Social monogamy

Abstract Social monogamy, by far the most common mating system in the Class Aves (Lack 1968), can be recognized by the apparently exclusive association of one female and one male as mates over some definable period of time, such as a nesting cycle, a breeding season, or even a lifetime. In birds, monogamy is usually closely associated with biparental care. (Although biparental care and monogamy actually refer to two distinct suites of behaviour-parental care and mating system, respectively-the two terms are so closely linked that they are often used interchangeably.) As noted previously, unlike any other group of vertebrates, social monogamy is the prevalent mating system in birds, with well over 90 per cent of all species estimated to exhibit this form of male-female association (Lack 1968). In view of its rarity in other classes of vertebrates, the frequency of monogamy in birds is striking and is a key behavioural-reproductive characteristic that sets this group apart from all other vertebrate taxa.