Habitat: Open country with some trees; in winter, also treeless terrain. Often in more open areas than other bluebirds. Breeding habitats not always in mountains; found in lowland prairies and sagebrush flats as well as alpine zones above treeline. In winter, most common in pinyon-juniper woods but also in open grassland, desert, farmland, even barren plowed fields.

The powder-blue male Mountain Bluebird is among the most beautiful birds of the West. Living in more open terrain than the other two bluebirds, this species may nest in holes in cliffs or dirt banks when tree hollows are not available. It often seeks its food by hovering low over the grass in open fields. During the winter, Mountain Bluebirds often gather in large flocks, even by the hundreds, sometimes associating with Western Bluebirds.

Feeding Behavior: Often forages by hovering over open field, then dropping to the ground when prey is spotted. Hovers more than other bluebirds. Also perches on rock or low branch and darts out to catch flying insects.

Eggs, young and diet: 5-6, sometimes 4-8. Pale blue, unmarked (occasionally white). Incubation is by female, about 13-17 days. Young: Both parents feed nestlings. Young leave the nest about 17-23 days after hatching, are tended by parents for another 3-4 weeks. 2 broods per year. Both parents feed nestlings. Young leave the nest about 17-23 days after hatching, are tended by parents for another 3-4 weeks. 2 broods per year. Mostly insects and berries. Feeds heavily on insects, including beetles, grasshoppers, caterpillars, crickets, ants, bees, and others. Also eats some berries, including those of mistletoe, juniper, hackberry, and other plants. Berries are particularly important in the diet in winter.

Nesting: Sometimes interbreeds with Eastern Bluebird where their ranges overlap. Nest: Apparently the female selects the site for the nest. Site is in a cavity, usually a natural hollow or old woodpecker hole in tree, or in a birdhouse. Sometimes nests in holes in dirt banks, crevices in cliffs or among rocks, holes in sides of buildings, old nests of other birds (such as Cliff Swallow or Dipper). Nest in cavity (probably built by both sexes) is loose cup of weed stems, grass, twigs, rootlets, pine needles, sometimes lined with animal hair or feathers.

Find This Bird: In the right places it can be a snap to find Mountain Bluebirds, as they are not shy of humans and live in fairly open country. They sit in the open on perches such as treetops, fence posts, and power lines. In summer in rural areas and ranches, particularly at higher elevations, you can often find them simply by driving rural roads and eyeballing such potential perches. In forested areas, look for them in large openings, particularly if there are aspen in the vicinity (aspen is a key cavity-providing tree in western montane forests). In winter, search for areas with berry-laden junipers and watch for flocks of birds feeding on those berries. Mountain Bluebirds often mix with Western Bluebirds, American Robins, and Cedar Waxwings when taking advantage of such fruity abundance.

Cool Facts: Historically, the Mountain Bluebird depended for nest sites on forest tree cavities excavated by woodpeckers. Today, many Mountain Bluebirds breed in artificial nest boxes, which tend to be situated in more open areas and have smaller openings to keep out marauders and bad weather. Most of what we know about Mountain Bluebirds comes from studies of these human-made nesting sites. A female Mountain Bluebird pays more attention to good nest sites than to attractive males. She chooses her mate solely on the basis of the location and quality of the nesting cavity he offers her—disregarding his attributes as a singer, a flier, or a looker.

A male Mountain Bluebird frequently feeds his mate while she is incubating and brooding. As the male approaches with food, the female may beg fledgling style with open beak, quivering wings, and begging calls. More often, she waits until her mate perches nearby, then silently flicks the wing farthest from him a signal that usually sends him off to find her a snack. Mountain Bluebirds compete fiercely with other cavity-nesters over nest sites.

Early spring arrival at nesting grounds, for example, helps them take possession of choice cavities before Tree Swallows can appropriate them. Northern Flickers sometimes enlarge the entrance holes of nest boxes before discovering the box is too small for their own use rendering the boxes permeable to weather and competitors such as European Starlings

The oldest recorded Mountain Bluebird was a female, and at least 9 years old when she was recaptured and rereleased during banding operations in Alberta in 2005. She had been banded in the same province in 1997.