Context. Mustering (gathering) feral horses (Equus ferus caballus) often cause mortalities, yet cause-specific details are lacking.

Aims. Given the need to optimise horse welfare, we analysed public horse muster data from the USA to understand specific causes of mortalities.

Methods. We coded 393 individual horse mortality reports for 92 cause-specific mortality terms (keywords informing the deciphering of specific causes of mortality classified as anatomical, causal or conditional) and demographic details (age, sex, and body condition). Data were derived from 50 musters across seven states with at least one horse mortality. Musters were coded for type (helicopter or bait), emergency or regular planned efforts, and number of horses mustered and shipped daily.

Key results. More horses were euthanased than died naturally (330 (84.0%) and 39 (9.9%) respectively), and more horses had chronic than acute conditions (317 (80.7%) and 76 (19.3%) respectively), with both trends holding for both sexes and across ages. Body condition scores (BCS) for female horses were skewed low, whereas male horse BCS data were more normally distributed. Female horses had lower BCS than did male horses (P < 0.001). On average, each horse mortality had two cause-specific mortality terms, ranging from 1 to 7. Only 57 horses (14.5%) had terms describing anatomy, cause and condition, concurrently. Phi coefficients (ϕ; indicators of fidelity and constancy) for cause-specific terms were related to demographic or muster attributes and were analysed with post hoc ANOVA tests of estimated marginal means to allow for ranking. Female horses were most often described as emaciated, weak, and starving, whereas male horses were described as lame, arthritic, blind or dangerous. Bait trapping and emergency musters included horses that were starving, dehydrated and weak.

ConclusionsGenerally, disorders associated with legs and feet, eyes, necks and nutrition were the most prevalent cause-specific mortality issues. Using a machine learning approach, validation and test accuracy were high for predicting euthanasia versus natural mortalities, but low for predicting acute versus chronic mortalities. Individual horse demographics or daily muster features had a greater relative influence than did capture type or emergency status in both comparisons.

ImplicationsThese results provide practical insight for potential cause-specific mortalities relative to demographics and muster techniques.

Context. Dogs are increasingly being used in conservation work to collect information on species abundance, distribution, occupancy and other biological measures. Monitoring feral cats through the use of detection dogs could provide a useful technique to complement existing feral cat survey and control methods.

Aim. To demonstrate and quantify the ability of trained detection dogs to reliably and efficiently detect feral cat scats when present in woodland conservation reserves in the Wheatbelt of Western Australia.

Methods. Cat scats were randomly placed into 466 1.5 ha (150 m × 100 m) quadrats in Tutanning Nature Reserve, Western Australia, and the location of the scat was recorded. Quadrats were then independently searched by dogs walking a central transect line and the locations of all scats detected were recorded, with the distance from the scat to the transect subsequently being calculated. Data collected allowed the relationship between distance from the transect and detection probability to be used to assist modelling of detection probabilities.

Key results. Dogs detected scats in 213 (55%) of 384 quadrats that were searched using a single transect line method. All indications of a find by the detector dogs were associated with a cat scat (no false indications). Detection probabilities for scats declined with distance from the transect line and with an increasing age of the scat. Simulations to investigate management options for cat control programs quantified effort required to detect cat scats under varying densities.

Conclusion. Dogs were highly efficient at detecting scats within the woodland environment of the Western Australian wheatbelt. The effort required to detect a scat was considerably higher when cat density was low.

Implications. On the basis of the detection probabilities derived from the present study, trained scat-detection dogs can be expected to efficiently search woodlands and find cat scats by using an effective sweep width of 100 m (50 m either side of a transect) when scats are fresh. Sweep widths need to be reduced significantly if it is important to locate scats that have been exposed to the elements for greater periods of time, or to search habitats where terrain and vegetation cover are more challenging.

Context. Disease is increasingly becoming a driver of wildlife population declines and an extinction risk. Vaccines are one of the most successful health interventions in human history, but few have been tested for mitigating wildlife disease. The transmissible cancer, devil facial tumour disease (DFTD), triggered the Tasmanian devil’s (Sarcophilus harrisii) inclusion on the international endangered species list. In 2016, 33 devils from a DFTD-free insurance population were given an experimental DFTD vaccination before their wild release on the Tasmanian northern coast.

Aim. To determine the efficacy of the vaccination protocol and the longevity of the induced responses.

Method. Six trapping trips took place over the 2.5 years following release, and both vaccinated and incumbent devils had blood samples and tumour biopsies collected.

Key results. In all, 8 of the 33 vaccinated devils were re-trapped, and six of those developed DFTD within the monitoring period. Despite the lack of protection provided by the vaccine, we observed signs of immune activation not usually found in unvaccinated devils. First, sera collected from the eight devils showed that anti-DFTD antibodies persisted for up to 2 years post-vaccination. Second, tumour-infiltrating lymphocytes were found in three of four biopsies collected from vaccinated devils, which contrasts with the ‘immune deserts’ typical of DFTs; only 1 of the 20 incumbent devils with DFTD had a tumour biopsy exhibiting immune-cell infiltrate. Third, immunohistochemical analysis of the vaccinated devils’ tumour biopsies identified the functional immune molecules associated with antigen-presenting cells (MHC-II) and T-cells (CD3), and the immune checkpoint molecule PD-1, all being associated with anti-tumour immunity in other species.

Conclusions. These results correlate with our previous study on captive devils in which a prophylactic vaccine primed the devil immune system and, following DFTD challenge and tumour growth, immunotherapy induced complete tumour regressions. The field trial results presented here provide further evidence that the devil immune system can be primed to recognise DFTD cells, but additional immune manipulation could be needed for complete protection or induction of tumour regressions.

Implications. A protective DFTD vaccine would provide a valuable management approach for conservation of the Tasmanian devil.

Context. Wildlife surveys often rely on a single live-capture technique to sample animal populations. Yet, animal personality (e.g. bold vs shy) can drive heterogeneity in capture probability, leading to biased sampling during live-capture trapping surveys.

Aims. We tested whether a personality-related capture bias is similar between two live-capture techniques, or whether techniques with different capture mechanisms are biased towards certain spectrums of personality.

Methods. We compared two live-capture techniques commonly used for surveying lizards, namely, noosing and pitfall traps. Techniques were deployed several days apart to survey populations of a desert-dwelling agamid, the military dragon, and we used outdoor open-field arenas to test for personality traits relating to boldness, activity and exploration.

Key results. We found that noosing and pitfall traps sampled distinctly different spectrums of personality, with no individuals being captured by both techniques. Unexpectedly, noosing, which involved people approaching dragons to capture them, was biased towards shyer individuals that stayed close to shelter. In contrast, pitfall traps, which were generally set in open areas, were biased towards capturing individuals that moved further from shelter.

Conclusions. We demonstrated that different live-capture techniques can be biased towards different spectrums of personality. We attribute the relationship between personality and technique to an interaction between the capture mechanisms of each technique and individual perceptions of risk and microhabitat use.

Implications. To overcome biased and selective sampling and target individuals along a broad spectrum of personality, surveys should use complementary techniques that vary in their capture mechanisms.

Context. Safe and effective capture methods are crucial for improving our understanding and management of many wildlife species. The adaptation of established capture methods to novel situations requires critical evaluation because differences in environmental conditions and species’ susceptibility to trauma and capture myopathy can produce unexpected outcomes. Helicopter net-gunning has been a valuable tool for capturing wild deer in New Zealand and the Americas, but there are no practical records of its use in Australia and only one report of it being used to capture three fallow deer (Dama dama) elsewhere.

Aims. The present study aimed to evaluate the feasibility of a helicopter-based net-gun capture technique for wild fallow deer by quantifying the efficacy of the technique and the frequency of injuries and deaths.

Methods. We captured fallow deer over two 3-day operations at a 135 km² site in eastern Australia. We collected data on operational efficiency and variables expected to affect animal health and welfare, such as injuries and the duration of stressful procedures. We used GPS tracking collars with an accelerometer and a mortality-sensing function to monitor post-release survival and activity of fallow deer.

Key results. In total, 127 deer were targeted for capture, with nets fired at 64 deer (50%) and 27 deer captured (21%). Mortality within 30 days of capture was zero. Mean chase time was 2 min 46 s and mean total time from start of chase until release was 11 min 19 s. No animals were severely injured or euthanased, but hyperthermia was observed in 33% of captured animals.

Conclusions. Helicopter net-gunning was an effective and safe method for capturing wild fallow deer when compared with alternative methods.

Implications. We recommend that researchers consider using helicopter net-gunning to capture fallow deer in Australia and elsewhere, and other deer species in Australia.

Context. Long-term changes in the breeding phenology of bird communities have been widely studied. For many species, breeding appears to be starting earlier as temperatures increase. For south-eastern Australia, such a trend has not so far been demonstrated.

Aims. The aim was to determine how the date of laying of the first egg (FE; for sedentary species) or arrival times (for migratory species) responded to climatic factors such as rainfall, air temperature and the Southern Oscillation Index (SOI), and whether FE or arrival time showed a trend through time.

Methods. The date of laying of the first egg (FE) for 13 sedentary species of birds was recorded over 18 (1975–1984 and 2007–2014) breeding seasons (August to January) at a single site in a coastal forest in south-eastern Australia. The arrival times for seven migratory species were also recorded for these seasons.

Key results. Linear mixed models showed that FE was negatively correlated with the mean monthly SOI for April to July (A-J SOI), the period directly before the breeding season. Eggs were laid earlier when A-J SOI was positive and later when it was negative. SOIs calculated over different combinations of months showed that those for the January to March period had no influence on FE. FE was not related to minimum or maximum temperatures during April to July, despite increases in temperature between 1975 and 2014, nor was it related to rainfall between April and July. Mixed linear models showed that arrival date for migratory species became earlier between 1975 and 2014, but was uninfluenced by A-J SOI or rainfall.

Conclusions. Migratory species arrived earlier by 0.27 days per year. However, this was at least an order of magnitude smaller than annual temporal changes in FE for sedentary species (6–7 days) associated with cyclical SOI fluctuations. Changes in SOI dominated the annual breeding phenology of the community.

Implications. The mechanisms by which A-J SOI influences the timing of nesting may be related to the primary productivity of forests and the influence of this on insect abundance. There are few data on these factors.

Context. The more frequent and intense bushfires predicted under climate change are likely to heavily impact koalas living inside protected areas and intact forests, which makes koala habitat in asset protection zones more important. Understanding how koalas use different habitats in a mixed-tenure landscape can inform effective conservation management.

Aims. The aims of this study were to determine (1) the species and size of trees used by koalas, (2) whether choice of daytime trees was affected by available proportions of tree species and sizes in koala home ranges, and (3) whether developed land was used as frequently as native forest.

Methods. Tree use by koalas was determined by radio-tracking 10 koalas for an average of 12 months and recording the species and diameter of trees they occupied. To compare the proportions of tree species used by koalas with those available, tree availability was measured using random quadrats in the home ranges of five koalas that used forested areas extensively. The habitats used by 10 koalas were classified as native forest or developed land to investigate the importance of human-modified areas.

Key results. Eucalyptus punctata was a preferred tree species, but each individual used four to nine species. Tree species were not chosen solely on the basis of available proportions; some species were selected preferentially. Half of the koalas used more developed land than native forest. Koalas preferentially used trees with larger diameters than the mean of available trees, and selected larger trees in developed areas than in native forest and when re-using trees.

Conclusions. Despite the higher availability of trees in protected native forest at the site, 70% of the koalas used developed land in and around asset protection zones. Koalas whose home ranges were geographically close, but had different soil types and vegetation communities, were able to utilise different tree species.

Implications. Koalas would benefit from protection of remnant native forests containing preferred trees on shale cap soil and conservation of native vegetation corridors along fence lines and in paddocks in developed areas because they are valuable resources and connect patchy landscapes. Protecting koalas on developed land improves their likelihood of surviving bushfires, allowing recolonisation of surrounding protected areas.

Context. Determining population size or density is often fundamental for wildlife conservation. For nocturnal species, indices are commonly used in place of abundance estimates, with spotlighting indices (e.g. sighting rate per km) being prevalent. Distance sampling is a collection of techniques that provide estimates of wildlife abundance from line-transect data, by correcting raw counts for imperfect detection. These methods have rarely been used to assess the abundance of nocturnal arboreal mammals.

Aims. To develop and evaluate a method for estimating the abundance and density of nocturnal arboreal mammals using double-observer distance sampling, and to apply the approach to a survey of the southern greater glider (Petauroides volans) in the Strathbogie Ranges, Victoria, Australia.

Methods. Two observers, 15–20 min apart, surveyed 25 randomly located 500 m transects, and recorded greater gliders using spotlights and binoculars. Densities and abundances were derived from the line-transect data by using mark–recapture distance sampling (MRDS) models and were compared with conventional distance sampling analysis (CDS).

Key results. Using the double-observer approach, we estimated an overall density of 0.96 gliders ha⁻¹ (95% CI 0.60–1.50), giving a population estimate of 24 575 greater gliders across the Strathbogie Ranges (25 865 ha, 95% CI 15 620–38 661). The corresponding estimates for the study area derived using CDS applied to either both observers’ observations or to the first observer’s observations only, were 87% and 53% respectively, of the MRDS estimate. The analysis confirmed that the probability of detection of gliders along the transect line was less than one, justifying the use of the double-observer method to obtain accurate estimates of abundance.

Conclusions. The low detectability of greater gliders means that uncorrected spotlight counts will underestimate abundance, as will CDS. The double-observer method corrects for the negative bias associated with raw counts, enabling more accurate estimation of abundance for survey, monitoring and management purposes.

Implications. We recommend that double-observer distance sampling is adopted as a standard technique for estimating the abundance of greater gliders. The double-observer method potentially has wider relevance for assessing population size of other arboreal mammals, providing the assumptions of the approach can be met.