Hundreds of California native pigeons have died this winter due to a parasitic disease, state wildlife officials announced recently, another possible side effect of the drought.

California Department of Fish and Wildlife officials said they’ve noticed an increase of reported sick and dead band-tailed pigeons since early February, mostly around California’s Bay Area, central coast and foothills in the Sierra Nevada.

So far this winter, an estimated 200 to 300 pigeons have died from avian trichomonosis, a disease that mostly comes from the protozoan parasite Trichomonas gallinae during some winter seasons.

Infected birds develop “cheese-like” lesions in their mouth or throat, which lead to starvation or suffocation, said wildlife officials. Birds with the disease may appear weak, uncoordinated and swallow repeatedly or have difficulty breathing.

Though band-tailed pigeons are most susceptible to the disease, other bird species, incuding their predators, can also catch avian trichomonosis.

The parasite typically spreads in water sources like bird baths, fountains and livestock troughs.

“Historically, larger outbreaks generally have been associated with drier conditions because the pigeons may be more likely to share a reduced number of water sources and the parasite can spread more rapidly among birds in the flock,” said CDFW Senior Environmental Scientist Krysta Rogers, who is an avian disease specialist.

Community members can prevent disease transmission by removing bird feeders and bird baths, especially when pigeons are in the area. Observations of sick and dead pigeons may be reported to CDFW using its online mortality reporting form.