Cooperative Breeding

Cooperative breeders are animals where parents are assisted in protecting and provisioning their young by helpers that seldom or never breed themselves. Systems of this kind occur in birds, mammals and some fish, and have usually evolved from ancestors with monogamous breeding systems. Helpers are often previous offspring of breeders and are usually closely related to the young they help to raise though, in some systems, they can also be unrelated immigrants. Their contributions commonly enhance the growth and survival of juveniles and reduce the workload of their parents, increasing their fecundity. Cooperative breeding systems appear to have evolved where the costs of dispersal are high, helping provides substantial fitness benefits to related recipients or to helpers themselves and the fitness costs of helping are low.