Locating colonies of rare bats can be a time consuming process, as it is often difficult to know where to focus survey effort. However, identifying peaks of bat activity via acoustic monitoring may provide insights into whether a colony is locally present, and help screen out sites with low potential. Using a triage approach, we developed a survey methodology for locating colonies of the woodland-specialist barbastelle bat (Barbastella barbastellus). We investigated whether woodland occupancy by a colony could be predicted by acoustic data, and assessed the influence of survey effort (number of acoustic detectors deployed) on detectability. The methodology was then trialled in citizen science surveys of 77 woodlands, with follow-up radio-tracking surveys by specialists being used to confirm presence or absence. Using Receiver Operating Characteristic (ROC) curve analysis, we found that a threshold of four barbastelle passes recorded by at least one detector within one hour of sunset optimised the balance between the true- and false-positive rates. Subsequently, we found that a minimum survey effort of one detector per 6.25 hectares of woodland was needed to ensure a colony would be detected using this threshold, based on a survey sensitivity of 90%. Radio-tracking surveys in a subset of the woodlands, identified as having a high probability of being occupied by a colony based on acoustic monitoring, confirmed the presence of five previously unknown barbastelle maternity colonies. These results demonstrate that a triage system, in which high probability woodland sites are identified based on acoustic survey data, can be used to prioritise sites for future specialist surveys and conservation action.

The greater horseshoe bat Rhinolophus ferrumequinum is a rare species in the UK that relies heavily on undisturbed stone buildings in which to breed. Barn owls Tyto alba are also a protected species that roost and raise their broods in similar places. This overlap in roosting requirements can lead to barn owls moving into buildings containing well-established greater horseshoe bat maternity colonies. This in turn could result in disturbance and abandonment of the building by the bats. Such an event occurred at one of the largest greater horseshoe bat roosts in the UK in 2018 when the colony deserted the roost after barn owls moved in. We describe measures used to exclude the owls while retaining access for the bats, to encourage the colony to return. The suite of modifications consisted primarily of wooden baffles and smooth surfaces on the entrances and doorways. Monitoring showed that the interventions were effective in excluding barn owls whilst allowing bats to access the building. Exclusion of the owls resulted in the return of the greater horseshoe bat colony in similar numbers to 2017 when owls were absent (2022: 92% of the adults) and breeding resumed (2022: 93% of the juveniles in 2017). This paper is the first to evaluate the before and after effects of protecting a bat roost from disturbance or predation by other species.

After a significant population decline during the 20th century, populations of both greater and lesser horseshoe bats have increased over recent decades in Britain and populations of lesser horseshoe bats have increased in Ireland. Vincent Wildlife Trust (VWT) acquired 37 bat reserves since the 1980s with the aim to safeguard the sites and enhance the roosting and hibernation conditions in buildings that were often derelict and sub-optimal for bats. These measures have resulted in a strong population size increase of all colonies. However, populations have also been increasing throughout Britain and Ireland as a consequence of legal protection and milder winters resulting in higher survival rates. Therefore, it is not clear whether the measures that have taken place in VWT reserves have led to a greater increase than roosts that have not benefited from the same type of management. We aimed to compare population trends of horseshoe bat roosts under VWT management and non-VWT management from 1999 to 2020 in order to assess its effectiveness. For this, we analysed population trends at sites under different management types (VWT and non-VWT) for lesser horseshoe bats in Britain and Ireland and greater horseshoe bats in Britain. Our results indicated that populations in Britain under VWT management have increased by 366% (CI 225% - 580%) for greater horseshoe bats and 188% (CI 125% - 283%) for lesser horseshoe bats. Roosts that did not benefit from the same levels of management increased respectively by 164% (CI 132% - 199%) and 51% (CI 40% - 60%). In Ireland, populations of lesser horseshoe bats in VWT managed roosts increased by 217% (CI 118% - 364%) while non-VWT managed roosts remained stable (-0.44%; CI -23% - 29%). We conclude that management actions carried out by VWT of greater and lesser horseshoe bat roosts have helped populations recover at a faster rate by securing the integrity of buildings, improving access points and by providing optimal microclimatic conditions within the buildings.

Bats are highly social animals, and the interactions between individuals are likely to be important to their ecology and conservation. Social structures are affected by the physical environment (spatial factors), as well as varying over time and seasons (temporal factors). Compared with many other taxa, individual bats are capable of moving large distances, so experience a range of spatial locations. They have long life spans, providing opportunities to interact with others over a long period, and are often highly gregarious. Using a long-term data set, we examined the social behaviour, along with spatial and temporal influences, of greater horseshoe bats, Rhinolophus ferrumequinum, during hibernation using social network approaches. Across 17 years, 2808 individuals were monitored, yielding a total of 5952 records at 21 roost locations. We investigated how individuals' life history traits (sex, age and breeding status of females) and the frequency of observation affected social associations and identified factors that influenced the movement of individuals between locations. Older and male animals were significantly more central in the social network, and adult males may act as a link between socially separate individuals within the society. The social network had high nonrandom dyadic structuring, with assortment by age stronger in females than males, and this was likely to be influenced by spatiotemporal factors. In general, higher weighted betweenness scores were recorded in a noncore hibernaculum, suggesting that these sites, despite low numbers of bats being present, may act as locations to connect less-connected individuals, as well as communities. Finally, movements between hibernacula were only associated with the frequency of observation rather than any life history trait. These results illustrate the interconnectivity across sites, stressing the need for appropriate cross-jurisdiction species management plans to be created for species that utilize and move between multiple sites within the landscape. (c) 2022 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour.

Evidence-based approaches are key for underpinning effective conservation practice, but major gaps in the evidence of the effectiveness of interventions limit their use. Conservation practitioners could make major contributions to filling these gaps but often lack the time, funding, or capacity to do so properly. Many funders target the delivery of conservation and can be reluctant to fund primary research. We analysed the literature testing the effectiveness of interventions. Of a sample of 1,265 publications published in 2019 that tested conservation interventions, 96% included academics. Only 21% included conservation practitioners, of which just under half were first or last author. A community of conservation funders and practitioners undertook a series of workshops to explore means of improving the quality and quantity of intervention testing. A survey of the suggested proportion of conservation grants that should be allocated to testing intervention effectiveness showed practitioners tended to prefer larger percentages (median 3–6%) than funders (median 1–3%), but the overlap was considerable. Funders can facilitate the testing of interventions through a range of measures, including welcoming applications that incorporate testing, allocating funds to testing, and providing training and support to deliver testing. The funders represented by the authors of this paper have committed to these actions. Practitioners can contribute by committing to routine testing, benefiting from funding allocated specifically to testing, and establishing processes for testing interventions. The organisations of the practitioner authors have committed to test at least one intervention per year and share findings, regardless of outcome. Currently, practitioners rarely lead the testing of conservation actions. We suggest processes by which both funders and practitioners can make this routine. This will not only improve the effectiveness and cost-efficiency of practice, but also make conservation more attractive to funders.

Context Habitat suitability models (HSM) have been used to understand the impacts of landscape-scale habitat connectivity and gene flow mostly by assuming a regular decrease in the cost of movement as habitat improves. Yet, habitat selection and gene flow are governed by different behavioural processes which may limit the reliability of this approach as individuals are likely to disperse through unsuitable habitat for breeding. Objectives The aim of this study was to identify the optimal relationship between gene flow and HSMs for two bat species (Myotis bechsteinii and Eptesicus serotinus) in Britain by testing a range of nonlinear negative exponential functions for the transformation of HSMs into resistance surfaces. Methods We modelled habitat suitability using a hierarchical, multi-level approach that integrates models across three nested levels. Then, we measured the relationship between published genetics data of both species and six negative exponential transformations of the predicted outputs. Results The two most extreme transformations provided the best fit to genetic data for both M. bechsteinii (c = 32; R-2 = 0.87) and E. serotinus (c = 16; R-2 = 0.42). The negative linear transformations had the poorest fit. Conclusions These results suggest that bats are able to disperse through areas of poor habitat for breeding, but will avoid the most unsuitable areas. We recommend comparing multiple transformations of HSMs at different resolutions to gain a more accurate representation of gene flow across heterogeneous landscapes and to inform cost-effective, targeted management.

Abstract Molecular approaches to calculate effective population size estimates (Ne) are increasingly used as an alternative to long‐term demographic monitoring of wildlife populations. However, the complex ecology of most long‐lived species and the consequent uncertainties in model assumptions means that effective population size estimates are often imprecise. Although methods exist to incorporate age structure into Ne estimations for long‐lived species with overlapping generations, they are rarely used owing to the lack of relevant information for most wild populations. Here, we performed a case study on an elusive woodland bat, Myotis bechsteinii, to compare the use of the parentage assignment Ne estimator (EPA) with the more commonly used linkage disequilibrium (LD) Ne estimator in detecting long‐term population trends, and assessed the impacts of deploying different overall sample sizes. We used genotypic data from a previously published study, and simulated 48 contrasting demographic scenarios over 150 years using the life history characteristics of this species The LD method strongly outperformed the EPA method. As expected, smaller sample sizes resulted in a reduced ability to detect population trends. Nevertheless, even the smallest sample size tested (n = 30) could detect important changes (60%–80% decline) with the LD method. These results demonstrate that genetic approaches can be an effective way to monitor long‐lived species, such as bats, provided that they are undertaken over multiple decades.

Increasing levels of road noise are creating new anthropogenic soundscapes that may affect wildlife globally. Bats, which form about a third of all mammal species, are sensitive bioindicators, and may be particularly vulnerable because of their dependency on echolocation. Here we present the first controlled field experiment with free-living bats. Using a Before-After-Control-Impact phantom road experimental design, we examine the impacts of traffic noise on their activity and feeding behaviour. Disentangling the impacts of traffic noise from other co-varying exposures such as habitat quality, the experiment demonstrates a significant negative effect on the activity of each of the five, ecologically different, species (genus for Myotis spp.) examined. This suggests that the results are widely applicable. The negative effects are largely attributable to noise in the sonic spectrum, which elicited aversive responses in all bat species tested,whereas responses to ultrasoundwere restricted to a single species. Our findings demonstrate that traffic noise can affect bat activity at least 20m away from the noise source. For Pipistrellus pipistrellus and Pipistrellus pygmaeus, feeding behaviour, as well as overall activity, was negatively affected. Ecological Impact Assessments are therfore needed wherever there are significant increases in traffic flow, and not just when new roads are built. Further research is required to identify effective mitigation strategies, to delineate the zone of influence of road noise, and to assess whether there is any habituation over time.

Abstract Monitoring postrelease establishment and movement of animals is important in evaluating conservation translocations. We translocated 39 wild pine martens Martes martes (19 females, 20 males) from Scotland to Wales. We released them into forested areas with no conspecifics in 2015, followed by a second release in 2016, alongside the previously released animals. We used radio‐tracking to describe postrelease movement and habitat selection. Six martens (15%) were not re‐encountered during the tracking period, of which four undertook long‐distance dispersal. For the remaining individuals, we characterized two phases of movement, “exploration” followed by “settlement,” that differed between releases. In the first release, martens remained in exploration phase for a mean of 14.5 days (SE = 3.9 days) and settled at a mean distance of 8.7 km (SE = 1.8 km) from release sites, whereas martens released in year two, alongside resident conspecifics, traveled away from release sites at a faster rate, settling sooner, at a mean of 6.6 days (SE = 1.8 days), but further, at a mean distance of 14.0 km (SE = 1.7 km) from release sites. Animals released in year one did not exhibit habitat preferences overall but within forests they favored recently felled areas, whereas animals released in year two showed strong selection for forested habitat but did not discriminate between forest types. The presence of conspecifics appeared influential for settlement and site fidelity of translocated martens and was associated with more rapid but more distant dispersal of the later cohort. Releases of animals in close proximity appeared to promote site fidelity and rapid establishment of ranges in the recipient environment.

Following nineteenth-century declines, polecats Mustela putorius are recolonising Great Britain. Polecat diet relates to two potential risks to recovery. First, rabbits Oryctolagus cuniculus , which are important prey for polecats, have experienced extreme population fluctuations, with near extirpation due to myxomatosis in the 1950s, recovery in 1960s–1990s and declines in 1990s–2010s. Second, polecats are secondarily exposed to anticoagulant rodenticides by eating contaminated rodents, and the frequency of polecat exposure to rodenticides is increasing. We analysed stomach contents from 99 polecats collected in 2012–2016 and compared results with earlier studies. Lagomorphs were the most abundant prey (66% frequency of occurrence, 95% confidence interval 53–74%), followed by other mammals (12%, 4–18%), amphibians (10%, 3–16%) and birds (7%, 1–13%). Diet varied seasonally; lagomorph occurrence was highest in spring and summer and lowest in autumn. Dietary niche breadth was greater in the 1960s, when rabbits were scarce, than in other decades, but did not differ between the 1990s and 2010s, indicating that diets have not diversified with recent rabbit declines. This may be because rabbit abundance is not yet low enough to cause dietary diversification or because polecats were collected in areas where rabbits were still abundant. Rodents did not increase in diet between the 1990s and 2010s and still occur with < 10% frequency, indicating that rodents need not contribute much to diet to expose polecats to rodenticides. This potentially limits the effectiveness of management actions designed to minimise polecat exposure to contaminated rodent prey.

1. Bats are important components of agricultural ecosystems. However, little is known about the extent to which bats use linear features when foraging and commuting in agricultural settings, when compared to the interior of fields. 2. As part of a large-scale citizen science project, bat detectors were placed in the centre of agricultural fields (arable and pasture) and along linear features (intensively managed hedgerows, sympathetically managed hedgerows and treelines). 3. Our results show that all 10 of the bat species groups identified were found both along linear features and in the middle of agricultural fields. Of the five species groups analysed further, all had significantly more bat activity along linear features compared to the middle of fields, except for Nyctalus noctula. However, our results showed that 29% of calls from Rhinolophus ferrumequinum were recorded in the middle of agricultural fields, compared to only 10% for Pipistrellus pipistrellus. Bat activity was more likely to be associated with treelines compared to other linear feature types. 4. Our results highlight the importance of linear feature management to bat conservation, but also the need to consider field centres during survey design and Environmental Impact Assessments.

Context The importance of habitat connectivity for wildlife is widely recognised. However, assessing the movement of species tends to rely on radio-tracking or GPS evidence, which is difficult and costly to gather. Objectives To examine functional connectivity of greater horseshoe bats (GHS, Rhinolophus ferrumequinum ) at a local scale using Circuitscape software; comparing our results against expert opinion ‘fly ways’. Methods Expert opinions were used to rank and score five environmental layers influencing GHS movement, generating resistance scores. The slope and resistance scores of these layers were varied, and validated against independent ground truthed GHS activity data, until a unimodal peak in correlation was identified for each layer. The layers were combined into a multivariate model and re-evaluated. Radio-tracking studies were used to further validate the model, and the transferability was tested at other roost locations. Results Functional connectivity models could be created using bat activity data. Models had the ability to be transferred between roost locations, although site-specific validation is strongly recommended. For all other bat species recorded, markedly more (125%) bat passes occurred in the top quartile of functional connectivity compared to any of the lower three quartiles. Conclusion The model predictions identify areas of key conservation importance to habitat connectivity for GHS that are not recognised by expert opinion. By highlighting landscape features that act as barriers to movement, this approach can be used by decision-makers as a tool to inform local management strategies.

It is often difficult to compare studies examining the effects of endectocides on dung fauna because of different experimental approaches, for example, active ingredients (eprinomectin, doramectin, ivermectin, moxidectin) and formulations (injectable, pour-on, spiked). To gain a better understanding, we performed a quantitative meta-analysis using 22 studies to assess the overall effect of endectocide residues on the occurrence (presence or absence) and abundance of aphodiine dung beetles. Our results document a positive effect on the occurrence of adult beetles, indicating that adults tend to be attracted to dung with residues. Conversely, larvae are less likely to occur in the presence of residues. Thus, either adults that colonize dung with residues do not lay eggs or, more likely, the larvae that hatch from these eggs die early in development. Abundance of adult and larval stages was shown to be significantly reduced in dung containing residues. When individual endectocides were compared, only ivermectin demonstrated a significantly negative effect on the abundance of both adults and larvae, possibly owing to a small sample size for other agents. In laboratory studies, only dung "spiked" with endectocides reduced the abundance of larvae, whereas during field research, only pour-on applications were shown to reduce the abundance of larvae. The present study further documents the nontarget effects of endectocide residues on dung-dwelling organisms, provides robust evidence on the consequences of different application methods, and emphasizes the need for standardized methodological techniques in future studies. Environ Toxicol Chem 2020;39:863-872. © 2020 SETAC.

Detection and monitoring of extant bat populations are crucial for conservation success. Non-invasive genetic analysis of bat droppings collected at roosts could be very useful in this respect as a rapid, costefficient monitoring tool. We developed species-specific real-time PCR assays for 18 British and Irish bat species to enable non-invasive, large-scale distribution monitoring, which were then applied to a field survey in Ireland. One hundred and sixty-four DNA samples were collected from 95 bat roosts, of which 73% of samples were identified to species, and the resident bat species were identified at 89% of roosts. However, identification success varied between roost types, ranging from 22% for underground sites to 92% for bat boxes. This panel of DNA tests will be especially useful in cases where roosts contain multiple species, where the number of bats present is small, or bats are otherwise difficult to directly observe. The methodology could be applied to the surveillance of proposed development sites, post development mitigation measures, distribution surveys, bat box schemes and the evaluation of agri-environmental bat box schemes.

Katherine A. SAINSBURY Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK. Email: ks547@exeter.ac.uk Richard F. SHORE Centre for Ecology & Hydrology, Lancaster Environment Centre, Lancaster LA1 4AP, UK. Email: rfs@ceh.ac.uk Henry SCHOFIELD The Vincent Wildlife Trust, 3 & 4 Bronsil Courtyard, Eastnor, Ledbury HR8 1EP, UK. Email: henryschofield@vwt.org.uk Elizabeth CROOSE The Vincent Wildlife Trust, 3 & 4 Bronsil Courtyard, Eastnor, Ledbury HR8 1EP, UK. Email: elizabethcroose@vwt.org.uk Ruairidh D. CAMPBELL Scottish Natural Heritage, Great Glen House, Inverness IV3 8NW, UK. Email: Roo.Campbell@nature.scot Robbie A. MCDONALD* Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK. Email: R.McDonald@exeter.ac.uk

The age profile of populations fundamentally affects their conservation status. Yet, age is frequently difficult to assess in wild animals. Here, we assessed the use of DNA methylation of homologous genes to establish the age structure of a rare and elusive wild mammal: the Bechstein's bat (Myotis bechsteinii). We collected 62 wing punches from individuals whose ages were known as a result of a long-term banding study. DNA methylation was measured at seven CpG sites from three genes, which have previously shown age-associated changes in humans and laboratory mice. All CpG sites from the tested genes showed a significant relationship between DNA methylation and age, both individually and in combination (multiple linear regression R-2 = 0.58, p < 0.001). Despite slight approximation around estimates, the approach is sufficiently precise to place animals into practically useful age cohorts. This method is of considerable practical benefit as it can reliably age individual bats. It is also much faster than traditional capture-mark-recapture techniques, with the potential to collect information on the age structure of an entire colony from a single sampling session to better inform conservation actions for Bechstein's bats. By identifying three genes where DNA methylation correlates with age across distantly related species, this study also suggests that the technique can potentially be applied across a wide range of mammals.

As a result of legal protection and population recovery, European polecats (Mustela putorius) in Great Britain are expanding into areas associated with greater usage of second-generation anticoagulant rodenticides (SGARs). We analysed polecat livers collected from road casualties from 2013 to 2016 for residues of five SGARs. We related variation in residues to polecat traits and potential exposure pathways, by analysing stable isotopes of carbon (δ13C) and nitrogen (δ15N) in their whiskers. 54 of 68 (79%) polecats had detectable residues of at least one SGAR. Bromadiolone (71%) was the most frequently detected compound, followed by difenacoum (53%) and brodifacoum (35%). Applying historical limits of detection to allow comparison between these new data and previous assessments, we show that in the 25 years from 1992 to 2016 inclusive, the rate of detection of SGARs in polecats in Britain has increased by a factor of 1.7. The probability of SGAR detection was positively related to increasing values of δ15N, suggesting that polecats feeding at a higher trophic level were more likely to be exposed. Total concentrations of SGARs in polecats with detectable residues were higher in polecats collected in arable compared to pastoral habitats, and in the west compared to the east of Britain. The number of compounds detected and total concentrations of SGARs increased with polecat age. There was no evidence of regional or seasonal variation in the probability of detecting SGARs, suggesting that the current risk of exposure to SGARs does not vary seasonally and has increased (from that in the 1990s) throughout the polecat's range. We recommend quantification of current practices in rodenticide usage, particularly in the light of recent regulatory changes, to enable assessment and mitigation of the risks of secondary exposure to rodenticides in non-target wildlife.

The Bechstein's bat (Myotis bechsteinii) is a rare sedentary bat considered to be highly reliant on the presence of ancient woodland. Understanding the genetic connectivity and population structure of such elusive mammals is important for assessing their conservation status. In this study, we report the genetic diversity and structure of M. bechsteinii across Britain and Europe. Assessments were made using 14 microsatellite markers and a 747 bp region of the mitochondrial cytochrome b gene. Nuclear DNA (microsatellites) showed high levels of genetic diversity and little inbreeding across the species range, though genetic diversity was slightly lower in Britain than in mainland Europe. Bayesian and spatial PCA analysis showed a clear separation between the British and European sites. Within Europe, the Italian population south of the Alps was isolated from the other sites. In Britain, there was genetic structuring between the northern and southern part of the geographical range. Despite there being little genetic divergence in mitochondrial DNA (mtDNA) sequences throughout most of Europe, the mtDNA patterns in Britain confirmed this separation of northern and southern populations. Such genetic structuring within Britain—in the absence of any obvious physical barriers—suggests that other factors such as land-use may limit gene-flow.

Artificial nighttime lighting has many effects on biodiversity. A proposed environmental management option, primarily to save energy, is to alter the duration of night lighting. Using the greater horseshoe bat Rhinolophus ferrumequinum as an example of a photophobic species, we explored roadside behaviour patterns throughout the night to assess the potential impact of part‐night lighting. We found a large primary peak in activity 1 h after sunset, followed by a smaller secondary peak before sunrise. Simulated part‐night lighting scenarios reveal that to capture a large proportion of bat activity, streetlights should be switched off before midnight. Current proposed uses of part‐night lighting are unlikely to capture natural peaks in activity for nocturnal species.