A 9-year study has uncovered some unusual behavior by common bottlenose dolphins living off the coast of Slovenia. Within one population of this species, the animals have divided into two groups that avoid contact by hunting at different times of day—a social strategy not known in marine mammals.

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A 9-year study has uncovered some unusual behavior by common bottlenose dolphins living off the coast of Slovenia. Within one population of this species, the animals have divided into two groups that avoid contact by hunting at different times of day—a social strategy not known in marine mammals.