Bay Nature magazineWinter 2001


Elephant Seals at Ano Nuevo

January 1, 2001

It’s time to make your reservations to witness one of local nature’s most dramatic spectacles: the annual return of the world’s largest mainland breeding colony of Northern elephant seals to Año Nuevo State Reserve on the San Mateo coast. Weighing in at up to two- and-a-half tons, with torpedo-shaped bodies 14 to 16 feet long, the male elephant seals engage in violent battles to assert their dominance and pass on their “alpha” genes. Females are smaller, averaging only 10 to 12 feet in length and weighing in at a mere 1,200 to 2,000 pounds. After giving birth to 75-pound pups, the mother seals fuel them with a super-rich milk that contains 55 percent fat. In less than a month, the pups grow to 250-350 pounds. Before swimming back out to sea in mid-March, the females mate. However, through a process called delayed implantation, it takes about four months for the fertilized eggs to implant in the mother’s uterine wall. This assures that she will have time to get back out to sea and begin feeding again before she has to start nourishing the egg. To view the seals of Año Nuevo you must sign up for the docent-led tours that run from Dec. 15 to March 15. For tour reservations, call (800) 444-4445. For more information, call (650) 879-2025 or log on to the Reserve’s web site at

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