Cooperative breeding

A breeding system in which individuals assist in raising young produced by another pair, often while foregoing or delaying their own reproduction.

Alloparental care: Care provided to young by an individual other than their genetic parents. Cooperative breeding is a social system built around care by individuals beyond the breeding pair.
Florida scrub-jay: A North American bird whose family groups often include nonbreeding helpers that assist at nests. It is a well-studied example of helpers assisting close relatives in a stable territory.
Hamilton's rule: An evolutionary condition for altruism: a behavior can spread when relatedness times benefit exceeds its cost. It formalizes when helping relatives can be favored by natural selection.
Biparental care: Care of offspring by both genetic parents. Unlike cooperative breeding, care is restricted to the offspring's two parents.
Inclusive fitness: An individual's genetic success through both its own reproduction and effects on relatives' reproduction. Helping relatives can spread a helper's genes even when it produces no offspring itself.
Seychelles warbler: A small island songbird in which subordinate females sometimes help dominant pairs raise young. Its population studies show how breeding vacancies affect helping and delayed dispersal.
Delayed dispersal: Remaining in the natal group beyond the age at which an individual could leave. Many helpers become available because young adults remain near their parents.
Communal breeding: A system in which multiple females lay eggs or give birth in a shared nest or group. Shared breeding can involve several mothers, unlike help directed at another pair's young.
Kin selection: Natural selection favoring traits that increase the reproductive success of genetic relatives. Relatedness can make costly help to another pair's young advantageous.
White-winged chough: An Australian bird that lives in groups where adults and juveniles help raise young. Its groups illustrate cooperative care among individuals with varying relatedness.

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