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Quantifying the cost‐effectiveness of alternative sampling methods is crucial for efficient biodiversity monitoring and detection of population trends. In this study, we compared the cost‐effectiveness of three novel sampling methods for detecting changes in koala (Phascolarctos cinereus) occupancy: thermal drones, passive acoustic recorders and camera trapping. Specifically, we fitted single‐season occupancy‐detection models to data recorded from 46 sites in eight bioregions of New South Wales, Australia, between 2018 and 2022. We explored the effect of weather variables on daily detection probability for each method and, using these estimates, calculated the statistical power to detect 30%, 50% and 80% declines in koala occupancy. We calculated power for different combinations of sites (1–200) and repeat surveys (2–40) and developed a cost model that found the cheapest survey design that achieved 80% power to detect change. On average, detectability of koalas was highest with one 24‐h period of acoustic surveys (0.32, 95% CI's: 0.26, 0.39) compared to a 25‐ha flight of drone surveys (0.28, 95% 0.15, 0.48) or a 24‐h period of camera trapping consisting of six cameras (0.019, 95% CI's: 0.014, 0.025). We found a negative quadratic relationship between detection probability and air temperature for all three methods. Our power and cost analysis suggested that 148 sites surveyed with acoustic recorders deployed for 14 days would be the cheapest method to sufficiently detect a 30% decline in occupancy with 80% power. We recommend passive acoustic recorders as the most efficient sampling method for monitoring koala occupancy compared to cameras or drones. Further comparative studies are needed to compare the relative effectiveness of these methods and others when the monitoring objective is to detect change in koala abundance over time. [ABSTRACT FROM AUTHOR]

Roost selection and diet are fundamentally important to bats and can vary geographically and with habitat. The greater broad-nosed bat (Scoteanax rueppellii) is infrequently captured and poorly known, meaning appropriate conservation actions are difficult to determine. To assess variation across different habitats, we collected faecal samples for dietary analysis and radio-tracked individuals to identify roost trees at four different sites across New South Wales, Australia. Analysis of droppings verified beetles as the main prey in each study area except one dominated by mangroves, and confirmed for the first time carnivory in wild-caught individuals from the presence of hair from other bat species in its droppings. Very large, hollow trees were used as maternity roosts, being typically larger than neighbouring trees. Roosting habitat varied from wet sclerophyll forest in gullies to old-growth mangroves, and tree species used as roosts also varied. Colony size at maternity roosts was often 50–100 bats and fidelity to the maternity roost varied, with some being switched almost daily and others occupied for at least several days. One maternity roost was re-used 2 years later. Both the importance of beetles in the diet and roosts located in more productive landscapes suggest coastal plains and foothills may represent key habitat. Understanding a species' ecology across different geographic regions provides a sound basis for improving its conservation. Greater broad-nosed bats were captured and radio-tracked in different regions to describe roosts used and diet. Beetles were the main prey in each study area except one dominated by mangroves, and for the first time carnivory in wild-caught individuals was documented. Very large, hollow trees were used as maternity roosts, but vegetation associations and tree species varied. [ABSTRACT FROM AUTHOR]

Context. It is notoriously difficult to estimate the size of animal populations, especially for cryptic or threatened species that occur in low numbers. Recent advances with acoustic sensors make the detection of animal populations cost effective when coupled with software that can recognise species-specific calls. Aims. We assess the potential for acoustic sensors to estimate koala, Phascolarctos cinereus, density, when individuals are not identified, using spatial count models. Sites were selected where previous independent estimates of density were available. Methods. We established acoustic arrays at each of five sites representing different environments and densities of koalas in New South Wales. To assess reliability, we compared male koala density estimates derived from spatial count modelling to independently derived estimates for each site. Key results. A total 11 312 koala bellows were verified across our five arrays. Koalas were detected at most of our sample locations (96-100% of sensors; n = 130), compared with low detection rates from rapid scat searches at trees near each sensor (scats at <2% of trees searched, n = 889, except one site where scats were present at 69% of trees, n = 129). Independent estimates of koala density at our study areas varied from a minimum of 0.02 male koalas ha-1 to 0.32 ha-1. Acoustic arrays and the spatial count method yielded plausible estimates of male koala density, which, when converted to total koalas (assuming 1:1 sex ratio), were mostly equivalent to independent estimates previously derived for each site. The greatest discrepancy occurred where the acoustic estimate was larger (although within the bounds of uncertainty) than the independent mark-recapture estimate at a fragmented, high koala-density site. Conclusions. Spatial count modelling of acoustic data from arrays provides plausible and reliable estimates of koala density and, importantly, associated measures of uncertainty as well as an ability to model spatial variations in density across an array. Caution is needed when applying models to higher-density populations where home ranges overlap extensively and calls are evenly spread across the array. Implications. The results add to the opportunities of acoustic methods for wildlife, especially where monitoring of density requires cost-effective repeat surveys. [ABSTRACT FROM AUTHOR]

Forests on private land have a wide range of uses that span activities such as recreation, primary production and nature conservation. Traditionally, it has been difficult for researchers to access private land to undertake systematic surveys. We used mini‐acoustic sensors (Audiomoth) mailed via the postal service to overcome landholder concerns about researchers accessing private property, with a focus on properties used for private native forestry.We surveyed koalas, an iconic threatened marsupial, in north‐east New South Wales, Australia using passive acoustics, with repeat surveys over consecutive nights to account for imperfect detection in an occupancy modelling framework.Over 3 years, we surveyed 128 sites and recorded 2,560 male bellows. Detection probability over seven nights was high (>0.79), but varied substantially between years, due to use of different sensors, housings and weather conditions. After accounting for detection probability, modelling revealed that koalas commonly occupied private native forests of the study region (probability of occupancy = 0.58 ± 0.08).Occupancy was modelled against several covariates and it varied with the landscape extent of sealed roads (₋ve), NDVI (₋ve) and a habitat suitability model (+ve, but minor). There was no support for occupancy in private forests to be related to a range of other factors including extent of surrounding cleared land, timber harvesting history, fire and other measured habitat features.Synthesis and applications. We conclude that mini‐acoustic recorders mailed to landholders were a highly effective method for assessing koala occupancy, after accounting for variable detection, and the approach could be deployed more widely for a range of species. Private native forests in partly cleared landscapes are commonly occupied by koalas, highlighting that this tenure is crucial for koala conservation and that practices seeking to balance conservation and production should be encouraged. In addition to sensitive habitat management in private forests, sealed road density is a major threat needing to be addressed. [ABSTRACT FROM AUTHOR]

Technologies for remotely observing animal movements have advanced rapidly in the past decade. In recent years, Australia has invested in an Integrated Marine Ocean Tracking (IMOS) system, a land ecosystem observatory (TERN), and an Australian Acoustic Observatory (A2O), but has not established movement tracking systems for individual terrestrial animals across land and along coastlines. Here, we make the case that the Motus Wildlife Tracking System, an open-source, rapidly expanding cooperative automated radio-tracking global network (Motus, https://motus.org) provides an unprecedented opportunity to build an affordable and proven infrastructure that will boost wildlife biology research and connect Australian researchers domestically and with international wildlife research. We briefly describe the system conceptually and technologically, then present the unique strengths of Motus, how Motus can complement and expand existing and emerging animal tracking systems, and how the Motus framework provides a much-needed central repository and impetus for archiving and sharing animal telemetry data. We propose ways to overcome the unique challenges posed by Australia's ecological attributes and the size of its scientific community. Open source, inherently cooperative and flexible, Motus provides a unique opportunity to leverage individual research effort into a larger collaborative achievement, thereby expanding the scale and scope of individual projects, while maximising the outcomes of scant research and conservation funding. [ABSTRACT FROM AUTHOR]

Three-dimensional structure of vegetation plays a key role in animal ecology and the arrival of LiDAR technologies has given ecologists the ability to understand species-habitat relationships in increasing detail. However, few studies have investigated the trait-environment relationships that underpin diverse animal relationships with vegetation structure. We used terrestrial laser scanning (TLS) and acoustic bat surveys to investigate relationships between forest structure and bat communities across a vegetation structural gradient at community, species and trait levels. We developed 20 measures of site scale vegetation structure and also quantified landscape scale vegetation cover and water availability. We predicted that overall bat activity would increase in open and decrease in cluttered vegetation, but this would vary with species, underpinned by ecomorphological traits. Overall bat activity was negatively associated with stem density, with total activity halving (from 380 to 190 calls night − 1 ) as stem densities increased from 60 to 1350 stems ha − 1 , while foraging activity declined from 8 to < 1 feeding buzzes night − 1 over the same range. Bat activity varied among species and structures and foraging strategy explained more of this variability than call, body size or wing traits. As predicted, above-canopy and edge-space foraging bats were negatively associated with local-scale clutter, while closed-space species were positively associated with cluttered stands. Stem density was the strongest predictor of bat-environment relationships, although there was evidence for differences in bat habitat use across different structural elements. Our study is the first to link detailed LiDAR-derived 3D forest structural metrics to multiple animal traits. [ABSTRACT FROM AUTHOR]