The Montana Department of Fish, Wildlife, and Parks (FWP) has announced that three juvenile grizzly bears had tested positive for highly pathogenic avian influenza (HPAI) this fall; these are the first documented cases of HPAI in grizzlies. The wild bears exhibited neurological symptoms including partial blindness and disorientation, and were euthanized due to illness and poor condition. It is suspected that the bears got the virus from consuming infected birds.
A list of confirmed cases of HPAI in mammals in the US during the 2022-2023 outbreak is available on the USDA website.