Résumé
The Mediterranean Basin is a biodiversity hotspot. Wetlands make a key contribution to this status, but many of them remain outside the Ramsar network fifty years after the establishment of the Ramsar Convention. Here we evaluate the extent to which the Mediterranean Ramsar network covers wetlands of international importance for wintering waterbirds using the Ramsar Convention criteria 2 (species of conservation concern), 5 (> 20,000 waterbirds) and 6 (1% of a population). These criteria were applied to 4186 sites in 24 Mediterranean countries using counts of 145 wintering waterbird species from 1991 to 2017. We identified 161 sites of international importance for waterbirds that have not yet been declared as Ramsar sites, which could be added to the 180 current Mediterranean Ramsar sites established based on waterbird criteria (criteria 5 and/or 6). Among these sites, a subset of 32 very important sites reached double the required level for at least one criterion and 95 were not protected by any site conservation status. Coastal wetlands represented half of the Ramsar gap for waterbirds. We identified that an additional 1218 monitored sites could be provisionally considered as internationally important and thus require more survey efforts to assess their status. This study highlights a lack of participation of the Mediterranean countries to build the Ramsar network for wetland protection. Our results should help policymakers and managers to prioritize future Ramsar site designation, notably in the Middle East and Western European region where important gaps were identified.