Western Bluebird

Sialia mexicana

The Western Bluebird breeds in semi-open country, excluding desert areas in western North America (British Columbia to central Mexico). Incapable of excavating the cavities they depend on for nesting, they rely on woodpeckers to supply their summer homes. Man-made bird houses have helped these birds overcome the fierce competition for natural cavities.

Research shows that 45% of studied nests held young birds that were not fathered by the male member of the nesting pair. Further, 19% of all the young were products of extramarital unions.

These birds spend winters in California, southwestern USA and northern Mexico.

Today’s science recognises six subspecies of Western Bluebirds. S. m. occidentalis breeds along the Pacific Coast from British Columbia. S. m. bairdi breeds in the North American interior from Utah and Colorado and south into northern Mexico. S. m. jacoti is resident from Texas Hill Country (Davis Mountains) south to norther Mexico. S. m. amabilis is resident Mexico (Chihuahua and Zacatecas). S. m. nelsoni is resident in central Mexico (Coahuila, Guanajuato, and Jalisco). S. m. mexicana is resident in southern Mexico.

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