The infection has occurred in eight states, including California, Tennessee and New Hampshire, requiring eight people to be hospitalized. No deaths are currently reported.
The agency cites interviews with patients and laboratory tests showing that contact with wild songbirds and bird feeders can lead to infection.
The California Department of Fish and Wildlife said it was “inundated” with calls about residents finding sick or dead birds in or around bird feeders, particularly around the state’s central coast and in the San Francisco Bay Area.
One species in particular, pine, is often the subject of those calls in the state.
Birds can become infected with salmonella when they eat bird seeds that have been contaminated with the droppings of other birds, often on the ground under bird feeders.
The agency says birds often carry bacteria, such as salmonella, and germs can be transmitted from birds to pets and to humans.
The Centers for Disease Control and Prevention says that salmonella in humans can include diarrhea, fever, and stomach cramps and usually last for four to seven days, and most people can recover without treatment. However, some serious cases require hospitalization.
The CDC recommends that people wash their hands immediately after touching a bird feeder or bird bath or handling a bird, even if they are wearing gloves. It is also recommended that you clean bird feeders outside of your home if possible.