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A test of a model for the evolution of avian polygyny revealed that 10 percent of male indigo buntings had two mates simultaneously and some had none. Old males acquired territories first, and yearlings moved into leftover space. Yearling males that obtained mates tended to form brief, monogamous bonds. Females mated to polygynists produced as many young as females mated to monogamists.
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Carey et al. (1975) studied this question.
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