When the pregnant females arrive, the dominating males have already selected their territory on the beach. Females cluster in groups called harems, which could consist up to 50 or more females surrounding one alpha male. Outside of these groups, a beta bull is normally roaming around on the beach. The beta bull helps the alpha by preventing other males accessing the females. In return, the beta bull might have an opportunity to mate with one of the females while the alpha is occupied.
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