Bulls ready to roar

Biggest bulls return for the breeding season

Mature bull elephant seals, foraging at sea for the past ten or twelve weeks, will start arriving at Piedras Blancas any day. They are at their biggest and loudest now. They are ready for action. The bulls will be on the beach until March. Great holiday viewing for visitors!

They are preparing for the breeding season, the high point of the year. The bulls are ready for battle when they arrive. They are in prime condition, with enough blubber to carry them through. They may not eat again until March, as long as 120 days.

This mature bull annunces his arrival on the beach at Piedras Blancas.

Arrival

The first bull usually arrives around Thanksgiving. It may look quiet at first.

Look for a big seal surfing in, arising from the waves as a monster from the deep. After a few galumphs up the beach, he stops. Without the buoyancy of water supporting all that blubber, he feels his full weight under gravity. He’s making the transition from life underwater to life on land.

Juvenile seals are still on the beach, lingering from their fall haul-out. They’ll soon get the message: It’s time for the Big Boys to take over. Some may find places on the beach to continue resting for a while. They may benefit from observing the adult social order. In a few years, they will be part of it.

Preparing for breeding season

The bulls have been feeding on fish and squid along North America’s continental shelf since August. They gained as much as 28 pounds a day. Leaving their feeding grounds, the bulls stopped eating and swam directly from as far north as the Aleutian Islands to return to southern beaches.

This is the long fast of their year. They can’t leave the beach to feed. The good feeding areas are hundreds of miles north. Besides, they need to stay on the beach to defend a harem until the females are ready to breed, a month after they give birth. That can extend into March, as females give birth in January and February.

It’s all worth it to them. Beachmasters, 12 or 13 years old, have only one or two good years at the top. They fight to take advantage of their power.

This younger bull is wiling to challenge older bulls for dominance.

Dominance hierarchy

On the beach, even before females arrive in December, they threaten and fight each other to establish the beach dominance hierarchy. Although threats and fighting establish the dominance hierarchy, dominance actually helps reduce conflict in the rookery. Bulls recognize each other’s call, and remember who won. They don’t need to fight again.

Viewers can see the dominance hierarchy acting out on the sand. One bull vocalizes a deep, grunting threat to another bull. All the bulls hear, and start clearing away, which is called displacement. One bull may respond by calling back, or by raising up and coming across the beach for the fight.

That’s when the titans clash. Chest to chest, biting with those big, two-inch, canines. The chest shield, torn and battered, drips blood. No quarter is given.

Most fights are brief, less than a minute, but some last half an hour, exhausting both fighters. They may cross the sand and continue the fight into the water.

The fight ends when one gives up and retreats. The winner my continue chasing him, biting his back. Take that!

This senior bull -- note the long proboscis, with a crease -- has seen years of breeding seasons.

Females soon follow

A solitary female or two may arrive in late November, but they will certainly be on the beach in December. They give birth within a few days of arriving on the beach. Look for the first pup in mid- to late-December.

That’s when the important part of the dominance hierarchy kicks in. Bulls guard their harems of females as best they can. It’s always imperfect, with subdominant bulls constantly challenging the beachmaster’s top position, or simply trying to get away with mating with a female on the edges of the harem.

Only the dominant bulls, the beachmasters, will get to breed freely, without threat by more dominant bulls. By the peak of the breeding season in January and February, beachmasters will reign over harems of 30-40 females on Central Coast beaches.

King Tides

Winter brings the highest tides of the year to the West Coast, King Tides. They are predictable, happening when the sun, moon, and Earth align to exert the greatest gravitational pull on the ocean. This year they will occur on the mornings of November 6, December 4-6, and January 2-3.

High tides may affect pups born within that high tide zone. Females who choose higher ground are more likely to raise their pups successfully to weaning. The most dominant bulls also stake their claim over these sections of beach.

California Coastal Commission invites the public to submit photos that illustrate how far the water 

First Bull Arrival contest

Friends of the Elephant Seal holds a contest every year, to guess when the first bull will arrive for the breeding season. Enter the First Bull contest here!

The winner gets an FES baseball cap, and praise from FES members and elephant seal admirers. Which is the main point, and the most fun!

Visiting the Viewpoint

A visit to see the elephant seals is good holiday entertainment. Look for long noses and big pink chest shields on massive bodies. The nose, technically proboscis, and chest shield continue to grow throughout the seal’s life. Bigger is older.

Friends of the Elephant Seal docents in blue jackets are available every day to answer questions.

Check the live webcam to see what’s happening on the beach. Highway 1 remains closed to the north, at Lucia Lodge, due to the Regent Slide between the lodge and Esalen Institute.

Bring your camera.  Always open, always free. The viewpoint is located within the Monterey Bay National Marine Sanctuary, federally protected and held in trust for the world.

 

Marine Mammal Center tests HPAI vaccine

Cow vaccine could help protect rare Hawaiian monk seal

The Marine Mammal Center is testing Highly Pathogenic Avian Influenza vaccine on elephant seals at its Sausalito hospital. If it is effective in producing antibodies, TMMC plans to vaccinate Hawaiian monk seals. TMMC’s Ke Kai Ola monk seal hospital is on the island of Hawaii.

Hawaiian monk seals are classified as Endangered, with only 1,600 seals surviving. They are “one of the rarest seal species in the world, and conservation efforts are critical to their survival,” according to the TMMC website.

HPAI infects birds and mammals

HPAI, caused by the H5N1 virus, is highly contagious and deadly to several species. It has now infected species from wild birds to domesticated birds and even to mammals. That species-to-species transmission makes a threat to global biodiversity.

Monk seals may be vulnerable to HPAI, as may the Central Coast’s herd of Northern Elephant Seals. In 2023, HPAI wiped out Southern Elephant Seals in Argentina, killing more than 96 percent of the pups, 17,500, born there, and an undetermined number of adult seals. Scientists studying the colony say it may take 100 years for the colony to recover to the numbers it had in 2022, 18,000. 

Elephant seals try the vaccine

Veterinarians advised testing the vaccine on elephant seals first, to avoid risk to the already precarious status of monk seals. National Oceanic and Atmospheric Administration officials, which have jurisdiction over National Marine Sanctuaries, also consulted on the trial.

“Northern elephant seal research has taken tremendous steps forward over the past decade within our shared network of west coast research partners,” says Dr. Sophie Whoriskey, Associate Director, Hawai’i Conservation Medicine at The Marine Mammal Center. “This vaccine trial on six in-care elephant seal pups at our Sausalito based hospital is especially significant given the great risk that Avian Influenza actively poses for marine mammals.”

1. The Marine Mammal Center’s Dr. Dane Whitaker (left), Associate Veterinarian, and Sarah Pattison (right), Director of Hospital Operations, collect a blood sample from a northern elephant seal patient during an Avian Influenza vaccine trial at the Center’s Sausalito, California, based hospital on July 14, 2025. Photo by Bill Hunnewell © The Marine Mammal Center

The six young elephant seals who were in the vaccine trial had been rescued and were already at the hospital for treatment. The vaccine is one that was reformulated by Zoetis, a veterinary pharmaceutical company, from the HPAI poultry vaccine for use on cows. HPAI in California dairy herds has caused milk production to decline more than 10 percent, and caused other costly herd problems. HPAI has been found in poultry flocks and dairy herds in other states and countries.  

HPAI has also affected egg production across the country. The only strategy for controlling HPAI in poultry flocks is to depopulate, kill, all the birds in the infected flock. The reduced production of eggs and milk has had uneven effects on consumer prices. 

Vaccinated and Placebo groups

The vaccine trial started in July, when three of the seals got the vaccine, and three got a placebo. Some briefly developed hives, including one who got the placebo, but the hives lasted only a few hours. One of the seals in the placebo group died. That seal’s death is under investigation. The seals were already at risk, hospitalized for other reasons.

All else proceeded well, with no other symptoms in either group. In late August, the researchers collected blood samples from the five seals, who had all recovered from the problems that caused them to strand and be treated at the hospital.

Healthy and able to survive in their wild home, they were released to resume their elephant seal lives.

1. Veterinary experts at The Marine Mammal Center’s hospital and visitor center in Sausalito, California, carefully place a post-release tracking tag on the head of a northern elephant seal pup as part of an Avian Influenza vaccine trial on August 27, 2025. Photo by Bill Hunnewell © The Marine Mammal Center

The blood samples they left behind will be evaluated for HPAI antibodies. With those results in hand, the TMMC team will decide whether vaccinating wild monk seals is worthwhile.

“These individual elephant seal patients are providing valuable information to inform any future vaccination efforts to a related species, Hawaiian monk seals, that are endangered and at heightened risk due to their current population size,” Dr. Whoriskey said. “This initial pilot study has showed us encouraging signs that this vaccine is safe and we are in the early stages of measuring the antibody response produced to determine whether it is also effective. As more information is gathered post-release on these seals, consultation and discussions with study partners will be key in finalizing any future vaccination plans.”

If they decide to vaccinate the monk seals, the veterinarian will use a pole syringe to inject seals on the beach, to keep distance between the veterinarian and the seal.

“We may decide to go forward even if we’re not seeing a very strong antibody response,” said Dr. Whoriskey, noting that the seals did not have any pre-existing immunity to the virus. “Something is probably better than nothing in this case.”

Immunizing wildlife

Vaccinating wildlife sounds impossible, but Ventana Wildlife Society has done it for the Central Coast condor flock. The research team captures every condor at least once a year, to check for lead poisoning, so they have the birds in hand to vaccinate.

California Condor Photo Ventana Wildlife Society

Ninety-eight condors of the Central Coast flock, 89 percent, have received at least one dose of the HPAI vaccine, and 72 of those 98 have received the second, booster, shot, and are fully vaccinated. 

In Arizona in 2023, an HPAI outbreak affected 25 California condors, killing 21 of them. California condors are also classified as Endangered.

The main threat to condor survival as a species is lead poisoning from consuming lead ammunition in carcasses shot by hunters. HPAI is another threat to the condor species’ tentative recovery from near-extinction in the 1980s.