Horicon Marsh. 4/12/90; Wisconsin, 13,355 ha, 43°30’00”N 88°38’00”W. The Site is one of the largest intact freshwater wetlands in the USA and also one of the largest cattail (Typha spp) marshes in the world. It is an important staging area for numerous species of migratory birds, especially for Canada geese (Branta canadensis) and mallards (Anas platyrhynchos). In the autumn, 80% of the Mississippi Flyway population of Canada geese (around 1.1 million birds) and 2% of the biogeographic population of mallards use the Site during their migration. Other species, some of them endangered, use the area as a staging, nesting or feeding site. Among these are the bald eagle (Haliaeetus leucocephalus), the whooping crane (Grus Americana) and the yellow-throated warbler (Dendroica dominica). Apart from its importance for migratory birds, the Site is also important for maintaining the biological diversity of the region given the rapid loss of wetlands in the State. It is estimated that the extent of wetlands has decreased by almost 50% since 1850 in most of Wisconsin and by as much as 90% in south-eastern Wisconsin. The main threats are associated to human activities; agricultural runoff has resulted in increased sediment and nutrient loading while the construction of wind farms has resulted in bird mortality. Ramsar Site no. 511. Most Recent RIS Information: 2011.