YUCCA VALLEY, Calif. (AP) _ A bird disease has killed hundreds of mourning doves and pigeons in California, and authorities said its spread has been aided by a drought and the use of bird feeders.

The outbreak among mourning doves was first reported in late March when a woman who keeps a feeder found 15 dead doves in a week's span, said Yucca Valley Animal Control supervisor Melanie Crider.

Tests by a California Department of Fish and Game veterinarian came back positive for trichomoniasis (pronounced trick-oh-mon-NYE-uh-sis). The parasite afflicts only pigeons and doves, though mourning doves appear particularly susceptible.

Crider estimates the number of dead birds has ``gone from the hundreds to maybe, perhaps a thousand.''

More birds could become infected unless residents stop feeding them or clean their feeders daily, she said.

A similar outbreak is killing hundreds of band-tailed pigeons, which feed in the wild, said Department of Fish and Game veterinarian Ben Gonzales. He said about 1,500 dead pigeons have been found in Los Padres National Forest and two other remote locations in northern California.

Strains of trichomoniasis are found in nature, causing infected birds to develop cankers in their mouths and throats that make it hard for them to breathe or swallow. Unable to swallow, they spit out contaminated food or water and pass the disease to healthy birds.

People should discard dying or dead doves because the disease can be transmitted to raptors if they eat infected birds, Crider said.