Thursday, February 2nd, 2023
Thursday, February 2nd, 2023

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Avian influenza hits South Dakota

“There are zombie geese everywhere.”

That’s the text I received last week from a friend hunting in northeastern South Dakota, where he’s been off and on all fall, most recently targeting snow geese as they move through the state. He’s a good source of information for me because he spends so much time afield, and I figured that if anyone is seeing waterfowl infected with avian influenza, or “bird flu,” it would be him.

If you’ve spent any time on the internet recently, you’ve likely seen pictures or videos of “zombie geese” displaying symptoms associated with the current strain of high pathogenic avian influenza: nervousness, tremors, lack of coordination, lack of energy, and other out-of-character behaviors for wild birds that usually are wary of interacting with humans.

Earlier this fall, I came across snow geese in the field acting in such a way, then last week I stumbled upon an infected juvenile blue goose while walking my dog in town, of all places. That led to the text exchange with my friend and his rather apocalyptic observation from another part of the state.

The images of infected birds, which seem to primarily be snow geese in South Dakota, that I have come across, both first-hand and those sent to me, are troubling. In some cases, hundreds of birds can be found in a single location that are apparently infected. In my 30-plus years of waterfowl hunting, I’ve never seen anything like it, so I reached out to Ducks Unlimited’s Mike Brasher to learn more.

“Waterfowl are no stranger to influenza viruses, and influenza viruses are known to circulate within wild waterfowl. The thing that makes this strain different is
that it seems to be causing illness and mortality in wild bird
populations. That’s something that we traditionally have not seen much,”
said Brasher, who serves as a senior waterfowl biologist for DU.

Although not a wildlife disease expert, Brasher’s position with DU has given him
cause and the opportunity in recent months to speak with such experts
and veterinarians at length about avian influenza.

Brasher said that prior to the late 1990s, it was rare to see a “high
pathogenic” strain of avian influenza in wild waterfowl populations.
That designation – high pathogenic versus low pathogenic – was developed
specifically in reference to the effect that these viruses had on
domestic poultry.

“The domestic poultry industry would classify these things as ‘high path’ or
‘low path’ based on the degree of mortality that they caused at poultry
facilities, but it was never really a concern for wild waterfowl
populations from a mortality or illness standpoint,” Brasher said. “But in the late 1990s
and early 2000s we saw these high-path viruses jump into wild waterfowl

Brasher is uncertain how the virus “jumped or transferred” or otherwise became
more common in wild waterfowl, but during the past 20 years, wildlife
disease experts have seen a rise in the presence of high-path strains of
the virus while conducting their surveillance work.

Still, concern with the effect of the virus on wild waterfowl populations
remained low because there was little mortality or illness associated
with it.

That is, until this year.

“It’s fair to say that what we are seeing with regard to avian influenza
illness and mortality in wild waterfowl right now is something that has
never really been seen before at this scale,” Brasher said. “That’s not
to say that it is unprecedented from a disease perspective within
populations of wild waterfowl, but just with respect to influenza we
have not seen anything of this scale ever before. That is concerning to
our wildlife disease experts, for sure.”

Reports of infected birds have come in from across the continent, and many of
those reports are of geese, including duskies and cacklers out west, and
snow geese, primarily, in the Central Flyway. Brasher said that a
coordinated effort between state and federal agencies to sample
hunter-harvested birds and those that are discovered dead or sick
indicates that this strain of the virus is showing up in many different
species of waterfowl.

“Pretty much any species of duck or goose that they’re testing, they’re finding
it,” Brasher said. “In terms of which species are most susceptible to
showing symptoms of the disease, the majority appear to be geese. There
are some inherent biases in that observation because these are big
birds, they inhabit big, open areas, and snow geese, especially, are
big, white birds that show up easily on the landscape …”

Brasher confirmed that the virus can spread from waterfowl to raptors, foxes,
and other scavengers, and he encouraged hunters to keep their dogs from
chewing on or eating a carcass.

My final question to him was simply, how does this end?

“I don’t know how this ends, and I don’t know that a lot of our disease experts have a great handle on that,” Brasher said. “Prior to the late ’90s and early 2000s, these highly pathogenic strains of avian flu hardly ever showed up in wild birds. They were
primarily restricted to commercial poultry facilities where they could
be kept under control and stopped from getting into wild populations.

“That changed somewhere, and we began to see over the past 20 or so years
periodic flare-ups of these highly pathogenic strains in wild birds.

That’s where we are now. Some wildlife disease experts say we have probably
reached a point where these high-path avian influenza viruses are going
to be with us for a long time, if not forever. That said, there aren’t
many waterfowl managers whom I talk to right now who are worried that
the virus will have an impact on waterfowl population levels at this

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