Identifying the potential wintering sites of the globally threatened Aquatic Warbler Acrocephalus paludicola using remote sensing

The Aquatic Warbler is a threatened Afro-Palaearctic migrant with a largely unknown distribution in the winter (non-breeding) season. Protection of wintering sites may be crucial for the conservation of the species. Previous studies have identified extensive areas of north-western sub-Saharan Africa that could potentially be occupied by the species during winter. However, these studies have not necessarily differentiated between potentially suitable and unsuitable habitat types at a spatial resolution appropriate for targeting field surveys. To identify specific sites that could be occupied by non-breeding Aquatic Warblers at a scale appropriate for targeted field surveys, we adopted a modelling approach that combined recent sightings from Djoudj, Senegal, with land cover and climate data. We produced maps of potential distribution using three maximum entropy models. While a paucity of sightings prevented a full test of these maps on independent records, the areas that were predicted to be potentially occupied included areas around which there are historical records. We suggest field surveys should be targeted towards sites in the Inner Niger Delta and a number of marshes along and away from the Niger River in Mali, and to sites in southern Mauritania.