July and August are the months to see mature bull elephant seals at Piedras Blancas. They return to the beach to molt their skin. That’s why they look so ratty.
Compared to the busy months of spring, when all the adult females and the juvenile seals are on the beach, and the winter breeding season, the beach looks empty. But the seals that are here are the biggest ones, the ones with the elephant-like trunk (technically, proboscis) that gives them their name.
Visitors often ask whether the seals rub their skin off with sand. The seals toss sand all the time. They are born tossing sand. It’s probably a way to fend off the sun’s heat, and maybe a response to stress. Females in labor often toss so much sand, they dig ditches at their sides.
They have a lot of blubber to keep them warm in the cold north Pacific waters where they hunt. They are deep divers, foraging at 1,000 feet deep and more. They are warm-blooded mammals, and their blubber insulates them against the cold. On the beach, they heat up in the sun, even on cloudy days. The sand gives some protection from the sun.
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As they mature, bulls grow a chest shield along with that nose, calloused skin that circles their neck. Both the nose and the chest shield continue to grow throughout their lives. As the nose grows, it develops a crease or notch. A bigger nose and shield mean an older seal. Look for a chest shield that extends higher around the neck than their eyes.
Two members of Friends of the Elephant Seal have been counting the bulls. They find that not all the bulls that were here during the breeding season came back to molt. Last year, 235 mature bulls were at Piedras Blancas to breed, but only 174 came back to this beach to molt.
The limited tagging system of small colored plastic tags on the back flippers makes it impossible to know which individuals didn’t return. A new project at Cal Poly will mark seals with large dyed numbers that will be easier to see from a distance. That will make it possible to follow more seals as individuals and learn more about their lives.
“We want to establish baseline data of known-age animals so we can understand the age structure of the population and their sexual maturity,” said Heather Liwanag, assistant professor of marine science at Cal Poly. “So many things about them are unanswered. It’s hard to identify them with the little flipper tags.”
Younger seals of both sexes are migrating and foraging in the open ocean now. They’ll return to the beach in the fall for a few weeks of rest.
The pregnant female seals are at sea, foraging for food. They left the beach after they molted their skin in May and June. They’ll return to the beach in December and January to give birth to their pups.
FES docents who staff the site have samples of elephant seal skin you can touch. Ask to see it. They are easily recognizable in their blue jackets. Docents are stationed at the site year round.
Christine Heinrichs’ column appears the fourth Thursday of each month and is special to The Cambrian.
Be an FES docent
Becoming a docent is a great way to learn about local natural history. Friends of the Elephant Seal is interviewing prospective guides in July and August for training classes beginning Sept. 9. Apply online, www.elephantseal.org, by email, firstname.lastname@example.org, or by phone, 805-924-1628.