Barbary doves (Streptopelia risoria) are easily kept and long-lived in captivity, living for up to 12 years. However, there have been cases of doves living over 20 years, and, in one case, of a dove living for 29 years In recent years they have been used extensively in biological research, particularly into the hormonal bases of reproductive behavior, because their sequences of courtship, mating and parental behavior have been accurately described and are highly consistent in form. Dove fanciers have bred them in a great variety of colors; the number of colors available has increased dramatically in the latter half of the twentieth century, and it is thought that this has been achieved by interbreeding with S. roseogrisea. Some of these doves carry a mutation that makes them completely white. These white Barbaries are most commonly used in stage magic acts. White Barbary doves are traditionally released in large public ceremonies, since it is a peace symbol in several cultures, and "dove releases" are also sometimes found at weddings and funerals. However, a release dove is, in fact, usually a homing pigeon, as Barbary doves lack the homing instinct and will die left out in the wild.