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The collection of animal position data via GPS tracking devices has increased in quality and usage in recent years. Animal position and movement, although measured discretely, follows the same principles of kinematic motion, and as such, the process is inherently continuous and differentiable. I demonstrate the functionality and visual elegance of smoothing spline models. I discuss the challenges and benefits of implementing such an approach, and I provide an analysis of movement and social interaction of seven jaguars inhabiting the Taiamã Ecological Station, Pantanal, Brazil, a region with the highest known density of jaguars. In the analysis, I derive measures for pairwise distance, cooccurrence, and spatiotemporal association between jaguars, borrowing ideas from density estimation and information theory. These measures are feasible as a result of spline model estimation, and they provide a critical tool for a deeper investigation of cooccurrence duration, frequency, and localized spatio‐temporal relationships between animals. In this work, I characterize a variety of interactive relationships between pairs of jaguars, and I particularly emphasize the relationships in movement of two male–female and two male–male jaguar pairs exhibiting highly associative relationships., I propose the use of smoothing spline models to explore animal movement and social interaction. I propose temporal‐state density estimation and localized mutual information measures to characterize behavior and strength of association between jaguars on a refined and unified time grid. I provide further characterization of time‐dependent male–male and female–male relationships in this region, an important step in determining conservation policy for an endangered neotropical predator.

Globally, marine animal distributions are shifting in response to a changing climate. These shifts are usually considered at the species level, but individuals are likely to differ in how they respond to the changing conditions. Here, we investigate how movement behaviour and, therefore, redistribution, would differ by sex and maturation class in a wide-ranging marine predator. We tracked 115 tiger sharks (Galeocerdo cuvier) from 2002 to 2020 and forecast class-specific distributions through to 2030, including environmental factors and predicted occurrence of potential prey. Generalised Linear and Additive Models revealed that water temperature change, particularly at higher latitudes, was the factor most associated with shark movements. Females dispersed southwards during periods of warming temperatures, and while juvenile females preferred a narrow thermal range between 22 and 23 °C, adult female and juvenile male presence was correlated with either lower ( 23 °C) temperatures. During La Niña, sharks moved towards higher latitudes and used shallower isobaths. Inclusion of predicted distribution of their putative prey significantly improved projections of suitable habitats for all shark classes, compared to simpler models using temperature alone. Tiger shark range off the east coast of Australia is predicted to extend ~ 3.5° south towards the east coast of Tasmania, particularly for juvenile males. Our framework highlights the importance of combining long-term movement data with multi-factor habitat projections to identify heterogeneity within species when predicting consequences of climate change. Recognising intraspecific variability will improve conservation and management strategies and help anticipate broader ecosystem consequences of species redistribution due to ocean warming. Supplementary Information The online version contains supplementary material available at 10.1007/s00442-021-05075-7.

\ₑprint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/2041-210X.13853; International audience; Miniature electronic devices have recently enabled ecologists to document relatively large amounts of animal trajectories. Modelling such trajectories may contribute to explaining the mechanisms underlying observed behaviours and to clarifying ecological processes at the scale of the population by simulating multiple trajectories. Existing approaches to animal movement modelling have mainly addressed the first objective, and are often limited when used for simulation purposes. Individual-based models generally rely on ad hoc formulation and their empirical parametrization lacks generability, while random walks based on mathematically sound statistical inference typically consist of first-order Markovian models calibrated at the local scale which may lead to overly simplistic description and simulation of animal trajectories. We investigate a recent deep learning tool—generative adversarial networks (GAN)—to simulate animal trajectories. GANs consist of a pair of deep neural networks that aim to capture the data distribution of some experimental dataset. They enable the generation of new instances of data that share statistical properties. This study aims at identifying relevant deep network architectures to simulate central-place foraging trajectories, as well as at evaluating GANs drawbacks and benefits over classical methods, such as state-switching hidden Markov models (HMM). We demonstrate the outstanding ability of deep convolutional GANs to simulate and to capture medium- to large-scale properties of seabird foraging trajectories. GAN-derived synthetic trajectories reproduced the Fourier spectral density of observed trajectories better than those simulated using HMMs. However, unlike HMMs, GANs do not adequately capture local-scale descriptive statistics, such as step speed distributions. GANs provide a new likelihood-free approach to calibrate complex stochastic processes and thus open new research avenues for animal movement modelling. We discuss the potential uses of GANs in movement ecology and future developments to better capture local-scale features. In this context, embedding HMM-based priors in GAN schemes appears as a promising research direction.

Acoustic telemetry (AT) is a rapidly evolving technique used to track the movements of aquatic animals. As the capacity of AT research expands it is important to optimize its relevance to management while still pursuing key ecological questions. A global review of AT literature revealed region-specific research priorities underscoring the breadth of how AT is applied, but collectively demonstrated a lack of management-driven objectives, particularly relating to fisheries, climate change, and protection of species. In addition to the need for more research with direct pertinence to management, AT research should prioritize ongoing efforts to create collaborative opportunities, establish long-term and ecosystem-based monitoring, and utilize technological advancements to bolster aquatic policy and ecological understanding worldwide.

This paper describes the exploration of the combined antenna–channel model for a horse hoof. An antenna of 25 mm × 40 mm is designed in the ISM 868 MHz band. During the characterization and design of the antenna, the dynamic and harsh environment of the horse hoof is taken into account throughout every step of the procedure because it is impossible to de-embed the antenna from its environment. The antenna and channel model are verified extensively by measurements in phantom and ex vivo. The antenna is verified to be robust against changes in the morphology of the horse’s hoof up to 50%. The dynamic environment was captured by considering different soil types and air, and the design was verified to be resilient against changes herein. The antenna performs well within the targeted band, with a fractional bandwidth of 8% and a gain of −2 dBi. Furthermore, a path loss model was constructed for a typical barn environment, and the antenna reaches a range of 250 m in the studied environment based on the LoRa technology. This research is important for monitoring horse health.

As populações de predadores pelágicos de topo têm vindo a decrescer drasticamente nas últimas décadas, sendo a sobrepesca considerada a principal responsável por estes declínios. As repercussões destes decréscimos são especialmente graves para as populações de tubarões, uma vez que, dado o seu lento ciclo de vida, estas espécies apresentam uma maior dificuldade em restabelecer os seus números após períodos de pesca intensiva. Além disso, dada a sua posição de topo na cadeia trófica, a remoção de tubarões dos ecossistemas gera efeitos em cascata nos níveis tróficos inferiores, tendo consequências graves e imprevisíveis para todo o ecossistema. Os tubarões azul (Prionace glauca) e anequim (Isurus oxyrinchus) são as duas espécies de tubarões pelágicos mais pescadas no Oceano Atlântico, constituindo, em conjunto, mais de 95% de todos os tubarões pelágicos capturados anualmente neste oceano e estando, respetivamente, classificadas como “quase ameaçada” e “em perigo” pelo IUCN. No entanto, continuam a existir graves problemas ao nível da regulamentação, monitorização e reporte da pesca destas duas espécies, tendo apenas no ano passado (2020) sido estabelecida uma quota máxima para a captura de tubarão azul no Oceano Atlântico, enquanto o tubarão anequim continua sem qualquer quota a restringir a sua captura. A determinação de áreas prioritárias para a conservação de predadores pelágicos de topo é complicada pela extrema mobilidade destes animais e a consequente dificuldade em identificar zonas de agregação devido à falta de dados fiáveis, uma vez que os estudos destas espécies estão historicamente restringidos a dados inerentes às pescas, sendo, por isso, extremamente enviesados. Porém, o advento da tecnologia de telemetria de satélite tem permitido descrever novos comportamentos, bem como uma melhor compreensão da real distribuição espacial e utilização de habitat, horizontal e vertical, destes predadores. Neste sentido, estudos anteriores utilizando dados de esforço de pesca e/ou telemetria de satélite têm sugerido a atração de uma grande variedade de predadores de topo por fenómenos dinâmicos de média dimensão, tais como frentes térmicas e vórtices oceânicos, que estará relacionada com movimentos de procura de alimento. Neste estudo, os movimentos de procura de alimento de 34 tubarões azuis e 24 tubarões anequins foram analisados relativamente à presença de frentes de oxigénio dissolvido (OD), que até agora não tinham sido consideradas na literatura. Para tal, estes tubarões foram capturados em 5 localizações diferentes do Oceano Atlântico Norte (Açores, Cabo Verde, ao largo de Nova Iorque e a sudoeste de Portugal e Inglaterra) e marcados com transmissores de satélite SPOT, que são fixados à barabatana dorsal e permitem seguir os seus movimentos horizontais com elevada precisão. Todas as variáveis ambientais foram extraídas da plataforma CMEMS’s (Copernicus Marine Environment Monitoring Service) Ocean Products, que disponibiliza dados oceanográficos diários e mensais recolhidos através de uma combinação de medições de satélites e de boias à superfície e a meia água. Para identificar a presença de frentes, foram calculados os gradientes máximos de OD (e temperatura) entre células adjacentes. Os resultados aqui apresentados sugerem que frentes de OD podem representar extensas zonas de alimentação para estas duas espécies, sendo esta relação particularmente evidente para os tubarões azuis. Dois tipos de frentes de OD foram identificadas como atrativas para estas espécies: frentes conjuntas de temperatura e OD, forte, persistente e verticalmente estruturadas, onde a grande produtividade existente cria importantes áreas de alimentação que, por sua vez, atraem predadores de níveis tróficos subsequentemente mais elevados; e frentes exclusivas de OD, associadas a zonas hipóxicas, onde a compressão de presas nas águas superficiais, mais oxigenadas, da coluna de água aumenta a probabilidade de encontro entre predador e presa. No entanto, apesar de ambas as espécies terem revelado afinidade para com estes fenómenos, diferenças importantes foram constatadas. Os tubarões azuis demonstraram uma maior relação com as frentes de OD que os tubarões anequins, enquanto o contrário se verificou em relação às frentes de temperatura, resultados que se coadunam com as diferentes estratégias metabólicas apresentadas pelas duas espécies. Presumivelmente, dada a menor taxa metabólica associada a uma estratégia ectotérmica, os tubarões azuis terão uma maior tolerância a diminuições momentâneas de oxigénio, explorando, por isso, zonas de frentes exclusivas de OD quando possível, tal como acontece nas zonas de oxigénio mínimo (ZOMs). Por outro lado, os tubarões anequins, dada a sua capacidade em manter uma temperatura corporal mais ou menos constante – endotermia - combinada com uma maior necessidade de oxigénio, tenderão a favorecer zonas de fortes gradientes térmicos. Este estudo reforça ainda a importância dos vórtices oceânicos para a alimentação de predadores pelágicos em águas oligotróficas, tendo os tubarões anequins revelado uma clara preferência por vórtices ciclónicos (VCs). Por outro lado, os tubarões azuis demonstraram uma utilização mais equilibrada de VCs e vórtices anticiclónicos (VACs), corroborando parcialmente estudos anteriores que sugerem uma relação entre procura de alimento por parte de predadores de topo e VACs, apesar de estes, há muito, serem considerados apenas como “desertos biológicos”. Os resultados aqui apresentados sugerem que a integração de frentes de OD em modelos utilizados para identificação e gestão de áreas prioritárias de conservação destas duas espécies poderá melhorar significativamente os seus resultados. Além disso, a adoção de medidas de gestão de stocks em tempo real, de acordo com a informação inferida destes modelos, tal como é feito, na Austrália, com o Atum Rabilho do Sul (Thunnus maccoyii), uma espécie ameaçada e com uma quota limite estabelecida, poderá melhorar significativamente a gestão e conservação destas espécies, sendo o mesmo, possivelmente, aplicável ao caso de outros predadores pelágicos de topo. Finalmente, este estudo realça a importância da telemetria de satélite para a aquisição de informação relativa aos padrões ecológicos de movimentação a larga escala de grandes predadores marinhos. Acresce que a análise destes movimentos em conjunto com dados oceanográficos permite inferir com maior confiança quanto à importância de determinadas áreas e fenómenos para estas e outras espécies, possibilitando assim, decisões mais informadas no que respeita à gestão de stocks e proteção de habitats de extrema importância ecológica e económica. Pois apenas melhorando o conhecimento que temos sobre os hábitos destas espécies podemos almejar impedir uma total perda da biodiversidade e uma completa disrupção dos ecossistemas marinhos. Pelagic top predator populations worldwide have suffered sharp decreases in abundance over the last decades, with overfishing being the main cause of such declines. Blue (Prionace glauca) and mako sharks (Isurus oxyrinchus) are the two most caught pelagic shark species in the Atlantic Ocean, being classified, respectively, as “near-threatened” and “endangered” by the IUCN red list. However, their catches remain highly unregulated, unmonitored, and unreported. Identification of priority areas for pelagic top predators’ conservation is hampered by the high mobility of these animals and the consequent difficulty in determining aggregation areas, yet mesoscale dynamic features such as thermal fronts and eddies have been suggested to attract a variety of large apex predators while foraging. In this study, the foraging movements of 34 blue and 24 mako sharks, satellite-tagged across 5 different locations in the North Atlantic Ocean, were analysed in relation to dissolved oxygen (DO) fronts, which until now had not been considered. The results presented here suggest that DO fronts might represent extensive foraging areas for these two species, but particularly for blue sharks. Two different DO front types were noticed to attract these species: strong, persistent, and vertically structured thermal-oxygen fronts, where high productivity creates important foraging opportunities; and oxygen-only fronts associated with hypoxic areas where the compression of prey in the more oxygenated surface waters results in higher predator-prey encounters. This study also reinforces the importance of eddies for pelagic predators foraging in oligotrophic waters. In addition, mako sharks revealed a clear preference for cyclonic eddies (CEs) while blue sharks showed a more balanced usage of CEs and anticyclonic eddies. These results strongly suggest the integration of DO fronts in conservation and management modelling, as they can substantially improve the identification of priority conservation areas for these two sharks and, possibly, many other pelagic top predators.

International audience; Animal telemetry is a powerful tool for observing marine animals and the physical environments that they inhabit, from coastal and continental shelf ecosystems to polar seas and open oceans. Satellite-linked biologgers and networks of acoustic receivers allow animals to be reliably monitored over scales of tens of meters to thousands of kilometers, giving insight into their habitat use, home range size, the phenology of migratory patterns and the biotic and abiotic factors that drive their distributions. Furthermore, physical environmental variables can be collected using animals as autonomous sampling platforms, increasing spatial and temporal coverage of global oceanographic observation systems. The use of animal telemetry, therefore, has the capacity to provide measures from a suite of essential ocean variables (EOVs) for improved monitoring of Earth's oceans. Here we outline the design features of animal telemetry systems, describe current applications and their benefits and challenges, and discuss future directions. We describe new analytical techniques that improve our ability to not only quantify animal movements but to also provide a powerful framework for comparative studies across taxa. We discuss the application of animal telemetry and its capacity to collect biotic and abiotic data, how the data collected can be incorporated into ocean observing systems, and the role these data can play in improved ocean management.

Baseline information is needed on migrations through US Mid-Atlantic Bight shelf waters in advance of offshore wind development. Acoustically-tagged Atlantic sturgeon and striped bass were detected from 2016-2019 in an array of 20 acoustic telemetry receivers centered on the Maryland Wind Energy Area and extending 10-50 km offshore. Both species were transient (mean residency < 3 days), but migration patterns differed seasonally and were related to depth and temperature. Generalized additive models showed that Atlantic sturgeon occur at inshore sites during spring while striped bass shifted toward the outer shelf as inshore waters cooled in winter. The movement of hundreds of tagged striped bass and sturgeon, originating from shelf waters from Maine to South Carolina suggests that the Wind Energy Area is part of a multi-species Atlantic coastal flyway, particularly during spring, fall, and winter periods. Thus, summer presents a potential window for wind tower construction.

This work was funded by the Natural Environment Research Council and the Department for Business, Energy and Industrial Strategy. The development of foraging strategies that enable juveniles to efficiently identify and exploit predictable habitat features is critical for survival and long-term fitness. In the marine environment, meso- and sub-mesoscale features such as oceanographic fronts offer a visible cue to enhanced foraging conditions, but how individuals learn to identify these features is a mystery. In this study, we investigate age-related differences in the fine-scale foraging behaviour of adult (aged ≥ 5 years) and immature (aged 2-4 years) northern gannets Morus bassanus. Using high-resolution GPS-loggers, we reveal that adults have a much narrower foraging distribution than immature birds and much higher individual foraging site fidelity. By conditioning the transition probabilities of a hidden Markov model on satellite-derived measures of frontal activity, we then demonstrate that adults show a stronger response to frontal activity than immature birds, and are more likely to commence foraging behaviour as frontal intensity increases. Together, these results indicate that adult gannets are more proficient foragers than immatures, supporting the hypothesis that foraging specialisations are learned during individual exploratory behaviour in early life. Such memory-based individual foraging strategies may also explain the extended period of immaturity observed in gannets and many other long-lived species. Publisher PDF

Our data consist of measurements of 22 sharks' movements within a 366-acre tidal basin. The measurements are made at irregular time points over a 16-month interval. Constant-length observation intervals would have been desirable, but are often infeasible in practice. We model the sharks' paths at short constant-length intervals by inferring their behavior (feeding vs transiting), interpolating their locations, and estimating parameters of motion (speed and turning angle) in environmental and ecological contexts. We are interested in inferring regional differences in the sharks' behavior, and behavioral interaction between them. Our method uses particle filters, a computational Bayesian technique designed to sequentially model a dynamic system. We discuss how resampling is used to approximate arbitrary densities, and illustrate its use in a simple example of a particle filter implementation of a state-space model. We then introduce a particular model formulation that uses conditioning to introduce unobserved parameters for the shark's behaviors. We show how the irregularly-observed shark locations can be modeled by interpolation as a set of movements at constant-length time intervals. We use a spline method for generating approximations of the ground truth at these intervals for comparison with our model. Finally, we demonstrate our model's estimates of the sharks' behavioral and ecological parameters of interest on a subset of the observed data.

TM and TP received support from IMBER-CLIOTOP and Macquarie University Safety Net Grant 9201401743. SB was supported under an Australia Research Council Super Science Fellowship. IDJ was supported by a Macquarie Vice-Chancellors Innovation Fellowship. TAP was supported by a CSIRO Julius Career Award and the Villum Foundation. The behavior of colony-based marine predators is the focus of much research globally. Large telemetry and tracking data sets have been collected for this group of animals, and are accompanied by many empirical studies that seek to segment tracks in some useful way, as well as theoretical studies of optimal foraging strategies. However, relatively few studies have detailed statistical methods for inferring behaviors in central place foraging trips. In this paper we describe an approach based on hidden Markov models, which splits foraging trips into segments labeled as "outbound", "search", "forage", and "inbound". By structuring the hidden Markov model transition matrix appropriately, the model naturally handles the sequence of behaviors within a foraging trip. Additionally, by structuring the model in this way, we are able to develop realistic simulations from the fitted model. We demonstrate our approach on data from southern elephant seals (Mirounga leonina) tagged on Kerguelen Island in the Southern Ocean. We discuss the differences between our 4-state model and the widely used 2-state model, and the advantages and disadvantages of employing a more complex model. Publisher PDF

This work was supported by SMRU Ltd (now SMRU Marine) in the form of a PhD fellowship (T.P.). Completion of the manuscript was supported by a National Research Foundation Scarce Skills Postdoctoral Fellowship at the University of Cape Town, South Africa (T.P.). The CTD-SRDL data presented in this manuscript were collected as part of a project funded by the Natural Environment Research Council (NERC) grants NE/E018289/1 and NER/D/S/2002/00426. For diving animals, animal-borne sensors are used to collect time-depth information for studying behaviour, ranging patterns and foraging ecology. Often, this information needs to be compressed for storage or transmission. Widely used devices called conductivity-temperature-depth satellite relay data loggers (CTD-SRDLs) sample time and depth at high resolution during a dive and then abstract the time-depth trajectory using a broken-stick model (BSM). This approximation method can summarize efficiently the curvilinear shape of a dive, using a piecewise linear shape with a small, fixed number of vertices, or break points. We present the process of abstracting dives using the BSM and quantify its performance, by measuring the uncertainty associated with the profiles it produces. We develop a method for obtaining a confidence zone and an index for the goodness-of-fit (dive zone index, DZI) for abstracted dive profiles. We validate our results with a case study using dives from elephant seals (Mirounga spp.). We use generalized additive models (GAMs) to determine whether the DZI can be used as a proxy for an absolute measure of fit and investigate the relationship between the DZI and the dive shape. We found a strong correlation between the residual sum of squares (RSS) for the difference between the detailed and abstracted profiles, and the DZI and maximum residual (R4), for dives resulting from CTD-SRDLs (69% deviance explained). On its own, the DZI explained a lower percentage of deviance which was variable for abstracted dives with different numbers of break points. We also found evidence for systematic differences in the DZI for different dive shapes (65% deviance explained). Although the proportional loss of information in the abstraction of time-depth dive profiles by BSM is high, what remains is sufficient to infer goodness-of-fit of the abstracted profile by reversing the abstraction process. Our results suggest that together the DZI and R4 can be used as a proxy for the RSS, and we present the method for obtaining these metrics for BSM-abstracted profiles. Postprint