Low-cost open-source recorders and ready-to-use machine learning approaches provide effective monitoring of threatened species

Passive acoustic monitoring is a powerful tool for monitoring vocally active taxa. Automated signal recognition software reduces the expert time needed for recording analyses and allows researchers and managers to manage large acoustic datasets. The application of state-of-the-art techniques for automated identification, such as Convolutional Neural Networks, may be challenging for ecologists and managers without informatics or engineering expertise. Here, we evaluated the use of AudioMoth — a low-cost and open-source sound recorder — to monitor a threatened and patchily distributed species, the Eurasian bittern (Botaurus stellaris). Passive acoustic monitoring was carried out across 17 potential wetlands in north Spain. We also assessed the performance of BirdNET — an automated and freely available classifier able to identify over 3000 bird species — and Kaleidoscope Pro — a user-friendly recognition software — to detect the vocalizations and the presence of the target species. The percentage of presences and vocalizations of the Eurasian bittern automatically detected by BirdNET and Kaleidoscope software was compared to manual annotations of 205 recordings. The species was effectively recorded up to distances of 801–900 m, with at least 50% of the vocalizations uttered within that distance being manually detected; this distance was reduced to 601–700 m when considering the analyses carried out using Kaleidoscope. BirdNET detected the species in 59 of the 63 (93.7%) recordings with known presence of the species, while Kaleidoscope detected the bittern in 62 recordings (98.4%). At the vocalization level, BirdNet and Kaleidoscope were able to detect between 76 and 78%, respectively, of the vocalizations detected by a human observer. Our study highlights the ability of AudioMoth for detecting the bittern at large distances, which increases the potential of that technique for monitoring the species at large spatial scales. According to our results, a single AudioMoth could be useful for monitoring the species' presence in wetlands of up to 150 ha. Our study proves the utility of passive acoustic monitoring, coupled with BirdNet or Kaleidoscope Pro, as an accurate, repeatable, and cost-efficient method for monitoring the Eurasian bittern at large spatial and temporal scales. Nonetheless, further research should evaluate the performance of BirdNET on a larger number of species, and under different recording conditions (e.g., more closed habitats), to improve our knowledge about BirdNET's ability to perform bird monitoring. Future studies should also aim to develop an adequate protocol to perform effective passive acoustic monitoring of the Eurasian bittern.CPG acknowledges the support from the Ministerio de Educación y Formación Profesional through the Beatriz Galindo Fellowship (Beatriz Galindo – Convocatoria 2020)

Using a novel visualization tool for rapid survey of long-duration acoustic recordings for ecological studies of frog chorusing

Continuous recording of environmental sounds could allow long-term monitoring of vocal wildlife, and scaling of ecological studies to large temporal and spatial scales. However, such opportunities are currently limited by constraints in the analysis of large acoustic data sets. Computational methods and automation of call detection require specialist expertise and are time consuming to develop, therefore most biological researchers continue to use manual listening and inspection of spectrograms to analyze their sound recordings. False-color spectrograms were recently developed as a tool to allow visualization of long-duration sound recordings, intending to aid ecologists in navigating their audio data and detecting species of interest. This paper explores the efficacy of using this visualization method to identify multiple frog species in a large set of continuous sound recordings and gather data on the chorusing activity of the frog community. We found that, after a phase of training of the observer, frog choruses could be visually identified to species with high accuracy. We present a method to analyze such data, including a simple R routine to interactively select short segments on the false-color spectrogram for rapid manual checking of visually identified sounds. We propose these methods could fruitfully be applied to large acoustic data sets to analyze calling patterns in other chorusing species

Incorporating Climate Change Refugia Into Climate Adaptation in the Acadia National Park Region

Climate change is predicted to have significant impacts on New England’s biodiversity. If emissions continue unabated, mean global temperature is predicted to rise by 3-5 ºC by the end of the century, and well beyond the range of natural variability. Changes are already evident in Acadia National Park (ACAD). Between 1895 and 2010, annual precipitation significantly increased in ACAD by 16% and temperatures by 0.8 ºC; the rate of temperature increase in the park is expected to be 3-6 times greater by 2100, particularly in inland portions. Identifying climate change refugia for representative species can provide valuable information for adapting to climate change. Climate change refugia are areas relatively buffered from contemporary climate change over time that enable persistence of valued physical, ecological, and socio-cultural resources. Many of the physical characteristics and microclimatic gradients that can create climate change refugia – such as high spatial heterogeneity in topography and habitat, proximity to large water bodies, and regular inland diffusion of coastal fog – are present in ACAD

Bioacoustics as a research tool for avian ecology and conservation

1. Ecological data from effective survey and monitoring methods are vitally important for evidence-based nature conservation. This need is increasingly being met by technological developments that enable new approaches for collecting biodiversity data. Among these, acoustic techniques can potentially improve the detection and census of vocal taxa such as birds, and can inform habitat quality assessments. 2. Although improvements in hardware and software for acoustic data capture and analysis are providing new tools for scientific researchers and conservation managers, the advancing technology needs to be matched by methodological understanding, good practice, and accepted protocols. These norms and standards do not yet exist for effective application by users. 3. The published work presented here sets out novel research on bird bioacoustics and freshwater ecoacoustics, applying this to species and habitats of high conservation concern. The publications aim to show how the acoustic approach may be used to determine occupancy, assess population size, understand behaviour and determine community characteristics. Vocal activity rates in bird species are studied and occupancy models created, to interpret acoustic data captured in the field. Different song types, potentially related to breeding status, are identified for a priority species. The ecoacoustic approach is used to assess freshwater ecosystem quality, based on the overall soundscape. 4. The results of the published works have been used to better target acoustic monitoring studies and improve the quality of existing survey methods. This knowledge transfer has been enabled by the development and publication of acoustic protocols for bird survey and freshwater habitat assessment. Further testing is still required to establish optimal standard practices for survey and monitoring, but bioacoustics and ecoacoustics offer significant new approaches for more effective monitoring of species and habitats of conservation concern

Robotics and Automated Systems for Environmental Sustainability: Monitoring Terrestrial Biodiversity

It is critical to protect Earth’s biodiversity, not just for its own intrinsic value, but also for the ecosystem services it underpins. Yet biodiversity is in crisis, with up to 1 million animal and plant species at risk of extinction, many within decades. This dire projection has captured world attention and triggered major mitigation efforts, but we are faced with problems in assessing global trends in biodiversity – which species, taxa, habitats and ecosystems are suffering the greatest declines? Are current mitigation measures having any positive impact? To answer key questions such as these, ecologists are seeking the help of robotics and automated systems (RAS) experts in the monumental task of attempting to monitor the state of biodiversity.In this White Paper, we have surveyed recent literature and consulted more than 120 international expert ecologists and engineers working in the fields of biodiversity and robotics. We have done this to evaluate the potential for developing robotic and autonomous systems that could massively extend the scope of terrestrial biodiversity monitoring across habitats globally. The complexities of biodiversity itself, and the many barriers and challenges that must be overcome in monitoring it, are formidable. We assess each of these barriers in turn, highlighting currently available RAS solutions, as well as nascent technologies that may be relevant to future RAS for biodiversity (RAS-BD) monitoring. Using this information, we have drawn up a roadmap of actions needed to address the barriers that should be easiest to overcome. Encouragingly, we find that a variety of existing RAS capabilities may be transferable to a biodiversity monitoring context. Beyond these are the harder barriers, where promising novel ideas being researched at UK universities and research institutes may, in time, become integral parts of future RAS-BD monitoring technology. We believe that RAS-BD technology has great potential to complement and considerably extend the field survey work undertaken by expert human observers. In the UK, we are fortunate in having particular strengths in both biodiversity and robotics research; as a nation we are in an ideal position to integrate them and become a leading force in the development and application of RAS-BD monitoring. To this end, we propose these recommendations that we hope will guide future government strategy in an area that is vital to the future of humanity:● The creation and funding of an integrated multidisciplinary task force, including academics and industry specialists with expertise in RAS and biodiversity, to support technological research and development.● Future UK funding and focus should be prioritised to utilise existing RAS capabilities to develop first generation RAS-BD technology for monitoring biodiversity.● Relevant nascent technologies being researched by numerous UK academic teams need increased and accelerated research and development funding to turn pioneering concepts into enhanced RAS-BD technology suited to overcoming the hardest monitoring barriers that ecologists encounter.● Education strategies should be developed to foster links between aspiring engineers, biologists andcomputer technologists, both in the curriculum of schools, and at later stages in universities and research facilities

Passive acoustic monitoring and audio subsampling: optimizing autonomous methods for avian biodiversity assessments

Tese de mestrado, Biologia da Conservação, 2022, Universidade de Lisboa, Faculdade de CiênciasThe global decline of bird populations has prompted the search for innovative tools to inventory and monitor their communities. While standard surveys require an observer in the field, autonomous sound recorders are an alternative that demands less expertise and is more scalable in time and space. The literature is not consensual on the efficiency of this method and the factors that influence it, particularly in multispecies studies, although recent attempts have yielded encouraging results towards its applicability in practical monitoring situations. In this study, we conducted a set of observer and recorder-based bird point counts in cork oak woodlands in Portugal, in winter season. We compared both methods in terms of richness values and species-by-species, and assessed the role of the observer and sampling time in recorder performance. Additionally, we compared species richness values obtained through three types of intermittent audio file subsampling, and by intermittent and continuous approaches. We found the observer detected significantly more species, but its presence did not influence the recorder’s results and the pool of species detected by both was similar. We found time of sampling to be relevant in autonomous recorders. The degree of intermittence generated different cost/benefit scenarios for audio processing. Lastly, intermittent subsampling surpassed the number of species detected through continuous subsampling by a factor of two. The results of this study showed that recorders tended to perform well in biodiversity surveys in winter, while being more flexible in scaling, especially when small portions of audio are analysed. However, they also suggest the observer should not be dismissed a priori, and highlight the complexity of factors that may influence the recorder’s performance. We encourage future studies to test this performance over a variety of different time, spatial, and species-related constraints, to maximize the universality of a future all-year autonomous method monitoring protocol.O declínio global das populações de aves promoveu a procura de ferramentas inovadoras para inventariar e monitorizar as suas comunidades. Enquanto as amostragens tradicionais necessitam de um observador no terreno, os gravadores automáticos são uma alternativa que requer menos conhecimento especializado e permite aumentar a escala espacial e temporal da amostragem. A literatura é ambígua sobre a eficiência deste método, particularmente em estudos multiespecíficos, apesar de trabalhos recentes terem mostrado resultados encorajadores acerca da sua aplicabilidade em situações de monitorização. Neste estudo, realizámos um conjunto de pontos de contagem de aves baseados em observadores e em gravadores em zonas de montado, em Portugal, durante o inverno. Comparámos ambas as abordagens em termos de riqueza específica e espécie a espécie, tendo analisado o papel do observador e da janela temporal de amostragem no desempenho dos gravadores. Adicionalmente, comparámos os valores de riqueza específica obtidos através de três tipos de subamostragem de ficheiros áudio. Por fim, comparámos abordagens contínuas e intermitentes. Os resultados mostraram que o observador detetou mais espécies e que a sua presença não influenciou os resultados dos gravadores, que detetaram uma amostra de espécies semelhante. A janela temporal de amostragem foi considerada relevante e teve impacto nas estimativas dos gravadores. O nível de intermitência de subamostragem gerou diferentes cenários de custo/benefício para o processamento de áudio. Por fim, a abordagem intermitente permitiu a deteção de duas vezes mais espécies do que a contínua. Estes resultados sugerem que os gravadores têm um bom desempenho em contextos multiespecíficos no inverno, sendo mais flexíveis a grande escala, particularmente quando são analisadas pequenas porções de áudio. Por oposição, sugerem também que o observador é relevante e evidenciam a complexidade de fatores inerentes ao desempenho dos gravadores. Reiteramos a necessidade de estudos futuros testarem este desempenho em variadas condições espaciais, temporais e de espécies para maximizar a universalidade de um futuro protocolo para monitorização automática aplicável durante todo o ano

Utility of acoustic indices for ecological monitoring in complex sonic environments

With the continued adoption of passive acoustic monitoring as a tool for rapid and high-resolution ecosystem monitoring, ecologists are increasingly making use of a suite of acoustic indices to summarise the sonic environment. Though these indices are often reported to well represent some aspect of the biology of an ecosystem, the degree to which they are confounded by various extraneous sonic conditions is largely unknown. We conducted an aural inventory across 23 field sites in Okinawa to identify the number of unique animal sounds present in recordings. Using these values of \u27measured richness\u27, we then examined how the performance of 11 commonly-used acoustic indices varied across a range of sonic conditions (including in the presence and absence of insect stridulation, audible wind or rain, and human-related sounds). Our analysis identified both well- and poor-performing acoustic indices, as well as those that were particularly sensitive to sonic conditions. Only two indices reflected measured richness across the full range of sonic conditions examined. A few indices were relatively insensitive to extraneous sonic conditions, but no index correlated with measured richness when masked by sound from broadband stridulating insects. Our results demonstrate considerable sensitivity of most commonly used acoustic indices to confounding sonic conditions, highlighting the challenges of working with large acoustic datasets collected in the field. We make practical recommendations for acoustic index use based on study design, with the aim of identifying the suite of acoustic indices with greatest utility as indicators for rapid biodiversity monitoring and management of the world\u27s natural soundscapes

Good practice guidelines for long-term ecoacoustic monitoring in the UK: with a particular focus on terrestrial biodiversity at the human-audible frequency range

Passive acoustic monitoring has great potential as a cost-effective method for long-term biodiversity monitoring. However, to maximise its efficacy, standardisation of survey protocols is necessary to ensure data are comparable and permit reliable inferences. The aim of these guidelines is to outline a basic long-term acoustic monitoring protocol that can be adapted to suit a range of projects according to specific objectives and size

Good practice guidelines for long-term ecoacoustic monitoring in the UK

The popularity of ecoacoustics as an innovative environmental discipline has enjoyed immensegrowth within the last five years, to a point where it is now becoming difficult to keep up withall the new research papers published. What soon becomes apparent, however, is a lack ofconsensus on which recording and analysis protocols to follow; partly a result of the differingrequirements of each research project, but also an historical artefact of the tropical originsof much of this research. As more acoustic long-term monitoring schemes start to becomeestablished throughout the UK and neighbouring countries there arises a need to adopt a morecommon set of protocols, more akin to our temperate conditions, to allow for valid future analysisand comparison. To that end a group of ecoacoustic researchers and practitioners met in June2022 to discuss the formulation of such a set. This work was then taken forward by the authors togenerate the guidelines contained herein.Digital technologies now allow us the ability to record our acoustic environments widely, withrelative ease; and to subject the resulting recordings to an ever-expanding range of analyticalmethods. This opens up the potential to create new approaches to gauging biodiversity andassessing the changing fortunes of species and their habitats. To maximise these benefits itis vitally important that we secure now, and into the future, data which will illustrate baselineassessments and highlight change. These guidelines therefore provide welcome instruction andconformity, particularly for those new to ecoacoustics. Please use them, as appropriate, to helpguide your own contributions to the growing awareness, and use, of sound as an environmentalmetric within the UK and Europe