Western Bluebird (Sialia mexicana) - California Western Bluebird with pictures, breeding distribution, urban adaptation, and taxonomy. - http://home.netcom.com/~bluebirds/webl.htm
Mountain Bluebird (Sialia currucoides) - Cornell Lab of Ornithology species account. - http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Mountain_Bluebird.html