Two wild mountain lions on Washington’s Olympic Peninsula have succumbed to bird flu, marking a worrying development in the spread of the disease between species.

The Washington Department of Fish and Wildlife (WDFW) and Panthera, a global wild cat conservation organization, confirmed the death on December 19.

One of the cats, a young male tracked with a collar, was found dead after his tracking signal showed no movement for hours.

The other, an uncollared male spotted by a resident near Blyn in Clallam County, was so weak and emaciated that he couldn’t jump a three-strand wire fence — an uncharacteristic struggle for a species known for its powerful agility.

“Twice I saw him go to the electric cow fence and get shocked and barely respond,” an individual who witnessed the trapped animal said in a statement. “He also rose up and rested 30-40 feet away from me several times and didn’t respond to my voice.

Mountain lions, also often referred to as cougars or cougars, are the first documented cases of bird flu in mountain lions in Washington, although similar incidents have been reported in other states.

The virus, known as type A H5N1, has been circulating in the region since 2022 and is increasingly affecting wildlife, including mammals.

“Canary in the Coal Mine”

Experts say the deaths of these apex predators could signal wider ecological consequences.

Mark Elbroch, director of the Puma Panthera program, called mountain lions “kind of like the canary in the coal mine.” As top carnivores, they reflect the health of the ecosystems they inhabit by scavenging pathogens from the bottom of the food chain, offering insight into the invisible patterns of disease spread.

How the virus got to cougars

The virus is suspected to have reached cougars through their diet, possibly infected birds or other prey such as raccoons.

Bird flu has been circulating in wildlife in Washington for years. The virus devastated a tern colony near Port Townsend in 2024, killed harbor seals in 2023, and recently caused the state’s first documented human cases.

While the US Centers for Disease Control and Prevention (CDC) still considers the risk to humans low, the virus has been detected in mammals across the country, including dairy cows and seals, prompting California to declare a state of emergency earlier this month.

What’s next?

Wildlife officials are trying to determine if bird flu poses a high risk of mountain lion mortality or if the two deaths are outliers.

Antibody testing could reveal whether cougars can survive exposure to the virus, offering hope that some may develop immunity.

“Once a disease is in a population, it’s incredibly difficult to control,” Haman said. “If none of them have the antibodies, I would be really concerned that if they were exposed, they wouldn’t survive.”

For now, conservation groups are focusing on enhanced control, although vaccination could be an alternative in the future.