Cooperative breeding

Although not common (only about 300 out of approximately 10,000 bird species have cooperative breeding), cooperative breeding does happen. Birds with helpers, regardless of whether the helpers are related or not, typically raise more offspring — sometimes twice as many — than birds without helpers.

There are two kinds of cooperative breeding among birds:

i Non-reproductive individuals helping other birds to reproduce: In some cases, the helpers are related; in other cases, they're not. Helpers who are related benefit because doing so increases their inclusive fitness (refer to the earlier section "Your fitness + your relatives' fitness = inclusive fitness" for details on inclusive fitness). Unrelated helpers benefit because if male dies they have the inside track on widow: wife and home all packaged together.

i Groups of reproductive individuals getting together and helping each other (often with some non-reproducing individuals, too): An example of this type of system is found with the groove-billed ani, as explained in the section "Other cooperative breeding behaviors."

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