The sediments are deposited in river estuaries, allowing reedbeds to expand. A total of 282 bird species have been recorded in Matsalu, among which 175 are nesting and 33 are transmigrant waterfowl. 49 species of fish and 47 species of mammals are registered in the area of the nature reserve, along with 772 species of vascular plants. Every spring over two million waterfowl pass Matsalu, including 10,000—20,000 Bewick's swans, 10,000 greater scaups, common goldeneyes, tufted ducks, goosanders and many others. A colony of up to 20,000 barnacle geese, over 10,000 greylag geese and thousands of waders stop on the coastal pastures in spring. The most numerous birds of passage (around 1.6 million) are long-tailed ducks. Approximately 35,000—40,000 ducks feed in the reedbeds in spring. In autumn, about 300,000 migratory waterfowl pass Matsalu. The wetland is the biggest autumn stopping ground of common cranes in Europe. The highest recorded number of cranes at the park has been 23,000. History Scientific research in Matsalu started around 1870, when Valerian Russow, the curator of the Natural History Museum of the University of Tartu, gave a short overview of birds near Matsalu Bay. Between 1928 and 1936 Eerik Kumari researched birds in Matsalu and suggested a creation of the bird protection area there in 1936. In 1939, parts of the bay (Virtsu-Puhtu) were protected for mud used in mud-baths. Research in Matsalu became regular in 1945, when the Institute of Botany and Zoology of the Estonian Academy of Sciences established a research base in Penijõe. Matsalu Nature Reserve was founded in 1957, mainly to protect nesting, moulting and migratory birds. The first permanent workers (administrators and scientists) started in 1958 and the Penijõe research base became the administrative centre of the newly created nature reserve. The Estonian Bird Ringing Centre (), the coordinator of bird ringing in Estonia, is also located in Penijõe. In 1976, Matsalu was included in the list of wetlands of international importance under the International Convention on the Protection of Wetlands (Ramsar Convention). The European Diploma of Protected Areas was awarded to Matsalu Nature Reserve in 2003 by the Council of Europe, in recognition of the park's success in preserving the diversity of habitats and the numerous species of birds and other biota groups in the nature reserve. Matsalu is the only nature reserve in Estonia to hold the European Diploma. The diploma was extended for five years in 2008.