Specimens frequently escape from collections, and in the 20th century a large feral population was established in Great Britain; more recently small numbers have bred in Ireland, concentrated in the parks of Dublin. There are now about 7,000 in Britain, and other populations on the European continent, the largest in the region of Berlin. Isolated populations exist in the United States. The town of Black Mountain, North Carolina has a limited population, and there is a free-flying feral population of several hundred mandarins in Sonoma County, California. This population is the result of several mandarin ducks escaping from captivity, then going on to reproduce in the wild.