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Laboratory Receives Reports of Dead Pine Siskins

It seems as if 2020 needed to squeeze in a bit more bad news as the year comes to an end. The District as well as the California Department of Public Health (CDPH) have observed a high number of dead bird calls describing a sparrow-like bird.  SMCMVCD laboratory staff have identified these birds to be Pine Siskins (Spinus pinus), which can often be confused for other finches or even American sparrows. Pine siskins are fairly small with yellow patches on the wings and a short, forked tail. Adults are predominately brown with heavy streaking throughout.  These birds are irruptive migrants, meaning they appear in large numbers some years and are often absent the next due to food availability or weather conditions. The National Audubon Society has confirmed the phenomenon across the United States, stating that the irruption is so strong, that Pine Siskins have also been migrating at night – a very unusual occurrence for the species. 

Dead Pine Siskins have been reported from Half Moon Bay, Burlingame, and San Carlos. One resident reported seeing eight dead birds within two days. The cause of this mortality is currently unknown, but one likely possibility is Salmonellosis, a disease caused by Salmonella bacteria. Previous outbreaks of Salmonella among Pine Siskins have occurred in California during the winter of 2012-13, 2015, and 2016. Birds become infected with the bacteria when they ingest contaminated food, water, or come into contact with objects such as bird feeders, baths, or perches. Due to this transmission mode, birds are almost exclusively exposed to Salmonella in locations with bird feeders. The disease is highly fatal to Pine Siskins with most birds dying within 24hours after infection. CDPH is working on confirming the cause of mortality with the California Department of Fish and Wildlife (CDFW). In the meantime, you can help keep this potential outbreak and other birdfeeder diseases at bay by following CDPH guidelines:

  1. For feeders: Take down feeders for at least two weeks to allow birds to disperse. Avoid using wooden feeders, as they are harder clean. Wash the feeder with warm soapy water to remove droppings. Then immerse the feeder in a bleach solution composed of 9 parts water to 1 part bleach. Soak the feeder for 10 minutes, scrub, and rinse thoroughly. Allow it to fully dry, ideally in the sun, before refilling. Wet feeders encourage mold growth on seeds.  Bird feeders should be disinfected every two weeks.
  2. For hummingbird feeders: No BLEACH! Change food often. Clean and fill with only enough to last 1-2 days but sooner if gets cloudy/moldy. Use vinegar and water in a 9:1 solution and special bottle brushes to get into small holes. Rinse thoroughly.
  3. For birdbaths: Birdbaths should be emptied and cleaned daily regardless of disease outbreaks. For a more thorough cleaning, make a 1:32 bleach solution in a jug to bring outside. Using a hard brush and scrub bath with soap and water, rinse and soak with bleach solution for 10 – 20 minutes. Cover the bath with a board while soaking to prevent birds bathing in bleach solution. Rinse very thoroughly and allow bath to dry before refilling.
  4. Wash hands thoroughly with soap and water after handling feeders or baths.

Unfortunately, birds are not the only ones that can be infected. Humans can potentially be exposed to Salmonella when handling the dead birds. For this reason, always wear gloves or use an inverted plastic bag or shovel to handle them. Then wash your hands thoroughly with soap and water.

District staff will provide updates on the cause of bird mortality when more information is provided by the State.

More information about bird diseases:

Audubon Report:

Cats at Risk for Salmonella – Songbird Fever

Resident reports of dead Pine Siskins are mostly occurring in San Mateo and Santa Clara County, but CDPH has also received a few reports from Sonoma, Yolo, and Santa Cruz County. It’s up to us to keep our feeders clean to not only protect birds from diseases but also – our cats! Outdoor feline friends that pick-up dead or dying Pine Siskins are exposed to potential diseases that the birds carry, including Salmonella.

The ingestion of a Salmonella contaminated bird can cause a severe or even life threatening disease referred to as songbird fever. The symptoms associated with songbird fever include fever, lethargy, loss of appetite, diarrhea, and vomiting. Cats may be sick for a week or more, with up to 10% dying from the disease. Salmonella is considered to be zoonotic, meaning it can be transmitted to people. Cats with songbird fever can spread the bacteria to humans when they are sick, as well as up to six weeks after the cat has recovered.

To protect songbirds, your cat, and yourself, it’s best to keep cats indoors.

Information from: &