Western Bluebird

The Western Bluebird (Sialia mexicana) is a small, stocky thrush with a length ranging from 15 to 18 cm. The male is resplendent with bright blue plumage on top and on the throat, contrasted by an orange breast and sides, and a distinctive brownish patch on the back. The underparts are gray, extending to the undertail coverts. Females are more subdued in coloration, with a duller blue body, wings, and tail, a gray throat, and a dull orange breast, leading to a gray belly and undertail coverts. Both sexes possess a thin, straight bill and a fairly short tail. Immature birds are less vivid and sport spots on their chest and back.

Identification Tips

To identify the Western Bluebird, look for the adult male's vivid blue upperparts and orange breast. Females and juveniles are more muted with grayish tones and spotted chests. The species can be distinguished from other bluebirds by the male's blue throat and the absence of orange on the mountain bluebird.

Habitat

This adaptable bird has made a home in a variety of habitats, including coniferous forests, farmlands, semi-open terrain, and even deserts.

Distribution

The Western Bluebird's range is quite extensive, with year-round populations in California, the southern Rocky Mountains, Arizona, and New Mexico, stretching down to Oaxaca and Veracruz in Mexico. During the breeding season, they can be found as far north as the Pacific Northwest, British Columbia, and Montana. Some northern populations migrate to warmer southern areas in winter.

Behaviour

These bluebirds are territorial, with males using their calls to assert dominance over their chosen area and to attract females. They are cavity nesters, often relying on old woodpecker holes or nest boxes, and face competition from other birds for these sites.

Song & Calls

The Western Bluebird's vocal repertoire includes a variety of mating songs, such as "cheer," "chur-chur," and "chup," which are instrumental in courtship and territory defense.

Breeding

Nesting in cavities or nest boxes, the Western Bluebird faces competition and predation, but has shown a preference for nest boxes, which can lead to earlier egg-laying and higher success rates. Clutches typically contain two to eight pale blue to bluish-white eggs, and in favorable conditions, parents may raise two broods per season.

Similar Species

The Eastern Bluebird (Sialia sialis) and the Mountain Bluebird (Sialia currucoides) are close relatives but can be differentiated by throat color and the presence or absence of orange plumage.

Diet and Feeding

Western Bluebirds forage by pouncing on ground-dwelling insects or by catching them in flight. They also consume berries and are known to visit bird feeders for mealworms and other insect offerings.

Conservation status

The IUCN Red List categorizes the Western Bluebird as Least Concern, indicating a stable population without significant immediate threats to its survival.