Crossing the Sahara by small jumps: the complete migration of the Western Orphean Warbler Curruca hortensis

Abstract We analyzed data retrieved from six multi-sensor loggers deployed on adult Western Orphean Warblers Curruca hortensis in France, to unravel the migration strategy of the species. Individuals followed a mostly direct, straight-line route towards wintering areas in North Senegal/South Mauritania, which was consistent across individuals and between autumn and spring migrations. Most migratory flights lasted around 6 h, covering approximately 300 km, with few variations even during the desert crossing, illustrating that the species crosses the Sahara by short, intermittent jumps. Individuals are likely using wadis with acacias along the route as stopover sites. Flights during spring were, on average, higher than during autumn. Long flights were performed at a median altitude of 2400 m, a few reaching up to 4000 m. Part of these flights were prolonged by a final flight at ground level, likely serving as repositioning flights during the early morning, to survey the landing area and identify suitable stopover habitats.