(NEXSTAR) — Songbirds are dying across Northern and Central California, and a common backyard feature is facilitating their fate.

In December, the California Department of Fish and Wildlife (CDFW) has been “inundated with calls from residents who are finding sick or dead finches at bird feeders,” the department said in a press release this week.

Most reports of dead birds have emerged from California’s Bay Area, Central Coast region and the Sierra Nevada.

After an investigation, the CDFW determined the cause of death to be an outbreak of Salmonellis, a disease caused by Salmonella bacteria.

Here’s how bird feeders come into play: Salmonellis is easily transmittable from bird to bird, and its spread is facilitated by the congregation of birds. Where do birds often get together? Where the food is.

“Salmonellis is almost exclusively reported from locations with bird feeders where birds congregate,” the CDFW said.

The agency urged residents to remove bird feeders and birdbaths and to instead let birds feed on natural seeds.

Birds get sick with Salmonellis when they “ingest food, water or come into contact with objects … contaminated with feces from an infected bird,” the CDFW noted. “Sick birds often appear weak, have labored breathing, and may sit for prolonged periods with fluffed or ruffled feathers.”

Residents can report dead birds to the CDFW’s Investigations Laboratory using this mortality reporting form, which helps biologists monitor the outbreak.

If you find a sick bird, call your local wildlife rehabilitation center for advice.

The CDFW urges those handling dead birds, bird feeders and baths to wear gloves and thoroughly wash their hands.