Bird flu killed two of the Olympic Peninsula’s several hundred mountain lions in recent weeks, and the nation’s foremost cougar expert told The Leader the weekend before Christmas that their fate could foreshadow death by virus for the peninsula’s remaining pumas.

“I hope it’s not the beginning of the end” for the cougars, Dr. Mark Elbroch, director of the puma program at Panthera, the global wild cat conservation organization, told The Leader Dec. 20. “It’s a possibility that their low genetic diversity may make them more susceptible to this sort of virus. We can’t say for sure, but it’s possible.”

Meanwhile, a private wild-cat sanctuary 15 miles north of Olympia lost 20 of its 37 exotic felines to bird flu. The losses at the Wild Felid Advocacy Center on Harstine Island included five African servals, four cougars and four bobcats, with the first case of H5N1 avian flu among the 20 animals confirmed by necropsy on Dec. 2.

“It’s been devastating,” Mark Mathews, director and founder of the center, said Dec. 21, “but I think we’re through the worst of it. The rest of the cats appear to be doing well.”

Biologists are trying to determine how the felines became infected. Remnants of pumpkin snacks, raw bones and vitamins given to the animals were among the possible contaminants being analyzed, Mathews said, “and cats do love to catch birds.”

Wild birds, especially waterfowl, can carry and spread the virus without showing signs of illness. H5N1 has for years infected domestic poultry, such as chickens, turkeys, ducks and geese. In the United States, the list of H5N1 casualties has recently come to include dairy cattle.

Gov. Gavin Newsom this month declared a state of emergency in California over the spread of bird flu after it ripped through herds of California dairy cows and caused sporadic illnesses in people across the country.

California has been looking for bird flu in large milk tanks during processing. State officials there have found the virus in 638 herds, representing roughly three-quarters of all affected U.S. dairy herds.

From March 25 to Dec. 20, bird flu was confirmed in 875 herds in 16 states, according to the U.S. Department of Agriculture. Washington was not one of those states.

Additionally, 64 people in nine states have been infected with bird flu during the 2024 outbreak, with mostly mild illness, according to the U.S. Centers for Disease Control and Prevention. One elderly person in Louisiana was in critical condition the week before Christmas with the nation’s first known severe illness caused by the virus, the CDC said.

Globally, from Jan. 1, 2003, to Nov. 1, 2024, 939 cases of human infection with H5N1 were reported from 24 countries, according to the World Health Organization. Of the 939 cases, 464 resulted in death, with a case fatality rate of 49%.

Despite the alarming death rate over nearly 20 years, the CDC has stressed that the virus poses low risk to the public. The agency continues to emphasize that there are no reports of person-to-person transmission and no signs that the virus has mutated to spread more easily among humans.

As for the wild cougars killed by H5N1 on the Olympic Peninsula, studies are still being performed to ascertain exactly what happened to them.

“We do know the strain we detected in these cougars is the one currently circulating in wild birds here in Washington, but we need more information to be able to address if these two cougars had the same identical strain and thus were exposed from the same source,” said Dr. Katie Haman, a veterinarian with the Washington Department of Fish and Wildlife.

“There is no indication of cougar-cougar transmission of H5N1,” she said.

Washington’s cougars can be divided into two groups that are separated by Interstate 5: Those west of the freeway —several hundred found on the Olympic Peninsula — and a larger group found east of the interstate. The freeway prevents members of the groups from crossbreeding, which would increase the genetic diversity of all of Washington’s cougars.

Breeding prevention between the two groups has led to lower genetic diversity and higher rates of inbreeding among the peninsula’s mountain lions, which makes them more susceptible to disease. 

While questions remain about how the two cougars became infected with H5N1, their deaths are not a total mystery. 

The first sick peninsula cougar, a wild uncollared young male, was reported to wildlife authorities after it was seen in a pasture near Blyn in Clallam County weak, bony and confused. A video taken by a passerby and provided to The Leader by Elbroch showed the animal too weak even to raise its tail, instead dragging it through mud as it went.

Despite being a member of a species renowned for its leaping ability, the cougar was unable to clear a 3-foot-tall barbed-wire fence.

Elbroch said the videographer recounted the mountain lion twice went to “the electric cow fence and get shocked and barely respond. It also walked up and rested several times within 30 to 40 feet from me and did not react to my voice and/or my truck.”

A state game warden called to the scene euthanized the animal. An autopsy revealed bird flu in the feline’s blood and grass in its stomach. The cougar died on Nov. 28. 

The second cougar was also a young male. It wore a Panthera tracking collar and had been named Zepplin by the conservation organization. A review of the collar’s tracking data showed that the cougar stopped moving and presumably died on Dec. 4. 

Panthera researchers monitoring Zepplin deduced that the cougar had been preying on seal pups and seabirds on beaches and racoons and other forest animals between Port Angeles and Clallam Bay, roughly 30 miles apart.

Unlike the first cougar, Zepplin “looked perfect, healthy and strong, yet he was dead,” Elbroch said. Testing of Zepplin’s brain stem confirmed the presence of H5N1. Sometimes animals die so quickly from the disease they do not display symptoms, Elbroch said. 

Racoons are a primary item on a peninsula cougar’s menu. Elbroch suspects that Zepplin ate an infected raccoon or an infected seabird. 

Mountain lions are the top predators of the Olympic Peninsula. But between the big cats’ compromised immune systems due to isolation and inbreeding, infected raccoons might lead to their downfall, Elbroch said. 

Anyone seeing a mountain lion showing signs of bird flu are asked to call 911. Although it would be difficult for a person to contract the virus from an infected cougar, authorities ask the public to avoid handling a dead puma.