Another incident of mass mortality among Canada geese has been observed in southern Manitoba, this time to the north of Winnipeg. Approximately 50 deceased geese were spotted on Monday, scattered across the frozen Red River in Lockport, a location situated roughly 15 kilometers north of Winnipeg. This recent occurrence follows the removal of 165 goose carcasses from retention ponds in Niverville, located about 20 kilometers south of Winnipeg. Tests conducted in a laboratory confirmed that these geese had succumbed to the highly pathogenic H5N1 strain of avian influenza virus.
Canadian Wildlife Service biologist Frank Baldwin stated in an interview with CBC Manitoba’s Information Radio host Marcy Markusa that while no carcasses from Lockport have been retrieved for testing yet, the sheer quantity and distribution of the deceased geese suggest a similar disease is responsible for their fatalities. Avian influenza, historically known as “fowl plague” since its identification in Italy in 1878, has evolved over time. The current dominant H5 strain, H5N1, surfaced in China in 1996 and has since proliferated globally, affecting both birds and mammals.
Baldwin highlighted that while birds typically coexist with the virus, this year has seen an unusual surge in goose mortality rates. Previously, migratory birds were carriers of the virus, spreading it to domestic poultry, which suffered the consequences. However, the scenario shifted in 2021 with the emergence of unprecedented wild bird die-offs. The first case of wild bird infection in Manitoba was recorded in spring 2022.
Despite the low risk of the H5N1 virus to humans, precautions are advised when encountering deceased birds to prevent potential transmission. Scavengers have been observed feeding on dead birds in Lockport, with several already confirmed to be infected with a variant of the H5 virus, including coyotes, otters, foxes, ravens, crows, snowy owls, and bald eagles. The importance of hunters practicing safe handling, hand hygiene, and thorough cooking of meat has been emphasized.
The prevalence of various avian influenza strains among migratory species is common, but the widespread circulation of H5N1 across Canada and globally is a cause for concern. Wild birds like geese, ducks, and shorebirds are known carriers of the virus during their migrations, often leading to new cases being detected. Baldwin explained that the geese in the Winnipeg area originate from diverse regions, including northern and southern Manitoba and even as far as Nunavut, based on recovered bands.
As part of surveillance efforts, Manitoba has tested 726 deceased birds this year, with 54 testing positive for H5N1. Although bird flu occurrences are not unusual during this period, the significant concentration of dead birds in specific locations like Niverville and Lockport is considered rare. Baldwin stressed the need for monitoring the impact of the virus on Canada geese, especially given the recent upsurge in mortality rates.
With cold weather driving non-migratory birds to remain in areas with open water, the virus can spread rapidly within the population. Close interactions between geese and ducks, the virus’s primary reservoir, are believed to be driving the current spike in mortality rates. Ducks possess a level of immunity to the virus due to past exposure to low pathogenicity avian flu strains, explaining their lower fatality rates compared to other bird species.
Individuals encountering sick or deceased birds are encouraged to report such instances to the provincial TIP line at 1-800-782-0076 for further investigation and assistance. The evolving situation underscores the importance of vigilant monitoring and preventive measures to mitigate the impact of avian influenza outbreaks on wildlife populations.