Avian Influenza

Updated on April 1, 2025.

Since last fall, HPAI (highly pathogenic avian influenza, aka H5N1) has continued to affect northern California, with confirmed cases in Riverside, Merced, Fresno, Sonoma, San Benito, Stanislaus, San Joaquin, Butte, and many other counties.

First detected in North America in December 2021, the virus spread rapidly across the U.S., killing over 168 million domestic birds. In California alone, more than 23 million birds in commercial and backyard flocks have been lost. The virus is now considered endemic in wild bird populations and has recently been detected in other species, including dairy cattle, highlighting its persistent spread through the environment.

In early 2025, the USDA approved the first avian influenza vaccine for poultry, developed by Zoetis. However, rollout will be slow and complex, and it will likely be years—if ever—before vaccination is available to backyard flocks. Until then, strict biosecurity remains the most effective way to protect your birds. You can follow the latest confirmed detections on the USDA website.

From a CDFA newsletter:

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Avian influenza is a highly contagious and often fatal disease in birds. The disease is spread through movement of infected or exposed birds, direct or indirect contact with infected wild and/or domestic birds, or contact with the virus on fomites (surfaces or objects) such as hands, shoes, clothing, or feet and hair of rodents and other animals. It is critical for poultry owners to be vigilant and take proper measures to prevent disease (biosecurity) and protect their birds.

Here are some avian biosecurity recommendations:

• Prevent contact between domestic and wild birds by bringing your birds into an enclosure that is covered.

• Wash your hands before and after handling your birds. This includes when handling birds from coop to coop.

• If you have bodies of water on your property such as ponds or ditches, consider draining them to avoid attracting wild birds, and keep your domestic birds away from this potentially contaminated water.

• Use sanitized well or city water for your birds.

• Prevent rodents and predators from entering your coop.

• Prevent pets such as cats and dogs from eating dead wild birds.

• Keep feed covered and spills cleaned up to avoid attracting wild birds and rodents.

• Wash and disinfect boots and equipment when moving between coops.

• Do not share equipment or supplies with neighbors.

• Clean and disinfect equipment and other supplies between uses.

• Clean and disinfect your shoes and vehicle tires after visiting feedstores and other places frequented by other poultry owners or wild bird hunters..

• Avoid visiting places where wild birds congregate such as lakes and ponds.

Monitor your birds for the following symptoms:

• Trouble breathing

• Clear, runny discharge from nose, mouth, and eyes

• Lethargy or lack of energy

• Loss of appetite

• Drinking less

• Swollen eyes, head, wattles, or combs

• Discolored or bruised comb, wattles, or legs

• Stumbling, falling, or twisted neck

• Sudden death

Poultry owners with flocks that have experienced any unusual/suspicious illness or deaths should call our CDFA Sick Bird Hotline at 866-922-BIRD (2473).

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Below are some examples of how sanctuaries have been protecting their resident birds.

Mother Clucker's Microsanctuary uses multiple biosecurity stations with disinfectant footbaths and a driveway blockade to minimize risk of contamination.

Zinger Ranch farm sanctuary added a clear tarp on top of the chicken run to prevent wild birds' poop falling into their chicken area.

Four Roots Ranch & Sanctuary have locked up their birds in their run and added a large insect netting on top to prevent wild birds' poop falling into their chicken area. You will notice they also added lots of enrichment to keep their birds busy and fight boredom while they can't free range. They also wear boot covers every time anyone steps into the run.

Kindred Farm sanctuary wrapped their bird and bunny areas with a netting to prevent any wild birds from entering. They plan to keep it after the outbreak as it also protects their residents from predators.

Herd and Flock animal sanctuary is keeping all their birds in their barns, protecting all their outdoor runs with netting, and implementing a strict biosecurity protocol for everyone who needs to care for the birds.

They recently participated to a roundtable discussion about this outbreak. Listen here.

At the moment, we are enforcing biosecurity by requiring all our visitors to wash their hands and wear the clogs or shoe covers we provide. If they have chickens at home, we asked them to come with clean clothes.

In short, treat your chicken area as a bubble: nothing in, nothing out.