Originally published April 20, 2022. Updated March 22, 2023.
Many people are concerned about the 2022-2023 outbreak of avian influenza, or bird flu, that is affecting domestic poultry, waterfowl, raptors, and some shorebirds in the U.S. and Canada. Because the current strain (H5N1) causes heavy losses to poultry, it is referred to as highly pathogenic avian influenza, or HPAI. Note that transmission of avian influenza from birds to humans is very rare. To date, one person in the U.S. has tested positive for avian influenza and developed mild symptoms, in Colorado in April 2022.
This particular strain of avian influenza virus affects a wide variety of wild birds, including raptors such as Red-tailed Hawks, owls, crows, vultures, and waterfowl such as Canada Geese and Mallards (see details below). The virus is shed in the saliva, mucus, and feces of infected birds and is transmitted to other birds via ingestion or inhalation. There have been reports of mammals, such as red foxes, skunks, bobcats, fishers, and bears, also infected with avian influenza, likely from eating infected birds.
Because of widespread mortalities in some types of wild birds, there has been confusion about whether people should take down their feeders to stop the spread of this disease among wild birds. In April 2022 and March 2023, we checked in with Dr. Julianna Lenoch, who directs the USDA APHIS National Wildlife Disease Program, and we’ve compiled the following summaries of key points regarding HPAI, especially among songbirds and other feeder visitors.
Low Risk of Avian Flu to Songbirds
There has been widespread transmission of avian flu to wild bird species including waterfowl and raptors. The virus has also been found in mammals that prey on dead birds. However, transmission to songbirds and other typical feeder visitors has been low (less than 2% of all cases reported in wild birds), although this may change with increased testing or changes to the virus. That means 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.
We also always recommend that you follow any recommendations put out by your state government, even in cases where that advice conflicts with ours. We are updating this page as the situation develops.
How do we know songbirds are at low risk?
- USDA APHIS has a strong, multiyear surveillance program that routinely samples wild birds, including flocks of songbirds (and other species such as Rock Pigeons and Mourning Doves that are often around humans), for the presence of avian influenza. Since January 2022 they’ve detected the HPAI strain in 6467 wild birds, with 104 detections in wild songbirds (see below for a list of species). Latest info about the outbreak.
- Avian influenza does not affect all types of birds equally. The “highly pathogenic” part of the term HPAI refers specifically to the severity of the disease in poultry, not necessarily in other bird species. For example, waterfowl often carry and transmit bird flu, and with the current strain they sometimes get sick or die. Raptors are much more sensitive to the disease. Domestic poultry are extremely susceptible to HPAI and spread the disease easily, leading to up to 100% mortality of affected flocks.
- Songbirds are much less likely than waterfowl to contract avian influenza and less likely to shed large amounts of virus, meaning they do not transmit the disease easily. (See Shriner and Root 2020 for a detailed review in the journal Viruses.)
- According to a separate study in the Journal of Wildlife Diseases, “…although passerines and terrestrial wild birds may have a limited role in the epidemiology of IAV [avian influenza A viruses] when associated with infected domestic poultry or other aberrant hosts, there is no evidence supporting their involvement as natural reservoirs for IAV.” (Slusher et al. 2014)
- For these reasons, it is unlikely that bird feeders will contribute to an outbreak among songbirds.
If songbirds are at low risk, why are people who keep poultry advised to take down their bird feeders?
- The main concern with songbirds is the chance that a rare individual might transmit an infection to poultry. This is a concern because poultry are so much more vulnerable than songbirds to HPAI.
- The key intervention is to keep songbirds away from poultry; it’s less important to keep songbirds away from each other.
- If you have a backyard poultry flock, these are the most important steps to take:
(click for full info on these biosecurity measures from USDA APHIS)
- make their food inaccessible to wild birds
- make their water inaccessible to wild birds
- keep poultry indoors or otherwise physically separated from wild birds, if possible
- change your clothes and wash hands before tending to poultry (or pet birds)
- As a secondary measure, USDA APHIS recommends for poultry owners to take down wild bird feeders or keep them well away from their captive flock
If you keep nest boxes:
Avian influenza is only rarely transmitted to humans, according to the USDA. The Centers for Disease Control and Prevention considers the general public health risk from avian flu to be low. Nevertheless, our NestWatch project always advises good hygiene and highly recommends that people wear disposable gloves and/or wash their hands thoroughly after checking nest boxes. Most birds that use nest boxes are songbirds, which are at low risk for contracting or transmitting avian influenza. If you monitor waterfowl or raptor nests (e.g., Wood Duck, Common Merganser, Canada Goose, American Kestrel, Barred Owl), we suggest you wear gloves, change or wash gloves and disinfect equipment between nest boxes, wear a mask when cleaning out nest boxes, and change clothes and footwear before visiting any domestic poultry.
If you are a wildlife rehabilitator:
Wildlife rehabilitators should take precautions when accepting sick birds so that they don’t inadvertently introduce HPAI to the rest of their patients. Here’s further guidance for rehabbers, from USDA APHIS. Rehabbers in New York State are also encouraged to contact the Cornell Wildlife Health Lab for more information.
If You Keep Chickens or Ducks:
See latest information from the USDA Animal Plant and Health Inspection Service.
What to do if you find a sick or dead bird:
Avoid handling sick or dead birds. Instead, call your state wildlife health agency; they can determine cause of death and send the bird to the appropriate lab for testing. Additionally, keep pets (including pet birds) away from sick or dead wild birds.
- Avoid contact with birds that appear sick or have died.
- Avoid contact with surfaces that have bird feces.
- If you must touch sick or dead birds:
- Wear gloves and a face mask.
- Place dead birds in a double-bagged garbage bag.
- Throw away your gloves and facemask after use.
- Wash your hands well with soap and warm water.
Bird flu is not a risk to food safety. Poultry and eggs that are safely handled and cooked to an internal temperature of 165°F are safe to eat.
If you feel sick after having contact with sick or dead birds, contact your health care provider.
- Latest outbreak statistics from USDA APHIS, including a map of states where HPAI has been detected in wild birds this year, and list of all detections
- USDA APHIS page about avian influenza in wild birds
- FAQ about avian influenza and wild birds (USDA APHIS)
- Simple biosecurity measures for preventing avian influenza on farms (USDA APHIS)
Wild bird species with HPAI detections in 2022–2023
Updated March 10, 2023. Total number of detections in wild birds: 6,467. Detections in songbirds: 104. See 2022–2023 Detections of Highly Pathogenic Avian Influenza in Wild Birds for latest detections.
Songbirds (12 species)
American Crow (51 total: 1, California; 1, Colorado; 6, Iowa; 1, Kansas; 1, Massachusetts; 1, Michigan; 6, Minnesota; 2, New York; 19, North Dakota; 2, Oregon; 1, South Dakota; 4, Washington; 6, Wisconsin)
American Robin (1, North Dakota)
Black-billed Magpie (5 total: 1, Colorado; 1, Idaho; 3, Wyoming)
Boat-tailed Grackle (1, Florida)
Common Grackle (2 total: 1, Arizona; 1, Montana)
Common Raven (32 total: 12, Alaska; 11, California; 2, Colorado; 1, Minnesota; 4, Montana; 1, Washington; 1, Wisconsin)
Dark-eyed Junco (1, Minnesota)
Fish Crow (5 total: 4, Florida; 1, New York)
Great-tailed Grackle (3, Kansas)
House Sparrow (1, Nebraska)
Red-winged Blackbird (1, Michigan)
Tree Swallow (1, Alaska)
Non-Songbirds (114 species)
American Black Duck
American White Pelican
Great Black-backed Gull
Great Blue Heron
Great Horned Owl
Greater White-fronted Goose
Iceland Gull (Thayer’s)
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