It’s Valentine’s Day, and love is in the air… not only for those of you who are looking forward to a romantic evening with your special someone, but also for thousands of northern elephant seals (Mirounga augustirostis) up and down the California coast. Late winter is mating season for these enormous marine mammals!
The reproductive cycle of the northern elephant seal begins in early December, when males, or bulls, haul themselves out of the water and set up camp on protected, isolated beaches. The newly arrived bulls fight brutally amongst themselves to establish a dominance hierarchy, and although these fights rarely result in death, they often leave participants severely battered. Only the very largest and strongest bulls gain the right to territory on the beach, and the right to mate with the female elephant seals that arrive on the beach in mid-December. The rest are forced to retreat to the remote edges of the beach.
Female elephant seals, or cows, arrive pregnant from last year’s breeding season. They give birth in late December to early January, and immediately begin to nurse their pups. Nurtured by their mother’s fatty and nutrient-rich milk, elephant seal pups grow quickly, gaining almost 150 pounds in just a few weeks. Adult males and females, however, do not eat for the duration of the breeding season, since their usual diet consists of oceanic organisms like fish and squid. While they are on land, elephant seals live off of their ample fat reserves.
Once the elephant seal pups have been weaned, the “pupping season” is over and females will begin to mate with the dominant bulls on the beach. A high-ranking bull may mate with as many as 100 cows in a single breeding season. Unfortunately for the lower-ranking bulls, dominant males fiercely defend their territories, so the majority of males on the beach will not get to mate with a single female… although some manage to sneak in a little romance while the big guys are distracted.
About two months after the end of the pupping season, adult elephant seals abandon the beach, leaving the pups behind to learn to swim and forage on their own. Three months later, the pups will be nearly fully grown and ready to undertake their first long sea voyage. They have quite a trek ahead of them. Northern elephant seals spend most of the year foraging near the Aleutian Islands, off the coast of Alaska!
Those of us living in coastal California are fortunate enough to be able to watch the elephant seal breeding season unfold in our own backyards. For more information on where to find elephant seals, check out Año Nuevo State Reserve in Southern San Mateo County. Rangers here lead guided elephant seal walks from December 15 to March 31. Some MSI members will be taking one of these tours later this month, so check back soon for a firsthand report!