David Grémillet

French National Centre for Scientific Research | CNRS · Centre d'Ecologie Fonctionnelle et Evolutive

Fisheries transform marine ecosystems and compete with predators [1], but temporal trends in seabird-fishery competition had never been assessed on a worldwide scale. Using catch reconstructions [2] for all fisheries targeting taxa that are also seabird prey, we demonstrated that average annual fishery catch increased from 59 to 65 million metric t...

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection...

We explored the implications of reaching the Paris Agreement Objective of limiting global warming to <2°C for the future winter distribution of the North Atlantic seabird community. We predicted and quantified current and future winter habitats of five North Atlantic Ocean seabird species (Alle alle, Fratercula arctica, Uria aalge, Uria lomvia and...

Each winter, the North Atlantic Ocean is the stage for numerous cyclones, the most severe ones leading to seabird mass-mortality events called ‘‘winter wrecks.’’ During these, thousands of emaciated seabird carcasses are washed ashore along European and North American coasts. Winter cyclones can therefore shape seabird population dynamics by affect...

Satellite remote-sensing and wildlife tracking allow researchers to record rapidly increasing volumes of information on the spatial ecology of marine megafauna in the context of global change. This field of investigation is thereby entering the realm of big data science: Information technology allows the design of completely new frameworks for acqu...

Since the last Arctic Monitoring and Assessment Programme (AMAP) effort to review biological effects of mercury (Hg) on Arctic biota in 2011 and 2018, there has been a considerable number of new Arctic bird studies. This review article provides contemporary Hg exposure and potential health risk for 36 Arctic seabird and shorebird species, represent...

Accelerometry has been widely used to estimate energy expenditure in a broad array of terrestrial and aquatic species. However, a recent reappraisal of the method showed that relationships between dynamic body acceleration (DBA) and energy expenditure weaken as the proportion of non-mechanical costs increase. Aquatic air breathing species often exe...

Temporal trend analysis of (total) mercury (THg) concentrations in Arctic biota were assessed as part of the 2021 Arctic Monitoring and Assessment Programme (AMAP) Mercury Assessment. A mixed model including an evaluation of non-linear trends was applied to 110 time series of THg concentrations from Arctic and Subarctic biota. Temporal trends were...

Flying seabirds are adapted for windy environments 1,2 . Despite this, storms can cause widespread strandings and wrecks, demonstrating that these seabirds are not always able to avoid or compensate for extreme conditions 3,4,5,6,7 . The maximum wind speeds that birds can operate in should vary with morphology and flight style ⁸ , but this has been...

Studies performed in humans and farm animals indicate that infrared thermography can be used to estimate the body temperature of homeotherms. However, this method has seldom been validated for wild animals in their natural environment. To fill this major gap, we shot facial infrared thermograms of red-footed boobies (Sula sula) in situ, while remot...

Fear effects of predators on prey distributions are seldom considered in marine environments , especially over large spatial scales and in conservation contexts. To fill these major gaps, we tested the Seascape of Fear Hypothesis in the Benguela marine ecosystem off South Africa. Using electronic tracking data, we showed that Cape gannets and their...

In colonial seabirds, ecological divergence may occur in the absence of physical barriers, driven by the isolation of populations due to distance, or the adaptation to local environment. In migratory seabirds, the geographic segregation among breeding populations can persist year round (i.e., strong migratory connectivity) when populations breeding...

The conservation of migratory marine species, including pelagic seabirds, is challenging because their movements span vast distances frequently beyond national jurisdictions. Here, we aim to identify important aggregations of seabirds in the North Atlantic to inform ongoing regional conservation efforts. Using tracking, phenology, and population da...

Electronic tracking technologies revolutionized wildlife ecology, notably for studying the movements of elusive species such as seabirds. Those advances are key to seabird conservation, for example in guiding the design of marine protected areas for this highly threatened group. Tracking data are also boosting scientific understanding of marine eco...

Our societies will change following the COVID-19 crisis, as well as ocean management. Here we present 10 action points in a marine context, to re-energize our economies and avert the biodiversity and climate change crises of which the present COVID-19 crisis represents a portend: (1) promote carbon neutral economies to mitigate global warming; (2)...

MONDRETI, R., DAVIDAR, P., RYAN, P.G., THIEBOT, J.B. & GREMILLET, D. 2020. Seabird and cetacean occurrence in the Bay of Bengal associated with marine productivity and commercial fishing effort. Marine Ornithology 48: 91–101. At-sea observations of seabirds and cetaceans provide essential baseline information about their biogeography and behaviour...

https://arctox.cnrs.fr/en/home/ Mercury (Hg) is a natural trace element found in high concentrations in top predators, including Arctic seabirds. Most current knowledge about Hg concentrations in Arctic seabirds relates to exposure during the summer breeding period when researchers can easily access seabirds at colonies. However, the few studies f...

Seabirds are one of the most threatened of all bird groups, with a marked community-wide decline across the last decades. Yet, some seabird species are more resilient than others, and it is essential to study under which conditions even these highly resilient organisms are affected by global changes. Here, we report such a case in northern gannets...

Sharing the same wintering grounds by avian populations breeding in various areas may synchronize fluctuations in vital rates, which could increase the risk of extinction. Here, by combining multi-colony tracking with long-term capture-recapture data, we studied the winter distribution and annual survival of the most numerous Arctic seabird, the li...

The Arctic is entering a new ecological state, with alarming consequences for humanity. Animal-borne sensors offer a window into these changes. Although substantial animal tracking data from the Arctic and subarctic exist, most are difficult to discover and access. Here, we present the new Arctic Animal Movement Archive (AAMA), a growing collection...

Aim In migratory species, individuals often use fixed and individual‐specific migration strategies, which we term individual migration strategy fidelity (IMSF). Our goal was to test if guillemots have flexible or fixed individual migration strategies (i.e. IMSF), if this behaviour is consistent across large parts of the genus’ range and if they wer...

Despite the limited direct anthropogenic mercury (Hg) inputs in the circumpolar Arctic, elevated concentrations of methylmercury (MeHg) are accumulated in Arctic marine biota. However, the MeHg production and bioaccumulation pathways in these ecosystems have not been completely unraveled. We measured Hg concentrations and stable isotope ratios of H...

Social information percolates through a variety of channels to influence animal decision making, with a notable effect on reproductive and feeding success. Colonial central place foragers can reduce time to locate ephemeral food patches and/or increase foraging rate by following their informed peers, parasitizing direction of returning successful f...

A group of ocean experts brainstormed about the most pressing actions to be taken in favour of ocean conservation in the context of SARS-CoV2

Our paper reports findings on at-sea distributions of both seabirds and cetaceans in the Bay of Bengal. Our study is the first systematic attempt in creating baseline information for this data-poor region. We carried out 39 days of vessel-based observations from 2012 to 2014 over a total linear distance of 4722.3 km. We observed 2697 seabirds of 17...

France's double game with environmental issues

To use seabirds as ecological sentinels of marine ecosystems under the incidence of global changes, it is essential to understand linkages between their spatial ecology and environmental conditions. Such information is still lacking for some key areas, including in Europe. We studied the spatial ecology of European shags (Phalacrocorax aristotelis)...

The identification of geographic areas where the densities of animals are highest across their annual cycles is a crucial step in conservation planning. In marine environments, however, it can be particularly difficult to map the distribution of species, and the methods used are usually biased towards adults, neglecting the distribution of other li...

Identifying drivers of population trends in migratory species is difficult, as they can face many stressors while moving through different areas and environments during the annual cycle. To understand the potential of migrants to adjust to perturbations, it is critical to study the connection of different areas used by different populations during...

Climate change could overturn bird migration: Transarctic flights and high-latitude residency in a sea ice free Arctic

This report describes the results from fieldwork carried out on breeding seabirds in Northeast Greenland as part of the Northeast Greenland Environmental Study Program. Results of GPS-tracking of Sabine’s gulls and ivory gulls are described, as well as surveys of thick-billed murre colonies and a variety of studies on little auks.

Climate models predict that by 2050 the Arctic Ocean will be sea ice free each summer. Removing this barrier between the Atlantic and the Pacific will modify a wide range of ecological processes, including bird migration. Using published information, we identified 29 arctic-breeding seabird species, which currently migrate in the North Atlantic and...

A global analysis recently showed that seabird breeding phenology (as the timing of egg-laying and hatching) does not, on average, respond to temperature changes or advance with time (Keogan et al. 2018 Nat. Clim. Change 8, 313–318). This group, the most threatened of all birds, is therefore prone to spatio-temporal mismatches with their food resou...

Patterns of behavioural variation and migratory connectivity are important characteristics of populations, particularly at the edges of species distributions, where processes involved in influencing evolutionary trajectories, such as divergence, mutual persistence, and natural hybridization, can occur. Here, we focused on two closely related seabir...

1.Dispersal is a key mechanism enabling species to adjust their geographic range to rapid global change. However, dispersal is costly and environmental modifications are likely to modify the cost‐benefit balance of individual dispersal decisions, for example, by decreasing functional connectivity. 2.Dispersal costs occur during departure, transienc...

Wildlife that exploit human-made habitats hosts and spreads bacterial pathogens. This shapes the epidemiology of infectious diseases and facilitates pathogen spill-over between wildlife and humans. This is a global problem, yet little is known about the dissemination potential of pathogen-infected animals. By combining molecular pathogen diagnosis...

Fisheries modify ecosystem balance by harvesting through marine food webs and producing large amounts of discards subsidizing scavengers. Among them, seabirds are the most conspicuous and have been benefiting from anthropogenic food sources generated by fisheries. However, this modified feeding behaviour also exposes them to threats, such as accide...

Migration is a fundamental behavioral process prevalent among a wide variety of animal taxa. As individuals are increasingly shown to present consistent responses to environmental cues for breeding or foraging, it may be expected that approaches to migration would present similar among-individual consistencies. Seabirds frequently show consistent i...

Age variation in reproductive performance is well-documented but the mechanisms underlying this variation remain unclear. Foraging efficiency is likely to be a key source of demographic variation as it determines the amount of energy that can be invested in fitness-related activities. Evidence of age-related changes in the foraging efficiency of ad...

Fisheries compete with seabirds for vanishing marine resources, but also produce fishery waste consumed by seabirds. Marine birds may therefore avoid or seek fishing vessels, and have evolved complex, plastic behavioural responses to vessel presence. Understanding these responses is essential to the conservation of a globally declining seabird comm...

Ongoing global changes apply drastic environmental forcing onto Arctic marine ecosystems, particularly through ocean warming, sea-ice shrinkage and enhanced pollution. To test impacts on arctic marine ecological functioning, we used a 12-year integrative study of little auks (Alle alle), the most abundant seabird in the Atlantic Arctic. We monitore...

The study of juvenile migration behaviour of seabird species has been limited so far by the inability to track their movements during long time periods. Foraging and flying skills of young individuals are assumed to be inferior to those of adults, making them more vulnerable during long-distance migrations. In addition to natural oceanographic effe...

Aim Animal movement is an important determinant of individual survival, population dynamics and ecosystem structure and function. Nonetheless, it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside the migratory period, we...

Aim Climate change is altering marine ecosystems worldwide and is most pronounced in the Arctic. Economic development is increasing leading to more disturbances and pressures on Arctic wildlife. Identifying areas that support higher levels of predator abundance and biodiversity is important for the implementation of targeted conservation measures a...

In the 21st century, nature-based tourism has often reached the magnitude of mass-tourism. Even if it generates substantial revenues which may contribute to enhanced conservation, this industry is based on finite resources, such as accessible places rich in scenic beauty or charismatic wildlife. This is very much the case for the UNESCO site of Scan...

1.Animals are expected to be judicious in the use of the energy they gain due to the costs and limits associated with its intake. The management of energy expenditure (EE) exhibited by animals has previously been considered in terms of three patterns: the constrained, independent and performance patterns of energy management. These patterns can be...

Most large raptors on migration avoid crossing the sea because of the lack of atmospheric convection over temperate seas. The osprey Pandion haliaetus is an exception among raptors, since it can fly over several hundred kilometres of open water. We equipped five juvenile ospreys with GPS-Accelerometer-Magnetometer loggers. All birds were able to fi...

For effective monitoring in social‐ecological systems to meet needs for biodiversity, science, and humans, desired outcomes must be clearly defined and routes from direct to derived outcomes understood. The Arctic is undergoing rapid climatic, ecological, social, and economic changes and requires effective wildlife monitoring to meet diverse stakeh...

We carried out population counts of a nesting colony of terns (Sternidae) on Pitti Island, an official seabird sanctuary, on 17 February 2013, 10 March 2013, and 10 February 2014. We also assessed population trends over previous years using data from earlier surveys. We estimated the number of nests and eggs, and recorded loss of eggs by predation,...

Species distribution models (SDMs) are statistical tools aiming at mapping and predicting species distributions across landscapes. Data acquisition being limited in space and time, SDM are commonly used to predict species distribution in unsampled areas or years, with the expectation that modelled habitat–species relationships will hold across spat...