Search

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]

Bat boxes are often installed as substitute habitats to offset the loss of large, hollow‐bearing trees. However, emerging evidence suggests that they are failing to achieve intended conservation outcomes as they only support generalist species. Despite these concerns, the effect of bat boxes on the dynamics of bat communities remains understudied. We assessed the bat community in reserves where bat boxes had been installed in comparison with reserves where they had not using ultrasonic surveys in 16 small bushland reserves throughout Sydney, Australia. Reserves containing bat boxes and those without had comparable species diversity and composition; however, the activity of the dominant species, Gould's wattled bat (Chalinolobus gouldii), was significantly higher at sites with bat boxes. Species that commonly forage in open vegetation, including C. gouldii, were significantly positively associated with sites that had bat boxes. Occupation of boxes by bats was not recorded in the study due to limited information on their locations, so further research is required to understand the direct effects of boxes and the bats that occupy them on the bat community. If bat boxes continue to be recommended as a biodiversity offset, a greater understanding of the potential impact they have on altered competitive relationships and community dynamics is essential. [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]

As a worldwide taxon inhabiting a diverse range of habitats and environmental conditions, bats also demonstrate some of the greatest variation in reproductive strategies of any mammalian order. Whilst monoestry is the predominant mating pattern of bats within the temperate zone, polyoestry and variants of this mode are more prevalent at tropical latitudes. As a tropical species occurring in a temperate climate in the southern extent of its range, the reproductive phenology of the golden-tipped bat (Phoniscus papuensis) is poorly understood. Here we present the first evidence of polyoestry in this species, an uncommon reproductive trait in Australian bats. The influence of weather and increase in prey density (orb-weaving spiders) are suggested as potential drivers for what appears to be a positive facultative breeding response to a pulse of resources. This observation demonstrates that there is still much to learn about the basic natural history and reproductive strategies of Australian bats. The reproductive traits in many Australian species of bat remain poorly known. We present the first evidence for multiple litters (polyoestry) in the golden-tipped bat. We discuss the tropical origins of golden-tipped bats and conditions which may have facilitated multiple births in the first breeding season following the 2019/2020 Black Summer fires. [ABSTRACT FROM AUTHOR]

Fire is a major disturbance for forests and its impacts can be complex, influenced by a range of factors including fire severity and frequency. Changes to global climate have increased the frequency and lengthened the window for wildfires. Anthropogenic fires are now commonly used to try to mitigate the risk and spread of wildfires or for ecological purposes, yet it is unclear how many flora and fauna species respond to this lower severity and more patchily distributed treatment. We assessed day-roost selection by a threatened narrow space bat, Nyctophilus corbeni, after a management burn left a mosaic of unburnt forest, low severity (ground scorch) burnt and higher severity (midstorey to crown scorch) burnt forest. Radio-tracking was used to identify day-roosts of 11 individuals (8 lactating females and 3 males) during the maternity season. Characteristics of day-roost trees (n = 42 trees) were similar for males and lactating females and were comparable to other day-roosts used elsewhere in the broader study area, with bats selecting moderately sized (23–24 cm dbhob) dead buloke (Allocasuarina luehmannii) with hollows. However, roost selection at the scale of the neighborhood varied by sex and was random for lactating females. Selection of the post-burn mosaic by males was non-random at all scales of assessment greater than a 100 m neighborhood, with bats selecting areas burnt by low-severity fire at these scales, but avoiding areas of higher severity fire. Locally, there were ~14 more hollow trees per ha surrounding roosts in areas burnt by low severity fire than in the unburnt forest, whereas forest burnt by higher severity fire had on average ~8 fewer hollow trees per hectare. Our study confirmed that dead buloke with hollows is a key resource for N. corbeni that should be prioritized for retention, particularly when identifying areas to offset habitat loss. Patchy management fires appear to be compatible with roosting habits of breeding N. corbeni, provided hollow resources are not impacted by fire. Management burns may promote roosting habitat for male bats, but areas of higher severity burns need to be minimized. Further research is needed to assess the use of the post-burn mosaic for nightly movements, including foraging. The effects of repeated burning on hollow availability and roost selection by N. corbeni should be investigated to identify suitable intervals between fires for this threatened species. [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]

Aim: Mega‐fires are predicted to increase with climate change. Australia experienced the largest ever documented forest fires in 2019–2020, but the response of most taxa remains poorly known. We used acoustic arrays to estimate impact of the mega‐fires on the density of an iconic marsupial. Location: North‐east New South Wales, Australia. Time period: Pre‐fire density estimated in 2018–2019 and post‐fire density in 2019–2020. Major taxa studied: Koala, Phascolarctos cinereus. Methods: We estimated male density before and after fires using large acoustic arrays and spatial count models. Acoustic arrays sampled three timber production forests with a gradient in fire severity and three unburnt controls in national parks. Results: Koalas were temporarily extirpated where high fire severity dominated the landscape, but some localized recovery was evident after 1 year. Where moderate severity fire dominated, density was reduced by about 50% within 1 year, but koalas were widespread throughout the burnt area. In our third area dominated by low severity fire, no impact was detected as pre‐ and post‐fire uncertainty intervals overlapped. Control sites surveyed at similar times showed little change in density between years. There was no relationship between pyrodiversity and koala density. Within arrays broadly dominated by moderate or high severity fire, density 1 year after fire was lower in burnt patches of both low and high severity fire. Regionally, 9.8% of landscape samples (2 km × 2 km) in koala habitat were dominated by high fire severity, while a further 6.1% were dominated by moderate fire severity, suggesting c. 13% decline in koala density. Main conclusions: A substantial impact of high severity fire was confirmed. Severe impacts were localized across the landscape, recovery had begun within a year and resilience was evident where low severity fire dominated. However, more frequent fires in the future will compound koala losses. [ABSTRACT FROM AUTHOR]

The 2021 annual forum of the Royal Zoological Society of NSW raked over the ashes of the unprecedented "Black Summer" bushfires of 2019–2020 in eastern and southern Australia to assess how forest ecosystems and their constituent fauna had fared. This paper provides an overview of the 21 studies that were presented at the forum, now as papers in this theme edition of Australian Zoologist. All the authors were unanimous in their agreement about the unparalleled extent and severity of the fires and the magnitude of their ecological impacts. Whereas much of the focus of the 2019–2020 fires was on vertebrates, significant research was also carried out on a diverse range of invertebrate taxa. The studies of the invertebrate groups found that different taxa respond variably to fire and also emphasised the difficulties in judging the full impact of the fires due to taxonomic impediments. An underlying theme in almost all studies was that long-term and broad-scale monitoring of fauna and faunal habitats is essential if we are to build a robust understanding of how animals respond to fire, and in turn how managers can mitigate the impacts of fire in future. Such monitoring will need to incorporate the effects of other disturbance factors, such as habitat fragmentation, drought, salvage logging and longwall mining, that interact with fire, and also trial new methods to track and assist fauna to cope with the changing fire regimes. Several studies advocated the use of novel and emerging technologies to achieve better monitoring of fauna, while others proposed mapping of large scale, as well as micro-refuges, to maximise fire resilience, or the use of supplementary resources such as nest boxes and artificial roosts to replace those lost in fires. We concur with all the authors that a critically important way to protect and manage our native fauna is through expanded and sustained research and monitoring programs, and by making the key results available to managers and policy makers via peer-reviewed publication. [ABSTRACT FROM AUTHOR]

A population of Yellow-bellied Glider Petaurus australis on the Bago Plateau, on the NSW south-western slopes, was first surveyed across 126 sites in 1995 and this subsequently became the baseline for further population monitoring. A subset of 48 sites was resurveyed in 2010, and about one third of the sites (~40) were surveyed annually on a rotating panel between 2013–2019. Wildfire significantly impacted the Bago Plateau during 2020 and 51 sites were resurveyed post-fire in 2020/21. An occupancy modelling approach was used to estimate trends in occupancy between 1995 and 2020/21, including the influence of various covariates. Initial occupancy was positively associated with the extent of Montane Gums and mixed Wet Peppermint/Montane Gum forest types within a 450 m radius of the survey site. Supported models revealed that colonisation over time was positively associated with the density of hollow-bearing trees at a site, while extinction was positively associated with the extent of high severity wildfire at a site. Despite wide confidence intervals, the long-term occupancy trend showed a stable to slight increase between 1995 and 2019, but a ~26% reduction following wildfire. The increasing trend occurred despite a long-term rainfall deficit that was punctuated by occasional above average years during the survey period. There was no evidence that timber harvesting influenced occupancy by the gliders, although harvesting is predominantly focused within stands containing Alpine Ash Eucalyptus delegatensis, with monospecific stands generally avoided by the glider. [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]

In Australia, there are at least 50 000 derelict mines, many of which provide habitat for cave-roosting bats. Grating of derelict mines, be it horizontal (adits) or vertical (shafts) drives, is commonly undertaken to prevent human access, though longer-term responses of bats are largely unknown. We assessed the long-term (2–20 years) effects of grating on bats by documenting trends in emergence activity and bat abundance at grated and ungrated derelict mines and quantified behavioural responses of bats in autumn and winter. Emergence activity was dominated by the eastern horseshoe bat (Rhinolophus megaphyllus) with limited activity of other less manoeuvrable species. Both emergence activity and minimum colony size at horizontal adits were 8–9 times greater than at vertical shafts, with bats observed emerging from only 2 of 13 shafts. Emergence activity and minimum colony size were 7–10 times greater at adits with 'bat friendly' grating (horizontal bars with spacing >125 mm) than at other treatments (ungrated adits and adits with standard grating). In winter, there were 4–11 times more aborted exit attempts per bat at adits with 'bat friendly' grating compared with other treatments, which corresponded to greater emergence activity. Emergence activity and minimum colony size were not related to spacing between bars or time since grating, indicating rapid habituation by R. megaphyllus. However, circling at grates continued for many years and bentwing bats (Miniopterus spp.) made little use of these sites. Bat-friendly grates appear to be an effective management option for R. megaphyllus , but alternatives need to be trialled for other species. Derelict mines can provide habitat for cave-roosting bats but are often grated to prevent human access, with little known about the long-term responses of bats. We assessed the long-term effects of grating on bats and found that although there was rapid habituation to grated mines, altered flight behaviour was present decades after grating and there was little use of these sites by threatened species. This suggests that alternative management of derelict mines is required to conserve threatened bat roosting habitat. Photo by Leroy Gonsalves. [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]

Bat boxes are frequently used as conservation and habitat-offset measures, yet their effectiveness is equivocal, particularly in Australia. Boxes used in Australia are largely voluminous-type boxes with Chalinolobus gouldii (Gould's wattled bat) frequently dominating their use. We tested multichambered boxes comprising fissure-type cavities made from either plywood (~20 000 cm3) or woodcement (~7400 cm3). We investigated whether occupancy was influenced by box colour (white boxes facing morning sun versus black boxes facing afternoon sun), box material/size, chamber width (15 mm versus 20 mm) and box host (tree versus pole). Boxes were monitored over 1.8 years. Overall, 245 bat observations were recorded. Boxes were frequently used (15% of 1088 box checks) by Nyctophilus geoffroyi (lesser long-eared bat), a species uncommonly reported to use boxes, which used 50 of the 64 boxes (78%), including for maternity roosting (n = 6). In comparison, C. gouldii was rarely detected (1% of box checks). Two other species were also found in boxes at low frequencies. Modelling showed a preference by N. geoffroyi for black boxes, the larger plywood box and boxes installed on poles. Fissure-type boxes appear to meet the roost requirements of N. geoffroyi but not that of C. gouldii , the species principally detected in voluminous-type boxes and postulated to gain a competitive advantage. The black woodcement box was the second most frequently used design, demonstrating that this long-lasting box material can be a suitable alternative to the less durable plywood material. Given that just one species commonly used boxes, there is a need for further research on box designs. The frequent use of bat boxes as conservation and habitat-offset tools has outpaced the research required to implement bat box programs effectively. We tested narrow-chambered boxes. These boxes were attractive for Nyctophilus geoffroyi (lesser long-eared bat) but not for Chalinalobus gouldii (Gould's wattled bat), a species postulated to gain a competitive advantage where voluminous-type boxes are installed. N. geoffroyi showed a preference for warm boxes and the plywood box. Given that just one species commonly used the tested boxes, there is a need for further research on box designs. [ABSTRACT FROM AUTHOR]

Bat boxes frequently form part of hollow‐bearing tree offsets; however, their effectiveness is poorly documented. We investigated the effectiveness of a bat box program designed to partially offset tree hollow loss from clearing for a coal mine. During the first year of monitoring, we detected bats in 5% of 1,308 box checks. Only 3 of 13 local tree cavity‐roosting bat species/species groups used boxes and occupancy was not strongly associated with modeled box and site attributes. In the second year, we tested two hypotheses that may explain the relatively low box use: (1) solar exposure of boxes was inadequate for heterothermic bats and (2) available box designs were of low suitability. Relocating boxes to increase solar exposure did not increase use, or enhance the temperature profiles of relocated boxes. Introduction of a new box design led to 11 times higher use compared with existing designs for Nyctophilus spp. (long‐eared bat). Overall, our data suggest that the bat box program was ineffective due to few bat species using boxes, infrequent box use by three species, and rarity of maternity roosting. The knowledge gap of species‐specific box designs and roosting ecology limits the effectiveness of boxes to offset cleared hollow‐bearing trees. Lack of knowledge and the widespread use of bat boxes to offset lost tree hollows highlights the need to (1) rigorously protect hollow‐bearing trees and (2) advance our understanding of species‐specific roost ecology, box design preferences and mechanical hollow creation into trees, before artificial hollows can be considered a meaningful offset measure. [ABSTRACT FROM AUTHOR]

Context. Tree cavities suitable to rear young are a key resource in managed landscapes to support viable populations of tree cavity-roosting bats. Little is known about the selection of cavities for maternity roosts, presumably because of the difficulty in accessing such roosts. Aims. Our study investigated physical and microclimate characteristics of maternity roosts of two species, namely, Gould's long-eared bat (Nyctophilus gouldi) and little forest bat (Vespadelus vulturnus). Methods. Maternity-roost cavities were identified in a timber-production landscape in south-eastern Australia. Roost trees (V. vulturnus n=5; N. gouldi n=9) and a subsample of available cavity-bearing trees (n=16) were climbed to obtain cavity characteristics. Key results. Vespadelus vulturnus used tree hollows exclusively, whereas N. gouldi used both tree hollows (n=7) and thick loose bark (n=2). No significant difference in roost-cavity characteristics was detected between the species. However, V. vulturnus selected significantly narrower cavity entrances (mean: 16±3 mm) than those of the available cavities. Temperature did not differ between maternity roosts and available cavities when investigated after the maternity season. However, a V. vulturnus maternity roost occupied for 33 consecutive days was warmer than mean roost and available cavities, suggesting that long-term roost use may be influenced by the thermal property of a cavity. Conclusions. Our study has provided the first detailed tree-cavity description of maternity roosts of N. gouldi and V. vulturnus. The nightly roost switching and the large variation of tree-cavity characteristics used by N. gouldi suggest that this species requires a high density of non-specific tree cavities that are large enough for colony formation, whereas preferred roost cavities for V. vulturnus are likely to be hollows comprising narrow entrances that facilitate long-term use. Implications. Our results highlighted the likely importance of narrow roost entrances for V. vulturnus, presumably for predator protection, and the conservation of tree cavities large enough for colonies to congregate. The formation of such hollows is likely to take many decades. Poor silvicultural practices, land clearing and inappropriate management of veteran trees have the potential to have an impact on this hollow resource. Our study also highlighted the need to further assess the importance of cavity microclimate for maternity-roost selection in warm climates. [ABSTRACT FROM AUTHOR]

The introduction to this special issue of the Journal on Bat Research in Australasia (Part 2) provides an overview of the papers in the issue. [ABSTRACT FROM AUTHOR]

Understanding maternity roost requirements is fundamental to guide timber production forest management given such roosts are vital to sustain bat populations. We tracked lactating females of three tree cavity-roosting species: Gould's long-eared bat (Nyctophilus gouldi) (n = 7), eastern broad-nosed bat (Scotorepens orion) (n = 6) and little forest bat (Vespadelus vulturnus) (n = 25), over five weeks in young (predominately <5 years old) forest regenerating from heavy timber harvest in southeast Australia. We aimed to investigate interspecific maternity roost selection in a regenerating landscape and by doing so, increase our understanding of the three species’ roost ecology. Sixteen V. vulturnus, 15 N. gouldi and six S. orion unique maternity roost trees were located. Bats displayed a degree of maternity roost selection plasticity, however, interspecific differences were found. Nyctophilus gouldi roosted selectively in retained riparian buffers, in trees of high senescence and switched roosts every day. Vespadelus vulturnus roosted in logged areas and displayed high roost site fidelity, with one roost used for 33 consecutive days. Scotorepens orion selected large live trees of low senescence. The preliminary data for this species suggests that females roost most days in ‘primary’ roosts but display a roost switching behaviour conforming to the fission-fusion model. Dead trees were identified to be important for both N. gouldi and V. vulturnus. Historical and recent logging at our study area drastically reduced cavity-bearing tree density to 1.4 trees per hectare in the logging zones (outside of exclusion areas), potentially limiting local populations of tree cavity-roosting bats and other cavity-dependent wildlife. Our data demonstrate that forest management must consider a range of maternity roost requirements to accommodate differences among species and highlight the importance of exclusion areas for roost habitat. We propose that an expanded ‘retention forestry’ approach should be implemented in logged areas that includes in-perpetuity forest patch retention to increase habitat complexity and continuity. [ABSTRACT FROM AUTHOR]

The Large-footed Myotis Myotis macropus is a threatened echolocating bat that uses a specialised 'trawling' foraging strategy to hunt for aquatic prey. While the species is well known in freshwater habitats, in 2014 it was recorded for the first time roosting and foraging in a sheltered bay on Sydney Harbour in the Port Jackson estuary. To investigate how widely distributed M. macropus was within the estuary (Parramatta River, Lane Cove River, Middle Harbour, harbour islands, west Harbour and east Harbour), 56 sampling sites were surveyed acoustically. Of these sites, 24 were in harbour bays/coves, 20 were in tributary bays, seven were along tributary channels/creeks, four were on the margins of harbour islands and a single site was located on a freshwater lake. We also investigated relationships between M. macropus activity and environmental variables to identify those that should be targeted for management. Radio-tracking of M. macropus at one known roost was carried out to assess roost fidelity and identify key foraging areas within the estuary. Myotis macropus was widespread in Port Jackson, being present at 92.6 % of sites, but with high activity (>90 passes night−1), including feeding buzzes (≥24.5 buzzes night−1) concentrated in a few 'hot spots'. Greatest activity was recorded in east Harbour (~70 passes night−1), west Harbour (~15.5) and Lane Cove River (~14), while lowest activity was on the Parramatta River (2) and Middle Harbour (10). Activity, including feeding, was significantly greater in harbour bays/coves when compared with other habitats. Radio-tracking revealed that bats roosting in west Harbour showed 100 % fidelity to the roost site over a three week period and were only recorded foraging in this zone and the nearby (1.2 km) Lane Cove River. Historical Zinc concentrations in surficial sediments was negatively associated with M. macropus activity, though heavy metals were also correlated positively with total suspended solids (TSS). While heavy metal concentrations in sediments were not associated with feeding activity, increased TSS was negatively associated with M. macropus activity and feeding. Best subsets regressions found that M. macropus activity was associated with TSS (−ve), mangrove cover (+ve), seagrass cover (+ve) and total water extent (−ve). We recommend further research on the negative association between TSS, heavy metals and M. macropus activity to identify the sensitivity of this species to past and present pollution events. [ABSTRACT FROM AUTHOR]

Anthropogenic noise is a concern in many ecological systems. One important source of noise pollution is traffic noise as it can dominate the soundscape in urban and peri-urban environments. Taxa that rely on acoustics for behavioural strategies are likely to be especially susceptible to noise, as noise can inhibit the perception of informational sounds. Bats use echolocation to hunt prey while foraging and are therefore prime candidates for adverse effects. Captive studies have shown that foraging efficiency can be significantly reduced in noisy environments for some bat species, and that these species actively avoid noisy areas. However, it remains unclear how this selective sensitivity manifests in urban environments. Given that mode of flying and use of echolocation is entwined with foraging strategies, we hypothesised that different foraging guilds (i.e. fast flyers versus slow flyers) may show different levels of sensitivity to noisy roads. We used transects running perpendicular to a major traffic route in Sydney, Australia, to record bat activity and traffic noise levels. Noise amplitude levels across each frequency band dropped by over 50% in the first 50 m, with high frequency components ( > 10 kHz) being especially soft at this distance. Furthermore, all traffic noise above 5 kHz was lost within the first 150 m from the road. Fast flying bats flew close to the road, despite the traffic noise. In contrast, slow flying species appeared to fly more often away from the road. However, few calls of slow flyers were recorded, probably reflecting their difficulty in detecting them using acoustic surveys as well as their earlier decline in these peri-urban environments. [ABSTRACT FROM AUTHOR]

The need to develop effective management strategies for insectivorous bat populations requires an understanding of factors influencing habitat use. Availability of pest prey, such as mosquitoes is likely to be one such factor. To assess whether this is the case, we radio-tracked Vespadelus vulturnus Thomas (little forest bat), a predator of Aedes vigilax Skuse (saltmarsh mosquito), in saltmarsh and adjacent coastal swamp forest during periods of high and low Ae. vigilax abundance. When mosquito abundance in structurally-open saltmarsh was similar to the more cluttered coastal swamp forest, use of saltmarsh by V. vulturnus was disproportionately greater than its availability, with saltmarsh selected preferentially for foraging. However, at times of low Ae. vigilax abundance in saltmarsh, use of saltmarsh by V. vulturnus was reduced and all habitats were used in proportion to availability in the study area. This is the first radio-tracking study to demonstrate a shift in foraging range by an insectivorous bat species correlated with fluctuations in the distribution and abundance of a particular prey resource. The shift in foraging range by V. vulturnus, corresponding with a spatio-temporal variation in abundance of Ae. vigilax highlights the importance of mosquitoes as a dietary item. Broadscale pest control of Ae. vigilax may have ecological implications for the diet and habitat use of V. vulturnus. An adaptive management approach is proposed, whereby careful monitoring of insectivorous bat populations is recommended before and after any application of broadscale mosquito control measures. We also suggest a precautionary approach is taken such that broadscale control of mosquitoes avoids the lactation period of bats, a time when their energetic demands are greatest and when there is reduced risk of contracting mosquito-borne diseases transmitted by Ae. vigilax. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Floodplain ecosystems across the world have declined with river regulation and floodplain development, reducing flood frequency and extent and fragmenting flood-dependent vegetation. There is growing evidence that these changes to flooding disproportionately affect terrestrial taxa, such as bats. We compared bat activity and insect abundance across the floodplain mosaic (river, lake, vegetated wetland, floodplain forest, floodplain woodland) representing decreasing flooding histories, and two dry habitats (dry vegetation, agricultural). We replicated these habitats in each of six floodplain systems of the Murray-Darling Basin, a large semi-arid river basin (1,042,730 km 2 ) in south-eastern Australia. Our sites were spread across > 400,000 km 2 , traversing climatic and hydrological gradients. Rivers and lakes with open water and riparian trees had greater total activity (5 times), foraging activity (14 times) and bat richness (1.5 times) than dry vegetation. Activities of all mesic bat species, as well as some widespread and arid-adapted bat species, were positively associated with floodplain habitats when compared with dry vegetation. Lowest overall total activity, foraging activity and richness were observed in dry agricultural (cropping, grazing and fallow) habitats, with two of six threatened species in our study area never recorded in agricultural habitats. Prey abundance was not correlated with bat activity or habitat. The mosaic of floodplain habitats appears to be of disproportionate value for bat communities compared to dominant land covers of agricultural and dry vegetation. Loss of floodplain habitats through continued river regulation and floodplain development are likely reduce diversity and abundance of bats that rely on floodplains for foraging and roosting. Lags in bat roost formation and forest structure mean these changes could take over a century to reverse. To sustain bat communities, we recommend increasing environmental flows to floodplains during the bat lactating season, implementing stronger protection of floodplains from river regulation and floodplain development and where possible, restoring floodplains affected by agriculture into functioning wetlands. [ABSTRACT FROM AUTHOR]

Insectivorous bats have often been touted as biological control for mosquito populations. However, mosquitoes generally represent only a small proportion of bat diet. Given the small size of mosquitoes, restrictions imposed on prey detectability by low frequency echolocation, and variable field metabolic rates (FMR), mosquitoes may not be available to or profitable for all bats. This study investigated whether consumption of mosquitoes was influenced by bat size, which is negatively correlated with echolocation frequency but positively correlated with bat FMR. To assess this, we investigated diets of five eastern Australian bat species (Vespadelus vulturnus Thomas, V. pumilus Gray, Miniopterus australis Tomes, Nyctophilus gouldi Tomes and Chalinolobus gouldii Gray) ranging in size from 4-14 g in coastal forest, using molecular analysis of fecal DNA. Abundances of potential mosquito and non-mosquito prey were concurrently measured to provide data on relative prey abundance. Aedes vigilax was locally the most abundant mosquito species, while Lepidoptera the most abundant insect order. A diverse range of prey was detected in bat feces, although members of Lepidoptera dominated, reflecting relative abundance at trap sites. Consumption of mosquitoes was restricted to V. vulturnus and V. pumilus, two smaller sized bats (4 and 4.5 g). Although mosquitoes were not commonly detected in feces of V. pumilus, they were present in feces of 55 % of V. vulturnus individuals. To meet nightly FMR requirements, Vespadelus spp. would need to consume ~600-660 mosquitoes on a mosquito-only diet, or ~160-180 similar sized moths on a moth-only diet. Lower relative profitability of mosquitoes may provide an explanation for the low level of mosquito consumption among these bats and the absence of mosquitoes in feces of larger bats. Smaller sized bats, especially V. vulturnus, are likely to be those most sensitive to reductions in mosquito abundance and should be monitored during mosquito control activities. [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]

Coastal lagoons provide key habitat for a wide range of biota but are often degraded by intense urbanization pressures. Insectivorous bats use these highly productive ecosystems and are likely to be impacted by their decline in quality. We compared bat activity and richness and invertebrate biomass and richness across a gradient of lagoon quality (9 lagoons) in the Greater Sydney region, Australia to determine the extent to which bats and their prey were impacted by lagoon degradation. Bats were more diverse and 19 times more active at higher quality lagoons. The trawling bat, Myotis macropus , was absent from all low quality lagoons, but these lagoons were used by other species such as Miniopterus schreibersii oceanensis . Invertebrate richness and biomass did not differ significantly across lagoon quality. We examined potential mechanisms of insectivorous bat decline at degraded lagoons by measuring toxic metal concentrations in bat fur, invertebrates and sediment. Lead and zinc were detected at environmentally significant levels in the sediments of lower quality lagoons. Furthermore, lead concentrations were 6 times the lowest observable adverse effects level for small mammals in the hair of one individual M. macropus . The present study demonstrates that coastal lagoons support a rich bat community, but ongoing development and pollution of these habitats is likely to negatively impact on insectivorous bat species, especially trawling species. [ABSTRACT FROM AUTHOR]