Across the United States, small songbirds have faced a rise in salmonellosis, a deadly infection caused by the salmonella bacteria.
A small finch called the pine siskin has taken the brunt of the disease, Amanda Bartlett reports for SFGate. Pine siskins migrate south from Canada each autumn when they run out of food, and this year, the birds have come to the U.S. in remarkably large numbers. Once a few birds pick up salmonella in the environment, they can easily spread it to others in the places where birds congregate.
To slow the spread of salmonella, local watering holes and eateries—birdbaths and bird feeders—need to close down for a few weeks. That will give the birds a chance to get some distance from one another and find dispersed, wild food sources.
“Once there’s an outbreak, it starts spreading pretty rapidly,” says ThinkWild wildlife hospital’s executive director Sally Compton to Bradley W. Parks at Oregon Public Broadcasting. Cases of salmonellosis began to rise in mid-November, per SFGate, and in early February California’s Department of Fish and Wildlife released a statement raising concerns about the disease outbreak and asking residents to take down their bird feeders.
Since then, wildlife officials have reported outbreaks in Oregon, Washington, Idaho and Utah, Jeff Tavss reports for Fox13 Salt Lake City. A concerning number of salmonella-infected goldfinches and pine siskins have also been found in North Carolina, Bailey Aldridge reports for the News & Observer.
Salmonella outbreaks tend to happen every winter as birds huddle on bird feeders, one of the most reliable sources of food, writes Portland Audubon’s Wildlife Care Center Manager Stephanie Herman in a blog. But this year has seen such an overwhelming number of pine siskins, feeders and birdbaths are especially crowded. This year’s extra-large migration, called an irruption, is notable even among similar events because the birds migrated at night, Andrew Del-Colle wrote for Audubon in October.
The Bird Rescue Center of Sonoma County noted that it’s seeing more than double the average number of intakes for this time of year, and more than 40 percent of those birds are pine siskins, per SFGate. American goldfinches, lesser goldfinches, house finches and purple finches have also been found with salmonellosis.
An infected bird can live for about a day once it shows symptoms, which include moving slowly, puffing out its feathers, and having swollen-looking eyes. The bird then spreads the salmonella through its poop, and birds frequently poop when they land on bird feeders or at bird baths.
"The next bird that comes along and either takes a drink out of that water or eats seeds that might be contaminated with the feces can get infected that way,” says California Department of Fish and Wildlife environmental scientist Krysta Rogers to Mary Franklin Harvin at KQED.
So what should you do if you find a dead bird in your yard? Compton tells OPB people should wear gloves to dispose of the dead bird, either double-bagging and putting it in the trash or burying it. Salmonella poses a risk to pets and people, so Portland Audubon adds that it is important to supervise dogs and cats when they are outdoors.
Bird feeders should also be cleaned regularly, either with soap and water or by soaking them in a diluted bleach solution. Ceramic, plastic, steel and glass are easier to clean than wood birdfeeders, and feeders that prevent seeds from getting wet also help prevent disease outbreaks.
“While regularly cleaning your bird feeders and baths is always recommended to prevent disease transmission, a more rigorous disinfecting schedule is required during an outbreak of salmonellosis, which is why we recommend temporarily removing feeders and water baths,” says DWR wildlife conservation biologist Adam Brewerton to FOX13 Salt Lake City. “We all love to see wild birds come to our feeders, but feeders that are not properly cleaned can pose more of a risk than a benefit for birds.”