Introduction to Elephant Seals
Elephant seals, Mirounga angustirostris, are true seals, or earless seals, members of the pinniped suborder. What marvelous creatures they are: huge blubbery males with the pendulous noses that give these beasts their name; winsome females whose faces seem to be etched with a permanent smile; and endearing plump babies with big brown eyes.
In the 1880's northern elephant seals were thought to be extinct, harvested by shore whalers and sealers for their blubber. The oil obtained from elephant seals is second in quality only to the sperm whale. A small group of between 20-100 elephant seals that bred on Guadalupe Island, off Baja California, survived the ravages of the seal hunts. Protected first by Mexico and later by the United States, they have steadily expanded their range. Today they are protected from hunting and harassment by the Marine Mammal Protection Act of 1972. The total population estimate for northern elephant seals in 2006 is around 170,000.
The breeding season begins in late November when mature bulls begin to arrive and fight to determine dominance. The females start arriving in the middle of December and continue to arrive until the middle of February. The first birth is around Christmas, but most births usually occur during the last two weeks of January. The females remain on the beach for about five weeks from the time they come ashore. Amazingly, the males are on the beach for up to 100 days. The seals are fasting while they are on land, and both males and females lose about 1/3 of their body weight during the breeding season.
Elephant seals form harems, in which the dominant, or alpha, male is surrounded by a group of females. On the periphery of the harem, the beta bulls wait in hopes of an opportunity to mate. They assist the alpha bull in keeping away the less dominant males. Fights between males can be bloody affairs in which the combatants rear up and slam their bodies against each other, slashing with their large canine teeth. However, not all confrontations end in battle. Rearing up on their hindquarters, throwing back their heads, showing off the size of their noses and bellowing threats is enough to intimidate most challengers. When battles do occur, it is rarely to the death.
The rookery is a very noisy place during the breeding season as males bellow threat vocalizations, pups squawk to be fed, and females squabble with each other over prime location and pups. Gargles, grunts, snorts, belches, bleats, whimpers, squeaks, squeals, and the male trumpeting combine to create the elephant seal symphony of sound.
The pups are usually born within 4-5 days of the female's arrival, and weigh between 60-80 pounds. They nurse for 24-28 days on the richest milk in the mammal world. Mating occurs during the last 2-3 days of nursing. The peak of mating activity is around Valentine's Day. Pups are weaned when the mother abruptly departs for sea. The weaned pups, dubbed "weaners," have quadrupled their birthweight and are nice and plump. They will lose about one-third of their weight during the "weaner fast," the 8-10 weeks they remain at the rookery, teaching themselves how to swim, before taking off on their first foraging trip.
While elephant seals are at sea in search of food they dive to incredible depths. Typically they dive between 1000-2000 feet, but the record is over 5000 feet. The average length of dive is 20 minutes, but they can dive for an hour or longer. When they resurface they only spend 2-3 minutes before diving again - and they continue this diving pattern 24 hours a day. Male and female elephant seals are believed to feed on different prey. The female diet is primarily squid and the male diet is more varied, comprised of small sharks, rays and other bottom-dwelling fish. In their search for food the males travel along the continental shelf to the Gulf of Alaska. The females tend to head north and west into more open ocean. Elephant seals make this migration twice a year, also coming back to the rookery to molt in late spring and the summer time. These two migrations total up to eight to twelve thousand miles of travel annually.
Human beings shed hair and skin all the time, but elephant seals go through a catastrophic molt, in which the entire layer of epidermis with the hairs attached is sloughed off in one concentrated time. The reason for this abrupt molt is that while at sea they spend most of their time in cold deep water. As part of the dive process the blood is diverted away from the skin. This helps them conserve energy and avoid losing body heat. By coming up on land to molt the blood can be circulated to the skin so a new layer of epidermis and hair can be grown.
Elephant seals are sexually dimorphic: the males are much larger than the females and only the males develop the long noses and chest shield. Females grow to 9-12 feet and weigh between 900-1800 pounds. Males grow to 14-16 feet long and weigh in at 3000-5000 pounds, or more. Female elephant seals give birth for the first time around 4 years old, though the range is between 2-6 years of age. Females are considered physically mature at age 6 and can live to a maximum of 20 years. Males enter puberty around 4 years of age, at which time the nose starts to grow. The nose is a secondary sexual characteristic, like a man's beard, and can reach the astonishing length of 2 feet. Males reach physical maturity around 9 years old. Prime breeding age is 9-12, and they can live to a maximum of 14 years.
What is an elephant seal? A deep-sea diver, a long distance traveler, an animal that fasts for long periods of time, elephant seals are extraordinary. They come together on land to give birth, mate, and molt but at sea they are solitary. Tremendous demands are placed on their bodies. The more you learn about these animals the more you will say WOW!
If you would like to learn more about these incredible animals, Friends of the Elephant Seal has a book available. For information on ordering Elephant Seals, go to the Gift Shop.