2022/2023 Global Avian Flu Outbreak in Colorado

Dead geese are scattered on the ice of local lakes and reservoirs. Egg prices are over $7 per dozen and the shelves are still bare. Friends and social media posts are recommending removing our songbird feeders. What is going on?

Since the winter and spring of 2021/2022 there have been outbreaks of highly pathogenic avian influenza around the globe. These outbreaks occur in most years but the extent of the current outbreak globally and in North America has been extensive (see recent outbreaks recorded by the Food and Agricultural Organization of the United Nations). Outbreaks can affect both wild and domestic birds. Rarely it is also passed to humans – which is a reason you should not handle sick or dead birds.

What Is Avian Flu?

Avian influenza, or avian flu for short, is an infectious disease in birds caused by Influenza Type A viruses (the same type as the most common human flu viruses). Some species of birds, including many waterfowl and aquatic birds, are reservoirs of the viruses and they can carry the disease without showing overt signs of being infected. There are both low pathogenic (LPAI) and high pathogenic (HPAI) categories of avian influenza based on the viruses impact on commercial poultry. The viruses are separated into different groups based on their surface proteins. The current virus is an H5N1 subtype. So you may see news stories referencing anything from “bird flu” to “HPAI” to “H5N1” but the stories are likely all referring to the same thing.

Outbreaks occur when an HPAI strain causes severe disease and high mortality in some species of birds. Avian flu is not new or unique to 2022 and 2023 – in fact, my first job after graduating college was to survey for avian flu in shorebirds in 2006. The current outbreak in North America, and Colorado, is more virulent than past outbreaks on this continent.

Detection of HPAI in wild and domestic birds by county in Colorado. Blue Counties = Positive wild bird cases. Red Counties = Positive domestic bird cases. Purple Counties = Positive cases in both domestic and wild birds. Map from Colorado Department of Agriculture.

Impacts on Domestic Birds

The H5N1 strain of avian influenza is particularly deadly to domestic poultry. To prevent spread in the agricultural industry, millions of birds have been culled globally in the last two year. The impacts are showing up on supermarket shelves. This impact has driven much of the news coverage of this outbreak.

Impacts on Wild Birds

As of January 5, 2023 HPAI had been detected in over 5,500 wild birds but only 75 detections in songbirds across the US. There were 13 species of songbird and 103 species of non-songbirds in which HPAI has been detected. Many of the non-songbirds include waterfowl (ducks, geese, swans, etc), aquatic birds (herons, shorebirds, seabirds, etc), game birds (grouse, turkeys, etc), and raptors (hawks, eagles, falcons, owls, etc). You can see all the detections on the USDA APHIS website.

The impact on wild birds in Colorado has mostly been limited to morbidity and mortality in geese, ducks, and raptors. There is ongoing research into the extent of the outbreak and impacts on overwintering waterfowl and raptors.

For more information, visit Colorado Parks and Wildlife’s avian influenza webpage. For a quick overview, read the informational flyer from Colorado Parks and Wildlife that includes more information; recommendations for hunters and falconers; and links to additional information.

What about my feeders?
If you are like me, I’ve seen a lot of different advice on what to do about my bird feeders during the outbreak. The Cornell Lab of Ornithology and All About Birds, published an article specifically on this topic, after consulting with Dr. Julianna Lenoch, director of the USDA APHIS National Wildlife Diseases Program.

They report, “… there is currently low risk of an outbreak among wild songbirds, and no official recommendation to take down feeders unless you also keep domestic poultry, according to the National Wildlife Disease Program. We do always recommend that you clean bird feeders and birdbaths regularly as a way to keep many kinds of diseases at bay.”

Consider reading the full article for more details of the data and research this recommendation is based on; more information on what to do if you keep backyard chickens, check nest boxes, or are a wildlife rehabilitator; and a list of North American species in which HPAI has been detected during 2022-2023. (The article was originally published April 20, 2022 and updated January 5, 2023.)

Can Humans Get Bird Flu?

While humans can get sick and even die from avian influenza including the H5N1 strain, it is quite rare. The only observation of a human getting H5N1 influenza from birds in the US in 2022 was here in Colorado (source: CDC), however, that involved an individual directly working with poultry that were infected. The individual recovered.

While currently, this virus is not very transmissible between birds and people or among people, new mutations could make the virus more transmissible or virulent. You should avoid contact with any sick or dead bird that you suspect may be infected with avian flu.

If you walk around an area where there is a lot of bird poo, especially if you see dead birds, you may want to consider cleaning your shoes before returning home or moving to another location. Similarly, anyone with pet chickens or other birds should be vigilant about handwashing. More information for those with backyard chickens can be found on the USDA website.

What to do if you find Sick or Dead Birds

Colorado Parks and Wildlife (CPW) recommends that if you find three or more dead wild birds in a specific area within a two-week period, or if you see live birds showing signs of disease, you should contact your local Colorado Parks and Wildlife office (details below).
If you find sick or dead birds and suspect avian influenza, please report the instance. Please do not approach or touch sick or dead birds. The individuals collecting birds for testing have appropriate personal protective equipment and qualifications to do the retrieval. Retrieval is much more complicated and unsafe for staff to remove carcasses from the ice but they are working on solutions.

Regardless of your method of reporting, please have the following information ready when submitting a report:
* Date of observation of sick/dead bird(s)
* Is ≥ 1 carcass intact & fresh (< 48 hrs)?
* Is ≥ 1 carcass accessible (not on ice)?
* Location (body of water, park, or address; county; and GPS coordinates, if known)
* Estimated total number of sick and dead birds
* Species (if not sure of exact species, report as specific as you can, e.g. “Cackling or Canada Goose”, “owl”)
* Age of bird(s) (or unkown)
* Sex of bird (s) (or unkown)
* Any additional comments
* Reporting party contact information (name, phone number, email; optional)

You can find a list of CPW offices here. CPW’s website says that they will not be able to respond to all calls as they are focusing responses based on surveillance and management priorities.

Courtney Rella is assisting in collecting reports of sick and dead birds to contribute to CPW’s ongoing data collection. Reports with the information above can be sent to dr.cawtney@gmail.com. If you do report to Courtney, you do not need to separately report to CPW as the data are combined. Reporting to Courtney reduces calls to CPW and allows for reporting over the weekend when CPW staff are not in the office to take calls.

Reports of dead or sick birds can help us better understand how Colorado avifauna is being affected by this avian flu outbreak