Many larger animals, such as wolf, bear and the European elk are today extinct. However, some species such as red deer are protected. Other small mammals, such as rabbits, foxes, badgers, hares, hedgehogs, and stoats, are very common and the European beaver has been reintroduced in parts of Scotland. Wild boar have also been reintroduced to parts of southern England, following escapes from boar farms and illegal releases. Many rivers contain otters and seals are common on coasts. Over 200 species of bird reside permanently and another 200 migrate. Common types are the common chaffinch, common blackbird, house sparrow and common starling; all small birds. Large birds are declining in number, except for those kept for game such as pheasant, partridge, and red grouse. Fish are abundant in the rivers and lakes, in particular salmon, trout, perch and pike. Sea fish include dogfish, cod, sole, pollock and bass, as well as mussels, crab and oysters along the coast. There are more than 21,000 species of insects.