The Mountain Bluebird has blue plumage all over. The male has a dark-blue head and wings, with a sky-blue chest, throat, and belly. This distinguishes it from the Western Bluebird, which has a rust-colored throat. The female Mountain Bluebird has a gray-blue head and wings, with a gray chest and belly. White markings on the wings of the female look like a series of scallops. The Mountain Bluebird also has a longer and thinner beak than the Western Bluebird. The Mountain Bluebird is generally silent except around dawn, when it gives a soft warbling whistle. The typical call is a "TURR-TURR", but the male also has a warble consisting of a series of "CHUR"s. Length is 6½ " to 7½ ".
Range: Year-round range is throughout California and eastward to southern Colorado, southern Utah, and northern Arizona and New Mexico. Summer and breeding range is from southern Alaska through most of western Canada, and south to Utah and Colorado. Winter range is southern Arizona and New Mexico. The Mountain Bluebird migrates over long distances.
Habitat: Like the Western Bluebird, the Mountain Bluebird is found in orchards, farmland, and open mountain meadows near trees. In some areas of Colorado the Mountain Bluebird does not migrate and can be found year-round in the warmer areas across the south-central parts of the state and in the desert regions along the western border. In winter the Mountain Bluebird is also found in treeless areas. In summer bluebirds are found in Colorado primarily in the western two-thirds of the state in open mountainous country from the open forests at about 5,000 feet to the sub-alpine and alpine zones up to 14,000 feet. They are often seen in meadows where they perch on fences and power lines, ready to dart out to catch flying insects. Typically seen in Colorado from early May through the summer.
Diet: The Mountain Bluebird typically swoops from a perch to snatch insects out of the air, but it can also hover over the ground when hunting insects. Mountain Bluebirds hover more than other bluebirds. Bluebirds also forage on the ground for beetles, grasshoppers, bees, ants, and other insects. They will also eats berries, such as mistletoe, hackberry, and juniper. They typically feed in the meadows, but nest in the nearby forests.
Reproduction: The Mountain Bluebird lays 4 to 6 eggs that are pale blue (occasionally white) without markings and hatches 1 or 2 broods per year. The birds arrive from the south, in flocks up to several hundred, as the spring snows retreat. They typically nest in holes or other cavities in trees. Occasionally nests in holes in cliffs or dirt banks, or in rock crevices or holes in buildings, if trees or other suitable sites are not available. They are often found in aspen forests in holes that have been hollowed out of the soft wood by woodpeckers. Though the Mountain Bluebird has traditionally nested in cavities in trees, it has also adapted well to nesting boxes. Young birds imprint on the nest box or cavity where they were raised and will choose a similar box or cavity to raise their own young.