Homosexual couples account for up to 20 percent of all pairings annually. Almost a quarter of all families are parented by homosexual couples that remain together for years. At times, male couples use the services of a female by mating with her. Once she lays a clutch of eggs, the wanna-be fathers chase her away and hatch the eggs. Other times, they just drive away heterosexual couples from their nests and adopt their eggs.