Originally published April 2022. Updated June 2024 to reflect further developments in the outbreak.
Many people are concerned about the outbreak of avian influenza, or bird flu, that began in 2022 and has affected domestic poultry, waterfowl, raptors, shorebirds, other species of birds, and some mammals in many parts of the world. Because the current strain (H5N1) causes heavy losses to poultry, it is referred to as highly pathogenic avian influenza, or HPAI. Note that the Centers for Disease Control considers transmission of avian influenza from birds to humans to be very rare. To date, four people in the U.S. have tested positive for avian influenza: a poultry worker in Colorado in April 2022 and three workers at dairy farms, one in Texas in March 2024 and two cases at separate farms in Michigan in May 2024 (details of the first case; details of the second case). All showed mild symptoms and recovered. In June 2024, the World Health Organization reported a hospitalized man in Mexico had died from a different strain of avian influenza (H5N2), though the organization deemed the risk to the general population as low.
Reports of Avian Flu in Birds
This particular strain of avian influenza virus affects a wide variety of wild birds, including hawks, eagles, falcons, owls, crows, vultures, shorebirds, game birds, seabirds, and especially waterfowl such as Canada Geese and Mallards (see list of species with HPAI detections, below). The virus is shed in the saliva, mucus, and feces of infected birds and is transmitted to other birds via ingestion or inhalation.
Because of the duration of this outbreak, its recent spread to mammal species, and widespread mortalities in some types of wild birds, there has been concern about whether it’s safe for people to feed 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. As of June 2024, there is no official recommendation for people to take down bird feeders because of the risk of avian influenza (see next section). The Centers for Disease Control has updates and recommendations about H5N1 in humans.
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. The CDC’s page on avian influenza in birds compiles additional helpful information and resources.
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 8,499 wild birds (plus 899 captive birds), with 179 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) - 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 chickens or ducks, please see also latest information from the USDA Animal Plant and Health Inspection Service.
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.
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.
Has Avian Flu Been Reported in Mammals?
There have also been reports of mammals such as red foxes, skunks, bobcats, fishers, and bears infected with avian influenza, likely from eating infected birds. Outside the U.S. avian flu has infected farmed mink and has caused losses at marine mammal colonies in South America. In March 2024 the USDA reported that avian flu has been found in cattle in several U.S. states. The CDC has additional information on avian flu in cattle and associated risks to humans.
Additional Resources:
Wild bird species with HPAI detections in 2022–2024
Updated June 6, 2024. Total number of detections in wild birds: 8,499 (plus 889 captive birds). Detections in songbirds: 179. See Detections of Highly Pathogenic Avian Influenza in Wild Birds for latest detections.
Songbirds (14 species)
American Crow (80 individuals, plus 9 unidentified crow spp.)
American Robin (1)
Black-billed Magpie (4, plus 4 unidentified magpie spp.)
Boat-tailed Grackle (1)
Common Grackle (4)
Common Raven (42)
Dark-eyed Junco (1)
Fish Crow (5)
Grackle spp. (unidentified; 2)
Great-tailed Grackle (4)
House Sparrow (17)
Red-winged Blackbird (1, plus 1 unidentified blackbird spp.)
Sparrow spp. (unidentified; 1)
Tanager spp. (unidentified; 1)
Tree Swallow (1)
Non-Songbirds (142 species)
American Black Duck
American Coot
American Kestrel
American White Pelican
American Wigeon
Arctic Tern
Bald Eagle
Barn Owl
Barred Owl
Black Skimmer
Black Turnstone
Black Vulture
Black-bellied Plover
Black-crowned Night-Heron
Black-legged Kittiwake
Blue-winged Teal
Bonaparte’s Gull
Brandt’s Cormorant
Brant
Broad-winged Hawk
Brown Pelican
Bufflehead
Cackling Goose
California Condor
California Gull
California Quail
Canada Goose
Canvasback
Caspian Tern
Cattle Egret
Cinnamon Teal
Common Eider
Common Goldeneye
Common Loon
Common Merganser
Common Murre
Common Tern
Cooper’s Hawk
Crested Caracara
Double-crested Cormorant
Dunlin
Eared Grebe
Eastern Screech-Owl
Eurasian Collared-Dove
Forster’s Tern
Fulvous Whistling-Duck
Gadwall
Glaucous Gull
Glaucous-winged Gull
Glossy Ibis
Golden Eagle
Great Black-backed Gull
Great Blue Heron
Great Egret
Great Horned Owl
Greater Sage-Grouse
Greater Scaup
Greater White-fronted Goose
Green Heron
Green-winged Teal
Harris’s Hawk
Herring Gull
Hooded Merganser
Horned Grebe
Iceland Gull (Thayer’s)
Laughing Gull
Lesser Scaup
Long-eared Owl
Mallard
Merlin
Mottled Duck
Mourning Dove
Muscovy Duck
Mute Swan
Neotropic Cormorant
Northern Fulmar
Northern Gannet
Northern Harrier
Northern Pintail
Northern Shoveler
Osprey
Pacific Loon
Parasitic Jaeger
Peregrine Falcon
Pied-billed Grebe
Prairie Falcon
Red-necked Grebe
Red-necked Phalarope
Red-shouldered Hawk
Red-tailed Hawk
Redhead
Ring-billed Gull
Ring-necked Duck
Ring-necked Pheasant
Rock Pigeon
Roseate Spoonbill
Ross’s Goose
Rough-legged Hawk
Royal Tern
Ruddy Duck
Ruddy Turnstone
Ruffed Grouse
Sabine’s Gull
Sanderling
Sandhill Crane
Sandwich Tern
Sharp-shinned Hawk
Short-billed Gull
Short-eared Owl
Short-tailed Shearwater
Snow Goose
Snowy Egret
Snowy Owl
Snowy Plover
Surf Scoter
Swainson’s Hawk
Trumpeter Swan
Tundra Swan
Turkey Vulture
Western Grebe
Western Gull
Western Sandpiper
Western Screech-Owl
White Ibis
White-winged Scoter
Wild Turkey
Willet
Wood Duck
Wood Stork
Avian flu has been detected in an additional 31 species of captive wild birds
