The Lonjsko Polje Nature Park follows a floodplain along the Sava River, which runs south-eastwards towards the border with Bosnia and Herzegovina. It is mainly composed of alluvial forests, but also wet meadows and pastures. This combination of habitats and their regular flooding and high groundwater levels provide the conditions for rich biodiversity. The 250 bird species found in the Park represent more than two-thirds of all those in Croatia. 138 species use the wetland for breeding, such as the white stork Ciconia ciconia and the Eurasian spoonbill Platalea leucorodia. The river ecosystem is also crucial to several fish species, providing refuge and spawning grounds to threatened species including the Danube salmon Hucho hucho, the leather carp Cyprinus carpio and the European mudminnow Umbra krameri. The wetland is of cultural as well as ecological importance, being sustained by traditional farming and other practices. The main threats include drainage and invasive alien species. The management plan is due to be updated for the 2019-2029 period.