Tracking of marine predators to protect Southern Ocean ecosystems.

Southern Ocean ecosystems are under pressure from resource exploitation and climate change1,2. Mitigation requires the identification and protection of Areas of Ecological Significance (AESs), which have so far not been determined at the ocean-basin scale. Here, using assemblage-level tracking of marine predators, we identify AESs for this globally important region and assess current threats and protection levels. Integration of more than 4,000 tracks from 17 bird and mammal species reveals AESs around sub-Antarctic islands in the Atlantic and Indian Oceans and over the Antarctic continental shelf. Fishing pressure is disproportionately concentrated inside AESs, and climate change over the next century is predicted to impose pressure on these areas, particularly around the Antarctic continent. At present, 7.1% of the ocean south of 40°S is under formal protection, including 29% of the total AESs. The establishment and regular revision of networks of protection that encompass AESs are needed to provide long-term mitigation of growing pressures on Southern Ocean ecosystems.

Threat management priorities for conserving Antarctic biodiversity.

Antarctic terrestrial biodiversity faces multiple threats, from invasive species to climate change. Yet no large-scale assessments of threat management strategies exist. Applying a structured participatory approach, we demonstrate that existing conservation efforts are insufficient in a changing world, estimating that 65% (at best 37%, at worst 97%) of native terrestrial taxa and land-associated seabirds are likely to decline by 2100 under current trajectories. Emperor penguins are identified as the most vulnerable taxon, followed by other seabirds and dry soil nematodes. We find that implementing 10 key threat management strategies in parallel, at an estimated present-day equivalent annual cost of US$23 million, could benefit up to 84% of Antarctic taxa. Climate change is identified as the most pervasive threat to Antarctic biodiversity and influencing global policy to effectively limit climate change is the most beneficial conservation strategy. However, minimising impacts of human activities and improved planning and management of new infrastructure projects are cost-effective and will help to minimise regional threats. Simultaneous global and regional efforts are critical to secure Antarctic biodiversity for future generations.

Climate and human stressors on global penguin hotspots: Current assessments for future conservation.

As charismatic and iconic species, penguins can act as "ambassadors" or flagship species to promote the conservation of marine habitats in the Southern Hemisphere. Unfortunately, there is a lack of reliable, comprehensive, and systematic analysis aimed at compiling spatially explicit assessments of the multiple impacts that the world's 18 species of penguin are facing. We provide such an assessment by combining the available penguin occurrence information from Global Biodiversity Information Facility (>800,000 occurrences) with three main stressors: climate-driven environmental changes at sea, industrial fisheries, and human disturbances on land. Our analyses provide a quantitative assessment of how these impacts are unevenly distributed spatially within species' distribution ranges. Consequently, contrasting pressures are expected among species, and populations within species. The areas coinciding with the greatest impacts for penguins are the coast of Perú, the Patagonian Shelf, the Benguela upwelling region, and the Australian and New Zealand coasts. When weighting these potential stressors with species-specific vulnerabilities, Humboldt (Spheniscus humboldti), African (Spheniscus demersus), and Chinstrap penguin (Pygoscelis antarcticus) emerge as the species under the most pressure. Our approach explicitly differentiates between climate and human stressors, since the more achievable management of local anthropogenic stressors (e.g., fisheries and land-based threats) may provide a suitable means for facilitating cumulative impacts on penguins, especially where they may remain resilient to global processes such as climate change. Moreover, our study highlights some poorly represented species such as the Northern Rockhopper (Eudyptes moseleyi), Snares (Eudyptes robustus), and Erect-crested penguin (Eudyptes sclateri) that need internationally coordinated efforts for data acquisition and data sharing to understand their spatial distribution properly.

Scaling up ocean conservation through recognition of key biodiversity areas in the Southern Ocean from multispecies tracking data.

Biodiversity is critical for maintaining ecosystem function but is threatened by increasing anthropogenic pressures. In the Southern Ocean, a highly biologically productive region containing many endemic species, proactive management is urgently needed to mitigate increasing pressures from fishing, climate change, and tourism. Site-based conservation is one important tool for managing the negative impacts of human activities on ecosystems. The Key Biodiversity Area (KBA) Standard is a standardized framework used to define sites vital for the persistence of global biodiversity based on criteria and quantitative thresholds. We used tracking data from 14 species of Antarctic and subantarctic seabirds and pinnipeds from the publicly available Retrospective Analysis of Antarctic Tracking Data (RAATD) data set to define KBAs for a diverse suite of marine predators. We used track2kba, an R package that supports identification of KBAs from telemetry data through identification of highly used habitat areas and estimates of local abundance within sites. We compared abundance estimates at each site with thresholds for KBA criteria A1, B1, and D1 (related to globally threatened species, individual geographically restricted species, and demographic aggregations, respectively). We identified 30 potential KBAs for 13 species distributed throughout the Southern Ocean that were vital for each individual species, population, and life-history stage for which they were determined. These areas were identified as highly used by these populations based on observational data and complement the ongoing habitat modeling and bioregionalization work that has been used to prioritize conservation areas in this region. Although further work is needed to identify potential KBAs based on additional current and future data sets, we highlight the benefits of utilizing KBAs as part of a holistic approach to marine conservation, given their significant value as a global conservation tool.

Ampliación de la conservación oceánica por medio del reconocimiento de áreas importantes de biodiversidad en el Océano Antártico a partir de datos de rastreo de varias especies Resumen La biodiversidad es fundamental para mantener la función de los ecosistemas, pero está amenazada por las crecientes presiones antropogénicas. En el Océano Antártico, una región con mucha producción biológica que contiene numerosas especies endémicas, se necesita urgentemente una gestión proactiva para mitigar las crecientes presiones de la pesca, el cambio climático y el turismo. La conservación basada en el sitio es una herramienta importante para gestionar los efectos negativos de las actividades humanas en los ecosistemas. El Estándar de Áreas Clave para la Biodiversidad (ACB) es un marco estandarizado que se utiliza para definir lugares vitales para la persistencia de la biodiversidad mundial con base en criterios y umbrales cuantitativos. Usamos datos del seguimiento de 14 especies de aves marinas y pinnípedos antárticos y sub­antárticos del conjunto de datos públicos Retrospective Analysis of Antarctic Tracking Data (RAATD) para definir las ACB de un conjunto diverso de depredadores marinos. Utilizamos track2kba, un paquete de R que permite la identificación de ACB a partir de datos telemétricos mediante la identificación de áreas de hábitat altamente utilizadas y estimaciones de abundancia local dentro de los sitios. Comparamos las estimaciones de abundancia en cada lugar con los umbrales de los criterios A1, B1 y D1 de las ACB (relacionados con especies amenazadas a nivel mundial, especies individuales restringidas geográficamente y agregaciones demográficas, respectivamente). Identificamos 30 ACB potenciales para 13 especies distribuidas por todo el Océano Antártico que eran vitales para cada especie individual, población y etapa del ciclo biológico para las que se determinaron. Estas áreas fueron identificadas como muy utilizadas por estas poblaciones con base a datos observacionales y complementan el trabajo en curso de modelos del hábitat y biorregionalización que se ha utilizado para priorizar las áreas de conservación en esta región. Aunque es necesario seguir trabajando para identificar posibles ACB basadas en conjuntos de datos adicionales actuales y futuros, destacamos los beneficios de utilizar las ACB como parte de un enfoque holístico de la conservación marina, dado su importante valor como herramienta de conservación global.

Reproductive performance and diving behaviour share a common sea-ice concentration optimum in Adélie penguins (Pygoscelis adeliae).

The Southern Ocean is currently experiencing major environmental changes, including in sea-ice cover. Such changes strongly influence ecosystem structure and functioning and affect the survival and reproduction of predators such as seabirds. These effects are likely mediated by reduced availability of food resources. As such, seabirds are reliable eco-indicators of environmental conditions in the Antarctic region. Here, based on 9 years of sea-ice data, we found that the breeding success of Adélie penguins (Pygoscelis adeliae) reaches a peak at intermediate sea-ice cover (ca. 20%). We further examined the effects of sea-ice conditions on the foraging activity of penguins, measured at multiple scales from individual dives to foraging trips. Analysis of temporal organisation of dives, including fractal and bout analyses, revealed an increasingly consistent behaviour during years with extensive sea-ice cover. The relationship between several dive parameters and sea-ice cover in the foraging area appears to be quadratic. In years of low and high sea-ice cover, individuals adjusted their diving effort by generally diving deeper, more frequently and by resting at the surface between dives for shorter periods of time than in years with intermediate sea-ice cover. Our study therefore suggests that sea-ice cover is likely to affect the reproductive performance of Adélie penguins through its effects on foraging behaviour, as breeding success and most diving parameters share a common optimum. Some years, however, deviated from this general trend, suggesting that other factors (e.g. precipitation during the breeding season) might sometimes become preponderant over the sea-ice effects on breeding and foraging performance. Our study highlights the value of monitoring fitness parameters and individual behaviour concomitantly over the long-term to better characterize optimal environmental conditions and potential resilience of wildlife. Such an approach is crucial if we want to anticipate the effects of environmental change on Antarctic penguin populations.

Decreasing prolactin levels leads to a lower diving effort but does not affect breeding success in Adélie penguins.

Current research on seabirds suggests a key role of hormones in the trade-off between self-maintenance and parental investment through their influence on foraging decisions during the breeding period. Although prolactin is known to have major effects on parental care, its role in foraging behavior has rarely been investigated in seabirds to date. The aim of this study was to assess the influence of an experimental decrease in prolactin levels on foraging decisions and its consequences on breeding success in free-living seabirds. To achieve this, we implanted bromocriptine (an inhibitor of prolactin secretion) in male Adélie penguins (Pygoscelis adeliae), monitored their foraging behavior using time-depth recorders over several trips, and recorded their reproductive output. On average 8±0.5days after implantation, we showed that bromocriptine administration led to an efficient decrease in prolactin levels. However, no differences were seen in foraging trip durations between bromocriptine-implanted birds and controls. Moreover, the time spent diving and the number of dives performed per trip were similar in both groups. By contrast, all diving parameters (including diving efficiency) were negatively affected by the treatment during the first at-sea trip following the treatment. Finally, the treatment did not affect adult body condition or chick growth and survival. Our study highlights the short-term negative effect of low prolactin levels on diving effort, but indicates that a short-term and/or low-magnitude decrease in prolactin levels alone is not sufficient to modify consistently the body maintenance or the parental investment of Adélie penguins.

Age-related variation in energy expenditure in a long-lived bird within the envelope of an energy ceiling.

Energy expenditure in wild animals can be limited (i) intrinsically by physiological processes that constrain an animal's capacity to use energy, (ii) extrinsically by energy availability in the environment and/or (iii) strategically based on trade-offs between elevated metabolism and survival. Although these factors apply to all individuals within a population, some individuals expend more or less energy than other individuals. To examine the role of an energy ceiling in a species with a high and individually repeatable metabolic rate, we compared energy expenditure of thick-billed murres (Uria lomvia) with and without handicaps during a period of peak energy demand (chick-rearing, N = 16). We also compared energy expenditure of unencumbered birds (N = 260) across 8 years exhibiting contrasting environmental conditions and correlated energy expenditure with fitness (reproductive success and survival). Murres experienced an energy ceiling mediated through behavioural adjustments. Handicapped birds decreased time spent flying/diving and chick-provisioning rates such that overall daily energy expenditure remained unchanged across the two treatments. The energy ceiling did not reflect energy availability or trade-offs with fitness, as energy expenditure was similar across contrasting foraging conditions and was not associated with reduced survival or increased reproductive success. We found partial support for the trade-off hypothesis as older murres, where prospects for future reproduction would be relatively limited, did overcome an energy ceiling to invest more in offspring following handicapping by reducing their own energy reserves. The ceiling therefore appeared to operate at the level of intake (i.e. digestion) rather than expenditure (i.e. thermal constraint, oxidative stress). A meta-analysis comparing responses of breeding animals to handicapping suggests that our results are typical: animals either reduced investment in themselves or in their offspring to remain below an energy ceiling. Across species, whether a handicapped individual invested in its own energy stores or its offspring's growth was not explained by life history (future vs. current reproductive potential). Many breeding animals apparently experience an intrinsic energy ceiling, and increased energy costs lead to a decline in self-maintenance and/or offspring provisioning.

Fine-scale spatial age segregation in the limited foraging area of an inshore seabird species, the little penguin.

Competition for food resources can result in spatial and dietary segregation among individuals from the same species. Few studies have looked at such segregations with the combined effect of sex and age in species with short foraging ranges. In this study we examined the 3D spatial use of the environment in a species with a limited foraging area. We equipped 26 little penguins (Eudyptula minor) of known age, sex, and breeding output with GPS (location) and accelerometer (body acceleration and dive depth) loggers. We obtained dietary niche information from the isotopic analysis of blood tissue. We controlled for confounding factors of foraging trip length and food availability by sampling adults at guard stage when parents usually make one-day trips. We observed a spatial segregation between old (>11 years old) and middle-aged penguins (between 5 and 11 years old) in the foraging area. Old penguins foraged closer to the shore, in shallower water. Despite observing age-specific spatial segregation, we found no differences in the diving effort and foraging efficiency between age classes and sexes. Birds appeared to target similar prey types, but showed age-specific variation in their isotopic niche width. We hypothesize that this age-specific segregation was primarily determined by a "cohort effect" that would lead individuals sharing a common life history (i.e. having fledged and dispersed around the same age) to forage preferentially together or to share similar foraging limitations.

Conservation features of the terrestrial Antarctic Peninsula.

Conserving landscapes used by multiple stakeholder groups requires understanding of what each stakeholder values. Here we employed a semi-structured, participatory approach to identify features of value in the terrestrial Antarctic Peninsula related to biodiversity, science and tourism. Stakeholders identified 115 features, ranging from Adélie penguin colonies to sites suitable for snowshoeing tourists. We split the features into seven broad categories: science, tourism, historic, biodiversity, geographic, habitat, and intrinsic features, finding that the biodiversity category contained the most features of any one category, while science stakeholders identified the most features of any stakeholder group. Stakeholders have overlapping interests in some features, particularly for seals and seabirds, indicating that thoughtful consideration of their inclusion in future management is required. Acknowledging the importance of tourism and other social features in Antarctica and ensuring their integration into conservation planning and assessment will increase the likelihood of implementing successful environmental management strategies into the future.

TerrANTALife 1.0 Biodiversity data checklist of known Antarctic terrestrial and freshwater life forms.

Background: Incomplete species inventories for Antarctica represent a key challenge for comprehensive ecological research and conservation in the region. Additionally, data required to understand population dynamics, rates of evolution, spatial ranges, functional traits, physiological tolerances and species interactions, all of which are fundamental to disentangle the different functional elements of Antarctic biodiversity, are mostly missing. However, much of the fauna, flora and microbiota in the emerged ice-free land of the continent have an uncertain presence and/or unresolved status, with entire biodiversity compendia of prokaryotic groups (e.g. bacteria) being missing. All the available biodiversity information requires consolidation, cross-validation, re-assessment and steady systematic inclusion in order to create a robust catalogue of biodiversity for the continent. New information: We compiled, completed and revised eukaryotic species inventories present in terrestrial and freshwater ecosystems in Antarctica in a new living database: terrANTALife (version 1.0). The database includes the first integration in a compendium for many groups of eukaryotic microorganisms. We also introduce a first catalogue of amplicon sequence variants (ASVs) of prokaryotic biodiversity. Available compendia and literature to date were searched for Antarctic terrestrial and freshwater species, integrated, taxonomically harmonised and curated by experts to create comprehensive checklists of Antarctic organisms. The final inventories comprises 470 animal species (including vertebrates, free-living invertebrates and parasites), 306 plants (including all Viridiplantae: embryophytes and green algae), 997 fungal species and 434 protists (sensu lato). We also provide a first account for many groups of microorganisms, including non-lichenised fungi and multiple groups of eukaryotic unicellular species (Stramenophila, Alveolata and Rhizaria (SAR), Chromists and Amoeba), jointly referred to as "protists". In addition, we identify 1753 bacterial (obtained from 348117 ASVs) and 34 archaeal genera (from 1848 ASVs), as well as, at least, 14 virus families. We formulate a basic tree of life in Antarctica with the main lineages listed in the region and their "known-accepted-species" numbers.

Accelerometry predicts daily energy expenditure in a bird with high activity levels.

Animal ecology is shaped by energy costs, yet it is difficult to measure fine-scale energy expenditure in the wild. Because metabolism is often closely correlated with mechanical work, accelerometers have the potential to provide detailed information on energy expenditure of wild animals over fine temporal scales. Nonetheless, accelerometry needs to be validated on wild animals, especially across different locomotory modes. We merged data collected on 20 thick-billed murres (Uria lomvia) from miniature accelerometers with measurements of daily energy expenditure over 24 h using doubly labelled water. Across three different locomotory modes (swimming, flying and movement on land), dynamic body acceleration was a good predictor of daily energy expenditure as measured independently by doubly labelled water (R(2) = 0.73). The most parsimonious model suggested that different equations were needed to predict energy expenditure from accelerometry for flying than for surface swimming or activity on land (R(2) = 0.81). Our results demonstrate that accelerometers can provide an accurate integrated measure of energy expenditure in wild animals using many different locomotory modes.

Holding time has limited impact on constitutive innate immune function in a long-lived Antarctic seabird, the Adélie penguin: implications for field studies.

There is great interest in measuring immune function in wild animals. Yet, field conditions often have methodological challenges related to handling stress, which can alter physiology. Despite general consensus that immune function is influenced by handling stress, previous studies have provided equivocal results. Furthermore, few studies have focused on long-lived species, which may have different stress-immune trade-offs compared to short-lived species that have primarily been tested. Here, we investigate whether capture and handling duration impacts innate immune function in a long-lived seabird, the Adélie penguin (Pygoscelis adeliae). We found no evidence for changes in three commonly used parameters of innate immune function upon holding time of up to 2 h, suggesting that immune function in this species is more robust against handling than in other species. This opens up exciting possibilities for measuring immune function in species with similar life-histories even if samples cannot be taken directly after capture.

Exposure, but not timing of exposure, to a sulfonylurea herbicide alters larval development and behaviour in an amphibian species.

Environmental contamination is one of the major causes of biodiversity loss. Wetlands are particularly susceptible to contamination and species inhabiting these habitats are subjected to pollutants during sensitive phases of their development. In this study, tadpoles of a widespread amphibian, the spined toad (Bufo spinosus), were exposed to environmental concentrations of nicosulfuron (0 µg/L; 0.15 ± 0.05 µg/L and 0.83 ± 0.04 µg/L), a sulfonylurea herbicide, during different phases of development. Tadpoles were exposed during embryonic (12.98 ± 0.90 days) or larval development (93.74± 0.85 days), or throughout both phases, and we quantified development duration, morphological traits and behavioural features as responses to exposure. Developing tadpoles exposed to nicosulfuron were larger, but with smaller body, and had shorter but wider tail muscles. They were also more active and swam faster than control tadpoles and showed diverging patterns of behavioural complexity. We showed that higher concentrations had greater effects on individuals than lower concentrations, but the timing of nicosulfuron exposure did not influence the metrics studied: Exposure to nicosulfuron triggered similar effects irrespective of the developmental stages at which exposure occurred. These results further indicate that transient exposure (e.g., during embryonic development) can induce long-lasting effects throughout larval development to metamorphosis. Our study confirms that contaminants at environmental concentrations can have strong consequences on non-target organisms. Our results emphasize the need for regulation agencies and policy makers to consider sublethal concentrations of sulfonulyrea herbicides, such as nicosulfuron, as a minimum threshold in their recommendations.

Environmental Drivers of Growth and Oxidative Status during Early Life in a Long-Lived Antarctic Seabird, the Adélie Penguin.

AbstractIn vertebrates, developmental conditions can have long-term effects on individual performance. It is increasingly recognized that oxidative stress could be one physiological mechanism connecting early-life experience to adult phenotype. Accordingly, markers of oxidative status could be useful for assessing the developmental constraints encountered by offspring. Although some studies have demonstrated that developmental constraints are associated with high levels of oxidative stress in offspring, it remains unclear how growth, parental behavior, and brood competition may altogether affect oxidative stress in long-lived species in the wild. Here, we investigated this question in a long-lived Antarctic bird species by testing the impact of brood competition (e.g., brood size and hatching order) on body mass and on two markers of oxidative damage in Adélie penguin chicks. We also examined the influence of parental effort (i.e., foraging trip duration) and parental body condition on chick body mass and oxidative damage. First, we found that brood competition and parental traits had significant impacts on chick body mass. Second, we found that chick age and, to a lesser extent, chick body mass were two strong determinants of the levels of oxidative damage in Adélie penguin chicks. Finally, and importantly, we also found that brood competition significantly increased the levels of one marker of oxidative damage and was associated with a lower survival probability. However, parental effort and parental condition were not significantly linked to chick levels of oxidative damage. Overall, our study demonstrates that sibling competition can generate an oxidative cost even for this long-lived Antarctic species with a limited brood size (maximum of two chicks).

A vision for incorporating human mobility in the study of human-wildlife interactions.

As human activities increasingly shape land- and seascapes, understanding human-wildlife interactions is imperative for preserving biodiversity. Habitats are impacted not only by static modifications, such as roads, buildings and other infrastructure, but also by the dynamic movement of people and their vehicles occurring over shorter time scales. Although there is increasing realization that both components of human activity substantially affect wildlife, capturing more dynamic processes in ecological studies has proved challenging. Here we propose a conceptual framework for developing a 'dynamic human footprint' that explicitly incorporates human mobility, providing a key link between anthropogenic stressors and ecological impacts across spatiotemporal scales. Specifically, the dynamic human footprint integrates a range of metrics to fully acknowledge the time-varying nature of human activities and to enable scale-appropriate assessments of their impacts on wildlife behaviour, demography and distributions. We review existing terrestrial and marine human-mobility data products and provide a roadmap for how these could be integrated and extended to enable more comprehensive analyses of human impacts on biodiversity in the Anthropocene.

King penguins adjust their diving behaviour with age.

Increasing experience in long-lived species is fundamental to improving breeding success and ultimately individual fitness. Diving efficiency of marine animals is primarily determined by their physiological and mechanical characteristics. This efficiency may be apparent via examination of biomechanical performance (e.g. stroke frequency and amplitude, change in buoyancy or body angle, etc.), which itself may be modulated according to resource availability, particularly as a function of depth. We investigated how foraging and diving abilities vary with age in a long-lived seabird. During two breeding seasons, small accelerometers were deployed on young (5 year old) and older (8/9 year old) brooding king penguins (Aptenodytes patagonicus) at the Crozet Archipelago, Indian Ocean. We used partial dynamic body acceleration (PDBA) to quantify body movement during dive and estimate diving cost. During the initial part of the descent, older birds exerted more effort for a given speed but younger penguins worked harder in relation to performance at greater depths. Younger birds also worked harder per unit speed for virtually the whole of the ascent. We interpret these differences using a model that takes into account the upthrust and drag to which the birds are subjected during the dive. From this, we suggest that older birds inhale more at the surface but that an increase in the drag coefficient is the factor leading to the increased effort to swim at a given speed by the younger birds at greater depths. We propose that this higher drag may be the result of young birds adopting less hydrodynamic postures or less direct trajectories when swimming or even having a plumage in poorer condition.

The role of individual variability on the predictive performance of machine learning applied to large bio-logging datasets.

Animal-borne tagging (bio-logging) generates large and complex datasets. In particular, accelerometer tags, which provide information on behaviour and energy expenditure of wild animals, produce high-resolution multi-dimensional data, and can be challenging to analyse. We tested the performance of commonly used artificial intelligence tools on datasets of increasing volume and dimensionality. By collecting bio-logging data across several sampling seasons, datasets are inherently characterized by inter-individual variability. Such information should be considered when predicting behaviour. We integrated both unsupervised and supervised machine learning approaches to predict behaviours in two penguin species. The classified behaviours obtained from the unsupervised approach Expectation Maximisation were used to train the supervised approach Random Forest. We assessed agreement between the approaches, the performance of Random Forest on unknown data and the implications for the calculation of energy expenditure. Consideration of behavioural variability resulted in high agreement (> 80%) in behavioural classifications and minimal differences in energy expenditure estimates. However, some outliers with < 70% of agreement, highlighted how behaviours characterized by signal similarity are confused. We advise the broad bio-logging community, approaching these large datasets, to be cautious when upscaling predictions, as this might lead to less accurate estimates of behaviour and energy expenditure.

Foraging range scales with colony size in high-latitude seabirds.

Density-dependent prey depletion around breeding colonies has long been considered an important factor controlling the population dynamics of colonial animals.1-4 Ashmole proposed that as seabird colony size increases, intraspecific competition leads to declines in reproductive success, as breeding adults must spend more time and energy to find prey farther from the colony.1 Seabird colony size often varies over several orders of magnitude within the same species and can include millions of individuals per colony.5,6 As such, colony size likely plays an important role in determining the individual behavior of its members and how the colony interacts with the surrounding environment.6 Using tracking data from murres (Uria spp.), the world's most densely breeding seabirds, we show that the distribution of foraging-trip distances scales to colony size0.33 during the chick-rearing stage, consistent with Ashmole's halo theory.1,2 This pattern occurred across colonies varying in size over three orders of magnitude and distributed throughout the North Atlantic region. The strong relationship between colony size and foraging range means that the foraging areas of some colonial species can be estimated from colony sizes, which is more practical to measure over a large geographic scale. Two-thirds of the North Atlantic murre population breed at the 16 largest colonies; by extrapolating the predicted foraging ranges to sites without tracking data, we show that only two of these large colonies have significant coverage as marine protected areas. Our results are an important example of how theoretical models, in this case, Ashmole's version of central-place-foraging theory, can be applied to inform conservation and management in colonial breeding species.

Plasticity in foraging strategies of inshore birds: how Little Penguins maintain body reserves while feeding offspring.

Breeding animals face important time and energy constraints when caring for themselves and their offspring. For long-lived species, life-history theory predicts that parents should favor survival over current reproductive attempts, thus investing more into their own maintenance than the provisioning of their young. In seabirds, provisioning strategies may additionally be influenced by the distance between breeding sites and foraging areas, and offshore and inshore species should thus exhibit different strategies. Here, we examine the provisioning strategies of an inshore seabird using a long-term data set on more than 200 Little Penguins, Eudyptula minor. They alternated between two consecutive long and several short foraging trips all along chick rearing, a strategy almost never observed for inshore animals. Short trips allowed for regular provisioning of the chicks (high feeding frequency and larger meals), whereas long trips were performed when parent body mass was low and enabled them to rebuild their reserves, suggesting that adult body condition may be a key factor in initiating long trips. Inshore seabirds do use dual strategies of alternating short and long trips, but from our data, on a simpler and less flexible way than for offshore birds.

Energy expenditure of freely swimming adult green turtles (Chelonia mydas) and its link with body acceleration.

Marine turtles are globally threatened. Crucial for the conservation of these large ectotherms is a detailed knowledge of their energy relationships, especially their at-sea metabolic rates, which will ultimately define population structure and size. Measuring metabolic rates in free-ranging aquatic animals, however, remains a challenge. Hence, it is not surprising that for most marine turtle species we know little about the energetic requirements of adults at sea. Recently, accelerometry has emerged as a promising tool for estimating activity-specific metabolic rates of animals in the field. Accelerometry allows quantification of the movement of animals (ODBA/PDBA, overall/partial dynamic body acceleration), which, after calibration, might serve as a proxy for metabolic rate. We measured oxygen consumption rates (V(O(2))) of adult green turtles (Chelonia mydas; 142.1±26.9 kg) at rest and when swimming within a 13 m-long swim channel, using flow-through respirometry. We investigated the effect of water temperature (T(w)) on turtle and tested the hypothesis that turtle body acceleration can be used as a proxy for V(O(2)). Mean mass-specific V(O(2)) (sV(O(2))) of six turtles when resting at a T(w) of 25.8±1.0°C was 0.50±0.09 ml min(-1) kg(-0.83). sV(O(2))increased significantly with T(w) and activity level. Changes in sV(O(2)) were paralleled by changes in respiratory frequency (f(R)). Deploying bi-axial accelerometers in conjunction with respirometry, we found a significant positive relationship between sV(O(2)) and PDBA that was modified by T(w). The resulting predictive equation was highly significant (r(2)=0.83, P<0.0001) and associated error estimates were small (mean algebraic error 3.3%), indicating that body acceleration is a good predictor of V(O(2)) in green turtles. Our results suggest that accelerometry is a suitable method to investigate marine turtle energetics at sea.