Avian influenza, commonly known as bird flu, continues to circulate among wild birds in Canada, but experts say the overall risk to human health remains low and caution against misguided efforts to control the virus that could harm wildlife and habitats.
Avian influenza is caused by Type A influenza viruses that occur naturally in waterfowl such as ducks and geese. While some species can carry the virus without showing symptoms, others –– including raptors –– experience higher rates of illness and death.
The viruses are classified as either low pathogenic avian influenza (LPAI) or high pathogenic avian influenza (HPAI), based on how severe the disease is in domestic poultry. Most avian influenza subtypes are low pathogenic and cause little to no illness in wild or domestic birds, posing no threat to people.
More concerning are highly pathogenic strains such as H5N1, which are extremely infectious and often fatal to domestic poultry. Newer HPAI strains have also been detected in Canada in recent years, including H5N2 in British Columbia and H5N5 in Newfoundland and Labrador.
Waterfowl are considered natural reservoirs for avian influenza and can spread the virus locally or over long distances during migration, primarily through contact with the droppings of infected birds. Other bird species –– and some mammals –– are believed to become infected mainly through consuming infected animals.
Despite widespread circulation, experts say avian influenza has had limited population-level impacts on waterfowl so far. Human infections remain rare, and public health officials maintain that the risk to people is low, with most cases occurring among workers in poultry operations.
“There have been cases in domestic poultry operations across Canada, and those farms have suffered significant losses due to mandatory depopulation measures,” officials note. In the United States, outbreaks have also been reported in dairy cattle, though those cases have so far been limited south of the border and are believed to be linked to contact with infected livestock such as poultry.
Matt Dyson, a research scientist with the Institute for Wetland and Waterfowl Research, says local cases make global wildlife health issues real for rural communities, showing the challenges happening close to home.
In December, avian influenza was confirmed as the cause of death for a flock of geese in Niverville. In Lockport, another group of geese was also found dead. While test results from the Lockport birds are still pending –– a process that can take several weeks –– their deaths are suspected to be linked to avian influenza.
“The impacts of avian flu are not always surprising, but they are unfortunate,” Dyson said. “It especially hits close to home when it’s happening in your community.”
Dyson explained avian influenza has not caused major declines in waterfowl populations, but scientists are actively monitoring the situation by collecting samples and running tests –– work that remains in its early stages for the H5N1 strain.
“We are effectively starting from ground zero when this virus first began circulating in late 2021 and scientists are still learning from the samples they’ve been collecting,” he said.
While researchers are still working to understand what factors contribute to avian flu outbreaks, Dyson said cases can spike during colder months, when food, water and habitat availability are reduced and birds congregate in smaller areas.
“We don’t know all of this information for sure,” he added. “But general wildlife ecology tells us that colder conditions can create those conditions where mortality events are more probable. When we observe really cold weather, we do see some correlation with sick birds and reduced habitat availability caused by greater ice cover.”
As long as open water remains available, he added, birds are likely to stay in the area.
Autumn migration patterns may also contribute to seasonal increases in cases. Dyson said younger birds, which are “immunologically naïve,” appear more likely to contract the virus and die due to their underdeveloped immune systems, though he noted that limited studies exist to fully support that theory.
Researching avian influenza presents challenges, Dyson said, explaining that scientists cannot simply bring wildlife in for examination.
“You just can’t put a call out to birds and ask them to come to the vet if they aren’t feeling well,” he said.
Still, advancements are being made, including work at Winnipeg’s National Centre for Foreign Animal Disease and the National Microbiology Laboratory.
“It’s cool to have local folks leading the charge on this research,” Dyson added.
Scientists continue to band, swab, and test birds as they work to better understand avian influenza and the H5N1 strain in particular. Dyson said public reporting plays an important role in that effort.
Anyone who encounters a sick or dead bird is advised not to touch it and to report it to the Canadian Wildlife Health Cooperative or a provincial authority. The more reports received, he said, the more data researchers can collect to track the virus.
Dyson also emphasized that while birds may die while infected with avian influenza, the virus is not always the sole cause.
“There are often multiple stressors, like malnutrition, parasites or environmental stress that, along with avian influenza, increase the risk of death in birds,” he said.
The Canadian Wildlife Health Cooperative tracks confirmed cases of avian influenza on its website.
Wildlife and conservation groups warn that fear and misinformation surrounding HPAI can lead to ineffective and harmful responses. Measures such as culling wild birds, draining wetlands or opposing habitat conservation projects do not stop the spread of the virus and can have unintended ecological consequences.
Hunters are encouraged to avoid harvesting birds that appear sick and to use gloves and wash hands thoroughly if handling birds is unavoidable. Poultry producers are advised to follow strict biosecurity measures, as domestic poultry have little natural immunity to HPAI and can experience near-total mortality if infected.
While landowners with wetlands may have concerns about waterfowl, current evidence suggests waterfowl are unlikely to be a significant source of direct transmission to poultry or cattle and wetlands themselves are not thought to pose a risk.
Members of the public are advised to limit direct contact with wild birds and their droppings, keep pets away from live or dead birds, and avoid feeding waterfowl and gulls. Properly cooked poultry products and pasteurized dairy products remain safe to consume.
Experts say continued monitoring, good hygiene and evidence-based decision-making remain the most effective ways to manage avian influenza –– without harming wildlife or wetlands.
“Overall, avian flu is not something someone needs to worry about on a daily basis,” Dyson shared. “So, get outside and enjoy nature.”
To report sick or dead birds in Manitoba, residents can contact the Canadian Wildlife Health Cooperative at 1-800-567-2033 or Manitoba Natural Resources and Northern Development at 1-800-782-0076. More information is also available through Ducks Unlimited Canada website at, www.ducks.ca/our-work/waterfowl/avian-flu-in-canada/.
