Dead Canadian geese are turning up more frequently across southern Ontario, and experts say bird flu is likely to blame.
As migratory birds return to Canada this spring, health officials are bracing for a potential surge in bird flu cases.
The highly pathogenic avian influenza (HPAI), subtype H5N1, has already impacted both wild and domestic birds, and even a human case in British Columbia, raising concerns about its rapid spread as flocks move across the country.
The situation gained attention after Parks Canada confirmed last week that a Canada goose in Rouge National Urban Park in Scarborough, Ont., tested positive for the virus. The bird’s remains showed clear signs of infection, and five other geese in the area have exhibited bird flu symptoms.
The Canadian Wildlife Health Cooperative (CWHC), told Global News on Tuesday that a growing number of bird flu cases have been detected across southern Ontario in recent weeks, primarily affecting Canadian geese, which are particularly vulnerable to the virus.
And as more birds start migrating north for the spring, Shayan Sharif, professor at the Ontario Veterinary College at the University of Guelph, said the avian flu will likely spread even more.
“There’s always a chance for migratory birds to spread the virus. I would say that’s really one of the main modes of transmission for this particular strain of virus,” he said.
“The virus seems to be hitchhiking with migratory birds and there are different kinds of migratory birds. Canada geese are included among those migratory birds. There are also others, like ducks and so forth, that could potentially carry the virus from one place to another place.”
Since Canada — especially Ontario — lies within major migratory flyways (large routes birds follow between their breeding and wintering grounds), like the Mississippi Flyway and, to some extent, the Atlantic Flyway, it could receive birds traveling from the south, some of which may be carrying the virus, Sharif added.
This concern appears to be playing out in real time.
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A TikTok user posted to the platform last week a video of what appeared to be several dead Canada geese half-submerged in the ice at a park in Brampton, Ont.
Days later, the user posted another TikTok video showing more geese in the park, some lifeless and others appearing weak or incapacitated.
The CWHC said the dead geese found in Brampton are suspected cases of avian flu and testing is currently underway to confirm the cause.
Avian flu is common among waterfowl, such as geese and ducks, but it can also spread to birds of prey that consume infected birds.
While rare, the virus has been detected in some terrestrial mammals, such as foxes. Domestic poultry, including chickens and turkeys, are also at risk, though transmission to humans remains uncommon.
Although a few bird flu outbreaks are currently ongoing in Canada, Sharif noted that the large outbreaks seen in British Columbia last fall have subsided for now.
That’s because experts are beginning to recognize a seasonal pattern in avian flu, with outbreaks typically occurring during migration periods in the fall and spring.
“Avian influenza viruses up until the most recent set of outbreaks that we’ve been witnessing since 2021 or 2022 … we always felt they don’t have a seasonal pattern of transmission,” Sharif said.
“But over the last three years or so, it’s become quite clear that this particular strain, because it hitchhikes with migratory birds, it does actually have a seasonal pattern and the seasonal pattern is fall and spring.”
However, he added that this doesn’t mean bird flu outbreaks can’t occur at other times of the year.
Migratory birds, like ducks and geese, spread bird flu by carrying the virus over long distances along their migration routes, Sharif explained.
They can get infected through contact with other sick birds or by spending time in contaminated environments such as wetlands and water sources. Once infected, they shed the virus in their droppings, saliva and nasal secretions, which can then contaminate food, water and habitats along their way.
What’s tricky is that some infected birds don’t show symptoms, so they can unknowingly spread the virus to others as they travel. When they stop at familiar places like ponds and wetlands during migration, they can introduce the virus to new bird populations, causing it to spread even further.
“The risk to the average person remains rather low, but what’s really important is that people exercise extra vigilance if they come across dead animals, especially wild birds,” said Matthew Miller, director of DeGroote Institute for Infectious Disease Research at McMaster University.
“They should avoid handling those animals and be extremely cautious with off-leash pets, particularly in open areas.”
Sharif echoed this warning.
If a bird infected with avian flu is consumed by a domestic animal, like a dog or cat, it could potentially pass the virus to the pet, causing it to become infected.
“For animals, especially for dogs, I would highly suggest that dogs be kept away from any dead birds or any potential areas where birds might have landed because we never know what kind of birds are carrying the virus,” he said.
When it comes to bird feeders, he added that while songbirds may not carry the virus, the feeders could attract waterfowl that do.
“If those feeders are attracting unwanted guests in the form of ducks and geese, I highly suggest thinking twice about having those feeders installed,” he said.
— With files from Global News’ Megan King
