Saturday, September 27, 2014

Juveniles crowd the beach

This week's column in The Cambrian:

The unusual anchovy bloom that attracted hundreds of humpback whales to our coast went unnoticed by the Piedras Blancas elephant seals. Pelicans, gulls, cormorants and sooty shearwaters fed wildly on the feast. Sea lions and bottlenose dolphins swept through the mass of small fish, so thick they appeared on fishing boats’ depth sounders.

The breaching whales and plunging pelicans attracted hundreds of human visitors all along the coast. But to the elephant seals, it was just another sunny day. They aren’t interested in food while they are on the beach anyway.

They fast, not eating at all, for the four to six weeks they spend at Piedras Blancas bluff. They live off their blubber. In that way, they are like desert animals. Elephant seals fasting on the beach are like camels that metabolize the fat in their humps when they don‘t have access to fresh water.

Elephant seals have physiological adaptations that conserve water, such as efficient kidneys and convoluted nasal passages that recapture moisture in their breath before they breathe it out. By conserving water, they conserve fat that would otherwise be metabolized.

“They are so different from other animals that we called them Martians in the lab,” said Susanna Blackwell, who earned her doctorate for her study of elephant seals.

In September, juvenile seals arrive for their fall haul-out. That’s the simple description of what’s going on: Seals haul themselves out on to the sand, and there they stay. They arrive one by one, some unknown signal drawing them back to the beach.

The herd gradually increases until thousands are on the beach during October. Then those who arrived earliest begin their return to the sea. One by one, they slip into the surf, until only a few are left when the adult males start arriving in late November for the breeding season.

The juvenile seals range from their first year to 6 years old. The ones that were born earlier this year are returning from their first migration. They left the beach in March and April. No adult seal guided them. How they find their way is one of their mysteries. They entered the ocean, swam away, and hunted enough fish and squid to survive.

That first migration may be only as far as Vancouver Island, although some make it all the way to Alaska. All the ones on the beach have gone north and found their way back to the Central Coast. The smallest seals on the beach have overcome their first ocean challenge.

Mostly they sleep on the beach, but as youngsters do, they cavort with each other. Males tussle, on the beach and in the water. Older seals are generally bigger, but since females never get as big as males, that’s only one indicator of age. Among adolescent males, that distinctive nose starts to grow at age 5. The seals on the beach in September with bigger noses are older.


Compare the noses you see to distinguish a 5-year-old from a 6-year-old. A docent in a blue jacket can show you a drawing that illustrates how the nose develops. They can also let you handle a piece of skin that molted off earlier this year. They are always happy to answer questions and help you appreciate the seals.

Read more here: http://www.sanluisobispo.com/2014/09/22/3258594_elephant-seals-piedras-blancas.html?rh=1#storylink=cpy

Tuesday, August 12, 2014

Harbor seal visitor

A harbor seal pup rested on the sand at Piedras Blancas yesterday. He was a cute little guy, immediately recognizable as different from the other youngsters who are already arriving for their fall haul-out.
The adults don't take much notice of the juveniles. This youngster sleeps peacefully among his elders. They all enjoyed the cool, wet kelp as a bed.
Other males continue to work on their fighting skills. Active fighting was mostly in the water.






On the beach, dominance confrontations were confined to threat and retreat, as between these two.

Saturday, July 26, 2014

Cambrian Elephant Seal Column

I now write the Elephant Seal column for the local newspaper, The Cambrian. Here's my first column.

Tattered and torn.

That’s what the adult male elephant seals that are on the beach now look like. Their molting skin is peeling off. It looks awful, but it’s normal.

The adult males return to the beach for a month or so of quiet time in July and August, while they get their new skin for the coming year.

The old skin is brown, contrasting with the pearly gray new skin underneath.

Their skin keeps its scars, so senior seals continue to display their battle history.

Molting skin all at one time, called a catastrophic molt, is unusual for mammals. Snakes peel their skin off to grow, and some insects and crustaceans split their outer skin off, but seal skin just falls off in pieces.

Visitors often ask whether the seals are rubbing their skin off with sand. I’ve never seen a seal do that. They toss sand on their backs, but that’s a way to regulate temperature.

These seals are comfortable in very cold water. They are deep divers, foraging at 1,000 feet deep and more, in the icy waters of the North Pacific. 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.

Summer is the low point for the number of seals on the beach, but that’s relative. There are seals on the beach year-round.

In July and August, the adult males are here, the ones with the big nose (technically, proboscis) that gives them their name. There are lots of them out there, especially at the north end.

Friends of the Elephant Seal posts a sign in the parking lot, directing visitors to the best place to see the seals that day. Seals are always coming and going.
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 to grow their pups. 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.

Friends of the Elephant Seal 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.

Becoming a docent is a great way to learn about local natural history. Training is free, coming up on Sept. 13, Oct. 11, 18 and 25. Docents serve four three-hour sessions each month.

For more information and to register for the 2014 training sessions, call 924-1626 or use the online docent application: http://www.elephantseal.org/Friends/docent_application.html.

Read more here: http://www.sanluisobispo.com/2014/07/24/3166207/elephant-seal-molting-piedras.html?sp=/99/177/183/429/887/#storylink=cpy

Monday, July 7, 2014

Summer vacation

Lots of visitors discovering the elephant seals! Several good examples of molting easy to see on the beach.
Lots of big, fat males on the beach. They make me think of how many  fish and squid they have eaten to get so big.
These big males show their seniority with their large chest shields. Youngsters sparred in the water, but mostly life was quiet today.
This boy made himself comfortable on his brothers.


Monday, June 30, 2014

Adult males

It's summer, and the adult males are back on the beach.
 This one lets the audience know he's here. He's gained plenty of weight on his post-breeding season foraging migration.
 They are piled up, although this isn't a very busy time of year. The age range is from five years to maturity. Some could be as old as twelve. They are in varying stages of molting, accounting for the brown skin peeling off to reveal gray skin underneath.
Time to settle down and get some rest.

Tuesday, June 17, 2014

A pup's first year

My friend Charmaine Coimbra has created a video following a pup's first year, from birth to the first migration.

She took the photos at Piedras Blancas, documenting the progression from
 birth in January

through weaning in February,

learning to swim in March, and departing for that first migration north to feed in April. She's put music to it and it's a great photo essay.

Thanks, Charmaine!

Friday, May 30, 2014

Molting in May

 A sunny day on the beach. This young male couldn't resist pestering a female who wanted to be left alone.
 This tail looked especially ragged.
 A lot of youngsters, especially males, played in the water.
 Get rid of that nasty old brown skin!
Most were happy just to rest on the sand.