Stratégies migratoires en présence de barrières écologiques et différence de vulnérabilité à la prédation chez des pluviers nichant dans l'Arctique

RÉSUMÉ: Identifier les processus et les facteurs affectant la distribution géographique et les limites de répartition des espèces demeure l'une des questions fondamentales de l'écologie et de la biogéographie. Les barrières écologiques peuvent avoir une influence majeure sur la répartition d'une espèce en limitant la dispersion et l'évolution des routes migratoires. Les facteurs biotiques tels que la prédation peuvent aussi affecter la répartition, mais leurs effets à large échelle sont difficiles à estimer et souvent surpassés par les facteurs abiotiques tels que le climat ou les barrières écologiques. Nous avons étudié les effets des barrières écologiques sur les stratégies migratoires et le rôle potentiel de la prédation des nids sur l'aire de nidification de limicoles arctiques, un groupe d'oiseaux connu pour ses grandes migrations et particulièrement affecté par les variations dans la pression de prédation. Notre premier objectif était d'examiner la stratégie migratoire utilisée par le Pluvier grand-gravelot (Charadrius hiaticula) le long de la route migratoire transatlantique caractérisée par la présence de barrières écologiques majeures. Notre second objectif était de i) quantifier la vulnérabilité relative des nids de pluviers à la prédation chez des espèces ayant des aires de nidification contrastées, le Pluvier grand-gravelot et le Pluvier doré (Pluvialis dominica/apricaria/fulva), et de ii) déterminer si la différence de vulnérabilité à la prédation pouvait s'expliquer par leur habitat de nidification respectif. À l'Île Bylot dans l'Arctique canadien, nous avons équipé des Pluviers grand-gravelot nicheurs de géolocalisateurs afin de retracer leurs migrations. Nous avons aussi quantifié la survie des nids des Pluviers grand-gravelot et dorés durant trois étés et estimé le risque de prédation dans l'habitat de chacune des espèces à l'aide de nids artificiels. Nos résultats provenant des géolocalisateurs (n=20) ont révélé des stratégies migratoires contrastées entre les saisons. Les résultats ont révélé un patron migratoire contrasté entre les saisons, montrant que les pluviers minimisent les distances de vol au-dessus de l'océan au printemps en faisant un détour pour faire halte en Islande. À l'automne, cependant, la plupart des individus traversent l'océan en un vol direct du sud du Groenland jusqu'en Europe de l'Ouest, aussi loin que le sud de l'Espagne, avant de rejoindre leur aire d'hivernage en Afrique de l'Ouest. Ces résultats soutiennent l'hypothèse que les routes migratoires minimisant les distances de vol au-dessus des barrières écologiques sont favorisées par la sélection naturelle, à moins que les pluviers puissent bénéficier de l'assistance éolienne facilitant une traversée directe. Le suivi de nidification et les nids artificiels ont révélé que i) le Pluvier grand-gravelot, présentant une aire de répartition très large et nichant le long des rives rocailleuses, montre un taux de survie des nids plus élevé que le Pluvier doré qui lui niche en toundra mésique, et que ii) cette différence dans le risque de prédation des nids s'explique, du moins en partie, par le type d'habitat de nidification. Nous suggérons que les espèces adaptées à nicher dans des habitats moins risqués seraient plus aptes à persister dans des régions caractérisées par une pression de prédation élevée, et ainsi maintenir une aire de répartition plus large. -- Mot(s) clé(s) en français : Répartition, Barrières écologiques, Arctique, Migration transatlantique, Risque de prédation, Habitat refuge, Détour migratoire, Limicoles, Charadrius hiaticula. -- ABSTRACT: Identifying processes and factors affecting species distribution remains a fundamental question in ecology and biogeography. Ecological barriers can have a major influence on the distribution of a species by limiting dispersal and constraining migration routes. Biotic factors like predation can also influence distribution, but their effects at broad spatial scales are difficult to assess and often overwhelmed by abiotic factors like ecological barriers and climate. We studied the effect of ecological barriers on migration strategies and the potential role of nest predation on breeding range in arctic shorebirds, known for their long-distance migrations and particularly affected by variations in predation pressure. Our first objective was to investigate the migration strategies of the Ringed Plover (Charadrius hiaticula) along the transatlantic migration route, characterized by significant ecological barriers. The second objective was to i) quantify the relative vulnerability of plover nests to predators in species with contrasting breeding ranges, the Ringed Plover and the Golden Plovers (Pluvialis dominica/apricaria/fulva), and ii) examine if differences in vulnerability to predators could be explained by their respective nesting habitat. On Bylot Island, in the Canadian Arctic, we equipped nesting Ringed Plovers with geolocator devices to track their migrations. We also quantified the nest survival of Ringed and Golden Plovers over three summers and conducted artificial nest experiments to quantify predation risk in the nesting habitat used by each species. Our results from geolocators (n=20) showed contrasting seasonal migration strategies, with Ringed Plovers minimizing continuous flight distances over the ocean in spring by making a detour to stop in Iceland. In autumn, however, most individuals crossed the ocean in one direct flight from Southern Greenland to Western Europe, as far as Southern Spain, before reaching their wintering area in West Africa. These results support the hypothesis that migration routes minimizing flight distances over ecological barriers are favored by natural selection, unless plovers can benefit from wind assistance. Nest monitoring and artificial nests also revealed that i) the widely distributed Ringed Plovers nesting along stony riverbanks showed a higher nest survival rate than the Golden Plovers nesting in mesic tundra and ii) the difference in nest predation rate was at least partly driven by nesting habitat type per se. We suggest that species adapted to nesting in less risky habitat are more likely to persist in regions characterised by high predation pressure, and hence can have broader distribution. -- Mot(s) clé(s) en anglais : Distribution range, Ecological barriers, Arctic, Transatlantic migration, Predation risk, Refuge habitat, Migration detour, Shorebirds, Charadrius hiaticula

Stratégies migratoires en présence de barrières écologiques et différence de vulnérabilité à la prédation chez des pluviers nichant dans l'Arctique

RÉSUMÉ: Identifier les processus et les facteurs affectant la distribution géographique et les limites de répartition des espèces demeure l'une des questions fondamentales de l'écologie et de la biogéographie. Les barrières écologiques peuvent avoir une influence majeure sur la répartition d'une espèce en limitant la dispersion et l'évolution des routes migratoires. Les facteurs biotiques tels que la prédation peuvent aussi affecter la répartition, mais leurs effets à large échelle sont difficiles à estimer et souvent surpassés par les facteurs abiotiques tels que le climat ou les barrières écologiques. Nous avons étudié les effets des barrières écologiques sur les stratégies migratoires et le rôle potentiel de la prédation des nids sur l'aire de nidification de limicoles arctiques, un groupe d'oiseaux connu pour ses grandes migrations et particulièrement affecté par les variations dans la pression de prédation. Notre premier objectif était d'examiner la stratégie migratoire utilisée par le Pluvier grand-gravelot (Charadrius hiaticula) le long de la route migratoire transatlantique caractérisée par la présence de barrières écologiques majeures. Notre second objectif était de i) quantifier la vulnérabilité relative des nids de pluviers à la prédation chez des espèces ayant des aires de nidification contrastées, le Pluvier grand-gravelot et le Pluvier doré (Pluvialis dominica/apricaria/fulva), et de ii) déterminer si la différence de vulnérabilité à la prédation pouvait s'expliquer par leur habitat de nidification respectif. À l'Île Bylot dans l'Arctique canadien, nous avons équipé des Pluviers grand-gravelot nicheurs de géolocalisateurs afin de retracer leurs migrations. Nous avons aussi quantifié la survie des nids des Pluviers grand-gravelot et dorés durant trois étés et estimé le risque de prédation dans l'habitat de chacune des espèces à l'aide de nids artificiels. Nos résultats provenant des géolocalisateurs (n=20) ont révélé des stratégies migratoires contrastées entre les saisons. Les résultats ont révélé un patron migratoire contrasté entre les saisons, montrant que les pluviers minimisent les distances de vol au-dessus de l'océan au printemps en faisant un détour pour faire halte en Islande. À l'automne, cependant, la plupart des individus traversent l'océan en un vol direct du sud du Groenland jusqu'en Europe de l'Ouest, aussi loin que le sud de l'Espagne, avant de rejoindre leur aire d'hivernage en Afrique de l'Ouest. Ces résultats soutiennent l'hypothèse que les routes migratoires minimisant les distances de vol au-dessus des barrières écologiques sont favorisées par la sélection naturelle, à moins que les pluviers puissent bénéficier de l'assistance éolienne facilitant une traversée directe. Le suivi de nidification et les nids artificiels ont révélé que i) le Pluvier grand-gravelot, présentant une aire de répartition très large et nichant le long des rives rocailleuses, montre un taux de survie des nids plus élevé que le Pluvier doré qui lui niche en toundra mésique, et que ii) cette différence dans le risque de prédation des nids s'explique, du moins en partie, par le type d'habitat de nidification. Nous suggérons que les espèces adaptées à nicher dans des habitats moins risqués seraient plus aptes à persister dans des régions caractérisées par une pression de prédation élevée, et ainsi maintenir une aire de répartition plus large. -- Mot(s) clé(s) en français : Répartition, Barrières écologiques, Arctique, Migration transatlantique, Risque de prédation, Habitat refuge, Détour migratoire, Limicoles, Charadrius hiaticula. -- ABSTRACT: Identifying processes and factors affecting species distribution remains a fundamental question in ecology and biogeography. Ecological barriers can have a major influence on the distribution of a species by limiting dispersal and constraining migration routes. Biotic factors like predation can also influence distribution, but their effects at broad spatial scales are difficult to assess and often overwhelmed by abiotic factors like ecological barriers and climate. We studied the effect of ecological barriers on migration strategies and the potential role of nest predation on breeding range in arctic shorebirds, known for their long-distance migrations and particularly affected by variations in predation pressure. Our first objective was to investigate the migration strategies of the Ringed Plover (Charadrius hiaticula) along the transatlantic migration route, characterized by significant ecological barriers. The second objective was to i) quantify the relative vulnerability of plover nests to predators in species with contrasting breeding ranges, the Ringed Plover and the Golden Plovers (Pluvialis dominica/apricaria/fulva), and ii) examine if differences in vulnerability to predators could be explained by their respective nesting habitat. On Bylot Island, in the Canadian Arctic, we equipped nesting Ringed Plovers with geolocator devices to track their migrations. We also quantified the nest survival of Ringed and Golden Plovers over three summers and conducted artificial nest experiments to quantify predation risk in the nesting habitat used by each species. Our results from geolocators (n=20) showed contrasting seasonal migration strategies, with Ringed Plovers minimizing continuous flight distances over the ocean in spring by making a detour to stop in Iceland. In autumn, however, most individuals crossed the ocean in one direct flight from Southern Greenland to Western Europe, as far as Southern Spain, before reaching their wintering area in West Africa. These results support the hypothesis that migration routes minimizing flight distances over ecological barriers are favored by natural selection, unless plovers can benefit from wind assistance. Nest monitoring and artificial nests also revealed that i) the widely distributed Ringed Plovers nesting along stony riverbanks showed a higher nest survival rate than the Golden Plovers nesting in mesic tundra and ii) the difference in nest predation rate was at least partly driven by nesting habitat type per se. We suggest that species adapted to nesting in less risky habitat are more likely to persist in regions characterised by high predation pressure, and hence can have broader distribution. -- Mot(s) clé(s) en anglais : Distribution range, Ecological barriers, Arctic, Transatlantic migration, Predation risk, Refuge habitat, Migration detour, Shorebirds, Charadrius hiaticula

Beyond body condition: Experimental evidence that plasma metabolites improve nutritional state measurements in a free-living seabird

International audienceThe ability to efficiently measure the health and nutritional status of wild populations in situ is a valuable tool, as many methods of evaluating animal physiology do not occur in real-time, limiting the possibilities for direct intervention. This study investigates the use of blood plasma metabolite concentrations, measured via point-of-care devices or a simple plate reader assay, as indicators of nutritional state in free-living seabirds. We experimentally manipulated the energy expenditure of wild black-legged kittiwakes on Middleton Island, Alaska, and measured the plasma concentrations of glucose, cholesterol, B-hydroxybutyrate, and triglycerides throughout the breeding season, along with measures of body condition (size-corrected mass [SCM] and muscle depth). Supplemental feeding improved the nutritional state of kittiwakes by increasing feeding rate (higher glucose and triglycerides, lower cholesterol), and flight-handicapping caused a slight nutritional decline (lower glucose and triglycerides, higher cholesterol and B-hydroxybutyrate). Glucose and triglycerides were the best indicators of nutritional state when used alongside SCM, and improved upon commonly used metrics for measuring individual condition (i.e. SCM or mass alone). Metabolite concentrations varied across the breeding period, suggesting that the pre-laying stage, when feeding rates tend to be lower, was the most nutritionally challenging period for kittiwakes (low glucose, high cholesterol). Muscle depth also varied by treatment and breeding stage, but differed from other nutritional indices, suggesting that muscle depth is an indicator of exercise and activity level rather than nutrition. Here we demonstrate potential for the use of blood plasma metabolites measured via point-of-care devices as proxies for evaluating individual health, population health, and environmental food availabilit

Long-term tracking of an Arctic-breeding seabird indicates high fidelity to pelagic wintering areas

Site fidelity is driven by predictable resource distributions in time and space. However, intrinsic factors related to an individual’s physiology and life-history traits can contribute to consistent foraging behaviour and movement patterns. Using 11 yr of continuous geolocation tracking data (fall 2008 to spring 2019), we investigated spatiotemporal consistency in non-breeding movements in a pelagic seabird population of black-legged kittiwakes Rissa tridactyla breeding in the High Arctic (Svalbard). Our objective was to assess the relative importance of spatial versus temporal repeatability behind inter-annual movement consistency during winter. Most kittiwakes used pelagic regions of the western North Atlantic. Winter site fidelity was high both within and across individuals and at meso (100-1000 km) and macro scales (>1000 km). Spatial consistency in non-breeding movement was higher within than among individuals, suggesting that site fidelity might emerge from individuals’ memory to return to locations with predictable resource availability. Consistency was also stronger in space than in time, suggesting that it was driven by consistent resource pulses that may vary in time more so than in space. Nonetheless, some individuals displayed more flexibility by adopting a strategy of itinerancy during winter, and the causes of this flexibility are unclear. Specialization for key wintering areas can indicate vulnerability to environmental perturbations, with winter survival and carry-over effects arising from winter conditions as potential drivers of population dynamics. : Spatial distribution · Individual consistency · Migration · Repeatability · Nearest neighbor distance · Biologging · Global Location Sensors · GL

Long-term tracking of an Arctic-breeding seabird indicates high fidelity to pelagic wintering areas

Site fidelity is driven by predictable resource distributions in time and space. However, intrinsic factors related to an individual’s physiology and life-history traits can contribute to consistent foraging behaviour and movement patterns. Using 11 yr of continuous geolocation tracking data (fall 2008 to spring 2019), we investigated spatiotemporal consistency in non-breeding movements in a pelagic seabird population of black-legged kittiwakes Rissa tridactyla breeding in the High Arctic (Svalbard). Our objective was to assess the relative importance of spatial versus temporal repeatability behind inter-annual movement consistency during winter. Most kittiwakes used pelagic regions of the western North Atlantic. Winter site fidelity was high both within and across individuals and at meso (100-1000 km) and macro scales (>1000 km). Spatial consistency in non-breeding movement was higher within than among individuals, suggesting that site fidelity might emerge from individuals’ memory to return to locations with predictable resource availability. Consistency was also stronger in space than in time, suggesting that it was driven by consistent resource pulses that may vary in time more so than in space. Nonetheless, some individuals displayed more flexibility by adopting a strategy of itinerancy during winter, and the causes of this flexibility are unclear. Specialization for key wintering areas can indicate vulnerability to environmental perturbations, with winter survival and carry-over effects arising from winter conditions as potential drivers of population dynamics. : Spatial distribution · Individual consistency · Migration · Repeatability · Nearest neighbor distance · Biologging · Global Location Sensors · GLSpublishedVersio

Multi-colony tracking of two pelagic seabirds with contrasting flight capability illustrates how windscapes shape migratory movements at an ocean-basin scale

Migration is a common trait among many animals allowing the exploitation of spatiotemporally variable resources. It often implies high energetic costs to cover large distances, for example between breeding and wintering grounds. For flying or swimming animals, the adequate use of winds and currents can help reduce the associated energetic costs. Migratory seabirds are good models because they dwell in habitats characterized by strong winds while undertaking very long migrations. We tested the hypothesis that seabirds migrate through areas with favourable winds. To that end, we used a multi-colony geolocator tracking dataset of two North Atlantic seabirds with contrasting flight capabilities, the black-legged kittiwake (Rissa tridactyla) and the Atlantic puffin (Fratercula arctica), and wind data from the ERA5 climate reanalysis model. Both species had on average positive wind support during migration. Their main migratory routes were similar and followed seasonally prevailing winds. The general migratory movement had a loop-shape at the scale of the North Atlantic, with an autumn route (southward) along the east coast of Greenland, and a spring route (northward) closer to the British Isles. While migrating, both species had higher wind support in spring than in autumn. Kittiwakes migrated farther and benefited from higher wind support than puffins on average. The variation in wind conditions encountered while migrating was linked to the geographical location of the colonies. Generally, northernmost colonies had better wind support in autumn while the southernmost colonies had a better wind support in spring, with some exceptions. Our study helps in understanding how the physical environment shapes animal migration, which is crucial to further predict how migrants will be impacted by ongoing environmental changes.Funding provided by: Norwegian Ministry for Climate and the Environment*Crossref Funder Registry ID: Award Number: Funding provided by: Norwegian Ministry of Foreign Affairs*Crossref Funder Registry ID: Award Number: Funding provided by: Norwegian Oil and Gas Association*Crossref Funder Registry ID: Award Number: Funding provided by: SEAPOP program *Crossref Funder Registry ID: Award Number: Funding provided by: Institut Polaire Français Paul Emile VictorCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100004796Award Number: 330Funding provided by: Natural Environment Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000270Award Number: NE/R016429/

Multi‐colony tracking of two pelagic seabirds with contrasting flight capability illustrates how windscapes shape migratory movements at an ocean‐basin scale

International audienceMigration is a common trait among many animals allowing the exploitation of spatiotemporally variable resources. It often implies high energetic costs to cover large distances, for example between breeding and wintering grounds. For flying or swimming animals, the adequate use of winds and currents can help reduce the associated energetic costs. Migratory seabirds are good models because they dwell in habitats characterized by strong winds while undertaking very long migrations. We tested the hypothesis that seabirds migrate through areas with favourable winds. To that end, we used the SEATRACK dataset, a multi‐colony geolocator tracking dataset, for two North Atlantic seabirds with contrasting flight capabilities, the black‐legged kittiwake Rissa tridactyla and the Atlantic puffin Fratercula arctica , and wind data from the ERA5 climate reanalysis model. Both species had on average positive wind support during migration. Their main migratory routes were similar and followed seasonally prevailing winds. The general migratory movement had a loop‐shape at the scale of the North Atlantic, with an autumn route (southward) along the east coast of Greenland, and a spring route (northward) closer to the British Isles. While migrating, both species had higher wind support in spring than in autumn. Kittiwakes migrated farther and benefited from higher wind support than puffins on average. The variation in wind conditions encountered while migrating was linked to the geographical location of the colonies. Generally, northernmost colonies had a better wind support in autumn while the southernmost colonies had a better wind support in spring, with some exceptions. Our study helps understanding how the physical environment shapes animal migration, which is crucial to further predict how migrants will be impacted by ongoing environmental changes

Ecological insights from three decades of animal movement tracking across a changing Arctic

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 of more than 200 standardized terrestrial and marine animal tracking studies from 1991 to the present. The AAMA supports public data discovery, preserves fundamental baseline data for the future, and facilitates efficient, collaborative data analysis. With AAMA-based case studies, we document climatic influences on the migration phenology of eagles, geographic differences in the adaptive response of caribou reproductive phenology to climate change, and species-specific changes in terrestrial mammal movement rates in response to increasing temperature.</p

Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology

Gould E, Fraser H, Parker T, et al. Same data, different analysts: variation in effect sizes due to analytical decisions in ecology and evolutionary biology. 2023.Although variation in effect sizes and predicted values among studies of similar phenomena is inevitable, such variation far exceeds what might be produced by sampling error alone. One possible explanation for variation among results is differences among researchers in the decisions they make regarding statistical analyses. A growing array of studies has explored this analytical variability in different (mostly social science) fields, and has found substantial variability among results, despite analysts having the same data and research question. We implemented an analogous study in ecology and evolutionary biology, fields in which there have been no empirical exploration of the variation in effect sizes or model predictions generated by the analytical decisions of different researchers. We used two unpublished datasets, one from evolutionary ecology (blue tit, Cyanistes caeruleus, to compare sibling number and nestling growth) and one from conservation ecology (Eucalyptus, to compare grass cover and tree seedling recruitment), and the project leaders recruited 174 analyst teams, comprising 246 analysts, to investigate the answers to prespecified research questions. Analyses conducted by these teams yielded 141 usable effects for the blue tit dataset, and 85 usable effects for the Eucalyptus dataset. We found substantial heterogeneity among results for both datasets, although the patterns of variation differed between them. For the blue tit analyses, the average effect was convincingly negative, with less growth for nestlings living with more siblings, but there was near continuous variation in effect size from large negative effects to effects near zero, and even effects crossing the traditional threshold of statistical significance in the opposite direction. In contrast, the average relationship between grass cover and Eucalyptus seedling number was only slightly negative and not convincingly different from zero, and most effects ranged from weakly negative to weakly positive, with about a third of effects crossing the traditional threshold of significance in one direction or the other. However, there were also several striking outliers in the Eucalyptus dataset, with effects far from zero. For both datasets, we found substantial variation in the variable selection and random effects structures among analyses, as well as in the ratings of the analytical methods by peer reviewers, but we found no strong relationship between any of these and deviation from the meta-analytic mean. In other words, analyses with results that were far from the mean were no more or less likely to have dissimilar variable sets, use random effects in their models, or receive poor peer reviews than those analyses that found results that were close to the mean. The existence of substantial variability among analysis outcomes raises important questions about how ecologists and evolutionary biologists should interpret published results, and how they should conduct analyses in the future