Avian influenza detected in grizzly bears

Avian influenza has leaped into Montana’s bear population.

According to a press release from Montana Fish, Wildlife and Parks (FWP) on Tuesday, three juvenile grizzly bears tested positive for highly pathogenic avian influenza (HPAI) virus during the fall of 2022. The three bears — one near Augusta, one near Dupuyer and another near Kalispell — were observed to be in poor condition, and exhibited disorientation and partial blindness, among other neurological issues, officials said.

The bears were euthanized due to their sickness and poor condition.

These were the first documented cases of HPAI in grizzly bears. A fox and a skunk in Montana tested positive for HPAI last year and the virus has been found in raccoons, black bears and even a coyote in other states and countries, FWP said.

“We suspect these mammals probably get the virus from consuming infected birds,” FWP Wildlife Veterinarian Jennifer Ramsey said.

Avian influenza (AI) virus is a naturally occurring virus in birds. AI viruses are classified into two groups, based on the severity of disease they cause in infected poultry. Low pathogenic AI viruses generally cause no clinical illness, or only minor symptoms in birds. HPAI viruses are extremely infectious and fatal to poultry and some species of wild birds.

To date, there have been 17 cases reported in Montana’s domestic poultry flocks, leading to the deaths of more than 82,000 birds, most recently a small backyard flock of 10 in Cascade County reported Jan. 10.

Avian influenza was found among a Flathead County commercial flock for the second time in late December, with the first case leading to the death of seven birds here in July.

First detected in domestic birds in Indiana on Feb. 8, 2022 the current AI strain had been detected in wild birds in Newfoundland and Labrador in eastern Canada in December 2021. Since first being detected in the eastern United States in January 2022, it has spread to all four bird migration flyways, including the Central and Pacific flyways, which covers parts of Montana.

The 2022 HPAI variant continues to have a significant effect on commercial and backyard flocks, with nearly 58 million birds in 47 states affected nationally.

The only states that have not reported cases are Louisiana, West Virginia and Hawaii.

Winter temperatures have led to a resurgence of the illness, with cases jumping from a total of 2.11 million in October 2022 to 5.07 million through the end of the year.

Although the Centers for Disease Control and Prevention (CDC) considers risk of HPAI spread to humans to be very low, people should take precautions when handling game birds, sick or dead birds and mammals they find. Whenever possible, avoid contact with sick or dead wildlife. Even if an animal is not suspected to have died from a contagious disease, gloves should be worn if a dead animal must be handled for disposal.

FWP staff would like to know about unusual or unexplained cases of sickness and/or death of wild birds and animals. Cases can be reported by calling a local wildlife biologist or the wildlife lab in Bozeman at 406-577-7880 or 406-577-7882.