I observed a male Western Bluebird (Sialia mexicana) capture a western fence lizard (Sceloporus occidentalis), the first reported incidence of vertebrate-directed raptorial behavior in the Western Bluebird. There are no previously published reports of Western Bluebirds capturing vertebrate prey, although there is one previous report of a Western Bluebird carrying an unidentified lizard in the manner of a prey item, and a few reports of predation on vertebrates by the congeneric Eastern Bluebird (Sialia sialis).