"When we talk about impacts to domestic poultry, this virus causes almost 100 percent mortality in poultry flocks. We’re seeing that with backyard poultry flocks. They die in a very short period of time. The birds are getting sick, and they’re dying very quickly from this virus," says Maggie Baldwin, the Colorado State Veterinarian.
This HPAI strain, which has been around in North America since late 2021 after coming here from other continents, was first seen in Colorado in March 2022, in wild geese in the northeast section of the state. The first domestic bird case was seen in April, and from then through November 2022, HPAI mortalities were seen in raptors, waterfowl and vultures throughout the state.
As of January 20 of this year, more than 6,246,700 commercial chickens in Colorado have been affected by the illness, along with 985 backyard poultry and over 12,000 game birds in the state, according to the Colorado Department of Agriculture.
This type of ravaging of commercial birds is what has led egg prices to jump up across the country. The disease can be transmitted by a poultry worker stepping on infected goose feces and dragging that into a barn. Or by small infected birds getting inside a poultry facility. Or even by a migratory bird pooping on a facility while flying above.
The Colorado Department of Agriculture and the U.S. Department of Agriculture work together on handling situations in which there's a suspected outbreak of avian flu at an egg-producing facility in Colorado. If there's a confirmed positive test for the avian flu, then all of the birds at that facility have to be whacked.
"We like to say 'depopulated' or 'euthanized,'" says Olga Robak, a spokesperson for the CDA, noting that the birds need to collectively be put down because of trade-agreement protocols, the fact that the birds are likely to die anyway, and to prevent the virus from entering the food system.
It's also about humane treatment of the birds, according to Baldwin, since the virus will almost certainly kill the animals.
"This virus causes systemic disease," says Baldwin. "The most common clinical sign that we see is sudden death. The most common that we see are a bunch of birds die at one time."
When the CDA learns about a possible case of bird flu, it sends a team to test the birds; samples are then sent to an animal lab at Colorado State University. If the test shows up as a presumptive positive, then the sample is sent to a U.S. Department of Agriculture lab in Iowa to confirm the test.
Sometimes, euthanasia can wait until after the confirmed test results come back. But if the birds are all clearly dying or about to die, officials may opt for slaughtering the birds before the confirmed test results come back.
One way to off the chickens is to pump carbon dioxide into their lodgings. Another method is to pump water-based foam into their barn, leading them to die of suffocation.
"If there is enough room on site, they can be buried. They can also be composted. Or they can be disposed of either in commercial or municipal trash. It really depends on the size of the operation, what their facility looks like," Robak says.
The bird flu hasn't been tough on chickens alone, however. Wild birds have also started dying en masse in Colorado, including in one recent incident where over a thousand dead geese were found along a single reservoir in northeast Colorado.
"Unlike prior strains of Highly Pathogenic Avian Influenza in North America, this particular strain is causing widespread mortality in some species of wild birds, particularly in snow geese, raptors and vultures. This strain has also caused mortality in several mammal species, especially in skunks and foxes," the Department of Colorado Parks & Wildlife notes on its website.
And the problem has come to the cities as well, leading the Denver Department of Public Health & Environment to send out an advisory on January 25 instructing people not to touch or pick up a dead bird with bare hands.
"With Highly Pathogenic Avian Influenza impacting birds across Denver and much of the region, the Denver Department of Public Health & Environment (DDPHE) and Denver Parks & Recreation (DPR) remind residents that birds and wildlife can carry disease. Residents should never handle wildlife and should keep pets away from sick or dead birds," Tammy Vigil, a DDPHE spokesperson, says.
According to Vigil, her department and Parks & Rec have seen increasing calls from Denverites about "dead waterfowl," most of which are geese, in certain city parks, including Town Center Park in Green Valley Ranch as well as City Park and Washington Park.
Some of the crows at the 1700 block of Grant Street have died of the avian flu.
Conor McCormick-Cavanagh
"If you find a dead bird on private property, you can dispose of the bird yourself, but avoid direct contact with the remains. Wear disposable gloves, bag the bird carefully, and put it in an appropriate outdoor (preferably covered) trash receptacle, then call 311 to report it. If you’re not comfortable with disposing of the bird yourself, you can call 311 for removal," Vigil says.
And humans and their pet masters should also stay away from any bird that appears sick, such as ones exhibiting symptoms like tremors or lack of coordination, swelling around the head, neck and eyes, lack of energy or movement, coughing, gasping for air, sneezing or diarrhea, according to Vigil.
Parks & Rec is also discouraging residents from trying to retrieve dead geese on icy ponds or lakes in Denver.
"Don’t go on ice to retrieve dead or sick geese. This is another reason to keep your pets on leashes — to avoid the dangers of falling through the ice, as well as possible infection to your pet," Vigil says.
Risk of bird-to-human transmission of the avian flu is rare, but it can happen, typically when a person spends a lot of time around or touching a dead bird and then touching his mouth, eyes or nose, according to DDPHE.
Per Baldwin, there have not been any bird flu "clinical cases in humans" in Colorado.
The hazard of bird-to-pet transmission is also low, but odds increase for transmission if a mammal eats an infected bird.
Also in Denver, a beloved murder of crows numbering in the tens of thousands that hang out in the evenings on the 1700 block of Grant Street have gotten hit with the bird flu, too. While those birds crap all over the sidewalk and on parked cars, recent 311 complaints have been about dead crows.
"Those crows were tested for avian flu, and they came back positive," Vigil says.
The danger extends beyond the crows in Denver, too.
Meanwhile, because of rising egg prices, some Denver residents have started buying chickens to hatch their own eggs.
"A lot of people don't know that Highly Pathogenic Avian Influenza is a high risk to those birds," Robak says.
In fact, the way these birds get avian flu is by getting pooped on by birds passing overhead.
"We encourage people to keep their outdoor pets in a fine-mesh enclosure to prevent wild birds from ‘visiting,'" says Kenyon Moon, a Denver-based urban bird expert, who adds that chain link alone won't work. "Hardware cloth on all six faces is ideal, as that also keeps out rats and mice."
Although Baldwin is unsure of how bad the avian flu outbreak will get in Colorado, she does believe there will be an uptick in infections in the coming months as birds start to migrate more. But there are biosecurity steps that bird-owning people can take, some of which are listed in the USDA's Defend the Flock tool, that can mitigate avian flu risk.
"I think it’s important to share those tools with the bird-owning public. Yes, this is scary. Yes, this is worrisome and concerning, and here’s what you can do about it. Here’s how you can protect your birds at home," Baldwin says.
