To stop or not? Mediterranean migrants differ in both arrival condition and refuelling success after barrier crossing

Understanding refuelling performance at stopover sites is central to elucidating the migration strategies of passerines, particularly at Mediterranean landfall islands where birds arrive after crossing major ecological barriers. We investigated fuel deposition dynamics and potential flight range in five long‐distance migrant passerines (Great Reed Warbler, Sedge Warbler, Common Nightingale, Wood Warbler and Garden Warbler) using long‐term ringing data (2007–2024) from the Antikythera Bird Observatory, Greece. We quantified arrival fuel load, fuel deposition (FD) and flight range and applied generalized additive mixed models (GAMMs) to assess factors shaping refuelling performance. FD increased with stopover duration, with some levelling during longer stays, and was highest among birds arriving with low fuel loads. Seasonal timing also influenced refuelling, with later‐arriving individuals exhibiting higher FD, consistent with compensatory strategies during delayed migration. Species showed some variation in arrival condition and clearer differences in refuelling performance. Wood Warblers arrived with persistently low reserves and exhibited the lowest fuel deposition, while both Wood Warblers and Sedge Warblers showed comparatively limited increases in flight range during their stopover. Although individuals of both species gained fuel and improved their flight range, these gains were smaller than those observed in Garden Warblers and Common Nightingales. In contrast, Garden Warblers and Common Nightingales achieved substantially greater post‐stopover flight ranges, frequently exceeding 200 km after refuelling on Antikythera. Model‐predicted flight ranges closely matched observed values, confirming robust model performance. These findings highlight Antikythera as an important spring stopover site for migrants crossing the Sahara and Mediterranean barriers while revealing substantial interspecific differences in refuelling success.