Researchers Monitor Bird Flu Outbreak in Elephant Seals at Año Nuevo

UC Santa Cruz and UC Davis teams are 'cautiously optimistic' about containing the virus after it killed thousands of seals in South America.

Published on Mar. 9, 2026

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Researchers from UC Santa Cruz and UC Davis have detected an outbreak of avian influenza, or bird flu, in a population of northern elephant seals at Año Nuevo State Park. At least seven weaned seal pups have tested positive for the H5N1 virus, and more samples are being analyzed. This is the first known case of the virus in this seal population and the first instance of a marine mammal contracting bird flu in California. The team is closely monitoring the situation, but they are cautiously optimistic that the outbreak can be contained, as it began after the peak of the breeding season when many adult seals had already left the park.

Why it matters

The outbreak at Año Nuevo is significant because it follows a devastating 2023 bird flu epidemic in South America that killed over 17,000 elephant seals, as well as hundreds of thousands of seabirds and sea lions. Researchers are concerned about the potential for the virus to spread to other marine mammals, but the timing of the California outbreak, after the breeding season, may help limit its impact on the local seal population.

The details

The UCSC and UC Davis research teams have been closely monitoring the elephant seal colony at Año Nuevo for decades, collecting data on the seals' behavior and population dynamics. When some pups were found dead and others showed symptoms like weakness and tremors, the researchers quickly collected samples and confirmed the presence of the H5N1 avian influenza virus. The researchers are currently testing samples from 60 more seals, and they are working with various agencies to oversee the outbreak and watch for signs of the virus spreading to other species.

  • The first seven cases of avian influenza were confirmed in late February 2026.
  • The breeding season at Año Nuevo typically runs from late December through March.

The players

UC Santa Cruz

A university that has been conducting long-term research on the elephant seal population at Año Nuevo State Park for over 60 years.

UC Davis

A university that is collaborating with UCSC on the current avian influenza outbreak, including testing samples and providing expertise.

Esin Ickin

A Ph.D. student in the Beltran Lab at UC Santa Cruz who is part of the research team monitoring the bird flu outbreak.

Dr. Megan Moriarty

The campus veterinarian at UC Santa Cruz who is supervising the elephant seal research team's visits to the colony during the outbreak.

Año Nuevo State Park

A California state park that is home to a large breeding colony of northern elephant seals, which is the focus of the current avian influenza outbreak.

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What they’re saying

“Since we all care deeply about the seals, seeing this is devastating.”

— Esin Ickin, Ph.D. student, Beltran Lab, UC Santa Cruz (Mercury News)

“We're cautiously optimistic that it is going to be contained.”

— Esin Ickin, Ph.D. student, Beltran Lab, UC Santa Cruz (Mercury News)

“It's a really popular tour, and it draws visitors from all over, so the park definitely looks different right now than it would on a normal day in the beginning of March.”

— Jordan Burgess, Deputy District Superintendent, Santa Cruz District, California State Parks (Mercury News)

What’s next

The judge in the case will decide on Tuesday whether or not to allow Walker Reed Quinn out on bail.

The takeaway

This outbreak highlights the potential for avian influenza to spread between different species of marine mammals, as seen in the devastating 2023 epidemic in South America. While researchers are cautiously optimistic about containing the virus at Año Nuevo, the situation underscores the need for continued monitoring and preparedness to protect vulnerable marine wildlife populations.