Breeding Season

A single mature bull elephant seal shifted his weight onto the sand at Piedras Blancas in mid-November. He’s the first of a couple hundred who will arrive for the breeding season.

Make a visit to the seals part of your Thanksgiving festivities.

Docents called him Romeo, although he didn’t show much energy. He has been swimming for weeks to return from as far as Alaska. He is taking some well-earned rest before the excitement of the females’ arrival.

Big and blubbery

He’s nice and fat. That’s an advantage to the bulls, who fast while they are on the beach. Recent research has shown that the bulls stop eating on their journey back to the Central Coast, and don’t start eating until they get back to Alaska, in March. They go without food for about five months.

They need a hefty load of blubber to carry them through the challenges of other bulls, to reach the season’s reward, mating with willing females. That’s in the future now. Pregnant females don’t usually arrive until December. After they have their pups, they nurse them for a month or so, coming into heat at the end of nursing and becoming receptive to mating.

Mating involves a lot of barking and tail flipping, but eventually they get the job done. That happens in late January and February. At least some bulls generally stay on the beach until March, when the last female leaves, so it’s a long time between fish dinners.

Young seals prepare to depart

Many juvenile seals remain on the beach through December. They are on the beach for their Fall Haul-Out, a six-week rest. More of those are males than females, because females mature earlier than males. Six-year-old males are still practicing their fighting moves on each other, while females the same age are having their first, second, and even third pups.

A few adult females may be on the beach. They are, for some reason, not pregnant. Whether they mate with younger bulls, or are able to mate under water, isn’t yet known. Over 90 percent of female seals have a pup every year. Those who skip a year present researchers with questions for which they have not yet found answers.

Beach transition

More adult bulls will arrive over the course of November and December. Look for an elephant-like trunk that hangs down onto the sand when the seal is resting, with a notch across it. Pink chest shields are another sign of maturity. Callused pink skin that extends up as far as the eyes when the seal is lying prone is typical of senior bulls.

The first pup of the season is usually born around mid-December. It’s onesy-twosy at first, increasing in frequency as hundreds of females arrive and more pups are born.

Citizen Science opportunity

The Coastal Commission invites all to photograph the extent of King Tides, coming up December 4 and 5. The photos document high water levels, showing how sea level rise will affect the coastline. Find the photo submission form here. Check out the photos taken in previous years of San Luis Obispo beaches. The tide inundated the rookery beaches, chasing seals to the edge of the bluffs.