Bird flu has killed thousands of Florida's wild birds this year. Is it here to stay?

dead bird
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It was the morning of Jan. 22 when the fears of Florida wildlife biologists became reality.

Reports of a highly infectious new bird flu strain had been confirmed a month prior in Canada, the launching pad for several migratory bird species that make their way to Florida. Biologists had been watching with anxious anticipation as birds wandered closer.

Then, it arrived.

The dreaded day unfolded when hunters in Palm Beach County turned over two ducks, just shot and killed, for routine disease testing at a checkpoint hosted by the U.S. Department of Agriculture. The pair of blue-winged teal ducks, with a white stripe down their faces and powder-blue wing feathers, were the first two animals in the state to test positive for the untreatable Highly Pathogenic Avian Influenza.

"That was page one," said Mark Cunningham, a fish and wildlife health subsection leader for the Florida Fish and Wildlife Conservation Commission.

"We're on page 500 now."

That day kicked off a busy year for Cunningham and his small team of veterinarians and wildlife technicians as they tried to track the unprecedented arrival of the virus. Fast forward 11 months, and thousands of are estimated dead, including beloved species like and great horned owls.

"It's certainly been a busy year. There really is no comparison," Cunningham said in an interview with the Tampa Bay Times. "This is the first time we've had a highly pathogenic avian flu in Florida's wild birds. And it's really blown up."

More than half of all Florida counties have confirmed or suspected cases of the extremely infectious bird flu strain this year. The epicenter of the outbreak initially emerged in Brevard County and along Florida's Atlantic Coast in early February, as hundreds of lesser scaup ducks, a common North American diving duck with a black head, began showing signs of neurological distress. It has since spread as far north as Okaloosa and as far south as Miami-Dade.

On paper, the U.S. Department of Agriculture shows roughly 1,450 cases in Florida through November. But the true total is suspected to be much higher than that, Cunningham said. Many cases are presumed positive, but haven't undergone formal testing. Take, for instance, the state's black vulture population: A sharp spike in bird flu cases was recently reported in vultures because an infected animal will often return to its roost before it dies. Then its fellow vultures will feed on the virus-laden carcass, spreading the disease further.

That cycle can't be fully documented with testing, but the cases are out there. As Cunningham spells it out: If biologists see 50 dead birds and test three of them, and all three are confirmed to have the virus, the other 47 are suspected positive.

"We estimate that it's well into the thousands of birds that have died," Cunningham said. And there's "well over 2,000 confirmed cases" of vultures alone.

The state wildlife commission says there is a "low risk" of humans contracting the virus, and no human cases have been confirmed in Florida this year. In April, a human case was confirmed in Colorado after somebody became infected when handling poultry that was presumed to be carrying the virus, according to the Centers for Disease Control and Prevention. The person reported symptoms of fatigue for several days before recovering.

Still, wildlife officials "caution that you avoid contact with these birds and contact your public health department with any concerns of a potential infection or exposure," the agency writes on a webpage dedicated to the outbreak.

In the Tampa Bay area, at least six have died from avian influenza, according to the latest U.S. Department of Agriculture data. That includes a trio of great horned owls that were all confirmed dead on the same day, June 29, and a bald eagle, black vultures and mallard ducks in Hillsborough County.

Infected birds can, in some cases, be asymptomatic. That was what happened with the first two ducks that tested positive in January. They didn't appear sick on the outside, Cunningham said. But some species can show visible symptoms, like lethargy, tremors, circling and seizures, according to the Florida wildlife agency. Sometimes birds are found dead with no signs of injury.

Unlike other states, Florida has, for now, avoided cases spreading to commercial poultry flocks, according to Madeline Brezin, the deputy digital director for the Florida Department of Agriculture & Consumer Services. It's a different story in other states: At least 1.8 million egg-laying hens will be killed in Nebraska and a 6-mile "control zone" was created after bird flu was confirmed there over the weekend, the Nebraska Department of Agriculture announced Saturday.

"It is critically important that this does not occur in Florida," the state's wildlife agency warns on its website.

But backyard poultry flocks here haven't been as lucky.

At least 21 backyard flocks across 11 Florida counties were confirmed with bird flu since August, according to state agriculture data provided by Brezin. That includes two flocks in Hillsborough County, confirmed between Oct. 28 and Nov. 16, and one in Pasco on Oct. 26. The infected birds were mostly chickens, but there were also domestic ducks, geese, peafowl and guineas.

Wild populations of aquatic birds like pelicans and gulls have also succumbed to the virus in Florida, federal agriculture data show. The University of Florida announced in September that a bottlenose dolphin in Dixie County contracted bird flu in the first known case in North America. It likely came into contact with an infected bird along Florida's Gulf Coast, according to researchers.

Now that migratory waterfowl are returning to Florida, Cunningham predicts a surge of cases in duck and vulture populations in the Panhandle area this winter, he told the Times. Last year, the virus came from eastern Canada along the Atlantic Coast. This year, it's likely to come from what's called the Mississippi Flyway, a bird migration path that stretches from the Great Lakes to the Gulf of Mexico.

There was a spike in Florida in September and October, and one theory is that Hurricane Ian stressed out birds and increased bird flu's spread, according to Cunningham. Despite the unprecedented year and the busy workload, the team tasked with tracking the virus says there have been plenty of lessons learned as new science emerges. One is that the virus affects species differently; another is that the virus was supposed to fade away in warmer temperatures, but has persisted in the Florida heat.

"We've learned a lot. It's definitely a concerning disease," Cunningham said. "Now that it's been circulating in the population for about a year, hopefully soon it'll start to taper off. That's the question of the day."

©2022 Tampa Bay Times.
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