At-sea movements of wedge-tailed shearwaters during and outside the breeding season from four colonies in New Caledonia

International audienceThe wedge-tailed shearwater (WTS) population of New Caledonia is one of the largest in the world, yet its biology and foraging ecology are poorly known. We studied WTS from 4 colonies in New Caledonia. We examined foraging behaviour and habitats using GPS receivers and light sensors during and outside the breeding season, respectively, and compared our findings with those from other WTS populations worldwide. During breeding, New Caledonian WTS alternated short foraging trips close to the colony over the lagoon, or off the reef edge, with longer trips over distant, deep waters. Whereas neighboring colonies overlapped at sea, especially during short trips, there was a clear separation of foraging zones between the pairs of colonies located in the southern versus northwestern parts of New Caledonia. Although WTS actively foraged and commuted to foraging zones during the day, they mainly returned to the colony or rested at night, indicating that they feed mainly during the day. Active foraging did not take place in more productive areas, suggesting that it may instead be related to the presence of sub-surface predators. Outside the breeding season, birds from 3 colonies had similar trans-equatorial migratory behaviour. All left New Caledonia at the same time of the year with a fast, northeasterly movement and wintered over deep waters in the same sector of the northwestern tropical Pacific Ocean. At overwintering sites, they spent most of their non-foraging time presumably sitting on the water, especially at night, making a slow westward movement before returning to New Caledonia. WTS from New Caledonia forage over warm, oligotrophic deep waters throughout their life cycle, and the species appears to have a flexible foraging strategy adapted to the various environmental conditions encountered across its wide tropical range

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world's oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species.B.L.C., C.H., and A.M. were funded by the Cambridge Conservation Initiative’s Collaborative Fund sponsored by the Prince Albert II of Monaco Foundation. E.J.P. was supported by the Natural Environment Research Council C-CLEAR doctoral training programme (Grant no. NE/S007164/1). We are grateful to all those who assisted with the collection and curation of tracking data. Further details are provided in the Supplementary Acknowledgements. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.Peer reviewe

Global assessment of marine plastic exposure risk for oceanic birds

Plastic pollution is distributed patchily around the world’s oceans. Likewise, marine organisms that are vulnerable to plastic ingestion or entanglement have uneven distributions. Understanding where wildlife encounters plastic is crucial for targeting research and mitigation. Oceanic seabirds, particularly petrels, frequently ingest plastic, are highly threatened, and cover vast distances during foraging and migration. However, the spatial overlap between petrels and plastics is poorly understood. Here we combine marine plastic density estimates with individual movement data for 7137 birds of 77 petrel species to estimate relative exposure risk. We identify high exposure risk areas in the Mediterranean and Black seas, and the northeast Pacific, northwest Pacific, South Atlantic and southwest Indian oceans. Plastic exposure risk varies greatly among species and populations, and between breeding and non-breeding seasons. Exposure risk is disproportionately high for Threatened species. Outside the Mediterranean and Black seas, exposure risk is highest in the high seas and Exclusive Economic Zones (EEZs) of the USA, Japan, and the UK. Birds generally had higher plastic exposure risk outside the EEZ of the country where they breed. We identify conservation and research priorities, and highlight that international collaboration is key to addressing the impacts of marine plastic on wide-ranging species

Stratégies d’alimentation et d’exploitation de l’espace océanique par deux espèces de Procellariidés en Nouvelle-Calédonie : Application à la conservation

Foraging strategies of Procellariidae (shearwaters and petrels) depend on many environmental and intrinsic factors, and their knowledge is often the basis for conservation measures for these species at sea. Their study also provides information on the presence and abundance of species associated with their feeding grounds. This thesis aims to provide information on the movements and use of ocean space and trophic resources by two species of Procellariidae breeding in New Caledonia: the wedge-tailed shearwater (Ardenna pacifica) and the Tahiti petrel (Pseudobulweria rostrata). In this purpose, we combined the study of their at-sea movements by GPS tracking with the study of their diet by stable isotope analysis and DNA barcoding.The main foraging areas and the type of prey consumed were identified for each species and each population during their breeding period. The mechanisms of intraspecific segregation between the different populations and interspecific segregation allowing the cohabitation of the two species were highlighted. Different environmental factors determining the foraging strategies of the species were also revealed. Finally, taking into account these different parameters and interactions within and between species, this thesis aimed to determine oceanic areas with high conservation stakes, in order to provide elements of decision support to the managers of the Coral Sea Natural Park, the 4th largest marine protected area of the Planet.Les stratégies de recherche alimentaire chez les Procellariidés (puffins et pétrels) dépendent de nombreux facteurs environnementaux et intrinsèques et leur connaissance est souvent à la base des mesures de conservation de ces espèces en mer. Leur étude permet également d’apporter des informations sur la présence et l’abondance d’espèces associées à leurs zones d’alimentation. Cette thèse vise à apporter des éléments de connaissance sur les déplacements et l’utilisation de l’espace océanique et des ressources trophiques par deux espèces de Procellariidés se reproduisant en Nouvelle-Calédonie : le puffin fouquet (Ardenna pacifica) et le pétrel de Tahiti (Pseudobulweria rostrata). Pour cela, nous avons combiné l’étude de leurs déplacements en mer par suivi GPS avec l’étude de leur régime alimentaire par l’analyse d’isotopes stables et le barcoding ADN.Les principales zones d’alimentation et le type de proies consommées ont été identifiés pour chaque espèce et chaque population pendant leur période de reproduction. Les mécanismes de ségrégation intra-spécifique entre les différentes populations et de ségrégation interspécifique permettant la cohabitation des deux espèces ont été mis en évidence. Différents facteurs environnementaux déterminant les stratégies d’alimentation des espèces ont également été mis en évidence. Enfin, tenant compte de ces différents paramètres et interactions au sein et entre espèces, cette thèse a visé à déterminer des zones océaniques hauturières à fort enjeux de conservation, afin notamment de fournir des éléments d’aide à la décision aux gestionnaires du Parc Naturel de la Mer de Corail, la 4ème plus grande aire marine protégée de la Planète

Food and space use strategies oceanic by two species of Procellariidae in New Caledonia : Application to conservation

Les stratégies de recherche alimentaire chez les Procellariidés (puffins et pétrels) dépendent de nombreux facteurs environnementaux et intrinsèques et leur connaissance est souvent à la base des mesures de conservation de ces espèces en mer. Leur étude permet également d’apporter des informations sur la présence et l’abondance d’espèces associées à leurs zones d’alimentation. Cette thèse vise à apporter des éléments de connaissance sur les déplacements et l’utilisation de l’espace océanique et des ressources trophiques par deux espèces de Procellariidés se reproduisant en Nouvelle-Calédonie : le puffin fouquet (Ardenna pacifica) et le pétrel de Tahiti (Pseudobulweria rostrata). Pour cela, nous avons combiné l’étude de leurs déplacements en mer par suivi GPS avec l’étude de leur régime alimentaire par l’analyse d’isotopes stables et le barcoding ADN.Les principales zones d’alimentation et le type de proies consommées ont été identifiés pour chaque espèce et chaque population pendant leur période de reproduction. Les mécanismes de ségrégation intra-spécifique entre les différentes populations et de ségrégation interspécifique permettant la cohabitation des deux espèces ont été mis en évidence. Différents facteurs environnementaux déterminant les stratégies d’alimentation des espèces ont également été mis en évidence. Enfin, tenant compte de ces différents paramètres et interactions au sein et entre espèces, cette thèse a visé à déterminer des zones océaniques hauturières à fort enjeux de conservation, afin notamment de fournir des éléments d’aide à la décision aux gestionnaires du Parc Naturel de la Mer de Corail, la 4ème plus grande aire marine protégée de la Planète.Foraging strategies of Procellariidae (shearwaters and petrels) depend on many environmental and intrinsic factors, and their knowledge is often the basis for conservation measures for these species at sea. Their study also provides information on the presence and abundance of species associated with their feeding grounds. This thesis aims to provide information on the movements and use of ocean space and trophic resources by two species of Procellariidae breeding in New Caledonia: the wedge-tailed shearwater (Ardenna pacifica) and the Tahiti petrel (Pseudobulweria rostrata). In this purpose, we combined the study of their at-sea movements by GPS tracking with the study of their diet by stable isotope analysis and DNA barcoding.The main foraging areas and the type of prey consumed were identified for each species and each population during their breeding period. The mechanisms of intraspecific segregation between the different populations and interspecific segregation allowing the cohabitation of the two species were highlighted. Different environmental factors determining the foraging strategies of the species were also revealed. Finally, taking into account these different parameters and interactions within and between species, this thesis aimed to determine oceanic areas with high conservation stakes, in order to provide elements of decision support to the managers of the Coral Sea Natural Park, the 4th largest marine protected area of the Planet

Suivi de la persistance sur les parcs éoliens: Recommandations pour estimer la mortalité

International audienceEnvironmental impact assessments (EIAs) of windfarms require counting bat and bird carcasses around turbinesto assess the number of individuals killed by collision or barotrauma. In order to accurately estimate mortalityfrom carcass counts, most studies correct mortality by the probability of carcass removal between fatalitysearches, data that is obtained through persistence trials. However, there is currently no consensus on persistencetrial design and estimation methodology. This study aimed to assess the sensitivity of several estimatorsemployed during EIAs to collect persistence data. To this end, the persistence time of 266 carcasses was surveyedcontinuously using camera traps. This continuous observation data was resampled to generate virtual datasetscollected using different survey intervals. Several estimators were then used to estimate mortality from a subsampleof carcasses for each carcass survey interval. Mortality estimates obtained by the different estimatorswere very similar when persistence was observed continuously. However, differences between estimatorsemerged when persistence survey intervals widened, and even more so when fatality searches were conductedless frequently. The GenEst estimator seemed to produce less biased and more accurate mortality estimatescompared to other estimators frequently used for EIAs. Based on these findings, we recommend limiting searchintervals during persistence surveys as much as possible. If persistence time is low, we also recommendincreasing fatality search frequency. For estimators using mean persistence time, the latter should be calculatedusing the median time between the last observation of the carcass and its first absence.Les évaluations de l'impact environnemental (EIE) des parcs éoliens nécessitent le comptage des cadavres de chauves-souris et d'oiseaux autour des turbines pour évaluer le nombre d'individus tués par collision ou barotraumatisme. Afin d'estimer avec précision la mortalité à partir des comptages de cadavres, la plupart des études corrigent la mortalité par la probabilité de retrait des carcasses entre les recherches de mortalité, données obtenues par des tests de persistance réalisés sur les parcs. Cependant, il n'existe actuellement aucun consensus sur la conception des tests de persistance et la méthodologie d'estimation de la mortalité intégrant ce facteur de correction. Cette étude vise à évaluer la sensibilité de plusieurs estimateurs utilisés lors des EIE pour réaliser l'estimation de persistance. À cette fin, le temps de persistance de 266 carcasses a été surveillé en continu à l'aide de pièges photographiques. Ces données d'observation continue ont été rééchantillonnées pour générer des ensembles de données virtuels collectés à différents intervalles. Plusieurs estimateurs ont ensuite été utilisés pour estimer la mortalité à partir d'un sous-échantillon de carcasses pour chaque intervalle de suivi de la persistance. Les estimations de la mortalité obtenues par les différents estimateurs étaient très similaires lorsque la persistance était observée en continu. Cependant, des différences entre les estimateurs sont apparues lorsque les intervalles de suivi de persistance se sont élargis, et encore plus lorsque les suivis de mortalité étaient menés moins fréquemment. L'estimateur GenEst semble produire des estimations de mortalité moins biaisées et plus précises par rapport à d'autres estimateurs fréquemment utilisés pour les EIE. Sur la base de ces résultats, nous recommandons de limiter les intervalles de recherche lors des enquêtes sur la persistance autant que possible. Si le temps de persistance est faible, nous recommandons également d'augmenter la fréquence des recherches de mortalité. Pour les estimateurs utilisant le temps de persistance moyen, ce dernier devrait être calculé en utilisant le temps médian entre la dernière observation de la carcasse et sa première absence

Diazotroph-Derived Nitrogen Assimilation Strategies Differ by Scleractinian Coral Species

International audienceReef-building corals generally thrive in nutrient-poor tropical waters, where among other elements, nitrogen (N) availability often limits primary productivity. In addition to their close association with endosymbiotic dinoflagellates of the family Symbiodiniaceae, enabling an effective use and retention of dissolved inorganic nitrogen (DIN), scleractinian corals have developed strategies to acquire new N: (1) They can ingest N-rich sediment particles and preys (from picoplankton to macro-zooplankton) via heterotrophy, including diazotrophs [plankton fixing dinitrogen (N 2 ) and releasing part of this nitrogen—Diazotroph-Derived N (DDN)—in seawater], a pathway called “heterotrophic nutrition on diazotrophs”; (2) Symbiotic diazotrophs located in the coral holobiont have the molecular machinery to fix N 2 , a pathway called “symbiotic N 2 fixation”. Here we used the 15 N 2 isotopic labeling in a series of incubations to investigate the relative contribution of each of these DDN transfer pathways in three worldwide distributed coral species: Acropora muricata , Galaxea fascicularis, and Pocillopora damicornis . We show that N provision via “symbiotic N 2 fixation” is negligible compared to that obtained via “heterotrophic nutrition on diazotrophs,” with DDN assimilation rates about a thousand times lower for P. damicornis and G. fascicularis , or assimilation rates via “symbiotic N 2 fixation” almost nil for A. muricata . Through heterotrophic feeding on planktonic diazotrophs, only G. fascicularis and P. damicornis can successfully obtain N and fulfill a large part of their N requirements (DDN asimilation rates: 0.111 ± 0.056 and 0.517 ± 0.070 μg N cm –2 h –1 in their Symbiodiniaceae, respectively). Whereas this contribution is again negligible for A. muricata . They also largely consume the picoplankton that likely benefit from this DDN ( Prochlorococcus and Synechococcus cells; respectively, 2.56 ± 1.57 10 4 and 2.70 ± 1.66 10 4 cell h –1 cm –2 for G. fascicularis ; 3.02 ± 0.19 10 5 and 1.14 ± 0.79 10 4 cell h –1 cm –2 for P. damicornis ). The present study confirms the different dependencies of the three tested species regarding heterotrophy, with P. damicornis and G. fascicularis appearing highly efficient at capturing plankton, while A. muricata , considered as mainly autotroph, does not rely on these food resources to meet its N and energy needs

Nest-site selection and its influence on breeding success in a poorly-known and declining seabird: The Tahiti petrel Pseudobulweria rostrata

The Tahiti petrel (Pseudobulweria rostrata) is a rare and declining seabird whose breeding biology and nest-site selection are poorly known. Nest-site selection is critical to seabird population fitness, and understanding the factors driving it is essential for designing effective conservation measures. Here, we measured several variables (topographical, physical and environmental) to characterize Tahiti petrel nesting habitats and burrows (i.e., width, height, depth and type: rocky cavity, dug into the soil or under a root) on Nemou Island in New Caledonia. The data were clustered using the HCPC (Hierarchical Clustering on Principal Component) method to identify principal habitat groups. This method was combined with logistic regressions to examine the influence of the variables on nest-site selection and breeding success. Our results showed that nest-site selection is linked to habitat groups (a combination of substrate and vegetation data), slope, orientation and soil depth, while breeding success is only influenced by nest characteristics (i.e., burrow type and width). Tahiti petrels prefer to nest on steep slopes in mature forests with rocky substrate and deep soil. Burrows were scatterred in small sub-colonies or isolated pairs, suggesting that nest-site selection depends on habitat quality rather than conspecific density. The study also revealed that breeding success is lower in rocky cavities and increases in burrows with wide entrances. Our nest-site selection survey is the first for the genus Pseudobulweria, and provides critical information for designing effective conservation programs in New Caledonia and the Pacific

Recovery of insular seabird populations years after rodent eradication

Seabirds have been particularly affected by invasive alien species (IAS), which has led to the implementation of numerous eradication campaigns for the conservation of these keystone and highly vulnerable species. Although the benefits of IAS eradications for seabird conservation have been demonstrated, the recovery kinetics of different seabird populations on islands after eradication remains poorly evaluated. Here we present the results of an original long-term monitoring of the number of breeding pairs of seven seabird species on a small atoll, Surprise Island, New Caledonia (southwestern tropical Pacific). This long-term monitoring consists in a yearly core survey of the marine avifauna of the island conducted from 4 years before to 4 years after rodent eradication (conducted in 2005) combined with multiple one-time surveys from ∼10 years before and ∼15 years after eradication. This study was designed to evaluate how different seabird species responded to the eradication of invasive rodents in an insular environment. We found that three species responded positively to eradication with differences in lag-timing and sensitivity. The number of breeding pairs increased for two species in the four year post eradication due to immigration while one species showed a longer response time with an increase in pairs more than 10 years after eradication. Furthermore, we showed that long-term sampling is necessary to observe the responses of the seabird populations on the island. Our study confirms the positive effects of IAS eradication on seabirds and emphasizes both the importance of mid/long-term pre- and post-eradication surveys to decipher the mechanisms of seabird recovery and confirm the benefits of eradication for conservation purposes