The first step in the elephant seal mating ritual involves battles for supremacy between males. Afterwards, the dominant males drive away the weaker ones and establish harems of 30 to 100 females. The bulls then copulate with the cows in their harems. Only a few of the most powerful bulls have an opportunity to mate.
The ritual begins in mid-winter, typically in December, at breeding grounds on remote beaches that are protected from storms and pounding surf. The bulls arrive first and commence battling. Although conflicts are often brutal and bloody, they are seldom fatal. Large bulls may resolve confrontations by vocalizing and posturing, while smaller and younger males are often merely chased away. A dominant bull fasts and lives on his storage of blubber for up to 3 months during mating season in order to remain near the harem and defend it. Sometimes younger males may attempt to copulate with females when the dominant bull is distracted, but they typically flee when the bull gives chase.
Females fast for several weeks while nursing their pups. The gestation period is 11 months, after which pups are born and start nursing immediately. The pups nurse for about 1 month, gaining about 10 pounds a day. During this time, the female mates again with the dominant male. Shortly after weaning her pup, the mother abandons it and returns to the sea.