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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

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 additio

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.

Floodplain wetlands are threatened worldwide by climate change, river regulation, pollution and vegetation clearing. Insectivorous bats are high trophic level terrestrial predators that potentially rely on availability of fresh water and aquatic prey subsidies of floodplains. In this thesis, I led a meta-analysis into continental scale relationships between Australian bats and wetlands. Next, I examined relationships between bat species, their prey and structural and flooding variables, in the Murray-Darling Basin Australia, using acoustic bat surveys and terrestrial laser scanning. Finally, I investigated the role of aquatic subsidies in floodplain bat diets using stable isotopes.The meta-analysis revealed that floodplain wetlands supported comparatively higher activity of bats than surrounding dry habitats and compared to wetlands in other ecoregions in Australia. In field surveys, bats were most active in rivers and lakes with open water and riparian trees where total activity, foraging activity and richness were 5, 12 and 1.5 times greater than dry vegetation respectively. Bat preference for open structure was apparent in managed flooded forests, with total activity in unthinned regrowth 60% lower than mature open forest and thinned regrowth. Insect biomass, however, was greater in regrowth compared to mature sites, indicating that forest structure was more important for bat habitat use than prey availability. Detailed surveys of vegetation structure revealed that bat activity was negatively associated with stem density, with total activity halving (from 380 to 190 calls per night) as stem densities increased from 60 to 1350 stems per ha, while foraging activity declined from 8 to < 1 feeding buzzes over the same range. Foraging strategy, rather than call or morphological traits, was the most important trait driving this relationship with forest structure, with edge-space bats negatively correlated with stem density, while closed-space bats were positively corre

Schemes designed to make farming landscapes less hostile to wildlife have been questioned because target taxa do not always respond in the expected manner. Microbats are often overlooked in this process, yet persist in agricultural landscapes and exert top-down control of crop pests. We investigated the relationship between microbats and measures commonly incorporated into agri-environment schemes, to derive management recommendations for their ongoing conservation. We used acoustic detectors to quantify bat species richness, activity, and feeding in 32 linear remnants and adjacent fields across an agricultural region of New South Wales, Australia. Nocturnal arthropods were simultaneously trapped using black-light traps. We recorded 91,969 bat calls, 17,277 of which could be attributed to one of the 13 taxa recorded, and 491 calls contained feeding buzzes. The linear remnants supported higher bat activity than the fields, but species richness and feeding activity did not significantly differ. We trapped a mean 87.6 g (±17.6 g SE) of arthropods per night, but found no differences in biomass between land uses. Wider linear remnants with intact native vegetation supported more bat species, as did those adjacent to unsealed, as opposed to sealed roads. Fields of unimproved native pastures, with more retained scattered trees and associated hollows and logs, supported the greatest bat species richness and activity. We conclude that the juxtaposition of linear remnants of intact vegetation and scattered trees in fields, coupled with less-intensive land uses such as unimproved pastures will benefit bat communities in agricultural landscapes, and should be incorporated into agri-environment schemes. In contrast, sealed roads may act as a deterrent. The "wildlife friendly farming" vs "land sparing" debate has so far primarily focussed on birds, but here we have found evidence that the integration of both approaches could particularly benefit bats.