Promiscuity in Monogamous Colonial Birds

Promiscuous behavior by mated colonial monogamous birds of 18 species is examined in the light of the existing theory of energetic investments (Trivers 1972). Evidence is presented showing that the belief that female energetic investment far outweighs previous male energetic investment is not necessarily true. In light of the breeding biology of the 18 species, it is felt that females defend themselves against forced extrapair copulations (FEPC's) in order to maintain their pair bond and protect the investment of the male. This will aid in preventing his desertion of the nest and thus her loss of investment in the offspring.