The importance of wetlands for the Greater Spotted Eagle <i>Clanga clanga</i> wintering in the Mediterranean Basin

Summary The Greater Spotted Eagle is an extremely rare species which is strongly associated with wetlands during the breeding period. The winter habitats of this vulnerable species have not been extensively studied so far, although eagles spend over one third of the year there, and these are therefore also crucial for the conservation of the species. We investigated the distribution of Greater Spotted Eagle wintering grounds in the Mediterranean Basin on the basis of telemetry data from individuals caught in breeding grounds, detailed species counts during wintering in Greece, and a literature search. We found that at least 300–400 individuals (c.15% of the European population) winter in the Mediterranean Basin, sometimes numbering a few dozen in particular river valleys. Individuals used on average 89.7 km 2 home ranges for wintering. The Maxent model of wintering habitats performed with high reliability, indicating that most of the coastline along the Mediterranean Sea and some parts of the Black Sea are suitable for the wintering of this species. The distribution of coastal marshes was the most informative for the model. Compositional analyses done for home ranges of GPS tracked individuals and wintering sites in Greece showed the highest preference for salines and salt marshes but also a high preference for coastal lagoons and water courses. We link wetland preference with the availability of medium size prey, optimal for this species, and prey specialisation common to breeding sites.