Most birds have only one mate, the advantage is that both parents help to rear the young. Some birds, however, practice polygamy ie having more than one mate. Male Wrens often do this, especially where food is plentiful and the hen can feed the young on her own. There are two types of polygamy - simultaneous pairing with two or more females and successive polygamy, when the male initiates consecutive broods with different females. Male Wrens do both.
