The Western Bluebird (Sialia mexicana) is a medium-sized thrush. Adults have a gray belly. Males are bright blue on top and on the throat with a red breast; they have a brown patch on their back. Adult females have duller blue wings and tail, a brownish breast and a gray crown, throat and back.
Their breeding habitat is semi-open country across western North America, but not desert areas. They nest in hollow spaces or in nest boxes, competing with Tree Swallows, House Sparrows and European Starlings for natural nesting locations.
Northern birds migrate to the southern parts of the range; southern birds are often permanent residents. These birds wait on a perch and fly down to catch insects, sometimes catching them in midair. They mainly eat insects and berries.