More than 50 dead Canada geese found on frozen river in Lockport, Man.

Another mass die-off of Canada geese has been found in southern Manitoba, this time north of Winnipeg.

An estimated 50 dead geese were seen on Monday, lying in the snow on the frozen Red River in Lockport, about 15 kilometres north of Winnipeg.

That discovery comes after 165 goose carcasses were removed last week from retention ponds in Niverville, about 20 kilometres south of Winnipeg. Lab tests confirmed they died from the highly pathogenic H5N1 strain of the H5 avian influenza virus.

"We haven't collected any of those carcasses [in Lockport] yet for testing, but just based on the number and the distribution, we suspect that the same disease is killing these birds," Canadian Wildlife Service biologist Frank Baldwin told CBC Manitoba Information Radio host Marcy Markusa on Tuesday.

Bird flu, or avian influenza, was called "fowl plague" when it was identified in Italy in 1878 and has slowly evolved, the U.S. Centers for Disease Control and Prevention website says. The current dominant H5 strain, H5N1, emerged in China in 1996 and has since spread globally, affecting birds and mammals.

"So the virus is something that the birds have evolved with, but it's a bit of an interesting situation this year, because we haven't seen this level of mortality in geese before," Baldwin said.

In the past, the virus didn't really harm migratory birds, who carried it and transmitted it to domestic poultry, which did become ill.

That changed in 2021, when unprecedented wild bird die-offs started to show up, Baldwin said. The first case in wild birds in Manitoba was detected in spring 2022.

The Public Health Agency of Canada considers the H5N1 virus low-risk to humans. Canada has only ever had two confirmed human cases: one in 2014 in a returning traveller who acquired it somewhere else, and the other — the first domestically acquired case — in British Columbia in late 2024.

Nonetheless, Baldwin said people need to take precautions around dead birds. They should not be handled and pets should be kept away from them.

At least one goose in Lockport appears to have been picked at by scavengers, and Baldwin said a large number of scavengers have already been confirmed by a provincial veterinary lab this fall to have been infected by a form of the H5 virus, including coyotes, otters, foxes, ravens and crows, snowy owls and bald eagles.

Hunters should pluck birds in open spaces, regularly wash their hands and make sure meat is fully cooked.

Many avian influenza strains circulate among migratory species without causing widespread disease, but H5N1 is currently circulating widely across Canada and in many parts of the world, a spokesperson for Manitoba's Department of Natural Resources said in an email.

Wild birds, particularly geese, ducks, and shorebirds, are known to spread the virus between regions during spring and fall migrations, which is when new cases are most often detected.

The geese around the Winnipeg region at this time are from northern and southern Manitoba and as far away as Nunavut, based on the bands that have been recovered, Baldwin said.

The provincial spokesperson said 726 dead birds have been tested in Manitoba this year, and 54 have been positive for H5N1.

Even though it's not uncommon to see bird flu at this time of year, the sheer number of dead birds in one location, as in Niverville and Lockport, is rare, Baldwin said.

"It's definitely concerning because it's not something we've seen before. I was down in Niverville and just seeing the number of dead birds on the several ponds in town was pretty striking," he said.

"And in communication with other colleagues across Canada, just that number of dead birds in one area is not something that they've experienced either.”

He hasn't been able to determine the full impact on Canada geese. The latest data from annual banding is from 2023, Baldwin said.

"It's possible it's having more of an impact in the last year or two than it has since it originally came in 2021."

When the weather gets cold, the birds that haven't yet migrated concentrate in the remaining areas of open water, making it easy for the virus to move through the population very quickly, Baldwin said.

They also come into closer contact with ducks, "which are really thought to be the main reservoir of the virus," he said.

"And that's what we think is causing this peak in mortality now."

Ducks have a lot of background immunity from exposure to low pathogenicity avian flu viruses and are believed to have an increased level of immunity to the virus, which is why there's few of those showing up dead, Baldwin said.

Anyone coming across sick or dead birds can call the provincial TIP line at 1-800-782-0076.