Salmonellosis Outbreak

Because of the decreasing number of Pine Siskins in Santa Clara County, SCVAS believes that it is safe for local birders to put out bird feeders and baths again.  You should thoroughly clean feeders and baths before putting them back out.  Consider using feeders that have room for fewer birds (like tube feeders instead of platforms), which reduces crowding.

If you see Pine Siskins at your feeders or baths, or sick birds of any species, take these items down again for at least a week, allowing the birds to disperse, and clean your feeders and baths before putting them out again.

Sanitation is always important when providing food and water to birds.  SCVAS urges you to clean your feeders and baths regularly, and to keep the areas underneath them clean.  Disease organisms are present year-round, regardless of whether you see sick birds.

Please read our FAQ below, which contains cleaning instructions for seed and suet feeders, hummingbird feeders, and bird baths, and advice about how often they should be cleaned.

Sick Pine Siskin by Julie Amato

Sick Pine Siskin by Julie Amato

Humans can get salmonellosis from contact with bird feeders and baths, wild birds, and pets, and there is currently a human outbreak linked to this outbreak among birds. Use caution when handling feeders, baths, and animals.

As an alternative to bird feeders, consider planting native plants in your yard.  These are an excellent natural food source for birds, in addition to providing many ecosystem benefits.  Links to more information about gardening for birds are in the FAQ below.

FREQUENTLY ASKED QUESTIONS

What is the best way to clean seed and suet feeders?

Scrub seed and suet feeders in warm, soapy water, taking care to remove all debris, then soak them in a diluted bleach solution (9 parts water to 1 part bleach) for 10 minutes.  (A bleach solution more effectively reduces Salmonella bacteria than soap and water alone.) Rinse the items thoroughly, then allow them to dry completely before using them again.

You should clean seed and suet feeders once every two weeks, or more often if they receive heavy use.

What is the best way to clean a hummingbird feeder?

Disassemble the feeder, then scrub it with hot water.  Allow it to air dry before using again.

If there is mold or mildew on the feeder, do a deeper cleaning.  Fill a bowl with a diluted vinegar solution (2 parts water to 1 part vinegar).  Disassemble the feeder, then immerse the parts in the solution and allow them to soak for one hour.  Remove, then scrub and rinse thoroughly.  Air dry before using again.

Do not use dish soap or bleach on hummingbird feeders.  The National Audubon Society recommends cleaning these feeders twice a week in warmer weather, and once a week in cooler weather.  If the birds empty the feeders more frequently, you should clean them each time that they are empty.

For more information, watch National Audubon’s video on how to clean a hummingbird feeder.

What is the best way to clean a bird bath?

Dispose of any water that is in the bath, then scrub the bath thoroughly with a weak vinegar solution (9 parts water to 1 part vinegar).  Rinse thoroughly, and allow to dry before refilling.  Avoid synthetic soaps or cleaning products - their residue can take the oils out of bathing birds’ feathers.  

Bird baths should be cleaned at least two or three times a week.  The water in the bath should be emptied and refilled every day.

See this National Audubon Society article about why it’s important to keep bird baths clean.

Where can I get more information about gardening for birds?

SCVAS has a video on gardening for birds in Santa Clara County.  The Santa Clara Valley chapter of the California Native Plant Society also has information about native plant gardening to help birds and other wildlife in our area.  In addition, the National Audubon Society has many resources on plants for birds.

Why has the number of Pine Siskins in Santa Clara County dropped during April?

Many of the Pine Siskins in Santa Clara County are migratory, coming from their breeding grounds to spend the fall and winter here. During the spring, these birds migrate out of the area, going to their breeding grounds further north.

What does a Pine Siskin look like and how does it behave in yards?

Pine Siskins are small songbirds that are part of the finch family.  They are heavily streaked, brown and white birds, with bright, lemon-colored stripes on their wings and tail (this color is often more visible when the birds are flying).  They have dark, thin, pointed bills.  The birds often flock together, and are frequently seen in large numbers at backyard bird feeders and baths.  They are seed eaters but will sometimes eat suet too.

I don’t live in Santa Clara County.  Do your recommendations apply to me?  Where can I get information about the salmonellosis outbreak in my area?

SCVAS’s assessment that it is safe to put out feeders and baths again is based on data about the abundance of Pine Siskins in Santa Clara County.  We have not evaluated data for areas outside of our county.  If you live elsewhere, we suggest you contact your local Audubon chapter (find it here) or wildlife rescue center for advice.

What is salmonellosis and how does it affect birds?

Salmonellosis is a disease that results from infection with Salmonella bacteria.  Among birds, it is a highly contagious, deadly disease, transmitted through contaminated feces.  

Sick birds are observed almost exclusively at bird feeders and baths.  These are places where birds congregate in close proximity, which allows the disease to quickly spread.  Sick birds usually die within 24 hours of infection.

Sick birds often appear puffy and lethargic; some may have swollen, partly-closed eyes. Birds can be asymptomatic and still pass on the disease.

Can birds besides Pine Siskins get salmonellosis?

Yes.  Many bird species can get salmonellosis.  At bird feeders and baths, the disease is often observed in birds that are part of the finch family, like Pine Siskins, Lesser Goldfinches, and American Goldfinches.

Salmonellosis outbreaks occur periodically among birds.  Why was this winter’s outbreak so bad?

The winter 2020-21 outbreak is linked to the presence of unusually large numbers (an “irruption”) of Pine Siskins in the United States during this time period.

Pine Siskins are abundant in Canada, and are also found in the northern U.S. and in areas of high elevation throughout North America.  Conifer seeds are part of the birds’ diet, and when the winter cone crops are poor further north, siskins migrate south in search of food, which is what happened this winter.

Can people get salmonellosis from birds, bird feeders, and bird baths?

Yes.  On April 1, the Centers for Disease Control and Prevention (CDC) announced that they are investigating an outbreak of salmonellosis among humans that is linked to the current salmonellosis outbreak among wild birds.  Genome sequencing shows that the strain of Salmonella infecting people in this outbreak is closely related to the strain that has infected Pine Siskins this winter.  So far, the majority of human cases are reported in Washington, Oregon, and California.  Almost all of the sick people own bird feeders, had contact with a wild bird that was sick or dead, or have pets that had access to wild birds.  

To reduce the possibility of getting sick, you should always wash your hands after handling bird feeders and baths, and you should not touch wild birds with your bare hands.  For details, please visit the CDC’s web page on the current salmonellosis outbreak among humans.

Can pets spread the Salmonella bacteria to people?

Yes.  While it is uncommon for pet cats and dogs to become sick with salmonellosis, they can be carriers of the Salmonella bacteria and spread it to people, causing human illness.  Pets should be kept away from bird feeders and baths, and the areas under them.  

The CDC recommends washing your hands after touching your pet or your pet’s supplies, and after picking up your pet’s feces.  For more details, please visit the CDC’s web page on the salmonellosis outbreak.

More information 

Salmonella - Cornell Wildlife Health Lab 

Salmonella outbreak linked to wild songbirds - Centers for Disease Control and Prevention

A healthy Pine Siskin feasting on sweetgum seeds, by Barry Langdon-Lassagne

A healthy Pine Siskin feasting on sweetgum seeds, by Barry Langdon-Lassagne

If you have questions about this topic, please contact us at backyardbirds@scvas.org.

If you found this information helpful, please consider making a small donation or becoming a member of SCVAS. Your support allows us to deliver on our mission - promoting the enjoyment, understanding, and protection of birds and other wildlife by engaging people of all ages in birding, education, and conservation.

Text by Julie Amato

Banner Photo: Pine Siskin by Tom Grey

Last Update: 5/13/21