Wildlife translocations are gaining acceptance as a valuable conservation tool for threatened Australian fauna. The 2019–2020 bushfire crisis has significantly affected koala habitat across four states, and translocations, when properly implemented, could facilitate the demographic and genetic recovery of affected populations. Current translocation policies lack an appropriate spatial framework to guide conservation actions and this could lead to unexpected or undesirable outcomes with the potential to hinder population recovery. To address these concerns, we propose development of a spatial framework based on knowledge of population genetic structure and population-specific dispersal patterns estimated from molecular data. At an operational level, application of a spatial genetic framework obviates the need to specify restrictive translocation limits, reduces reliance on subjective interpretations of population structure, and provides the potential to improve translocation success and conservation outcomes. We strongly encourage implementation of a spatial genetic framework and its integration into the decision-making process for selection and prioritisation of release sites for translocated koalas by wildlife carers, researchers and wildlife managers. The proposed framework would also support koala conservation and management more broadly.

Context. Wild pigs (Sus scrofa) are a non-native, invasive species that can cause significant damage to agricultural crops, and native flora and fauna. In the United States, damage and control costs have been estimated at 1.5 billion USD. A combination of early sexual maturity, high fecundity, opportunistic eating and well established populations forces managers to control wild pig densities and resulting damages.

AimsThe present study aimed to examine the relationships among farmers’ positive and negative beliefs about wild pigs, their perceived risks associated with wild pigs and their acceptability of lethal management actions for controlling agricultural damage.

Methods. Data were obtained from a mail survey of Illinois farmers (n = 3035, response rate = 58%). Variables consisted of six belief statements (three negative, e.g. wild pigs are a source of disease, and three positive, e.g. ‘I enjoy seeing wild pigs around my property’), five perceived risk statements (e.g. wild pigs cause property damage) and four statements regarding the acceptability of lethal management actions for controlling the impact of wild pigs (e.g. shooting wild pigs from a helicopter).

Key results. The relationships between the negative and positive beliefs and the acceptability of lethal management were partially mediated by perceptions of risk (Hypothesis 1). Perceived risks associated with wild pigs were related to negative (Hypothesis 2) and positive (Hypothesis 3) beliefs about wild pigs, as well as acceptability of lethal management actions (Hypothesis 4) to control the impact of wild pigs. In addition, negative beliefs (Hypothesis 5) and positive beliefs (Hypothesis 6) were related to support for lethal control.

Conclusions. These relationships occurred despite the relatively low prevalence of wild pigs in Illinois and suggest that lethal actions are acceptable even though perceived risks are low.

Implications. Findings suggested that perceived risks associated with wild pigs were not substantially related to the attributes of the farm (e.g. farm ownership, crops grown, total acres farmed) or demographic characteristics (i.e. sex, age). Managers should focus on influencing the psychological indicators (e.g. negative and positive beliefs, perceived risks) to increase the acceptability of lethal management actions for mitigating the impacts of wild pigs.

Context. Exclusion fences are increasingly used to prevent interactions between predators (introduced and native) and assets such as endangered species or livestock. However, challenges remain in identifying when exclusion fences are an optimal investment and the intended outcome is likely to be achieved. The level of association with complementary methods of control that is needed is also unclear.

Aims. We aimed to quantify the interactions among factors that affect fencing efficiency, including the size of the fenced area, the fence permeability, the initial density of the predator population, and its survival of complementary control methods.

Methods. Using a spatially explicit, individual-based model, we simulated wild dog (dingo) populations as a proxy for describing predator dynamics inside a fenced area under different management practices and fence designs. We then fit a generalised linear model to the model outcomes to assess the effects of the four factors mentioned above.

Key results. Lethal control had a strong effect on wild dog density when the survival of control was lower than 0.5. Fences generally had an effect on wild dog density only when their permeability was lower than ∼1% and their effect was most noticeable when the initial density was very low (<2 dogs per 100 km²), or when survival of control was very low (<0.5). Conversely, when the initial density was very high (∼12 dogs per 100 km²), a fence with a low permeability (<1.5%) caused the paradoxical effect that wild dog density could be higher than that obtained with a more permeable fence. Wild dog eradication was possible only when survival of control was 0.25 or lower, except when either initial density or fence permeability were extremely low (<2 dogs per 100 km² and <0.1% respectively).

Conclusions. Our results demonstrated that large exclusion fences can be an effective aid in managing predator populations. We recommend that this tool should be used as a preventive measure before predators establish a population inside the area targeted for exclusion, in tandem with lethal control, or when an initial marked reduction of predator density can be achieved. We also demonstrated that eradication can be achieved only when a narrow combination of parameters is met.

Implications. Land managers should carefully evaluate when and at what scale control tools should be deployed to control wild dog populations. Landscape application of exclusion fences faces the challenge of high maintenance to ensure low permeability, coupled with very high sustained suppression of wild dog density, which are unlikely to be feasible options in the long term. Conversely, the same control techniques could provide efficient asset protection at a smaller scale where fence maintenance and sufficient control effort can be sustained.

Context. Populations of native mammals are declining at an alarming rate in many parts of tropical northern Australia. Fire regimes are considered a contributing factor, but this hypothesis is difficult to test because of the ubiquity of fire.

Aims. This preliminary study investigated relative abundance and richness of small mammals on a gradient of fire regimes in the Uunguu Indigenous Protected Area (north Kimberley, Australia).

Methods. Species were sampled using 40 unbaited camera traps, positioned for a year on 20 transects crossing the rainforest–savanna boundary at locations with comparable environment and geology but varying fire history. The relative importance of the factors ‘fire frequency’, ‘late dry season fire frequency’, ‘time since burnt’ and ‘vegetation type’ as predictors of the number of small mammal species and detections was tested using Spatial Generalised Linear Mixed Models to account for spatial autocorrelation.

Key results. Nine species of small mammals were observed. Mammals were more abundant and diverse in locations with low overall fire frequency, which was a better predictor than late dry season fire frequency or time since burnt. The model including fire frequency and vegetation explained the highest proportion of total variation in mammal diversity (R² = 42.0%), with most of this variation explained by fire frequency alone (R² = 40.5%). The best model for number of detections (R² = 20.9%) included both factors.

Conclusions. In the north Kimberley, small mammals are likely to be more abundant and diverse in areas with low fire frequency.

Implications. This natural experiment supports the theory that frequent fires are contributing to the decline of small mammals observed across northern Australia.

Context. The Asian water buffalo (Bubalus bubalis) is an introduced herbivore of the savannas and floodplains of northern Australia. Despite the significant environmental damage caused by water buffalo, important cultural and commercial stakeholders request this species is managed rather than eradicated. However, gaps in knowledge of buffalo ecology limit effective policy and planning.

Aims. To better understand how buffalo, at current population densities, respond to seasonally changing resources in the two key habitat types that they occupy in northern Australian – upland eucalypt savanna and seasonally inundated floodplain.

Methods. Satellite telemetry was used to record the location of a single female buffalo from each of 11 independent clans every hour over a 12-month period. Generalised linear mixed modelling was used to assess the extent to which buffalo movements, activity-space and site revisitation correlated with forage quality (inferred from the normalised difference vegetation index – NDVI) and localised buffalo density.

Key results. As the dry season progressed, forage quantity and quality within the activity-space of buffalo clans decreased. In response, buffalo inhabiting floodplain exhibited increased rates of movement and enlarged the size of their activity-space. This resulted in low repeated visitation of foraging areas in the late dry season and NDVI remained relatively high within these areas. In comparison, buffalo in upland savanna maintained similar rates of activity and occupied the same activity-space size throughout the year. This resulted in frequent revisitation of the same areas in the late dry season and NDVI reached as low as zero in these foraging areas. Clan size and localised buffalo density had no significant effect on measured movement parameters.

Conclusions. Buffalo exhibited a behavioural strategy in upland savanna that resulted in acute removal of green herbaceous vegetation within a few kilometres of the clan’s permanent water source. Buffalo inhabiting the floodplain used multiple wallows that reduced grazing impacts, but likely resulted in hoof-derived impacts over a broad area.

Implications. Current buffalo densities in Kakadu National Park appear to be well below carrying capacity but localised environmental degradation around permanent water sources remains severe in upland savanna.

Context. Ecologists need robust and effective methods to quantify the diet of animals. However, assessing dietary composition can be challenging because most animals are seldom observed eating, especially when studying rare or cryptic species.

Aims. Morphological analysis of scats has been extensively used previously, and recent advances in the accessibility of DNA barcoding techniques have also made molecular approaches a viable alternative for diet analysis from scats. We compared the results from two methods of scat analysis, to trial the use of contemporary approaches in scat analysis.

Methods. In the present study, we used morphological analysis and DNA barcoding of matter in scats to catalogue the diet of a generalist omnivore, the greater bilby (Macrotis lagotis Thylacomyidae), in the West Kimberley. The composition and diversity of diet items, as well as the taxonomic identification level, were compared between methods.

Key results. Each method provided complimentary results; morphological analysis uncovered the type of matter consumed (e.g. root, seed) and relative proportion of the total undigested content, whereas DNA barcoding could assign such matter to a taxon. Even though dietary DNA could be extracted from only 38% of scats, DNA barcoding identified a greater diversity of taxa in scats than did morphological analyses. Barcoding could detect the presence of highly-digestible items such as cossid moths (Cossidae) and spiders (Araneae).

Conclusions. Morphological analysis was useful for quantifying relative abundance of diet categories; however, DNA barcoding detected a greater diversity of dietary items within scats. Despite the expense of DNA barcoding, the method can more accurately identify the taxa consumed, whereas morphology can greatly underestimate dietary species diversity. However, the technical requirements for performing DNA analysis make it expensive, while resource-limited field ecologists can generally perform morphological analysis with appropriate training.

Implications. Researchers and land managers will benefit from using both approaches in concert to gain a robust understanding of the local bilby diet. However, the cost and limitations of DNA barcoding (particularly when dealing with degraded DNA) mean that this approach should only be employed when the quality of the genetic material within samples is suitable. We recommend conducting exploratory analysis using morphological analysis (potentially in the field), with follow-up DNA barcoding to detect highly digestible items in fresh scats.

Context. The population of saltwater crocodiles, Crocodylus porosus, in the Northern Territory, Australia, has been recovering from a period of intensive, unregulated harvest (1945–1971) since protection in 1971. Consequently, the management goal is shifting from restoring a seriously depleted population to managing an abundant population through controlled harvests for both commercial purposes and public safety.

Aims. We conducted this study to (1) examine whether the controlled harvest of eggs and adults since protection has had an adverse effect on population size and structure, and (2) explore the effect of future harvest scenarios on population size and structure by adjusting harvest levels of both eggs and adults.

Methods. On the basis of 40 years of population monitoring data and knowledge of population attributes from previous research, we developed density-dependent, structured matrix population models to explore our aims.

Key results. The models supported that the depleted population recovered rapidly under protection and that the harvest rates since protection were benign. The model estimated the 2017 harvested population, 46 years after protection, to be ∼102 000 non-hatchlings (>0.6 m crocodiles), of which 42.2% are large (>2.1 m total length) individuals. This is similar to the estimated population before the period of intensive, unregulated harvest. Like other crocodilians, the harvest simulations showed that the viability of the population is highly sensitive to adult survival rates. The estimated population should be able to sustain an annual harvest of up to 135 500 eggs if the harvest of large crocodiles remains small (<500 per year).

Conclusions. Although egg harvest has little impact on population size and structure, population size is sensitive to adult harvest.

Implications. Crocodile populations are highly sensitive to adult survival, which needs to be taken into account when considering future harvest scenarios.

Context. The ranges of many small, at-risk felid species occur almost entirely in unprotected areas, where research efforts are minimal; hence data on their density and activity patterns are scare.

Aims. We estimated density and activity patterns of Pallas’s cats on unprotected lands in central Mongolia during two periods (May–August and September–November) in 2019.

Methods. We used spatially explicit capture–recapture models to estimate population density at 15.2 ± 4.8 individuals per 100 km².

Key results. We obtained 484 Pallas’s cat images from 153 detections during 4266 camera-days. We identified Pallas’s cats using pelage markings and identified 16 individuals from 64 detections. Pallas’s cat activity was consistent between the two survey periods (∼0.50), with cats mainly active during crepuscular hours in the first period and strictly diurnal in the second.

Conclusions. We provide the first estimation of a Pallas’s cat population density using camera-trapping. Compared with other methods used, densities were high in our study area, which was likely to be due to a combination of highly suitable habitat and abundant prey. Seasonal shifts in the activity patterns of Pallas’s cats indicated a likely adaptive response to reduced risk of depredation by raptors.

Implications. We recommend August to November as the best time for camera-trapping surveys for Pallas’s cats, given their high daily activity and the easiest interpretation of images used for individual identification collected during this time. We also suggest that future camera-trapping surveys of Pallas’s cat be mindful of potential camera-trap avoidance through time.

Context. Outside its breeding season, the marsupial carnivore the spotted-tailed quoll (Dasyurus maculatus) is apparently largely unaffected by aerial baiting for dingoes and other wild dogs (Canis familiaris). However, the potential impact of aerial baiting during spring on female spotted-tailed quolls carrying and weaning young remains unquantified.

Aim. The survivorship of female quolls and their pouch young was investigated after aerial baiting at two sites representing the northern and southern part of their New South Wales range. The null hypothesis was that aerial baiting would not lead to direct mortality of any adult females or higher pouch young mortality over that reported in the published literature under normal conditions.

Methods. In total, nine female quolls with pouch young and eight male quolls were trapped, fitted with GPS/VHF collars containing mortality sensors and released at their point of capture. After trapping ceased, meat baits nominally containing 6 mg of 1080 and 50 mg of the biomarker rhodamine B were deployed by helicopter at both sites at the maximal permissible rate of 40 baits km⁻¹. We monitored collared quolls daily for 4–5 weeks for mortality then retrapped animals and sampled whiskers for evidence of the biomarker. The fate of pouch young was also followed throughout our study by examining pouches of adult females and camera trapping at maternal den sites.

Key results. No collared quolls died. After the daily monitoring period, 10 quolls, including all six collared female quolls, were trapped at the southern site, and whisker samples taken and assayed for Rhodamine B. Seven (4 females and 3 males) tested positive for rhodamine B, indicating consumption of baits. Separate bands of the biomarker in whisker samples indicated that most animals that tested positive had been exposed to multiple baits. At the northern site, four quolls (including two females and two males) tested positive for rhodamine B from the nine sampled. Post-baiting inspection of pouches of all trapped adult female animals, together with camera trapping at den sites, showed that the development of pouch young was unaffected by the baiting. Camera trapping arrays set across both sites continued to record the animals that were exposed to baits well beyond the baiting events, including evidence of breeding in a subsequent season.

Conclusion. Our aerial baiting programs had no observable impact on the collared female quolls, or their ability to raise and wean young. These findings are consistent with results from all previous field-based experimental studies, which show no population-level impacts of 1080 baits on spotted-tailed quolls.

Implications. Land managers should not be concerned about impacts of aerial baiting for wild dogs on spotted-tailed quolls, either in autumn or in spring during the breeding season.