A general framework for animal density estimation from acoustic detections across a fixed microphone array

Acoustic monitoring can be an efficient, cheap, non‐invasive alternative to physical trapping of individuals. Spatially explicit capture–recapture (SECR) methods have been proposed to estimate calling animal abundance and density from data collected by a fixed array of microphones. However, these methods make some assumptions that are unlikely to hold in many situations, and the consequences of violating these are yet to be investigated. We generalize existing acoustic SECR methodology, enabling these methods to be used in a much wider variety of situations. We incorporate time‐of‐arrival (TOA) data collected by the microphone array, increasing the precision of calling animal density estimates. We use our method to estimate calling male density of the Cape Peninsula Moss Frog Arthroleptella lightfooti. Our method gives rise to an estimator of calling animal density that has negligible bias, and 95% confidence intervals with appropriate coverage. We show that using TOA information can substantially improve estimate precision. Our analysis of the A. lightfooti data provides the first statistically rigorous estimate of calling male density for an anuran population using a microphone array. This method fills a methodological gap in the monitoring of frog populations and is applicable to acoustic monitoring of other species that call or vocalize

Lost Highway Not Forgotten: Satellite Tracking of a Bowhead Whale (Balaena mysticetus) from the Critically Endangered Spitsbergen Stock

The Spitsbergen bowhead whale stock is critically endangered. It is believed to number in the tens. Here we report results from the first satellite transmitter ever deployed on an individual from this stock. A female whale was tagged on 3 April 2010 (at 79˚54' N, 01˚03' E), but no locations were transmitted by the tag until 30 April 2010, after which data were received continuously for 86 days. Additionally, three small clusters of locations were transmitted later in the year; the latest was received 20 December 2010 (262 days after deployment). During the 86 days of continuous tracking, the whale initially remained in the middle of the Fram Strait, between 77˚45' N, 5˚ W and 80˚10' N, 5˚ E. For a two-week period starting around 10 June 2010, the whale traveled southwest down to 73˚40' N (at least 950 km). Subsequently it remained at southern latitudes between ~70˚ and 73˚ N until the tag stopped continuous transmissions on 24 July. Movement patterns analyzed using first-passage times (FTP), fitted as functions of various environmental variables using Cox Proportional Hazards models, showed that the whale spent most of its time in waters close to the ice edge with modest ice coverage, over areas where the bottom slope was relatively steep. Winter positions (27 November – 20 December 2010) revealed that the whale was back in the North at about 80˚ N. This information, in combination with recent data from passive acoustic listening devices, suggests that the Spitsbergen bowhead stock overwinters at high-latitude locations. The north-south movements of this whale during summer are consistent with the patterns that early whalers described for bowhead whales in this region in the 16th and 17th centuries.La population de baleines boréales de Spitzberg est en danger critique d’extinction. L’on croit qu’elle se chiffrerait dans la dizaine. Ici, nous faisons état des résultats obtenus à l’aide du premier émetteur satellite à n’avoir jamais été installé sur un individu de cette population. Une baleine femelle a été marquée le 3 avril 2010 (à 79˚54' N, 01˚03' E), mais aucun signal n’a été transmis par ce marquage avant le 30 avril 2010, après quoi nous avons reçu des données continuelles pendant 86 jours. Plus tard dans le courant de l’année, nous avons également reçu trois petits blocs d’information, dont le dernier a été transmis le 20 décembre 2010 (262 jours après la date du marquage). Au cours des 86 jours d’information continuelle, la baleine restait d’abord au milieu du détroit de Fram, entre 77˚45' N, 5˚ O et 80˚10' N, 5˚ E. Pendant une période de deux semaines commençant vers le 10 juin 2010, la baleine s’est déplacée vers le sud-ouest jusqu’à 73˚40' N (au moins 950 km). Par la suite, elle est restée dans les latitudes du sud entre ~70˚ et 73˚ N jusqu’à ce que le marquage cesse les transmissions continuelles le 24 juillet. Les habitudes de déplacement analysées en recourant aux temps du premier passage (FTP), ajustées à titre de fonctions de diverses variables environnementales s’appuyant sur les modèles des hasards proportionnels de Cox, ont laissé entrevoir que la baleine passait la plus grande partie de son temps dans les eaux à proximité des lisières de glace dont la couverture était modeste par rapport aux endroits où la pente du fond était relativement abrupte. Les positions enregistrées en hiver (du 27 novembre au20 décembre 2010) ont révélé que la baleine était retournée dans le nord à environ 80˚ N. Cette information, alliée aux récentes données provenant d’appareils d’écoute acoustique, suggère que la population de baleines boréales de Spitzberg passe l’hiver à de hautes latitudes. Pendant l’été, les mouvements nord-sud de cette baleine sont conformes aux habitudes de déplacement de la baleine boréale, telles que décrites par les anciens baleiniers dans cette région au cours des XVIe et XVIIe siècles

Killer whales (Orcinus orca) produce ultrasonic whistles

This study reports that killer whales, the largest dolphin, produce whistles with the highest fundamental frequencies ever reported in a delphinid. Using wide-band acoustic sampling from both animal-attached (Dtag) and remotely deployed hydrophone arrays, ultrasonic whistles were detected in three Northeast Atlantic populations but not in two Northeast Pacific populations. These results are inconsistent with analyses suggesting a correlation of maximum frequency of whistles with body size in delphinids, indicate substantial intraspecific variation in whistle production in killer whales, and highlight the importance of appropriate acoustic sampling techniques when conducting comparative analyses of sound repertoires

Effect of the overflows on the circulation in the Subpolar North Atlantic: A regional model study

An ocean circulation model for process studies of the Subpolar North Atlantic is developed based on the Geophysical Fluid Dynamics Laboratory (GFDL) Modular Ocean Model (MOM) code. The basic model configuration is identical with that of the high-resolution model (with a grid size of 1/3° × 2/5°) of the World Ocean Circulation Experiment (WOCE) Community Modeling Effort (CME), except that the domain of integration is confined to the area from 43° to 65°N. Open boundary conditions are used for the inflows and outflows across the northern and southern boundaries. A comparison with the CME model covering the whole North Atlantic (from 15°S to 65°N) shows that the regional model, with inflow conditions at 43°N from a CME solution, is able to reproduce the CME results for the subpolar area. Thus the potential of a regional model lies in its use as an efficient tool for numerical experiments aiming at an identification of the key physical processes that determine the circulation and water mass transformations in the subpolar gyre. This study deals primarily with the representation and role of the overflow waters that enter the domain at the northern boundary. Sensitivity experiments show the effect of closed versus open boundaries, of different hydrographic conditions at inflow points, and of the representation of the narrow Faeroe Bank Channel. The representation of overflow processes in the Denmark Strait is the main controlling mechanism for the net transport of the deep boundary current along the Greenland continental slope and further downstream. Changes in the Faeroe Bank Channel throughflow conditions have a comparatively smaller effect on the deep transport in the western basin but strongly affect the water mass characteristics in the eastern North Atlantic. The deep water transport at Cape Farewell and further downstream is enhanced compared to the combined Denmark Strait and Iceland-Scotland overflows. This enhancement can be attributed to a barotropic recirculation in the Irminger Basin which is very sensitive to the outflow conditions in the Denmark Strait. The representation of both overflow regions determine the upper layer circulation in the Irminger and Iceland Basins, in particular the path of the North Atlantic Current

Lenalidomide in combination with dexamethasone at first relapse in comparison with its use as later salvage therapy in relapsed or refractory multiple myeloma

This subset analysis of data from two phase III studies in patients with relapsed or refractory multiple myeloma (MM) evaluated the benefit of initiating lenalidomide plus dexamethasone at first relapse. Multivariate analysis showed that fewer prior therapies, along with β2-microglobulin (≤2.5 mg/L), predicted a better time to progression (TTP; study end-point) with lenalidomide plus dexamethasone treatment. Patients with one prior therapy showed a significant improvement in benefit after first relapse compared with those who received two or more therapies. Patients with one prior therapy had significantly prolonged median TTP (17.1 vs. 10.6 months; P=0.026) and progression-free survival (14.1 vs. 9.5 months, P=0.047) compared with patients treated in later lines. Overall response rates were higher (66.9% vs. 56.8%, P=0.06), and the complete response plus very good partial response rate was significantly higher in first relapse (39.8% vs. 27.7%, P=0.025). Importantly, overall survival was significantly prolonged for patients treated with lenalidomide plus dexamethasone with one prior therapy, compared with patients treated later in salvage (median of 42.0 vs. 35.8 months, P=0.041), with no differences in toxicity, dose reductions, or discontinuations despite longer treatment. Therefore, lenalidomide plus dexamethasone is both effective and tolerable for second-line MM therapy and the data suggest that the greatest benefit occurs with earlier use

Quantifying costs and rewards in optimal foraging models of the marine environment. Using bulk feeding mysticete whales as an example

Animals feed to maintain body condition and maximise fitness. Feeding is a multi-stage behaviour that encapsulates aspects of an animals' sensory and foraging ecology, and that can be divided into the following broad functional categories; prey detection, capture, and handling (assimilation of acquired energy stores). The evolutionary consequences of foraging have the potential to shape predator-prey dynamics, influence community and ecosystem structure; and to drive the evolution of physiological and morphological adaptations that minimise energetic costs and maximise energy uptake. Excess energy can be converted to fat (lipids) and stored to enhance reproductive potential or to protect against temporary (voluntary) starvation associated often with long distance migration or changes in prey distribution. Understanding how an animal balances these conflicting forces, and makes key foraging decisions is an important aspect to understanding their ecology. Simple questions such as how, when, where, why and what an animal chooses to feed on are difficult to answer without the development and application of new technologies. The development of new tools and analytical approaches is particularly important in the marine environment where these key life history decisions occur offshore and or at depth. Bulk feeding rorqual whales are amongst the largest species to have lived on Earth, and are major consumers of schooling krill and forage fish. Because of their size and ability to consume significant quantities of fish and krill they have an important role in structuring ecological communities. Lunge feeding is an energetically costly bulk feeding behaviour that is practised by all members of this super-family. To understand how energy fluxes pass through the consumer to be expressed as body condition it is first necessary to have reliable proxies of the energetic costs and gains associated with feeding. In this thesis methods for estimating these energy fluxes were explored using data from summer feeding (Balaenoptera physalus) and humpback whales (Megaptera novaeangliae) in Canada, and winter feeding humpback whales in northern Norway. Calibrated speed measurements were used as a proxy for the energetic costs associated with bulk feeding (lunge) and transport in baleen whales (chapter 2). Speed measurements were used to develop a lunge detector (chapter 3). Lunge speed and other kinematic variables associated with bulk feeding were used to identify species-specific signatures in feeding behaviour as a potential method for identifying prey type, and thus their caloric value as a proxy for energy uptake (chapter 4)). The feasibility of using new sensors, (i) sonar to measure prey density and dynamics from the perspective of the feeding whale (chapter 5), and (ii) an ultrasound to measure blubber depth in wild marine mammals as a proxy of body condition (chapter 6) were tested

A miniature biomimetic sonar and movement tag to study the biotic environment and predator-prey interactions in aquatic animals

International audienceHow predators find, select and capture prey is central to understanding trophic cascades and ecosystem structure.But despite advances in biologging technology, obtaining in situ observations of organisms and their interactionsremains challenging in the marine environment. For some species of toothed whales, echoes fromorganisms insonified by echolocation clicks and recorded by sound logging tags have provided a fine-scale viewof prey density, and predator and prey behaviour during capture attempts, but such information is not availablefor marine predators that do not echolocate. Here the development and performance of a miniature biomimeticsonar and movement tag capable of acquiring similar data from non-echolocating marine predators is reported.The tag, weighing 200 g in air, records wide bandwidth sonar data at up to 50 pings a second synchronously withfast-sampling sensors for depth, acceleration, magnetic field and GPS. This sensor suite enables biotic conditionsand predator behaviour to be related to geographic location over long-duration foraging trips by apex marinepredators. The sonar operates at 1.5 MHz with a 3.4° beamwidth and a source level of 190 dB re 1 μPa at 1 m.Sonar recordings from a trial deployment of the tag on a southern elephant seal contained frequent targetscorresponding to small organisms up to 6m ahead of the tagged animal. Synchronously sampled movement dataallowed interpretation of whether the seal attempted to capture organisms that it approached closely while thehigh sonar ping rate revealed attempts by prey to escape. Results from this trial demonstrate the ability of the tagto quantify the biotic environment and to track individual prey captures, providing fine-scale information onpredator-prey interactions which has been difficult to obtain from non-echolocating marine animals

A miniature biomimetic sonar and movement tag to study the biotic environment and predator-prey interactions in aquatic animals

How predators find, select and capture prey is central to understanding trophic cascades and ecosystem structure. But despite advances in biologging technology, obtaining in situ observations of organisms and their interactions remains challenging in the marine environment. For some species of toothed whales, echoes from organisms insonified by echolocation clicks and recorded by sound logging tags have provided a fine-scale view of prey density, and predator and prey behaviour during capture attempts, but such information is not available for marine predators that do not echolocate. Here the development and performance of a miniature biomimetic sonar and movement tag capable of acquiring similar data from non-echolocating marine predators is reported. The tag, weighing 200 g in air, records wide bandwidth sonar data at up to 50 pings a second synchronously with fast-sampling sensors for depth, acceleration, magnetic field and GPS. This sensor suite enables biotic conditions and predator behaviour to be related to geographic location over long-duration foraging trips by apex marine predators. The sonar operates at 1.5 MHz with a 3.4° beamwidth and a source level of 190 dB re 1  μPa at 1 m. Sonar recordings from a trial deployment of the tag on a southern elephant seal contained frequent targets corresponding to small organisms up to 6 m ahead of the tagged animal. Synchronously sampled movement data allowed interpretation of whether the seal attempted to capture organisms that it approached closely while the high sonar ping rate revealed attempts by prey to escape. Results from this trial demonstrate the ability of the tag to quantify the biotic environment and to track individual prey captures, providing fine-scale information on predator-prey interactions which has been difficult to obtain from non-echolocating marine animals

A general framework for animal density estimation from acoustic detections across a fixed microphone array

Acoustic monitoring can be an efficient, cheap, non‐invasive alternative to physical trapping of individuals. Spatially explicit capture–recapture (SECR) methods have been proposed to estimate calling animal abundance and density from data collected by a fixed array of microphones. However, these methods make some assumptions that are unlikely to hold in many situations, and the consequences of violating these are yet to be investigated. We generalize existing acoustic SECR methodology, enabling these methods to be used in a much wider variety of situations. We incorporate time‐of‐arrival (TOA) data collected by the microphone array, increasing the precision of calling animal density estimates. We use our method to estimate calling male density of the Cape Peninsula Moss Frog Arthroleptella lightfooti. Our method gives rise to an estimator of calling animal density that has negligible bias, and 95% confidence intervals with appropriate coverage. We show that using TOA information can substantially improve estimate precision. Our analysis of the A. lightfooti data provides the first statistically rigorous estimate of calling male density for an anuran population using a microphone array. This method fills a methodological gap in the monitoring of frog populations and is applicable to acoustic monitoring of other species that call or vocalize