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Résumé :
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Sedge Warblers Acrocephalus schoenobaenus that stopover along the Atlantic flyway refuelled at varying rates, depending on age, initial body condition and latitude; refuelling rates were poorly structured among sites, suggesting a broad capacity of birds to exploit various wetlands during stopover. To test how Sedge Warblers accumulate fuel during stopovers in a major migratory corridor along coastal Atlantic wetlands, from northern France to the Bay of Biscay in Spain, and to identify factors affecting the fuel deposition rate (FDR). We analysed 7,149 records of Sedge Warblers captured at least twice within the same site and year, collected over 32 years across 28 wetlands. We used linear mixed models to test the effect of age, initial body mass, date, latitude and habitat structure on FDR. Additionally, we modelled initial body mass as a response variable to examine large-scale variation in the arrival condition of birds, with age, date, latitude and habitat features as predictors. The fuel deposition rate declined with increasing initial body mass. The effect of latitude varied with age: for yearlings, refuelling rates increased from north to south, while adults showed relatively constant rates along the flyway. Initial body mass was higher in birds captured later in the season and in those using landscapes with smaller and more fragmented wetlands, but decreased with latitude. Habitat metrics had limited explanatory power. Sedge Warblers appeared to refuel opportunistically throughout the extensive network of wetlands that spans the Atlantic flyway. This finding reinforces the importance of preserving habitat connectivity along migratory routes and supports a landscape-scale conservation approach that integrates ecological functionality and behavioural flexibility.
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