At Año Nuevo State Park, peak elephant seal season usually means packed parking lots, muddy boots and visitors craning their necks for a glimpse of massive male seals sparring on the sand.
This week, the beach has been quieter.
Researchers discovered a “small number” of sick and dead northern elephant seals, mostly recently weaned pups, along with some seabirds at the state park located on the coast of San Mateo County south of Pescadero.
Multiple agencies collected samples and confirmed the first cases of bird flu in the seals at the park. The outbreak marks California’s first confirmed detection of highly pathogenic avian influenza in a marine mammal, according to a press release.
Officials said they are cautiously optimistic that most of the adult female seals had left the beach for their routine migrations before the outbreak began, and “most seals on the colony seem healthy.”
State parks officials temporarily closed the elephant seal viewing area at the Año Nuevo Coast Natural Preserve and canceled dozens of public tours and hundreds of reservations through March 1.
Officials said 22 school tours were also called off. Full refunds are available through Reserve California.
“Out of an abundance of caution, access is being paused to give wildlife space and allow for ongoing monitoring,” park officials said in a statement.
Año Nuevo is home to one of the largest mainland breeding colonies of northern elephant seals in the world. Every year, up to 10,000 elephant seals return to breed, give birth and molt their skin amongst the scenic dunes and beaches.
Adult males — which can weigh up to 5,000 pounds and are known for their inflatable trunk-like noses — battle for dominance, while females nurse their pups for about a month before abruptly weaning them and returning to sea.
That leaves weaned pups clustered onshore, fasting for weeks as they learn to swim and prepare for their first foraging trip. Wildlife experts say that stage can make them especially vulnerable to stressors, including disease.
The investigation involves scientists from UC Santa Cruz and UC Davis, along with California State Parks, the California Department of Fish and Wildlife, the California Department of Food and Agriculture, the California Department of Public Health, the California Marine Mammal Stranding Network, the U.S. Department of Agriculture and NOAA Fisheries.
Bird Flu has circulated widely among wild birds and marine mammals along the California coast in recent years, raising concerns about spillover in dense wildlife colonies.
For now, officials said they will continue to monitor. Visitors who still want a glimpse of the animals can tune into the park’s Año Nuevo Main Land Camera, which livestreams the colony from a distance.
Peak breeding season typically runs from December through March. Whether tours resume on schedule will likely depend on what the test results reveal — and how the colony fares in the days and weeks ahead.
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