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Context: Non-invasive identification of individual animals in wild populations can occur in species with unique coat patterns (e.g. zebras, giraffes, jaguars). However, identification in other species often relies on capture-mark–recapture techniques, involving physical handling of animals. Identification of individual koalas (Phascolarctos cinereus) is difficult and has so far relied mostly on invasive methods such as ear tagging, microchipping and/or collaring, which require capture. The validation of a non-invasive method to identify koalas could improve monitoring of individuals in the wild, allowing targeting of specific koalas in disease and survival studies, reducing the need to capture individuals. Aims: This study describes a novel effective method to identify koalas from their nose markings, specifically using the unpigmented pattern of the nose to determine unique features of individuals. Methods: Photographs of koalas from different populations in Victoria and New South Wales (NSW), Australia, were examined in the study. Nose patterns were traced from photographs and matched through visual assessment if they were thought to belong to the same individual. Differences in identification success between datasets from different populations and the effect of sex on match success were evaluated statistically. For the NSW koalas, the effect of lighting conditions and photographic angle were also assessed. Key results: Overall identification success was 89.7% (range 87.1–91.8%) and was not affected by any of the variables tested, demonstrating that nose patterns can be used reliably to identify individual koalas. Conclusions: The proposed non-invasive method is simple, yet accurate and stable over time, hence it offers a vital tool for monitoring endangered koalas whilst minimising human interference. Implications: Pattern-based recognition of koalas is cost-effective, reduces stress on the animals, has the potential to improve data collection and allows involvement of citizen scientists in monitoring of populations or individuals. Identification of individual koalas is difficult and relies mostly on invasive methods requiring capture. This study describes and validates a novel non-invasive method to identify koalas from their nose markings, using the unpigmented pattern of the nose to determine unique features of individuals. This new method offers a vital tool for monitoring endangered koalas whilst minimising human interference. Photograph by Koala Clancy Foundation. [ABSTRACT FROM AUTHOR]

Context. The population of introduced fallow deer (Dama dama) is thought to have increased exponentially across much of the island of Tasmania, Australia, since 2000. Historically, deer management decisions have relied on population trend data from vehicular spotlight surveys. Renewed focus on the contemporary management of the species requires development of more robust and precise population estimation methodology. Aims. This study demonstrates two aerial survey methods – conventional counts by trained human observers, and thermal imaging footage recorded during the same flights – to inform future survey practices. Methods. Conventional counts were carried out by three observers, two seated on the left side of the helicopter, and one on the right. A high-resolution thermal camera was fitted to the helicopter and was orientated to meet the assumptions of distance sampling methodologies. Both survey methods were used to generate deer population density estimates. Spatial distribution of deer was also analysed in relation to patches of remnant native vegetation across an agricultural landscape. Mark–recapture distance sampling was used to estimate density from human observer counts and provide a comparison to the distance sampling estimates derived from the thermal camera. Key results. Human observer counts gave a density estimate of 2.7 deer per km2, while thermal camera counts provided an estimate of 2.8 deer per km2. Deer population density estimates calculated via both methods were similar, but variability of the thermal camera estimate (coefficient of variation (CV) of 36%) was unacceptably high. Human observer data was within acceptable bounds of variability (CV, 19%). The estimated population size in central and north-eastern Tasmania for 2019 approximated 53,000 deer. Deer were primarily congregated within 200 metres of the interface between canopy cover and open pasture. Conclusions. The population density estimate provides a baseline for monitoring and managing the Tasmanian deer population. Human observer data was more precise than thermal camera data in this study, but thermal counts could be improved by reducing sources of variability. Implications. Improvements for the collection of thermal imagery are recommended. Future control efforts may be more efficient if they preferentially target habitat edges at this time of year, paired with random or grid-based searches where population density is lower. [ABSTRACT FROM AUTHOR]

Context: Passage efficiency is an important metric for quantifying the success of fish-passage remediation. Mark-recapture methods are typically employed to estimate fish-passage efficiency. Although biotelemetry methods have become a benchmark standard for such studies, they remain unfeasible for many small-bodies species because of the excessive size of electronic tags. Aims: This study compares two commonly deployed marking methods that are potentially suitable for estimating passage efficiency for small-bodied species, namely, visible implant elastomer (VIE) tagging and batch immersion staining with Rhodamine B. Methods: The critical swimming speeds and passage efficiency at a remediated culvert of Galaxias maculatus were compared for VIE-tagged, Rhodamine B-stained and control treatments. Key results Both critical swimming speeds and passage efficiency at the culvert were significantly lower in VIE-tagged Galaxias maculatus than in both control fish and fish stained with Rhodamine B. Conclusions Rhodamine B may be a suitable batch immersion stain for short-term (<4 day), non-destructive mark-recapture studies in small-bodied fishes, but VIE-tagging methods may result in underestimation of passage efficiency. Implications: It is important to evaluate the impact of marking techniques on the outcomes of mark-recapture studies to ensure that estimates of passage efficiency are accurate. Improving fish passage is essential for the recovery of freshwater biodiversity. Mark-recapture methods are often used to measure the effectiveness of efforts to restore river connectivity. This study shows that the method used to mark fish can significantly affect estimates of passage efficiency for a small-bodied fish that is distributed widely in the Southern Hemisphere. [ABSTRACT FROM AUTHOR]

Context: The variation observed in growth rate estimates of bryozoans raise questions regarding the validity of the methods used to measure growth in these animals. Naturally, the best way for measuring growth rate is to understand the growth in situ , but access is not always straightforward. Aims: This study assesses a field experiment for measuring in situ growth of heavily calcified bryozoans in the open ocean at 56 m, the deepest such deployment attempted for bryozoans. Methods: Cellaria immersa colonies were collected by dredge from the continental shelf off Otago, marked using calcein, mounted on a purpose-built frame, called 'Odyssey', and returned to the shelf for 3 months in the Austral summer (November–February). Key results: Data from 10 internodes indicated that growth was, on average, 0.97 ± 0.84 mm year−1 and showed some interesting intracolonial growth patterns. Conclusions and implications: The data obtained from this study are only indicative at this stage, but we have succeeded in developing a reproducible experimental set-up for in situ growth experiments of shelf bryozoans, enabling us to record growth, lifespan, and calcification rates of heavily calcified and ecologically important species. Understanding such key species is critical to identifying their role in the ecosystem and providing valuable information for future conservation initiatives. Bryozoans are distributed worldwide and are important reef builders. Methods used to define the age of bryozoan colonies are controversial, especially for species that grow on the continental shelf. In this work, we describe and utilise a new experimental design for measuring the growth of heavily calcified bryozoans in the open ocean, at 56-m depth, using the species Cellaria immersa. The results indicated a slow growth rate compared with other species, and some interesting growth patterns that occur within the colony. [ABSTRACT FROM AUTHOR]

Context: Understanding the effects that learned responses to being captured have on subsequent recapture rates and associated abundance estimates is important for developing accurate descriptions of populations and communities. Although variation in the willingness of individual turtles to be trapped is commonly mentioned in the literature, few studies have experimentally tested learned trap avoidance (or fondness) in turtles. Aims: To determine whether turtles learn to avoid traps, whether repositioning traps will lead to increased capture rates, whether this effect varies among species, and whether such relocations yield more accurate depictions of community structure. Methods: We studied a community of turtles in a small lake in south-eastern Kansas that included populations of red-eared slider turtles (Trachemys scripta elegans) and common musk turtles (Sternotherus odoratus). We trapped the lake for 35 consecutive days by using two concurrently deployed groups of traps. One group remained stationary for the duration of the study, whereas traps comprising the other group were moved to new locations on Day 14 and returned to their original locations on Day 28, thus dividing the trapping season into three periods. Key results: For both species, capture rates declined over time. However, traps in the moved group captured more T. s. elegans than did those in the stationary group during the second period and more S. odoratus during the third period. Traps in the moved group also had higher recapture rates in the second period. Population abundance estimates based on captures from the moved group, the stationary group, and the pool of all captures were similar for T. s. elegans , but for S. odoratus the stationary group of traps produced an abundance estimate much lower than those generated from the moved group and the pool of all captures. Conclusions: Both species exhibited learned avoidance of trap locations, but relocating traps had distinct effects on different species, and the accuracy of the observed community structure was improved by relocating traps. Implications: The movement patterns and catchability of individuals of different species within a community must be taken into consideration when developing trapping protocols. Even high-intensity trapping over a long period may not generate an accurate sample of the community if different species use the spatial environment in substantially different ways and learn to avoid trap locations. Learned responses of wildlife to trapping can introduce considerable bias into analyses based on repeated or long-duration surveys of a population. This study investigated the ability of freshwater turtles to learn and avoid the locations of traps. We documented learned trap avoidance and make recommendations for avoiding the sampling bias that results from this behaviour. Photograph by Donald McKnight. [ABSTRACT FROM AUTHOR]

Context: The western rock lobster fishery is recognised to be conservatively managed, with breeding stock levels estimated to be at record levels over the past decade. Despite this, anecdotal reports from commercial fishers identified an area of unexpectedly low catches in the centre of the fishery and lobsters' biogeographic distribution. Aim: To confirm the presence of this suspected 'low-catch' zone and examine the variability in catch and growth rates of lobsters if identified. Methods: This study conducted an intensive mark–recapture survey over 8 months to explore catch rate, density, movement and growth rates across this 'low-catch' zone and three comparable locations. Key results: In total, 9318 lobsters were caught and 7565 individuals were tagged during the study. Consistently low catch rates of under-sized lobsters were observed in the 'low-catch' zone, with catch rates increasing with distance from the zone. By contrast, similar catch rates of legal-sized lobsters were observed across all locations. Conclusions: The study confirmed low catch rates, for under-sized lobsters, within an area of perceived low catch rates within the centre of the fishery. The lack of difference found in legal-sized catch rates among locations is likely to be due to the low fishing pressure in the 'low-catch' zone, resulting from hyperstability of fishers adapting to the historical perceived low catch rate. Modelled data demonstrated the 'low-catch' zone to be associated with faster growth rates and high fine-scale migration, indicating a potential release from density-dependent processes. Implications: We anticipate that these results will be a useful starting point for future research into the mechanisms responsible for the unexpectedly low catch of sublegal lobsters within the 'low-catch' zone and the implications it may have on the wider population, both regionally and across the species distribution. The Western Rock Lobster fishery is recognised to be a conservatively managed fishery. However, anecdotal reports from commercial fishers identified an area of unexpectedly low catches. This study conducted an intensive mark–recapture survey over 8 months to explore this low-catch zone. We found a decreased abundance of sublegal lobsters, but consistent abundance of adults, indicating a hyper-stability of fishing catches, owing to fishers adapting to perceived low catch rates. This study provides a valuable baseline for further research. [ABSTRACT FROM AUTHOR]

Context: Intermittent rivers make up more than 50% of the world's rivers. Refuge waterholes in these systems are critical for survival of fish populations. Aim: This study investigated the effect that angling pressure imparts on native fish within refuge waterholes. Methods: Golden perch (Macquaria ambigua) size structure was analysed in eight refuge waterholes across three catchments of the northern Murray–Darling Basin. Waterhole characteristics were recorded, with town proximity or remoteness being adopted as a surrogate variable for angling pressure. Key results: Remoteness was found to be significantly correlated with median length, biomass, and proportion of legal-sized fish, but not with fish density. Sampling occurred after widespread connective flows, and the strength of remoteness as a predictor of median length suggests that redistribution of legal-sized golden perch on these flows was minimal. Legal-sized fish were poorly represented in the length–frequency distributions of near-town waterholes, and smaller size classes were well represented in most waterholes. Conclusion: This study suggests that populations of golden perch in refuge waterholes near towns face significant angling pressure, with impacts on size structure at a local level. Implications: These findings may have wider implications for the long-term resilience of the species. Town proximity was used to evaluate the effect of fishing pressure on golden perch populations in refuge waterholes of the northern Murray–Darling Basin. This study shows a fishing pressure 'gradient' with an increasing distance from town. Fishing pressure is shown to have a significant effect on the size structure of golden perch in refuge waterholes. [ABSTRACT FROM AUTHOR]

Context: Seasonal migration and movements of bats have important implications for their conservation. The southern bent-winged bat (Miniopterus orianae bassanii), a critically endangered cave-dwelling taxon in Australia, has been described as undertaking regional-scale migration between maternity and non-breeding caves. Aims: To describe the seasonal cycle of movements by the southern bent-winged bat, including migration and congregation events of different sex- and age-classes in the population. Methods: We tagged a total of 2966 southern bent-winged bats with passive integrated transponder (PIT) tags. Antennas were used to detect bats in flight at a major maternity cave and a key non-breeding cave in south-east South Australia, from January 2016 to August 2019. We used capture–resight histories to visualise population patterns and model the daily encounter probability for each sex- and age-class at the respective roost sites. Key results: Bats congregated at the maternity cave for most of the year, with different seasonal patterns among sex- and age-classes. Seasonal movements were associated with behaviour over winter months: most of the population dispersed from the maternity cave from May and a staged return occurred among population classes from July through September. A previously undescribed movement occurred in adult females and juveniles each year: these classes left the maternity cave in late summer, when juveniles became independent, and returned in early mid-autumn, later undertaking winter dispersal. Complex underlying movements of individuals occurred throughout the year, with individuals able to fly 72 km between roosting caves in just a few hours. Conclusions: Seasonal movements are a key aspect of the life history of this taxon. The newly reported movement of adult females and juveniles conforms to the maternal guidance hypothesis, whereby mothers guide their young to suitable non-breeding caves and hibernation sites. In addition to seasonal movements, some individuals moved 72 km between caves multiple times over short time periods, including on successive nights. This 72-km overnight flight distance more than doubles the previous distance used to inform management buffer zones. Extended congregation of bats at the maternity cave highlights resource limitation in the surrounding area as a potential threat to this population. Implications: The dynamic nature of the population has implications for the management of emerging risks, including mortality at windfarms and potential rapid spread of the exotic white-nose syndrome. Knowledge of the seasonal movements of small insectivorous bats is essential for their conservation. We describe the seasonal cycle of congregation and movement patterns of the southern bent-winged bat, a critically endangered taxon in southeastern Australia. We record previously unknown movements by this taxon, and a more-than doubling of the overnight flight distance currently used to define management buffer zones. These findings have important implications for managing emerging risks, such as mortalities at windfarms and potential spread of exotic disease. Photograph by Emmi van Harten. [ABSTRACT FROM AUTHOR]

Context: Previous research has shown the presence of an endangered humpback whale population breeding off the Pacific coast of Central America. However, little is known about the density, size, social-group structure and spatial habitat use of this subpopulation. Aim: The study goal was to characterise a potential breeding subpopulation of humpback whales in the waters off Nicaragua. Five objectives were used to achieve this goal: (1) estimate abundance, (2) determine encounter rates, (3) define group composition, (4) assess distribution, and (5) document habitat-use patterns. Method: Boat-based surveys were conducted between November and April at two study sites along the Pacific coast of Nicaragua in the winters of 2004–2008 and 2016–2020. Key result: Inter-annual mark–recapture estimates did not yield a reliable estimate of abundance. Encounter rates were lower for the northern study site than for the southern site. Group composition consisted of groups with calves, singers and competitive males. Conclusion: These results confirmed that Nicaragua is a breeding area based on known breeding-ground behaviours observed in other areas, and similar environmental characteristics. Implication: Distinct habitats were found at the two study sites, suggesting that Central American humpback whales might use different areas within the broader Central American breeding range according to their needs and activity. This paper presents information on the distribution, behaviour, ecology and population size of humpback whales observed off the Pacific coast of Nicaragua. Thought to be part of the endangered humpback whale population off the Pacific coast of Central America, little is known about the population characteristics of the whales off Nicaragua. This knowledge will be valuable for scientists and decision makers to help establish effective conservation measures. [ABSTRACT FROM AUTHOR]

A population of wild European rabbits (Oryctolagus cuniculus) was regularly monitored from November 1996 to April 2022, using mark--recapture as part of a longitudinal epidemiological study into two Australian rabbit biocontrol agents, rabbit haemorrhagic disease (RHD) and myxomatosis. A female rabbit, first captured as a subadult on 26 October 2009, was recaptured 16 times before its final capture on 19 February 2019. The longevity of this rabbit, from its calculated birth date to the date of its last capture, was 9.5 years. This is a record lifespan for a wild European rabbit acknowledging that such longevity might be specific to our site in temperate South Australia. It exceeds our previous reported record from the same site by 2 years. [ABSTRACT FROM AUTHOR]

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 500mtransects, 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Hawaiian fishponds, or loko i'a , are ancient aquaculture systems and models of sustainable aquatic resource management from traditional Native Hawaiian harvest practices. Of the 488 fishponds documented in ancient Hawai'i, only 38 are currently actively managed. Building on Indigenous and local knowledge, fishponds are being adapted to current community needs. Functional fishponds perpetuate culture, improve food security, enhance ecosystem services and transform conservation biology through Indigenous perspectives. Here we examine how Indigenous practices effectively maintain sustainable harvest of an introduced, but economically important, crab species, the mud crab, Scylla serrata (Forskål 1775). The State of Hawai'i has only a size limit, and no bag limits, for this species. With Indigenous management in a Hawaiian fishpond, limits are set and enforced in response to fluctuations in catch. We used a mark–recapture experiment to parameterise a size-structured population model, which we used to investigate the impact of changing harvest rates. Throughout the study period of 2017–20, the mean number of crabs per harvest was 28 individuals (s.d. = 7) and average catch per unit effort was 0.20 crabs per trap-hour (s.d. = 0.054). During winter, catch per unit effort was lower but mean crab size was larger than during summer. Model simulations indicated that current Indigenous practices are less likely to cause a decline in population growth rate than a strict size limit. Using information from Indigenous harvest practices and the mark–recapture study, we codeveloped a versatile crab population model that can be tailored to changing management objectives. Global concerns for food security have recently led to interest in indigenous knowledge systems. Hawaiian fishponds (loko i ' a) provide a model of sustainable aquatic resource management based on long-term experience from Native Hawaiian harvest practices. An introduced fishery species found in the loko i ' a is shown to be manageable with adaptive Indigenous practices. [ABSTRACT FROM AUTHOR]

Context: Precise and accurate estimates of animal numbers are often essential for population and epidemiological models, as well as for guidance for population management and conservation. This is particularly true for threatened species in landscapes facing multiple threats. Estimates can be derived by different methods, but the question remains as to whether these estimates are comparable. Aims: We compared three methods to estimate population numbers, namely, distance sampling, mark–recapture analysis, and home-range overlap analysis, for a population of the iconic threatened species, the koala (Phascolarctos cinereus). This population occupies a heavily fragmented forest and woodland habitat on the Liverpool Plains, north-western New South Wales, Australia, on a mosaic of agricultural and mining lands. Key results: All three methods produced similar estimates, with overlapping confidence intervals. Distance sampling required less expertise and time and had less impact on animals, but also had less precision; however, future estimates using the method could be improved by increasing both the number and expertise of the observers. Conclusions: When less intrusive methods are preferred, or fewer specialised practitioners are available, we recommend distance sampling to obtain reliable estimates of koala numbers. Although its precision is lower with a low number of sightings, it does produce estimates of numbers similar to those from the other methods. However, combining multiple methods can be useful when other material (genetic, health and demographic) is also needed, or when decisions based on estimates are for high-profile threatened species requiring greater confidence. We recommend that all estimates of population numbers, and their precision or variation, be recorded and reported so that future studies can use them as prior information, increasing the precision of future surveys through Bayesian analyses. We compared three methods of population estimation for the koala in rural New South Wales, namely, distance sampling, mark–recapture and home-range analysis. All methods produced similar estimations of population size, although the distance sampling had a lower precision than did the other methods. However, distance sampling required less effort and expertise, and was less invasive than were the other methods. Hence, we can recommend distance sampling for estimating koala population size, particularly in fragmented landscapes. Photograph by Mathew Crowther. [ABSTRACT FROM AUTHOR]

Context: Translocations have been widely used to re-establish populations of threatened Australian mammalian species. However, they are limited by the availability of sites where key threats can be effectively minimised or eliminated. Outside of 'safe havens', threats such as exotic predators, introduced herbivores and habitat degradation are often unable to be completely eliminated. Understanding how different threats affect Australian mammal populations can assist in prioritising threat-management actions outside of safe havens. Aims: We sought to determine whether translocations of the greater bilby to two sites in the temperate zone of South Australia could be successful when human-induced threats, such as prior habitat clearance, historic grazing, the presence of feral cats and European rabbits, could not be completely eliminated. Methods: Greater bilbies were regularly cage trapped at two translocation sites and a capture–mark–recapture study was used to determine survival, recruitment and population growth at both sites. Key results: Our study showed that bilbies were successfully translocated to an offshore island with a previous history of grazing and habitat clearance, but which was free of exotic predators. At a second site, a mainland exclosure with feral cats and European rabbits present, the bilby population declined over time. Adult bilbies had similar survival rates in both populations; however, the mainland bilby population had low recruitment rates and low numbers of subadults despite high adult female fecundity. Conclusions: The results indicated that past grazing and habitat clearance did not prevent the bilby population on the offshore island establishing and reaching a high population density. In the mainland exclosure, the low recruitment is probably due to feral cats predating on subadult bilbies following pouch emergence. Implications: The results demonstrated that the bilby, an ecologically flexible Australian marsupial, can be successfully translocated to sites with a history of habitat degradation if exotic predators are absent. At the mainland exclosure site, threat mitigation for bilbies should focus on control or eradication of the feral cats. The control of European rabbits without control of feral cats could lead to prey-switching by feral cats, further increasing predation pressure on the small bilby population. Translocations are an important conservation tool for Australian critical weight-range mammals. We assessed the success of translocations of the greater bilby to two sites within South Australia, and found that a population co-occurring with feral cats and European rabbits was declining because of a lack of recruitment into the adult population. We contend that the lack of recruitment in this population was due to predation by feral cats on subadult bilbies. Our results suggest that the bilby is rather tolerant of previous habitat disturbance, provided exotic predators are not present, and that safe havens for this species should exclude both red foxes and feral cats. Photograph by Karleah Berris. [ABSTRACT FROM AUTHOR]

Surgical adhesive is widely used to prevent shedding of injected PIT-tags, but the effect of this adhesive on individuals has not been documented. We recaptured 52 southern bent-winged bats up to 741 days after PIT-tagging. All recaptured individuals were in good body condition, with no signs of infection or skin irritation; however, temporary fur loss occurred at the injection site. We advocate that researchers consider the impact this may have on study species, particularly when PIT-tagging small mammals during cooler months. [ABSTRACT FROM AUTHOR]

Population monitoring is required to guide conservation programs. We conducted a capture–mark–recapture study of a population of the vulnerable green and golden bell frog (Litoria aurea) at the northern end of its range. Frogs were captured and marked over three breeding seasons (2015/16, 2016/17, 2017/18) in a large coastal lagoon. We aimed to: (1) produce annual estimates of population size to describe population trajectory, and (2) investigate monthly variation in abundance, capture probability, and temporary emigration to understand how these factors change at a finer temporal scale. Frog abundance varied across the three annual breeding seasons: 60–280 adult males, 120–190 adult females, and 90–420 subadults. We infer that the population is stable because adult abundance estimates were higher after 2015/16. Because our study sampled only half the available breeding habitat, the overall population may number 350–850 adults. Our modelling revealed >40 males but <20 females were detected in the sample area in our monthly samples. Estimates of temporary emigration were high (males: 0.54; females: 0.79), suggesting behaviour that made frogs unavailable for capture between months. Our results suggest that monitoring at greater than annual intervals should be adequate to monitor the future trend of this population. Population monitoring is required to guide conservation programs. We conducted a mark–recapture study of a population of the vulnerable green and golden bell frog in a large coastal lagoon in north-east New South Wales. We estimate that this population contains 350–850 adult frogs. Photo by D. Newell. [ABSTRACT FROM AUTHOR]

Context: Estimating animal abundance often relies on being able to identify individuals; however, this can be challenging, especially when applied to large animals that are difficult to trap and handle. Camera traps have provided a non-invasive alternative by using natural markings to individually identify animals within image data. Although camera traps have been used to individually identify mammals, they are yet to be widely applied to other taxa, such as reptiles. Aims: We assessed the capacity of camera traps to provide images that allow for individual identification of the world's fourth-largest lizard species, the perentie (Varanus giganteus), and demonstrate other basic morphological and behavioural data that can be gleaned from camera-trap images. Methods: Vertically orientated cameras were deployed at 115 sites across a 10 000 km2 area in north-western Australia for an average of 216 days. We used spot patterning located on the dorsal surface of perenties to identify individuals from camera-trap imagery, with the assistance of freely available spot ID software. We also measured snout-to-vent length (SVL) by using image-analysis software, and collected image time-stamp data to analyse temporal activity patterns. Results: Ninety-two individuals were identified, and individuals were recorded moving distances of up to 1975 m. Confidence in identification accuracy was generally high (91%), and estimated SVL measurements varied by an average of 6.7% (min = 1.8%, max = 21.3%) of individual SVL averages. Larger perenties (SVL of >45 cm) were detected mostly between dawn and noon, and in the late afternoon and early evening, whereas small perenties (SVL of <30 cm) were rarely recorded in the evening. Conclusions: Camera traps can be used to individually identify large reptiles with unique markings, and can also provide data on movement, morphology and temporal activity. Accounting for uneven substrates under cameras could improve the accuracy of morphological estimates. Given that camera traps struggle to detect small, nocturnal reptiles, further research is required to examine whether cameras miss smaller individuals in the late afternoon and evening. Implications: Camera traps are increasingly being used to monitor reptile species. The ability to individually identify animals provides another tool for herpetological research worldwide. Camera-trap imagery can be used to identify individuals on the basis of natural patterning or scars, yet studies to utilise such techniques have been almost entirely exclusive to mammals. We used camera-trap imagery to individually identify Australia's largest species of lizard, the perentie (Varanus giganteus), and report high observer confidence in individual identification accuracy. The findings of our study have provided a promising indication of the potential uses for camera traps in studying large lizards, and in herpetological research in general. Photograph by Harry Moore. [ABSTRACT FROM AUTHOR]

Nest site selection is likely to be important for the fitness of sea turtle populations, but data on the environmental drivers of nest site selection and other important parameters like nest site fidelity and inter-nesting and remigration intervals are limited. We address these questions using data on flipper tag resightings and track counts from flatback turtles (Natator depressus) from Delambre Island in Western Australia collected over 2–3 weeks each nesting season across six nesting seasons. The median inter-nesting interval was 13 days (range 9–17 days) and the mean ± s.d. remigration interval was 1.99 ± 0.95 years. Turtles had around 10% probability of returning to the same sector of the beach (150-m-long sections). The median distance between subsequent emergences (whether false crawls were included or not) was ~450 m. The number of turtles both emerging and successfully nesting was higher when air temperature and humidity were lowest and emergences increased slightly with tide height. Sector of the beach was by far the strongest predictor of nest site, with turtles showing preference for the less exposed side of the island. The results of this study will assist with future monitoring of this population and the management of threats related to coastal development and activities. In this study we assessed how often flatback turtles returned to nest and the environmental cues they use to time their nesting attempts. Turtles nested every 13 days within a season and returned to nest every 2 years on average within ~450 m of their previous nesting location. Turtles preferred to nest on the least exposed side of the island and when air temperature and humidity were lowest and tides were highest. [ABSTRACT FROM AUTHOR]

Context: Data obtained from camera traps are increasingly used to inform various population-level models. Although acknowledged, imperfect detection probabilities within camera-trap detection zones are rarely taken into account when modelling animal densities. Aims: We aimed to identify parameters influencing camera-trap detection probabilities, and quantify their relative impacts, as well as explore the downstream implications of imperfect detection probabilities on population-density modelling. Methods: We modelled the relationships between the detection probabilities of a standard camera-trap model (n = 35) on a remotely operated animal-shaped soft toy and a series of parameters likely to influence it. These included the distance of animals from camera traps, animal speed, camera-trap deployment height, ambient temperature (as a proxy for background surface temperatures) and animal surface temperature. We then used this detection-probability model to quantify the likely influence of imperfect detection rates on subsequent population-level models, being, in this case, estimates from random encounter density models on a known density simulation. Key results: Detection probabilities mostly varied predictably in relation to measured parameters, and decreased with an increasing distance from the camera traps and speeds of movement, as well as heights of camera-trap deployments. Increased differences between ambient temperature and animal surface temperature were associated with increased detection probabilities. Importantly, our results showed substantial inter-camera (of the same model) variability in detection probabilities. Resulting model outputs suggested consistent and systematic underestimation of true population densities when not taking imperfect detection probabilities into account. Conclusions: Imperfect, and individually variable, detection probabilities inside the detection zones of camera traps can compromise resulting population-density estimates. Implications: We propose a simple calibration approach for individual camera traps before field deployment and encourage researchers to actively estimate individual camera-trap detection performance for inclusion in subsequent modelling approaches. We quantified the influence of several variables on the probability of detection of an animal target (animal-shaped toy) inside the detection ranges of a standard camera-trap model (n = 35). Among others, we showed how detection probability is negatively influenced by distances from camera traps, speed of animal movement, as well as higher ambient temperatures (by decreasing differences between background surface temperatures and animal surface temperatures). Importantly, our results also indicated substantial variation in performance among individual camera traps of the same model. We then illustrated the impacts of persistent imperfect detection probabilities on resultant population-density models, and conclude with recommendations to estimate individual camera-trap performance for incorporation into subsequent analyses. Photograph by Trevor McIntyre. [ABSTRACT FROM AUTHOR]

Knowledge of the broad-scale movement patterns of sharks is essential to developing effective management strategies. Currently there is a large bias in studies focusing on species that are either large apex predators or found in tropical to subtropical regions. There is limited knowledge of the movements and migrations of benthic and temperate shark species. The present study used passive acoustic telemetry to investigate the movement patterns of a benthic shark species, the Port Jackson shark (Heterodontus portusjacksoni). Individuals were tagged with acoustic transmitters between 2012 and 2014 and their movements were monitored within Jervis Bay and along the east Australian coastline for up to 4 years. Male and female Port Jackson sharks demonstrated high levels of philopatry to both Jervis Bay and their tagging location across multiple years. Although males and females did not differ in their arrival times, females departed from Jervis Bay later than males. Approximately half the tagged individuals migrated in a southward direction, with individuals being detected at Narooma, Bass Strait and Cape Barron Island. This study provides conclusive evidence of bisexual philopatry in a benthic temperate shark species, confirming previous hypotheses, and presents the most detailed migration route for Port Jackson sharks to date. [ABSTRACT FROM AUTHOR]

Context. When understanding species occupancy, estimation of detection probability for the target species is often required, provided by repeated surveys. However, if the actual detection probability of the species is determined experimentally, such estimates are not required, and the reliability of the occupancy data obtained by a particular survey effort can be determined. Aims. The aim of this study was to determine the detection rate of tadpoles using visual field surveys, as well as to explore the effects of survey time, species and tadpole density on the tadpole-detection rate. The suitability of visual surveys for detecting tadpole occupancy was also assessed. Methods. Batch-identified tadpoles were released into several pools and repeatedly counted over successive days to calculate detection rates using visual observation. In Experiment 1, the effects of tag colour, survey time (morning vs night) and species on the detection rates of two species of tadpoles (Babina subaspera and Odorrana splendida) were examined. In Experiment 2, the effects of tadpole density on O. splendida were examined. Key results. Detection rates varied by survey time, species and tadpole density; mean rates ranged from 0.2 to 0.6 for B. subaspera and 0.4 to 0.8 for O. splendida, with higher rates at night. There was a negative relationship between detection rate and tadpole density. Based on these detection rates, it was calculated that single visual surveys of O. splendida tadpoles can achieve detection probabilities near 1.0 when more than four individuals occur in a patch. Conclusions. Variations in detection probability should be considered in field surveys. If the factors that cause variations in detection rates are controlled, visual surveys of tadpoles should, at least in some species, provide detection probabilities near 1.0. Implications. When repeated surveys to estimate species occupancy are not practicable, determination of the actual detection probability of the target species using real detection rates provides a robust alternative approach. [ABSTRACT FROM AUTHOR]

Estimating population size is crucial for managing populations of threatened species. In the Top End of northern Australia, populations of northern quolls (Dasyurus hallucatus), already affected by livestock grazing, inappropriate burning regimes and predation, have collapsed following the spread of the toxic cane toad (Rhinella marina). Cane toads are currently invading the Kimberley, where they pose a threat to quoll populations. To manage these populations, we need reliable methods for detecting and estimating quoll abundance. We deployed camera traps with lures containing tuna, peanut butter or no bait and found that baited cameras performed better than the unbaited control. Cameras with a tuna lure detected more individuals than cameras baited with peanut butter or no bait. Cameras with a tuna lure yielded more photographs per quoll than those baited with peanut butter or no bait. We identified individual quolls from unique spot patterns and found multiple photographs improved the accuracy of identification. We also found that population estimates for the sample area derived from camera trapping were consistent with those from live trapping using mark-recapture techniques. [ABSTRACT FROM AUTHOR]

Context. Distance sampling is used to estimate abundance for several taxa, including pronghorn (Antilocapra americana). Comparisons between population estimates derived from quadrat sampling and distance sampling suggest that distance sampling underestimates pronghorn density, likely owing to violations of the critical assumption of distance sampling that all pronghorn within the innermost distance band (A band; nearest to the aircraft) are detected. Aims. We sought to rigorously test the assumption that all pronghorn clusters are detected within the innermost distance band by applying a double-observer approach to an established pronghorn aerial-survey protocol. Additionally, we evaluated potential effects of cluster size, landscape composition and seat position (front seat versus rear) on the probability of detection. Methods. We conducted aerial line-transect distance-sampling surveys using independent, paired observers and modelled the probability of detection with mark-recapture distance-sampling (MRDS) analysis techniques that explicitly estimate the probability of detection for pronghorn clusters in the innermost distance band. We compared density estimates produced by the MRDS analysis with those produced by multiple-covariate distance sampling (MCDS), a method that assumes complete detection for clusters on the transect line. Key results. We identified violations ofthe assumption that all clusters within the innermost distance band were detected, which would contribute to proportional biases in density estimates for analysis techniques that assume complete detection. The frequency of missed clusters was modest from the front-seat position, with 45 of the 47 (96%) clusters in the A band detected. In contrast, the frequency of missed clusters was more substantial for the rear position, from which 37 of47 (79%) clusters in the A band were detected. Further, our analysis showed that cluster size and landscape composition were important factors for pronghorn sightability. Conclusions. When implementing standard survey methodologies, pronghorn aerial-line transect surveys underestimated population densities. A double-observer survey configuration allowed us to quantify and correct for the bias caused by the failure of observers to detect all pronghorn clusters within the innermost distance band. Implications. Population monitoring programs should incorporate double-observer validation trials to quantify the extent of bias owing to undetected clusters within the innermost distance band realised under typical survey conditions. Wildlife managers can improve the precision of pronghorn aerial line-transect surveys by incorporating cluster size and measures of landscape composition and complexity into detection models without incurring additional survey costs. [ABSTRACT FROM AUTHOR]

The lack of independently verifiable estimates of catches and fisheries independent estimates of abundance and fishing mortality are major sources of uncertainty in the management of many fisheries. DNA profiling provides the potential to substantially improve the quality of data for assessments and act as an additional deterrent to illegal, unreported, and unregulated (IUU) fishing. Barriers to the implementation of this technology include cost of sample collection and processing, forensic grade quality control, and the ability to apply undetectable tags. We present the results of a comparison of two current and one new (gene tag tool, GTT) sampling techniques, using the highly valued southern bluefin tuna as an example. We demonstrate that fish sampled with two techniques are highly unlikely to be recognised as 'tagged', whereas one technique was easily recognisable after 73 days. The GTT reduced handling beforeDNAextraction, whereas both other techniques require additional labour, adding to cost and potential contamination of the evidentiary chain. Evidence of cross-contamination in the Whatman FTA Elute samples suggests they may not be as suitable for at-sea field applications. Two of the three sampling techniques are capable of obtaining high quality tissue samples for stock assessment and chain of custody purposes in a cost-effective and unidentifiable manner. [ABSTRACT FROM AUTHOR]

Context. Understanding population dynamics of invasive species is crucial for the development of management strategies. Feral horses (Equus caballus) are a growing problem in the Tuan--Toolara State Forest (TTSF), a coniferous plantation in south-eastern Queensland, Australia. Aim. The population dynamics of the TTSF feral horses was not known. Therefore, the study was designed to characterise the major vital parameters of this population and, using these data, develop a long-term management plan. Methods. The study was conducted over 3 years (2011-14) involving 522 individually identified horses. Foaling rates were used to calculate fecundity. Body fat distribution was estimated using body condition score (BCS), which reflects the nutritional, metabolic and general health of individual animals. Multi state mark--capture population models were used to estimate age-specific survival, and the Leslie age-structured projection matrix model was used to determine the annual rate at which the population increased. Key results. The mean annual fecundity was low (0.23±0.07 s.d.). The mean BCS of the population was mid-range (2.55±0.51 s.d.) with adult females having lower scores than other age and gender groups. Survival estimates were consistently high (0.92-0.95) across all age groups. The average annual finite rate of population increase (l) for the 3 years of the study was 1.09. Sensitivity analysis demonstrated that the population growth rate was almost seven times more sensitive to changes in adult survival compared with juvenile survival, and almost twice as sensitive to changes in fecundity. Key conclusions. Population dynamics of the TTSF feral horses were comparable to other feral horse populations similarly challenged by environmental nutritional limitations. Implications. Defining population dynamics of the TTSF feral horses permits the formulation of management goals that can be audited and adapted as required. The most effective strategy for controlling population growth in the TTSF would involve the continuing removal of substantial numbers of adult females or manipulation of survival and/or fecundity. As selective removal will likely alter the adult sex ratio and age structure of the population, ongoing assessment is necessary to minimise adverse welfare outcomes. [ABSTRACT FROM AUTHOR]

Transgenerational marking is increasingly being used to study the early life history, biology and ecology of fishes. However, the timeframe over which the injected enriched stable isotopes remain in the mother and are passed onto her offspring is largely unknown. Similarly, we have relatively little knowledge of the effects of isotope labelling on the morphology of offspring. In this study, we injected adult female eastern rainbowfish (Melanotaenia splendida) with two doses (20 µg g-1 and 40 µg g-1) of enriched 137Ba or 87Sr stable isotopes to mark the otoliths of their larvae and examine the effects of isotope labelling on larvae morphology. Isotope ratios in larval otoliths were significantly different from controls in larvae hatched up to 174 days post-injection, indicating that enriched isotopes can mark the larvae of this daily spawning species up to 6 months after a single injection. Isotope-marked larvae displayed variable, but generally increased physical size, indicating that enriched stable isotope labelling may have some unintended effects on larvae morphology. Consequently, transgenerational marking provides a long-term tool for marking the offspring of M. splendida to disentangle their patterns of survivorship and dispersal, with the caveat that such studies should be interpreted in light of potential isotope-related changes in offspring morphology. Understanding the biology of fish is vital to successful conservation and management, yet studying fish larvae in the wild is difficult due to their small size. This study found that marking of eastern rainbowfish larvae was possible by injecting their mothers with enriched stable barium and strontium isotopes. This technique will facilitate research on the movement of rainbowfish larvae in tropical stream networks. [ABSTRACT FROM AUTHOR]

The article investigates the influence of sex and age on temporal variation in the frequency and direction of platypus, Ornithorhynchus anatinus, captures in fyke nets. Fyke netting surveys conducted in July, the month when the highest frequency of nightly captures was recorded, resulted in almost three times as many adults and subadults entering nets versus those scheduled in April and May. Significant sex-specific variation was evident in relation to monthly capture frequencies. Males were captured most frequently in August, the start of the breeding season, while females were captured most commonly in January, the peak period of lactation. The frequency of platypus captures likewise varied when considered on a nocturnal time scale.

The article presents a study on the life and population of the black-flanked rock-wallaby in the Western Australian wheatbelt. The sample rock-wallabies were assessed at the Mt. Caroline Nature Reserve from 2007 to 2010 in terms of their body conditions based on various climates. Results showed that black-flanked rock-wallabies achieved their peak body conditions during the early summer while their breeding rates peaked to 90 percent per year except 2007, with most of the reproduction occurring in autumn and late winter or spring seasons.

It has been suggested that platypuses (Ornithorhynchus anatinus) may avoid nets following capture, compromising abundance estimates using mark-recapture models. Here, we present the first direct evidence of net avoidance behaviour by the platypus. Using acoustic telemetry, we record a platypus bypassing several nets following capture. Understanding variation in capture probabilities will lead to better estimation of platypus abundance, which is currently lacking. [ABSTRACT FROM AUTHOR]

Context: The ability to monitor changes in population abundance is critical to the success of pest animal management and research programs. Feral cats (Felis catus) are an important pest animal, but current monitoring techniques have limited sensitivity or are limited in use to particular circumstances or habitats. Recent advances in camera-trapping methods provide the potential to identify individual feral cats, and to use this information to estimate population abundances using capture–mark–recapture (CMR) methods. Aims: Here, we use a manipulative study to test whether camera-trapping and CMR methods can be used to estimate feral cat abundances. Methods: We established a grid of infrared cameras and lure stations over three pastoral properties on Kangaroo Island, Australia, for 15 days. We then reduced the population abundance with an intensive trapping program and repeated the camera survey. We estimated population abundances using robust design CMR models, and converted abundance estimates to densities using home-range data from GPS tracking. We also calculated relative abundance indices from the same data. Key results: The CMR methods produced credible estimates of the change in population abundance, with useful confidence intervals, showing a statistically identifiable population decline from at least 0.7 cats km–2 before trapping down to 0.4 cats km–2 after trapping. The indexing method also showed a statistically identifiable decrease in abundance. Conclusions: Camera-trapping and CMR methods can provide a useful method for monitoring changes in the absolute abundance of feral cat populations. Camera-trap data may also be used to produce indices of relative abundance when the assumptions of CMR models cannot be met. Implications: These methods are widely applicable. The ability to reliably estimate feral cat abundances allows for more effective management than is generally available. [ABSTRACT FROM AUTHOR]