Conservation of marine ecosystems can be improved through a better understanding of ecosystem functioning, particularly the cryptic underwater behaviours and interactions of marine predators. Image‐based bio‐logging devices (including images, videos and active acoustic) are increasingly used to monitor wildlife movements, foraging behaviours and their environment, but generate complex datasets needing efficient analytical tools. We review advances in image‐based bio‐logging technology for ecological studies on marine fauna. Emphasis is placed on the diversity of data collected, merging research questions, challenges in image processing, and integration of Artificial Intelligence (AI) methods. Image‐based system issues, such as exposure, focus, blurriness, colour balance, moving background, perspective and scale variability are even more challenging in underwater images where conditions change constantly and cannot be controlled. We list computer vision tools and algorithms available for analyses of underwater images, including enhanced tracking algorithms that recognise objects and treat images as a time series. Although AI and computer vision methods offer ample and robust analytical solutions for (semi‐) automated image processing, their uptake by marine ecologists has been slow. Collaboration among ecologists, modellers, statisticians, engineers and computer scientists is needed to integrate ecological questions, data selection and computational methodology. We propose a four‐phase framework for image data processing and analysis (video checking and manipulation, image processing, image labelling and model development) accompanied by detailed python code. We also outline the additional complications in aligning the diverse scalar movement metrics from bio‐loggers along with image‐based data, such as acceleration, depth and location, which typically are collected at different resolutions. Building analytical frameworks for on‐board image data collection (e.g. lightweight models) is also explored. We advocate for a collaborative research community at the Ecology‐AI interface, emphasising sharing and exchange of both data and tools to drive cross‐disciplinary innovation. Beyond the Ecology‐AI interface, we pave the path for the application of insights from image‐based bio‐logging technology enabling collaboration among scientists, conservation managers, and policymakers. Systematic applications of computer vision tools to image‐based bio‐logging technology will enhance the power these data hold, informing about the status of marine ecosystems, testing and developing ecological theory and aiding conservation.

Mesoscale eddies are rotating vortices of water that perturb the local physical, chemical, and biological environment. In the Southern Ocean, penguins inhabit regions characterised by intense eddy activity, which can offer foraging opportunities. To better understand relationships between penguins and eddies, we collated tracking data for five species (emperor, king, chinstrap, Adélie, and macaroni penguins), totalling 3189 individuals from 59 colonies. Data were subset by colony and breeding stage to create 74 case studies. We then fitted Hidden Markov Models to penguin tracks to identify Area-Restricted-Search (ARS) behaviour (a proxy for foraging) and used Generalised Additive Mixed Models to relate behaviour to the presence of eddies. In 28 case studies, penguins displayed a pronounced increase in ARS within specific parts of eddies. All five species exhibited an association between ARS and eddies in several case studies, though substantial regional differences in association strength were observed. In life history periods when penguins experienced central place constraints, ARS was more frequently associated with eddies. By studying five extensive case studies in greater detail, we found that eddies possibly influenced trip trajectories by aggregating prey at submesoscale filaments around their peripheries, by interacting with the distribution of sea ice, and potentially by transporting key prey species in their interiors. In these case studies, eddy maturity, amplitude, and intensity also differed between eddies collocated with ARS and the background eddy field. When eddy abundance varied, foraging trip durations also varied, though with opposing trends depending on the colony and breeding stage. Eddy activity is projected to increase in the Southern Ocean, which in isolation would have mixed impacts on penguins, though the negative impacts of broad-scale changes in prey availability and sea ice concentration are likely to outweigh any impacts of changing eddy fields.

Environmental variability shapes species' population dynamics. Yet, the mechanisms linking environmental changes to individual-level metrics (e.g. foraging behaviour, body condition) and reproductive outcomes in the wild remain poorly understood. Energetics play a central role in mediating trade-offs between self-maintenance and reproduction under fluctuating environmental conditions. As such, it provides a powerful framework for identifying how individual responses to environmental variation scale up to influence population dynamics. Using a unique long-term monitoring and bio-logging dataset spanning over 25 years providing continuous measures of diving behaviour, feeding activity and daily energy expenditure, this study investigates how individual responses to environmental variation affect population dynamics. Focusing on Adélie penguins (Pygoscelis adeliae) during the energetically demanding chick-rearing phase, we integrated individual-level foraging and energetics data with colony-wide reproductive metrics to elucidate how environmental cues lead to life-history trade-offs. Winter sea-ice conditions exhibited a quadratic relationship with key individual behavioural and energetic parameters. Specifically, increased sea-ice concentration and delayed ice retreat led to longer foraging trips, reduced time spent diving and poorer body condition. At the population level, while energy expenditure was not associated with changes in reproductive outcome, increased foraging effort (time spent feeding per day) led to enhanced fledging success. Adverse on-land conditions, such as higher snowfall, had negative impacts on reproductive outcomes. These findings support the central role of energy as a common currency of maintenance and reproduction. By linking individual energetics to demographic performance, our work advances our understanding of how energy allocation strategies in response to environmental stressors shape population dynamics. These insights are crucial for improving predictive models of population trajectories and offer valuable guidance for conservation strategies aimed at mitigating the impacts of global change on ecosystems.

Understanding how animal behavior is modified by environmental stressors, including chemical contaminants, is of increasing importance given rapid anthropogenic environmental change. In this context, we explored whether mercury (Hg) contamination is associated with neophobia and risk-taking behavior in breeding, adult little auks (Alle alle), an Arctic seabird facing altered Hg exposure due to global change. During chick rearing, we presented novel objects of different colors near little auk nests at Hornsund, Svalbard. We quantified latency to enter the nest with food under control conditions and when confronted with novel objects, with neophobia defined as the difference between latency to enter during control verses novel object sessions. To assess whether little auks display personality variation in these behavioral traits, we quantified behavioral repeatability. Furthermore, we related neophobia behavior to blood Hg, baseline corticosterone (CORT), and chick provisioning rate. Little auks displayed neophobia, with latency to enter increasing from 40 to 80 s on average in response to novel objects. Latency to enter was individually repeatable within and across control and novel object sessions, suggesting repeatability in cautiousness. However, the neophobia response exhibited non-significant repeatability, perhaps due to habituation. Birds with elevated blood Hg (range: 0.3–0.8 µg g− 1 dry weight) took longer to enter the nest upon first appearance in control and novel object sessions, indicating elevated cautiousness. Unexpectedly, more neophobic birds had lower CORT. Findings support prior work suggesting that Hg might alter risk-taking behavior, calling for more work on this topic in animals at high Hg exposure risk. A growing number of studies are suggesting that exposure to metals, including mercury, might alter animal risk-taking behaviors. Yet, evidence from free-living populations remains equivocal. Mercury exposure may have particularly potent effects on animal behavior in marine environments, where mercury bioaccumulates. In this context, we explored associations between mercury contamination, parental risk-taking, and object neophobia behavior in little auks (Alle alle), an abundant, high Arctic seabird that is facing altered patterns of mercury exposure due to rapid Arctic climate change. We found that little auks exhibit significant object neophobia, and that birds with elevated blood mercury levels were more cautious when entering nests (reduced risk-taking), but did not exhibit increased neophobia. Our findings support prior work suggesting that mercury exposure might alter risk-taking behavior, calling for more work on this topic in animals at high mercury exposure risk.

Predator-prey interactions are a fundamental aspect of ecology that has generated sustained research interests. Progress in the field stems from a diverse range of approaches, from highly controlled yet simplified mathematical and agent-based models, to grounded but data-limited field studies. As a compromise between mathematical and observation-oriented methods, we introduce an original approach based on an outdoor game. In this game, biologged human players follow simple rules to impersonate predators and prey in a natural landscape augmented with synthetic resource patches and refuges. We investigated the behaviour, movement, functional response and spatial organization of over 25 players simultaneously monitored during nine simulations to determine whether the game could replicate realistic predator-prey dynamics. Results derived from our real-life simulations were consistent with ecological patterns expected in natural systems. We found that (a) predator and prey movements were driven by risk and reward trade-offs, (b) predators took advantage of linear features to travel at higher speed, making these areas risky for prey, (c) prey had nonlinear and risk-sensitive functional responses and (d) consumer-resource interactions were spatially modular and defined by players' movement rates and landscape features. Moreover, the comprehensive dataset generated through the game allowed for the exploration of phenomena that are challenging to study in natural settings, such as spatial memory and the influence of satiety on resource acquisition rates. The approach offers a simple, computationally accessible and genuinely amusing way to explore the complex ramifications of predator-prey interactions and test otherwise data-deficient hypotheses. The strength and originality of the method lies in the use of living agents-players-making decisions in a real-world setting. This aspect alleviates the computational and empirical burden of defining and estimating decision-related parameters needed to build simulators, while generating extensive datasets in a flexible experimental framework that is generally out of reach for empirical studies. It also offers immersive insights into predator-prey interactions, making it an engaging pedagogical tool that encourages creative thinking. The numerous possible scenarios that can be explored are only constrained by the investigator's creativity in adapting game rules and the players' desire to win.

Understanding how climate-driven changes in the Southern Ocean may alter predator–prey interactions is essential, for evaluating ecosystem-level consequences, yet many trophic relationships remain poorly documented. Shelled pteropods (Thecosomata) are key components of Southern Ocean zooplankton but are highly vulnerable to ocean acidification, and their role as prey for higher predators has rarely been confirmed. Here, we present the first direct video evidence of pteropod predation by chick-rearing Adélie penguins (Pygoscelis adeliae) near Dumont d’Urville Station, East Antarctica. Seven of eight video-instrumented birds consumed pteropods (N = 1,449 captures), predominantly Clio pyramidata, with two individuals relying heavily on them (> 60

Faced with unpredictable prey in dynamic ecosystems, seabirds have developed strategies to efficiently locate food, particularly during breeding when time and space are constrained. Using 13 yr of GPS data from 422 little penguins Eudyptula minor, we tested whether they rely on consistent foraging areas to reduce search times or respond to dynamic environmental cues. Our results suggest a combination of these strategies, depending on the spatial scale. Little penguins used only 32% of the potential foraging range, concentrating in shallow waters within 70 km and mostly east of their colony, as confirmed by our spatial density models. However, finer-scale analyses using kriging maps showed no recurring foraging hotspots over 13 yr, suggesting high inter-annual variability in prey availability. Despite this variability, penguins consistently spent more time in the most productive areas and also exploited more areas with favourable environmental conditions to access prey (thermocline, current, waves), even as these conditions shifted within and across breeding seasons. In years of poor conditions, they foraged farther from the colony, resulting in lower breeding success. These results emphasise the adaptability of little penguins to dynamic environmental conditions, but underscore the vulnerability of their foraging and breeding success to oceanographic variability in a climate-impacted ecosystem.

In the context of climate change, the increasing frequency of severe meteorological events, such as floods or droughts, is expected to impact various life history traits in organisms, primarily by altering the availability and quality of their trophic resources. Our study aimed to quantify the effects of meteorological conditions on the fine-scale space use of breeding white storks Ciconia ciconia. Birds were equipped with GPS/acceleration loggers in two breeding areas within the marshes of the French Atlantic coast and monitored over four years, including one year of drought. Specifically, we examined variations in home-range size, daily foraging distances, the proportion of time spent foraging, and daily activity levels in relation to drought conditions and individual state (sex, brood age and brood size). Our findings reveal that under drier conditions, storks increased their daily foraging distances, home-range size, and time spent foraging. Individuals with smaller broods travelled greater distances from the nest, and tended to exploit larger home-ranges. Their activity levels and time spent foraging increased with brood age and brood size, and were higher in females than in males. Our findings reveal how climate change, particularly drought, affects the foraging behaviour of a wetland top predator, and highlight the conservation challenges faced by wetland ecosystems.

Climate change is predicted to alter species interactions by exposing ecosystems to increasingly frequent and intense warm spells. In the mountain tundra, grazing by large herbivores, particularly reindeer, can limit shrub expansion and preserve Arctic plant diversity. However, the impact of rising temperatures on herbivores themselves remains understudied. Here, we combine long-term weather data with spatially explicit behavioural data from 31 free-ranging reindeer from three Swedish herding districts equipped with GPS, temperature sensors and tri-axial accelerometers over two consecutive summers to investigate how warming affects grazing. We hypothesise that both heat stress and insect harassment reduce grazing under warm conditions. First, we show that reindeer significantly reduce grazing beyond a body surface temperature (TR) of 20.3 degrees C, likely due to insect harassment. As reindeer speed sharply declines beyond 24 degrees C TR, our results suggest an onset of physiological heat stress, indicating that warm spells limit grazing through insect harassment, but also overheating. Second, warming also triggers a shift in habitat use, as reindeer relocate their grazing activity outside their primary grazing land for less favourable high-elevation habitats, further reducing foraging efficiency. These behavioural and spatial shifts result in a net loss of foraging, with no evidence of compensatory grazing. Third, we find that warm spells - defined as 24-hour periods with a maximum air temperature above 13 degrees C - have become more frequent over the last 30 years, now occurring for half of the summer. Overall, this study highlights how thermal discomfort can disrupt and relocate the foraging patterns of reindeer, a keystone herbivore in the tundra. Such reduced herbivory pressure could have severe cascading consequences by accelerating shrubification and contributing to local biodiversity loss. Hence, climate warming does not only alter abiotic conditions, but can also disrupt biotic processes that underpin the resilience of cold ecosystems.

Understanding the spatial and temporal at-sea distribution of marine predators throughout their annual cycle is crucial for identifying priority areas for conservation in the Southern Ocean. However, the delimitation of boundaries of the proposed East Antarctic Marine Protected Area (EAMPA) is largely based on species' breeding distributions, overlooking seasonal and annual shifts driven by sea ice variability. We studied the non-breeding distribution and space use of a key Antarctic eco-indicator species, the Adelie penguin, by tracking 62 individuals from Terre Adelie over five years using geolocators. Moulting occurred in areas of low sea ice concentration (SIC), whereas during winter, penguins migrated on average 1550 km westward from the colony to areas along the sea ice edge with high SIC (75 %). The inter-annual overlap of wintering grounds revealed high spatiotemporal consistency, indicating productive regions. Despite variability across years, tracked individuals moulted predominantly outside the proposed EAMPA, and only 16.3 % of winter locations fell within its boundaries. These findings provide new insights into the non-breeding ecology of Adelie penguins, and highlight a relevant gap in spatial coverage of critical moulting and wintering areas of this highly mobile species in the current EAMPA proposal.

Aim: To map presence, absence and ignorance of Antarctic seabird breeding occupancy at the spatial resolution of ice-free habitat sites to identify knowledge gaps and inform management and conservation. Location: East Antarctica between longitudes 30 degrees E and 150 degrees E. Methods: We develop a unifying spatial and inferential framework to compile and interpret observations of Antarctic seabird breeding occupancy. The spatial framework allowed consistent geo-referencing of observations at the spatial resolution of habitat sites. The compilation included published papers and datasets, unpublished reports, research station logs and unpublished field notes. Where possible, observations and inferences were validated by the 'experts' who originally collected data. The inferential framework categorised levels of uncertainty for inferring occupancy and distinguished knowledge of occupancy from ignorance. Results: After a century of observations, there are still knowledge gaps in seabird breeding occupancy along large sections of the East Antarctic coastline and across most of continental East Antarctica where breeding habitat is available. The spatial extent of knowledge and ignorance is strongly dependent on the level of certainty used to infer absence. Observations are clustered close to permanently occupied research stations, most of which are located on the coast, and biased in favour of species that are most emblematic of Antarctica or those with a less secure conservation status. The spatial and temporal coverage of observations in recent decades would be insufficient to effectively detect change in most species' breeding occupancy distributions across their range into the future. Main Conclusions: Our compilation and mapping of occupancy data contributes to practical conservation measures to mitigate impacts of human activities including aviation and fisheries on seabirds in Antarctica, and serves as a foundation to strategically improve future environmental management and conservation. We urge future occupancy monitoring to explicitly report the location of search effort and potential absence in addition to presence and to aim to close spatial knowledge gaps.

Rapid growth in bio-logging—the use of animal-borne electronic tags to document the movements, behaviour, physiology and environments of wildlife—offers opportunities to mitigate biodiversity threats and expand digital natural history archives. Here we present a vision to achieve such benefits by accounting for the heterogeneity inherent to bio-logging data and the concerns of those who collect and use them. First, we can enable data integration through standard vocabularies, transfer protocols and aggregation protocols, and drive their wide adoption. Second, we need to develop integrated data collections on standardized data platforms that support data preservation through public archiving and strategies that ensure long-term access. We outline pathways to reach these goals, highlighting the need for resources to govern community data standards and guide data mobilization efforts. We propose the launch of a community-led coordinating body and provide recommendations for how stakeholders—including government data centres, museums and those who fund, permit and publish bio-logging work—can support these efforts. Animal-borne electronic tags, or bio-loggers, are increasingly used for research and wildlife conservation. This Perspective discusses the importance of standardization, long-term archiving and sharing of bio-logging data, and outlines a roadmap to achieve these goals.

Endogenous reserves accumulated during migration stopovers help most migratory birds cope with environmental uncertainties and fuel energy demands associated with migration and/or reproduction. Migratory decisions, such as departure time, should thus be finely tuned to energy intake rate at stopover sites. However, the physiological drivers of these decisions remain poorly understood. Glucocorticoids such as corticosterone (CORT) are known to mediate the stress response in birds but also play a key role in the regulation of energy intake and behavior, particularly during demanding life-history stages. We investigated how baseline CORT influences bird energy acquisition and migratory decisions by manipulating the physiology of wild snow geese (Anser caerulescens atlanticus) through subcutaneous implantation of corticosterone pellets during spring stopover. Birds of similar body condition were paired, implanted with CORT or placebo pellets, and tracked with GPS-GSM collars and accelerometers to monitor foraging efforts, habitat use, and migration departure date. We measured foraging rates from accelerometer data and classified using an unsupervised algorithm calibrated with field video recordings. CORT-treated birds foraged 20% more on average than placebo individuals over 10 days, primarily by increasing foraging efforts rather than altering habitat use. Most of the difference occurred in the first days post-implantation (Foraging rates on Day 2, CORT: 0.4 [95% CI: 0.34, 0.47]; placebo: 0.3 [0.2, 0.36]) and gradually faded to zero afterward (Foraging rates on Day 10, CORT: 0.26 [0.21, 0.32]; placebo: 0.26 [0.21, 0.31]). These higher foraging rates advanced the median departure date of CORT-treated individuals by 2 days compared to placebo (median departure: CORT, May 17 [15, 17]; placebo, May 19 [17, 20]). Our experimental manipulation is one of the first to induce a positive shift in migration phenology and confirms the role of CORT baseline levels in modulating energy acquisition and migratory decisions in a wild bird species.

Changes in prey availability can lead to mismatches between consumers and resources, decreasing the fitness of consumers, especially during periods of high energy demand such as reproduction. We investigated interseasonal variation in the foraging behaviour of chick-rearing Adelie penguins, Pygoscelis adeliae, in a declining colony in the West Antarctic Peninsula to assess the impact of changes in prey abundance. Specifically, we analysed how these changes affect the energetic cost of males and females during the breeding season. Using information from foraging trips, diet, body condition and daily energy expenditure of 38 Adelie penguins breeding in Ardley Island, King George Island, in 2019/2020 and 2021/ 2022, we found that during low food availability conditions, penguins were forced to increase their foraging effort and their body mass was lower. Specifically, females extended their foraging trips, resulting in 40% higher energy expenditure compared to a year with high prey availability. We observed no significant changes in physiological condition, breeding success or trophic niche. The lower fat reserves and higher energy expenditure of females during the breeding season with low food availability may render them more vulnerable to the challenging conditions of the winter season, with potential negative consequences on population trends. (c) 2025 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Understanding how marine predators structure and adjust their foraging in response to prey field characteristics is a longstanding objective in marine ecology. This is particularly challenging in Southern Ocean ecosystems, where logistical and financial constraints hinder assessment of predator foraging and prey field information at relevant spatial and temporal scales. Here, we examine how Adelie penguins, Pygoscelis adeliae, a key Southern Ocean indicator species, perform and organize their foraging behaviour during two contrasting years of krill (Euphausia superba) abundance. Using multiyear krill acoustic data from King George Island in the West Antarctic Peninsula (WAP), we assess broad seasonal conditions in krill availability. We also analyse a suite of penguin biologging data (spatial location, dive and accelerometry-derived activities) during the same period to identify broad behavioural differences in their bout-diving activity, a classical measure of the temporal organization of foraging in diving predators. During years of high krill abundance and availability, penguins performed shorter dive bouts (consisting of shallower and shorter-duration dives), which were more concentrated in time and space. Despite these differences in bout structure, prey capture attempts occurred at the same rate within bouts. These findings challenge traditional interpretations assuming that increased bout durations (and related proxies of prey capture effort) signal increased krill patch abundance and profitability. Although additional data are required to understand the full scope of penguin bout diving and krill prey field associations, our work improves understanding of penguin behavioural variation and provides insights into how foraging behaviours could potentially be used to interpret krill availability at predator- and management-relevant scales. (c) 2025 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

Early life telomere length is thought to influence and predict an individual's fitness. It has been shown to vary significantly in early life compared to adulthood. Investigating the factors influencing telomere length in young individuals is therefore of particular interest, especially as the relative importance of heredity compared to post-natal conditions remains largely uncertain. Adélie penguins are eco-indicators of the Antarctic ecosystem and their population are currently undergoing variable trajectories due to climate change. Here, we conducted a correlative study to investigate how telomere length was influenced by external and internal factors in Adélie penguin chicks. We found that most of the parameters we tested, including sex, body mass, brood size and hatching order as well as parental foraging trip duration, did not significantly influence chick telomere length at 32 days. However, siblings had similar telomere length, suggesting that hereditary factors play a stronger role in determining telomere length at this stage compared to the post-natal environment. In addition, telomere length and oxidative damage did not directly correlate but did interact in a complex way mediated by chick mass. High levels of oxidative damage were associated with longer telomeres in heavy chicks, whereas they were associated with shorter telomeres in light chicks. Although this mass-dependent relationship between telomere length and oxidative damage needs to be confirmed in future studies, it could reflect two different scenarios: (1) short telomeres may mimic the cost of poor nutritional conditions and oxidative damage in light chicks; (2) long telomeres may be maintained despite high oxidative damage in heavy chicks thanks to optimal nutritional conditions.