Bird watchers across the U.S. received a sobering request this week amid rising concerns about an ongoing outbreak of the H5N1 bird flu virus in wild birds and poultry. On Wednesday, the Raptor Center at the University of Minnesota advised people to take down their bird feeders in order to discourage the congregating of song birds and help curb an “unprecedented outbreak” of highly pathogenic avian influenza (HPAI) in wild birds.
Scientists are urging caution in the face of many unknowns about this strain of HPAI, a particularly contagious and hard-to-kill version of the H5N1 virus, although it is thought to pose low risk to the general human population, per the U.S. Centers for Disease Control and Prevention. Experts know that certain wild bird species (like waterfowl and seabirds) are more likely to be vectors for the virus—which spreads via feces and respiratory secretions—without appearing ill, and that it’s common for raptor species (like eagles) to quickly develop severe illness and die. But less is understood about how this unusual outbreak of HPAI may spread or present in other less surveilled species, like songbirds.
“Unfortunately, we have a lot of gaps in knowledge about the role of songbirds in HPAI outbreaks,” veterinary epidemiologist and executive director Victoria Hall, DVM, wrote on the Raptor Center’s Facebook page. While experts have some data from past outbreaks in other countries to work with, this current outbreak is “unique” from those instances because of the extremely high levels of wildlife transmission seen with the strain of H5N1 currently circulating, Dr. Hall explained.
“During these unprecedented times, we recommend doing anything that we can to try and help our wild bird populations,” Dr. Hall said. “Because the science is unclear on the role of songbirds in this current H5N1 outbreak, one consideration is to not encourage birds to gather together at places such as bird feeders or bird baths. These are places where things like viruses could easily be exchanged between individuals.” The center is asking people to stop using bird feeders and bird baths for the next couple of months, until there is a significant decline in transmission rates.
The Raptor Center is testing and treating wild birds like bald eagles and great horned owls that are “intensely suffering from fatal neurological illness due to HPAI” on a daily basis, according to Dr. Hall—who notes that “humane euthanasia is the only tool we have left to help them.” Scientists at the raptor center have also observed severe illness connected to this outbreak in species like blue jays, crows, ducks, and geese.
Since this avian flu outbreak began in late 2021, the virus has been detected and reported in 637 wild birds in 31 states (as of April 8, 2022) and over 27,000,000 backyard and commercial poultry (as of April 15), per CDC data. The virus spreads particularly easily in the crowded, wet conditions at commercial poultry farms, requiring farmers to euthanize entire flocks—including over 24,000,000 chickens and turkeys in the U.S. over the past two months, as CBS Minnesota reports.