The Santa Rosa Press Democrat reports that California Highway Patrol officers found the dead birds near the roadway on Saturday and called in the state Department of Fish and Game to investigate.
The officers who found the birds described them as small with brown and black feathers. They were intact and had not been shot.
The reports come as other, larger bird deaths have been reported in Arkansas, Louisiana and other states.
Scientists say mass die-offs of wildlife happen regularly, and are usually unrelated and unreported.