons, SHNW) from southern Australia. The NHNW had very low mtDNA diversity, with shallow phylogeographic structure across its former range. A single mtDNA haplotype has been present in the extant population since at least 1937, suggesting a small long-term female effective population size and a possible pre-1937 bottleneck. In contrast SHNWs show four to five times higher mtDNA diversity and evidence of phylogeographic divergence across the Pleistocene Eyrean Barrier. Our results highlighted the need for further genomic analyses of the extant NHNW population, to estimate the extent of inbreeding and inbreeding depression and to help minimise loss of functional genetic diversity in this species.
Habitat loss and fragmentation pose significant challenges to wildlife, particularly in agricultural landscapes where natural habitats are heavily modified. This study investigated the shelter selection and activity patterns of short-beaked echidnas (Tachyglossus aculeatus) across a fragmented agricultural environment. Using GPS and VHF telemetry, we found that echidnas sheltered predominantly in woody habitats, using both natural and anthropogenic structures, but rarely sheltered in open paddocks despite foraging there. Shelter reuse was common and inversely related to core home-range size, suggesting deliberate reuse of known, high-quality sites. Echidnas rarely sheltered in open habitats, which prompted an experiment where we placed artificial shelters in open habitats to test whether echidnas would select novel artificial shelters if available. Echidnas demonstrated a clear preference for artificial shelters compared with the control group, suggesting that shelter availability drives echidna habitat selection. Activity patterns followed a consistent diel cycle, peaking approximately 8 pm and at moderate temperatures (similar to 20 degrees C), with a stronger link to time of day than to thermal cues. These findings reaffirmed the importance of preserving shelter-rich, woody habitats and suggests that targeted conservation measures, such as artificial shelters, could mitigate the ecological impacts of fragmentation and support biodiversity in human modified landscapes where the availability of shelter sites is limiting.
Canid pest ejectors (CPEs) are a mechanical device that avoids bait displacement and non-target issues encountered with traditional baiting, while delivering a poison dose. A range of lure heads can be interchanged to increase the attractiveness to the target species. Canid pest ejectors have not been widely trialled in Western Australia for fox control. Here, we examined the use of CPEs for fox control (non-toxic trial) in a non-target species rich conservation reserve in Western Australian's wheatbelt. Over 12 months, 10 CPEs were monitored using two camera traps per CPE. Five CPE lure head varieties were trialled to increase the attractiveness of the CPEs to foxes. Foxes fired CPEs on 10 occasions over the study, preferring sheep fat, fish oil and vanilla essence lure head over horse hoof and honey essence. Non-targets did not fire a CPE, only biting the lure heads on 14 occasions. Canid pest ejectors are a useful fox management tool in areas where baits are not appropriate or lures are required to entice wary foxes.
Fat-tailed dunnarts are a model species in marsupial research that have been used since the 1960s, but little is known about their endocrinology. Glucocorticoids modulate several vital physiological functions, helping animals adapt to their environment. Understanding glucocorticoid biology can provide insights into a species' fitness. Non-invasive hormone monitoring via faecal samples is a powerful tool that reduces or eliminates the need for capturing and handling animals but must be properly validated to ensure reliable results. This study aims to validate an enzyme immunoassay for monitoring faecal glucocorticoid metabolites (FGMs) in fat-tailed dunnarts. We compared the performance of four assays for monitoring adrenocortical activity in dunnarts following an open-field challenge. All four assays detected a significant increase in FGMs following the challenge, but the magnitude and consistency across individuals differed considerably. The cortisol enzyme immunoassay (AA-F) was selected as the best-performing assay to describe patterns of adrenocortical activity in the species. There was no significant difference in average FGM concentrations between males and females, although males showed a stronger response to the open-field test. Our study successfully validated an assay for the non-invasive measurement of FGMs in fat-tailed dunnarts, thereby helping understand their physiology and provide new insights for marsupial research.
Mycophagous species are significant ecosystem engineers. However, many of these species are difficult to survey, which limits scientific understanding of their ecology and impacts on ecosystems. This study aimed to determine a bait preference for opportunistic mycophagous mammals by comparing detection rates and duration of time spent in front of cameras at different baits. We used camera traps and four different bait types to attract mycophagous species in two sympatric habitat types in south-eastern Queensland. No specific species were targeted, but rather the study aimed to detect any mycophages that may be present in the ecosystem. In total, 399 mycophagous mammal detections from 11 species were recorded in the study. The detection rates using different baits varied among species, but overall, mycophagous mammals tended to spend longer in front of the camera trap, and be detected sooner, at cameras baited with the truffle oil bait. By determining which bait attracts the most mycophages, whether they be obligate or occasional consumers of fungi, ecologists can target survey efforts when investigating these fungi-vertebrate relationships.
Major roads are common within conservation reserves in Australia; however, few studies have described their impacts on wildlife. We investigated whether eight species of native mammals were influenced by a highway through a conservation reserve in north-east New South Wales. We conducted camera-trapping over a 17-month period at sites along the highway and at sites at varying distance (0.5-10 km) along service roads through adjoining forest. Evidence of a highway response on the basis of the probability of occupancy was strongest in the Vulnerable parma wallaby (Notamacropus parma), with occupancy increasing from 0.5 (0.26-0.66, 95%CI) at highway sites to 0.96 (0.74-1.0) at sites >3 km into the forest interior. For the Vulnerable long-nosed potoroo (Potorous tridactylus) and the swamp wallaby (Wallabia bicolor), the probability of detection increased by 10% from the highway to forest interior, but other factors (season or recent wildfire) induced greater variation in detection. The mountain brushtail possum (Trichosurus caninus) differed from all other species in showing higher detection near the highway (0.35, 0.30-0.41) than in the forest interior (0.18, 0.15-0.22). Enhanced habitat quality associated with the highway may explain this pattern. The Endangered spotted-tailed quoll (Dasyurus maculatus) was detected at 80% of sites, although too infrequently to adequately assess its response to the highway. Our study showed that an occupancy approach can be used to investigate responses of wildlife to roads. Further studies are needed to better understand if major roads through conservation reserves have an adverse influence of wildlife populations.
Accurate population estimates can show trends that are fundamental to detecting species' declines and to designing and assessing conservation strategies. We compared spotlighting, diurnal line transects and thermal drone flights for detecting koalas in a rural landscape and evaluated a time series of data at our site to test sampling error and understand the influence of survey type and temporal variability on population estimates. Historically, diurnal koala detections were biased towards searches with a southerly view, suggesting that aspect with relation to the sun was a source of sampling error. No method detected all koalas, with drone flights, diurnal surveys and spotlighting transects detecting, on average, 79%, 48% and 43% of koalas respectively across repeated surveys, but detection differences were not significant. Estimates of koala population density based on diurnal surveys had large confidence intervals. Combining techniques enhanced detection; a combination of drone and daytime surveys detected an average of 88% of koalas present. We conclude that, where possible, drone detection is currently the most effective way to detect koalas, and by combining methods, accuracy is improved.
We investigated whether the inland sugar glider (Petaurus notatus) showed a seasonal preference for chainsaw-carved tree hollows over nest boxes. We installed chainsaw hollows (CHs) and equivalent volume nest boxes (NBs) in pairs across eight sites in southern Australia. Twenty-one pairs of artificial hollows were surveyed on 17 occasions over a 3.4-year period. Dataloggers confirmed that in peak summer, temperatures were lower and fluctuated less within the CHs than within the NBs. Sugar gliders used both types of hollow, but detection in CHs was approximately twice as high as that in NBs. We found no evidence that CH use increased as ambient temperature increased or was higher in summer. Use of both types was greater in Year 3 than in Years 1 and 2. Although there are legitimate concerns around the fitness consequences of high and variable temperatures for mammals using nest boxes, our study does not support a discontinuation of nest box instalment. Habitat restoration for tree hollow-dependent wildlife is likely to be more effective if all options are available. Nest boxes have the advantage that they can be installed on small-diameter trees.
Tree hollow-dependent wildlife species are increasingly at risk of decline because of continuing depletion of their hollow resources and the long lag-time for their renewal. We investigated patterns of hollow use in the brush-tailed phascogale (Phascogale tapoatafa), a regionally threatened mammal in the south of its range. Twenty-five phascogales (13 males and 12 females) were radio-tracked for a duration (mean +/- s.e.) of 68.2 +/- 15.8 days. This produced 318 diurnal nest-site detections, encompassing 88 individual hollows and 23 nest boxes. Dead trees were used on 70.4% of occasions despite comprising 27.7% of trees. The mean distance between consecutive diurnal shelters was 157.9 +/- 65.9 m. Phascogales used up to eight nest sites (mean 3.2 per individual) but usually had one or two hollows which they used most frequently. Females used hollows with narrower entrances (mean: 6.3 +/- 0.6 cm) compared to males (8.3 +/- 0.6 cm). Internal measurements of accessible hollows showed that females selected hollows slightly larger, although not statistically different (24,846 +/- 8131 cm3) from those of males (19,447 +/- 5310.7 cm3). Our study has documented one of the highest frequencies of use of dead trees among studies on Australian marsupials and confirmed that this is a critical resource in forests where large trees are absent or uncommon. We observed a loss of 4.5% of these tree hollows over a 3-year period. Fire, storms and illegal firewood collection pose an ongoing threat to this vulnerable resource.
Population monitoring is fundamental to the conservation of threatened species such as the koala (Phascolarctos cinereus). This study extends by 2 years, a previous 8-year annual monitoring project of a koala population in north-east New South Wales. This study relied on audio-recorders and occupancy modelling to investigate whether the population has remained unaffected by the driest period on record followed by the wettest period on record. Audio-surveys were conducted at 42 sites over a 2-week period in each of 2022 and 2023. The probability of detection varied among types of audio-recorders, but averaged 0.45-0.88 per night, which equates to requiring 2-5 survey nights to have 95% confidence that koalas were detected. The probability of occupancy increased from 0.80 (95% CI, 0.66-0.94) in 2022 to 0.95 (95% CI, 0.89-1.0) in 2023. Local abundance of calling males detected by the more sensitive recorders increased from 1.6 +/- 0.2 in 2022 to 2.2 +/- 0.1 in 2023. The probability of occupancy when viewed across 10 years showed little change despite dramatic fluctuations in rainfall. This may reflect high local habitat suitability as well as occupancy being insensitive to variation in abundance because koalas are long-lived. Changes over time in the probability of detection may be more reflective of changes in abundance. This study highlights that the paucity of multi-year population studies on the koala means that our current understanding of koala population dynamics is inadequate for effective conservation.
The northern hairy-nosed wombat (NHW) (Lasiorhinus krefftii) is a critically endangered marsupial, reduced to a single population at Epping Forest National Park (EFNP) by the early 1920s. Two additional populations were established through translocations, including Richard Underwood Nature Refuge (RUNR) in 2009 and Powrunna State Forest in 2024. Because NHW are fossorial, soil suitability for burrow construction is critical for selecting future sites. However, little is known about how burrow architecture varies in different environments. This study assessed whether recent advancements in ground penetrating radar (GPR) technology, more sophisticated than those used in previous studies, could provide detailed, non-invasive mapping of NHW burrows and compare burrow depths among populations. Despite a limited sample size (n = 5), advanced GPR showed that burrows at RUNR were shallower in both maximum and mean depth than were those at EFNP. This variation is likely due to the loamier soils at RUNR, which offer greater structural integrity, thereby reducing the need for deeper excavation, as is required in the sandier soils of the EFNP. These findings inform both the selection of future translocation sites and the design of pre-dug starter burrows essential to NHW reintroductions.
