Bird Flu Detected in Northern Elephant Seals at Año Nuevo State Park, Raising Concerns for Marine Mammal Health

A highly pathogenic avian influenza (HPAI), commonly known as bird flu, has been confirmed in northern elephant seals at Año Nuevo State Park in California, marking the first such detection in a marine mammal in the state. The outbreak has prompted temporary closures of the park’s elephant seal viewing area and cancellation of public tours as officials work to monitor the situation and protect both wildlife and the public.

First Confirmed Cases and Closures

Researchers first detected a “small number” of sick and dead northern elephant seals, primarily recently weaned pups, along with some seabirds at Año Nuevo State Park in late February 2026. Following investigation, samples confirmed the presence of HPAI. As a precautionary measure, State Parks officials have 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 1st. Approximately 22 school tours have also been canceled, with full refunds available through Reserve California.

Multi-Agency Response and Monitoring

The investigation is a collaborative effort involving scientists from UC Santa Cruz, UC Davis, the National Oceanic and Atmospheric Administration (NOAA), the California Department of Fish and Wildlife, The Marine Mammal Center, and the NSF Center for Pandemic Insights. Teams are coordinating surveillance, sample testing, and observational monitoring to understand the clinical progression of the disease, transmission patterns, and potential population-level impacts. Approximately 1,350 seals were present at the colony when the outbreak began, and investigators have a unique opportunity to study the disease in a closely monitored population.

Public Health Risk and Precautions

Officials state that the public health risk is currently considered very low. However, agencies strongly advise against touching live or dead marine mammals and recommend keeping pets away from stranded or sick animals. Responders and researchers working with affected animals are utilizing personal protective equipment and adhering to established wildlife stranding network protocols.

Broader Context of HPAI

Historically, H5N1 has sporadically spread from wild birds to various mammalian species. Prior marine mammal cases have been documented in other regions of the United States. The current North American HPAI lineage has been widespread since 2021, affecting multiple wild and domestic species. Continued collaboration between wildlife biologists, veterinary clinicians, public health officials, and diagnostic laboratories will be crucial to track the outbreak, assess its impact on populations, and mitigate any potential zoonotic risks.

About Año Nuevo State Park

Año Nuevo State Marine Reserve and the adjacent Greyhound Rock State Marine Conservation Area are located approximately 50 miles south of San Francisco and 20 miles north of Santa Cruz. The area features an eight-mile stretch of alternating sandy and rocky shoreline and is home to one of the largest mainland breeding colonies of northern elephant seals in the world.