Acoustic Loggers Research Articles

Larger and older church forests promote bird species richness, diversity and resilience across northwest Ethiopia's deforested landscapes

Birds are vital bioindicators of biodiversity and ecosystem health, but their persistence and ecological roles are under severe threat from human activities in the Lake Tana Basin, Ethiopia. Rapid land and forest degradation driven by agricultural expansion, urbanization, and the rising demand for fuelwood imperil avian community structure and ecosystem functions in this region. However, amidst this ecological challenge, church forests have emerged as crucial sanctuaries. Despite their small size and isolation from each other by mainly agricultural land-use, these church forests provide indispensable ecosystem services and play a pivotal role in preserving biodiversity. Understanding the significance of church forests for avian biodiversity and the factors influencing bird species richness and community composition is paramount. To this end, a comprehensive survey was conducted in 24 church forests between November and December 2018. Data collection involved both point counts utilizing Audiomoth acoustic loggers and transect surveys. The study revealed a total of 131 bird species in the surveyed church forests, including endemic and threatened species. These birds exhibited diverse foraging habits and functional traits. Notably, church forest size and canopy cover were positively associated with species richness, highlighting the importance of preserving and potentially expanding these forested areas. Furthermore, the research identified key factors driving the similarity of bird communities in church forests, notably forest surface area, canopy cover, and altitude. Importantly, resilience metrics demonstrated significant positive relationships with species richness, emphasizing the conservation value of these unique ecosystems. Our study underscores the critical role of church forests in safeguarding avian biodiversity in the Lake Tana Basin, and our findings advocate for conservation efforts aimed at preserving and enhancing the region's church forests, as their continued degradation could jeopardize both ecological and socio-economic potential in this network of remnant forests.

Artificial Intelligence for Climate Change Biology: From Data Collection to Predictions.

In the era of big data, ecological research is experiencing a transformative shift, yet big-data advancements in thermal ecology and the study of animal responses to climate conditions remain limited. This review discusses how big data analytics and artificial intelligence (AI) can significantly enhance our understanding of microclimates and animal behaviors under changing climatic conditions. We explore AI's potential to refine microclimate models and analyze data from advanced sensors and camera technologies, which capture detailed, high-resolution information. This integration can allow researchers to dissect complex ecological and physiological processes with unprecedented precision. We describe how AI can enhance microclimate modeling through improved bias correction and downscaling techniques, providing more accurate estimates of the conditions that animals face under various climate scenarios. Additionally, we explore AI's capabilities in tracking animal responses to these conditions, particularly through innovative classification models that utilize sensors such as accelerometers and acoustic loggers. For example, the widespread usage of camera traps can benefit from AI-driven image classification models to accurately identify thermoregulatory responses, such as shade usage and panting. AI is therefore instrumental in monitoring how animals interact with their environments, offering vital insights into their adaptive behaviors. Finally, we discuss how these advanced data-driven approaches can inform and enhance conservation strategies. In particular, detailed mapping of microhabitats essential for species survival under adverse conditions can guide the design of climate-resilient conservation and restoration programs that prioritize habitat features crucial for biodiversity resilience. In conclusion, the convergence of AI, big data, and ecological science heralds a new era of precision conservation, essential for addressing the global environmental challenges of the 21st century.

Rice Fields as Important Habitats for Three Anuran Species-Significance and Implications for Conservation.

Agriculture can have different effects on wildlife depending on land-use type and extensive/intensive practices. The aim of this study was to establish the significance of rice fields in Central Bulgaria as anuran habitats. We used Audiomoth acoustic loggers to record calling activity at three sites near the city of Plovdiv-one shallow pond and two rice fields-from June to September in 2022 and 2023. We registered the three most widespread species in the region-Bufotes viridis, Hyla orientalis and Pelophylax ridibundus-and created pattern-matching models for them using the free web interface Arbimon, which enabled us to perform presence/absence counts and abundance estimates. At the beginning and the end of the rice vegetation period, water samples were collected and analysed for 62 substances. Substance concentrations were compared between ponds and with LC50 data from the available literature. We registered 19 and 21 substances in 2022 and 2023, respectively, with concentrations within the accepted limits, and although some metals were near risk levels, this was not reflected in the presence counts or the abundance estimates. The results indicated that frog activity was not related to any of the registered substances, but that it was positively correlated with daily rainfall and was higher in the rice fields.

Enhancing Pipe-Break Early Warning in Smart Water Networks: Distinguishing Leaks from Water Uses

This research presents a denoising technique developed for enhancing the identification of newly developed and/or developing leaks by acoustic loggers in smart water networks. The key challenge addressed is the differentiation of leak-induced signals from signals originating from other sources, such as customer water use, pumps operations and environmental noise. A spectral subtraction-based denoising technique is adapted to process the acoustic waves measured daily using wireless accelerometers. A newly captured wave file can be filtered based on a reference wave file, either one with a known nonleak noise source or one measured in the past at the same location, to highlight the differences or the evolution of the signals over time. This technique enhances the robustness of automated alarms in identifying leaks in water networks.

Native pedunculate oaks support more biodiversity than non-native oaks, but non-native oaks are healthier than native oaks: A study on street and park trees of a city

Trees in cities provide multiple ecosystem services. However, simultaneously ensuring healthy trees with high habitat diversity can be challenging in a harsh urban environment. We compared health, microhabitats, and bat activities between native (Quercus robur L.) and non-native (Quercus rubra L.) oaks growing in different urban habitats (street vs. park) in Karlsruhe, southwestern Germany. We randomly selected 167 oak trees with a diameter at breast height (DBH) >20 cm across the city from Urban Tree Registrar. We performed tree health assessment, dendrometric, and microhabitat inventory. We recorded the four-day bat activities on 45 native and non-native oaks with acoustic loggers installed on the trees. We found that non-native oaks were healthier than native oaks but provided less abundance and richness of microhabitats. Tree size (positive effect) and pruning (negative effect) strongly influence microhabitat richness and abundance. In addition, park trees hosted significantly more microhabitats than street trees. We recorded the activities of 9 bat species from 4 genera. Pipistrellus bats were more active in park trees than street trees. Long-eared bats (Plecotus) were more active near the native than non-native oaks. Bats are likely favored by microhabitats such as fork split, lightning scar, and woodpecker “flute” that are more common in less healthy trees. We conclude that non-native red oak can be planted alongside streets, where the conditions are harsher than in parks to better adapt to climatic changes and stay healthy with less maintenance. The preservation of native pedunculate oak trees, especially within parks, is paramount for urban biodiversity conservation because of their potential to provide microhabitats and supporting bats.

An Autonomous Acoustic Logger and Its Application as Part of a Hydrophysical Complex

An Autonomous Acoustic Logger and Its Application as Part of a Hydrophysical Complex

Echolocation activity of harbour porpoises, Phocoena phocoena, shows seasonal artificial reef attraction despite elevated noise levels close to oil and gas platforms

Abstract Harbour porpoises frequently alter their behaviour in response to underwater sound from shipping, seismic surveys, drilling and marine renewables. Less well understood is the response of porpoises to sounds emitted from oil and gas (O&G) platforms during routine operations. The responses are not easily predicted as platforms can act simultaneously and to varying degree as a source of disturbance through noise and attraction through an artificial reef effect with increased prey abundance and diversity. To investigate the presence and feeding behaviour of harbour porpoises around platforms, autonomous acoustic loggers were placed for up to 2 years, at 21 stations 0–25.6 km from the largest platform in the Danish North Sea. Harbour porpoises were detected at all distances year round in two distinct seasonal activity patterns. During July–January, porpoises were attracted to the platform as indicated by high foraging activity within 800 m of the platform. Echolocation activity levels were up to twofold higher than those observed at 3.2–9.6 km from the platform. Similar high echolocation activity was observed 200 m from neighbouring offshore installations located within 15 km, regardless of their size, during May–July. This study shows that porpoises may be attracted to offshore O&G platforms despite confirmed elevated underwater noise and are likely exploiting higher prey abundance in the vicinity of such structures. This is possibly due to increased prey availability created by the combined effect of the artificial reef formed by the underwater structure and the local protected area around all platforms where fishery is banned. Hard substrate and untouched seabed are rare and valuable habitats to many organisms in heavily trawled waters like the North Sea, and the ecological importance of these structures should be considered in the development of decommissioning strategies.

Managing Audio Monitoring Data with SIMON – Concept for Data Administration, Online Repository and Dissemination

Automated observations of natural occurrences play a key role in monitoring biodiversity worldwide. With the development of affordable hardware like the AudioMoth (Hill et al. 2019) acoustic logger, large scale and long-term monitoring has come within reach. However, data management and dissemination of monitoring data remain challenging, as the development of software and the infrastructure for the management of monitoring data lag behind. We want to fill this gap, providing a complete audio monitoring solution from affordable audio monitoring hardware, custom data management tools and storage infrastructure based on open source hard- and software, biodiversity information standards and integrable interfaces. The Scientific Monitoring Data Management and Online Repository (SIMON) consists of a portable data collector and a connected online repository. The data collector, a device for the automated extraction of the audio data from the audio loggers in the field, stores the data and metadata in an internal cache. Once connected to the internet via WiFi or a cable connection, the data are automatically uploaded to an online repository for automated analysis, annotation, data management and dissemination. To prevent SIMON from becoming yet another proprietary storage, the FAIR principles (Findable, Accessible, Interoperable, and Re-usable) Wilkinson et al. (2016) are at the very core of data managed in the online repository. We plan to offer an API (application programming interface) to disseminate data to established data infrastructures. A second API will allow the use of external services for data enrichment. While in the planning phase, we would like to take the opportunity to discuss with domain experts the requirements and implementation of different standards—namely ABCD (Access to Biological Collections Data task group, Biodiversity Information Standards (TDWG) 2007), Darwin Core (Darwin Core Task Group, Biodiversity Information Standards (TDWG) 2009) and Darwin Core Archive (Remsen et al. 2017)—connecting to external services and targeting data infrastructures.

Application of acoustic intelligent leak detection in an urban water supply pipe network

Abstract Different leakage detection technologies present different efficiency and precision of leakage detection in water distribution systems due to their own properties. This study aimed to investigate the use of acoustic sensors to locate the exact position of leaks, which work 24 hours per day in different modes, i.e. fixed installation and mobile exploration. The results showed that the maximum distance between the acoustic sensors installed on the pipeline was 380 m. Field application results indicated that detecting threshold of the distance was 300 m and the intensity ratio of leaking state noise (LSN) to background noise was 1.9 respectively. The pipeline length by manual hunting area (MHA) is 1.3 times longer than the acoustic logger tested area (ALTA), but the detected leakage points in MHA is 20% less than in ALTA. Furthermore, the cost of leakage detection in MHA was about 6,000 yuan/detected leakage point. That in ALTA was about 2,500 yuan/detected leakage point. The case study also indicates that the acoustic logger is a promising tool with the advantage of lower cost and faster detection, compared to manual ground listening with a sound stick. The acoustic leakage detection method can detect the leakage in different sized pipelines, whereas the manual detection was concentrated in small-sized pipelines.

Assessing the Effects of Banana Pingers as a Bycatch Mitigation Device for Harbour Porpoises (Phocoena phocoena)

Bycatch is a significant cause of population declines of marine megafauna globally. While numerous bycatch mitigation strategies exist, acoustic alarms, or pingers, are the most widely adopted strategy for small cetaceans. Although pingers have been shown to be an effective measure for numerous species, there are some concerns about their long-term use. Bycatch is recognised as a persistent problem in waters around Cornwall, United Kingdom, where several cetacean species are resident, with harbour porpoises (Phocoena phocoena) being the most-commonly sighted. In this study, we assessed the effects of a Banana Pinger (Fishtek Marine Limited) on harbour porpoises in Cornwall between August 2012 and March 2013. Two passive acoustic loggers (C-PODs; Chelonia Limited) were deployed 100m apart to record cetacean activity during cycles of active and inactive pinger periods. Harbour porpoises were 37% less likely to be detected at the C-POD near the pinger when the pinger was active, while they were only 9% less likely to be detected 100m further away. The effect of the pinger was constant over the study period at both C-PODs despite the temporal variation in harbour porpoise detections. In addition, we found no evidence of reduced pinger effect with changing environmental conditions. Furthermore, harbour porpoise detections at the C-POD near the pinger did not depend on the time elapsed since the pinger turned off, with harbour porpoises returning to the ensonified area with no delay. Together these results suggest that (1) harbour porpoises did not habituate to the pinger over an eight-month period, (2) the pinger effect is very localised, and (3) pinger use did not lead to harbour porpoise displacement over the study period, suggesting an absence of long-term behavioural effects. We suggest that the deployment of pingers on fishing nets would likely reduce net-porpoise interactions, thereby mitigating bycatch of harbour porpoises and potentially other cetacean species. As the small-scale fishery dominates in UK waters, there is an acute need for cost-effective mitigation strategies with concurrent monitoring to be implemented rapidly in order to address the problem of harbour porpoise, and more generally, cetacean bycatch.

Pingers reduce the activity of Burmeister’s porpoise around small-scale gillnet vessels

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 626:197-208 (2019) - DOI: https://doi.org/10.3354/meps13063 Pingers reduce the activity of Burmeister’s porpoise around small-scale gillnet vessels Thomas A. Clay1,2, Joanna Alfaro-Shigueto2,3,4, Brendan J. Godley2, Nick Tregenza5, Jeffrey C. Mangel2,3,* 1School of Environmental Sciences, University of Liverpool, Liverpool L69 3GP, UK 2Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall TR10 9EZ, UK 3ProDelphinus, Jose Galvez 780-E, Miraflores, Lima 15074, Peru 4Facultad de Biologia Marina, Universidad Cientifica del Sur, Panamericana Sur Km 19, Villa, Lima 15067, Peru 5Chelonia Limited, The Barkhouse, North Cliff, Mousehole, Cornwall TR19 6PH, UK *Corresponding author: j.mangel@exeter.ac.uk ABSTRACT: Incidental mortality (bycatch) in gillnet fisheries is a major threat to many cetacean populations. Acoustic alarms or pingers are a widely adopted management tool used to deter dolphins and porpoises from nets; however, their efficacy is largely species- and fishery-dependent. As such, results from experimental trials may have limited transferability to poorly studied species or fisheries. Here, we investigated the effect of pingers on the behaviour of Burmeister’s porpoise Phocoena spinipinnis in the vicinity of the Peruvian small-scale driftnet fleet. Over a 4 yr period (2009-2012), 116 control (without pingers) and 94 experimental (with pingers) fishing sets were observed, and porpoise acoustic activity around nets was recorded using passive acoustic loggers (C-PODs). We modelled variation in detection rates as a function of pinger use and habitat covariates, and found that in regions of preferred habitat associated with cooler (17-18°C), shallow waters (within the 100 m isobath), the use of pingers lead to an 86% reduction in porpoise activity around nets. Our results suggest that pingers are likely to be particularly effective at deterring Burmeister’s porpoises from fishing nets, and given the vast capacity of this and other fleets in the region, may substantially reduce mortality. This study also emphasizes the potential of passive acoustic monitoring to determine the effectiveness of bycatch mitigation measures, both for species for which visual observations are scarce, and also in regions where gathering statistically meaningful bycatch rates is logistically challenging. KEY WORDS: By-catch mitigation · Artisanal fisheries · Behavioural avoidance · Acoustic alarm · Passive acoustic monitoring · Marine mammal · Phocoena spinipinnis · C-POD · Peru Full text in pdf format Supplementary material PreviousNextCite this article as: Clay TA, Alfaro-Shigueto J, Godley BJ, Tregenza N, Mangel JC (2019) Pingers reduce the activity of Burmeister’s porpoise around small-scale gillnet vessels. Mar Ecol Prog Ser 626:197-208. https://doi.org/10.3354/meps13063 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 626. Online publication date: September 12, 2019 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2019 Inter-Research.

Artificial Light at Night Promotes Activity Throughout the Night in Nesting Common Swifts (Apus apus)

The use of artificial light at night (ALAN) is a rapidly expanding anthropogenic effect that transforms nightscapes throughout the world, causing light pollution that affects ecosystems in a myriad of ways. One of these is changing or shifting activity rhythms, largely synchronized by light cues. We used acoustic loggers to record and quantify activity patterns during the night of a diurnal bird – the common swift – in a nesting colony exposed to extremely intensive artificial illumination throughout the night at Jerusalem’s Western Wall. We compared that to activity patterns at three other colonies exposed to none, medium, or medium-high ALAN. We found that in the lower-intensity ALAN colonies swifts ceased activity around sunset, later the more intense the lighting. At the Western Wall, however, swifts remained active throughout the night. This may have important implications for the birds’ physiology, breeding cycle, and fitness, and may have cascading effects on their ecosystems.

Effects of vessel traffic and underwater noise on the movement, behaviour and vocalisations of bottlenose dolphins in an urbanised estuary

AbstarctThe potential disturbance of dolphins from tourism boats has been widely discussed in the literature, in terms of both physical vessel presence and associated underwater noise. However, less attention has been paid to the potential impact of non-tourism vessels, despite these being much more widespread and occurring in greater numbers throughout coastal dolphin habitats. The Indo-Pacific bottlenose dolphin (T. aduncus) community using the Fremantle Inner Harbour, Western Australia, is exposed to high levels of vessel traffic. To investigate whether behavioural responses could be occurring, a non-invasive combination of visual and acoustic monitoring was conducted using a theodolite and an autonomous acoustic logger. Dolphins significantly increased their average movement speeds in high vessel densities, but only for some activity states. Behavioural budgets also changed in the presence of vessels, with animals spending greater time travelling and less time resting or socialising. Finally, multiple whistle characteristics varied with rising levels of broadband noise, and other contextual variables. Despite being acoustically specialised for higher frequencies, dolphins had the strongest acoustic variation during low-frequency noise. This study highlights the complexity of disturbance responses in this species, confirming the need for consideration of both surface and acoustic behaviour alongside appropriate contextual data.

Long-term monitoring of captive red drum Sciaenops ocellatus reveals that calling incidence and structure correlate with egg deposition.

In the present study, quantitative data were collected to clarify the relationship between calling, call structure and eggs produced in a captive population of red drum Sciaenops ocellatus. Sciaenops ocellatus were held in four tanks equipped with long-term acoustic loggers to record underwater sound throughout a simulated reproductive season. Maximal sound production of captive S. ocellatus occurred when the photoperiod shifted from 13·0 to 12·5 h of light, and the water temperature decreased to c. 25° C. These captive settings are similar to the amount of daylight and water temperatures observed during the autumn, which is the primary spawning period for S. ocellatus. Sciaenops ocellatus exhibited daily patterns of calling with peak sound production occurring in the evenings between 0·50 h before dark and 1·08 h after dark. Spawning occurred only on evenings in which S. ocellatus were calling, and spawning was more productive when S. ocellatus produced more calls with longer durations and more pulses. This study provides ample evidence that sound production equates to spawning in captive S. ocellatus when calls are longer than 0·8 s and contain more than seven pulses. The fact that more calling, longer calls and higher sound pressure levels are associated with spawns that are more productive indicates that acoustic metrics can provide quantitative information on spawning in the wild.

Echolocation detections and digital video surveys provide reliable estimates of the relative density of harbour porpoises

SummaryRobust estimates of the density or abundance of cetaceans are required to support a wide range of ecological studies and inform management decisions. Considerable effort has been put into the development of line‐transect sampling techniques to obtain estimates of absolute density from aerial‐ and boat‐based visual surveys. Surveys of cetaceans using acoustic loggers or digital cameras provide alternative methods to estimate relative density that have the potential to reduce cost and provide a verifiable record of all detections. However, the ability of these methods to provide reliable estimates of relative density has yet to be established.These methodologies were compared by conducting aerial visual line‐transect surveys (n = 10 days) and digital video strip‐transect surveys (n = 4 days) in the Moray Firth, Scotland. Simultaneous acoustic data were collected from moored echolocation detectors (C‐PODs) at 58 locations across the study site. Density surface modelling (DSM) of visual survey data was used to estimate spatial variation in relative harbour porpoise density on a 4 × 4 km grid.DSMwas also performed on the digital survey data, and the resulting model output compared to that from visual survey data. Estimates of relative density from visual surveys around acoustic monitoring sites were compared with several metrics previously used to characterise variation in acoustic detections of echolocation clicks.There was a strong correlation between estimates of relative density from visual surveys and digital video surveys (Spearman's ρ = 0·85). A correction to account for animals missed on the transect line [previously calculated for visual aerial surveys of harbour porpoise in the North Sea was used to convert relative density from the visual surveys to absolute density. This allowed calculation of the first estimate of a proxy for detection probability in digital video surveys, suggesting that 61% (CV = 0·53) of harbour porpoises were detected. There was also a strong correlation between acoustic detections and density with Spearman's ρ = 0·73 for detection positive hours.These results provide confidence in the emerging use of digital video and acoustic surveys for studying the density of small cetaceans and their responses to environmental and anthropogenic change.

Detection rates of wild harbour porpoises and bottlenose dolphins using static acoustic click loggers vary with depth

Acoustic echolocation click loggers are widely used to study the presence and behaviour of coastal cetaceans. Various studies have examined their performance and how animal behaviour may affect click detection. This study examined the effect of logger depth in the water column on click detection rates for harbour porpoises (Phocoena phocoena) and bottlenose dolphins (Tursiops truncatus) at a coastal nearshore site. There were significantly more harbour porpoise clicks logged at the click loggers moored in the water column, closer to the surface, compared with those near the seabed. No such difference was recorded for bottlenose dolphins. The results were consistent throughout the study period and across sites, apart from a site closest to a possible feeding site, indicating that cetacean behaviour is among the possible factors explaining these findings. The study emphasizes the need for prior understanding of the target species and its habitat use, and stresses the importance of pilot studies to achieve reliable and meaningful data from static acoustic monitoring programs.

Variation in harbour porpoise activity in response to seismic survey noise.

Animals exposed to anthropogenic disturbance make trade-offs between perceived risk and the cost of leaving disturbed areas. Impact assessments tend to focus on overt behavioural responses leading to displacement, but trade-offs may also impact individual energy budgets through reduced foraging performance. Previous studies found no evidence for broad-scale displacement of harbour porpoises exposed to impulse noise from a 10 day two-dimensional seismic survey. Here, we used an array of passive acoustic loggers coupled with calibrated noise measurements to test whether the seismic survey influenced the activity patterns of porpoises remaining in the area. We showed that the probability of recording a buzz declined by 15% in the ensonified area and was positively related to distance from the source vessel. We also estimated received levels at the hydrophones and characterized the noise response curve. Our results demonstrate how environmental impact assessments can be developed to assess more subtle effects of noise disturbance on activity patterns and foraging efficiency.

Predictions from harbor porpoise habitat association models are confirmed by long-term passive acoustic monitoring

Survey based habitat association models provide good spatial coverage, but only a snapshot in time of a species' occurrence in a particular area. A habitat association model for harbor porpoises was created using data from five visual surveys of the Moray Firth, Scotland. Its predictions were tested over broader temporal scales using data from static passive acoustic loggers, deployed in two consecutive years. Predictions of relative abundance (individuals per kilometer of survey transect) were obtained for each 4 km × 4 km grid cell, and compared with the median number of hours per day that porpoises were acoustically detected in those cells. There was a significant, but weak, correlation between predicted relative abundance and acoustic estimates of occurrence, but this was stronger when predictions with high standard errors were omitted. When grid cells were grouped into those with low, medium, and high predicted relative abundance, there were similarly significant differences in acoustic detections, indicating that porpoises were acoustically detected more often in cells where the habitat model predicted higher numbers. The integration of acoustic and visual data added value to the interpretation of results from each, allowing validation of patterns in relative abundance recorded during snapshot visual surveys over longer time scales.

Pile driving zone of responsiveness extends beyond 20 km for harbor porpoises (Phocoena phocoena (L.))

Behavioral reactions of harbor porpoises (Phocoena phocoena) to underwater noise from pile driving were studied. Steel monopile foundations (4 m diameter) for offshore wind turbines were driven into hard sand in shallow water at Horns Reef, the North Sea. The impulsive sounds generated had high sound pressures [source level 235 dB re 1 microPa(pp) at 1 m, transmission loss 18 log(distance)] with a strong low frequency emphasis but with significant energy up to 100 kHz. Reactions of porpoises were studied by passive acoustic loggers (T-PODs). Intervals between echolocation events (encounters) were analyzed, and a significant increase was found from average 5.9 h between encounters in the construction period as a whole to on average 7.5 h between first and second encounters after pile driving. The size of the zone of responsiveness could not be inferred as no grading in response was observed with distance from the pile driving site but must have exceeded 21 km (distance to most distant T-POD station).

Habitat use of beluga whales revealed by acoustic loggers.

The detection of odontocete echolocation signals with acoustic loggers has proved to be a very effective way to monitor their distribution, seasonal patterns and habitat use. However, belugas (Delphinapterus leucas) have never been monitored using this methodology. In order to evaluate its viability, echolocation signals of captive belugas were analyzed and the performance of T-POD (Chelonia Ltd., UK) acoustic loggers in captivity and in the Arctic environment was tested. Results from captivity demonstrated the potential of beluga remote monitoring by T-PODs. Field tests were organized in different environmental conditions with different populations of belugas to ensure the validity and detection robustness of this method. T-PODs were deployed in Svalbard (Norway) in Spring 2007, in Yakutat (Alaska) in Spring 2008, and in Solovetsky (Russia) in Summer 2008. Instruments were deployed concurrently with visual observations and hydrophone recordings to compare presence/absence data from the three different methods. Results proved that T-PODs positively detected all the identified periods of beluga presence without false detections and revealed temporal distribution correlations with tide levels, feeding behaviors, and circadian rhythms in the echolocation activity. Results from this project indicate that beluga remote monitoring is feasible in the Arctic environment using acoustic loggers.