there is a wealth of birdlife, with 619 species recorded, of which 258 breed on the island or remain during winter. because of its mild winters for its latitude, great britain hosts important numbers of many wintering species, particularly waders, ducks, geese and swans. other well known bird species include the golden eagle, grey heron, common kingfisher, common wood pigeon, house sparrow, european robin, grey partridge, and various species of crow, finch, gull, auk, grouse, owl and falcon. there are six species of reptile on the island; three snakes and three lizards including the legless slowworm. one snake, the adder, is venomous but rarely deadly. amphibians present are frogs, toads and newts. there are also several introduced species of reptile and amphibian.