Highly contagious strain of avian flu detected in three Montana grizzlies

Three western Montana grizzly bears euthanized last year were infected with highly pathogenic avian influenza, or HPAI, a virus that is extremely infectious and often fatal to both domestic and wild birds, state wildlife officials said.

According to a release from Montana Fish, Wildlife and Parks, the test results represent the first time HPAI has been documented in grizzly bears. In addition to a wide variety of wild birds, the virus has been found in mammals such as raccoons, black bears and skunks. 

FWP said the bears were in poor condition and exhibited blindness, disorientation and other neurological issues. All three were living in western Montana, one in the Kalispell area and two along the Rocky Mountain Front. They were euthanized last fall due to their poor health and found to have been carrying HPAI.

The agency suspects the grizzlies contracted the virus after eating infected wild birds.

Although the detection was “somewhat unexpected,” Montana State Veterinarian Martin Zaluski said in an interview with Montana Free Press that this strain’s transmissibility, lethality and widespread distribution could easily create an opportunity for a scavenger to become infected by feeding on a bird that succumbed to the virus. Zaluski also noted that this virus circulates more widely in colder months. 

As of Jan. 10, 107 wild birds in Montana have tested positive for HPAI along with a fox and skunk, according to the National Wildlife Disease Program.

HPAI has also been a source of concern for poultry producers, both nationally and statewide. The Animal and Plant Inspection Service, an agency administered by the U.S. Department of Agriculture, reports that more than 82,000 domestic birds in Montana have been impacted by the virus. It’s been detected in 16 flocks. Outbreaks in Glacier and Cascade counties last April were particularly lethal, resulting in the deaths of 54,200 and 22,00 birds, respectively.  

When it’s detected in a flock, the surviving birds are typically killed by producers or Department of Livestock personnel to prevent future spread.

After a summertime decline in infections, positive detections are starting to tick up again for both wild and domestic birds, state officials said.

The transmissibility of HPAI had played a prominent role in recent discussions about an FWP-administered, pheasant-raising program in Montana. 

Following the Legislature’s $1 million allocation to establish the program in 2021, inmates of the Montana State Prison began raising pheasants for release on state lands as part of a youth hunting initiative. The program, which was conceived as a hunter-recruitment tool, has been criticized by conservationists leery of its price tag and the broader implications of raising wildlife in captivity. 

Zaluski said the pheasants raised as part of that program are routinely tested and no HPAI infections have been found in that flock.

Although the Centers for Disease Control and Prevention consider humans to be at low risk of HPAI infection, FWP advises people who handle sick or dead birds or mammals to take precautions to avoid infection. 

FWP Wildlife Veterinarian Jennifer Ramsey said individuals who are handling or disposing of dead animals should use gloves. She also advises waterfowl hunters to minimize contact between domestic dogs and sick or dead birds, clean their quarry outside and take care to cook it properly.

The department is asking Montanans who observe unusual or unexplained cases of sickness or death in wild birds or other wildlife to contact a local wildlife biologist or the state’s wildlife lab in Bozeman. Ramsey said there is no treatment for the virus.