Signs and sounds

After working the fence line for some time, the Mountain Bluebird may disappear over the next ridge or clump of trees, leaving behind a soft warbling song. It has a louder song, which is heard most often in pre-dawn hours, during the breeding season.

Habits and Habitat

The Mountain Bluebird’s preferred habitat is sparsely treed grasslands. They require cavities for nesting. During winter, Mountain Bluebirds travel in flocks, often with Western Bluebirds and Sparrows, and feed on insects and small fruit, such as mistletoe, hackberry, and currants.

They typically begin to move north in March, but often arrive in northern latitudes when snow still blankets much of the ground and temperatures still dip below -20°C. These hardy birds can usually withstand short spells of cold and stormy weather; however, during prolonged severe conditions they may freeze or starve to death. Mountain Bluebirds sometimes migrate alone but more often travel in flocks of up to 50 birds (rarely up to 200). They travel during the day at a leisurely pace, stopping frequently to feed.

They can sometimes be seen strung like brilliant blue jewels along a barbed wire fence, scanning bare patches of ground for weed seeds and dead insects. Highly aggressive birds, they usually sit at least a metre apart. There is a continual flashing of blue, as first one and then another leaves its perch momentarily to pick up a tasty morsel.

Feeding and Breeding

Like other thrushes, Mountain Bluebirds are ground-feeders and eat mostly insects. Where elevated perches are not readily available, particularly near nest sites, the Mountain Bluebird will obtain most of its food by hovering in the air a metre or more above the ground in a hawk-like manner, as it searches the earth below for food. Other members of the thrush family do not use this hovering technique.

Before the tail end of the migration has passed through, resident Mountain Bluebirds have fanned out over areas with suitable nesting habitat. Sparsely treed grasslands, wooded ravines and valleys, badlands, and mountains all meet the nesting requirements of Mountain Bluebirds, but they tend to avoid treeless plains.

The males often arrive first, and waste little time in searching out suitable nesting sites: woodpecker excavations and decayed cavities in trees are used where available.  In built-up areas, they move into machinery, nooks and crannies in buildings, fence-posts, and utility poles. Recently, the birdhouse has become an important nesting site.

Once the male has found cavities to his liking, he entices a prospective mate to inspect them. The male goes in and out of each cavity, fluttering excitedly about the female and calling continually, all in an effort to have her accept the site. This exuberant display may last, off and on, for hours or even days, until a female finally condescends to try out the cavity for size. She decides whether to accept or reject the site.

After a nest site is agreed upon, both birds defend the immediate area. They  build the nest of dry grass stems and finer plant material, while continuously watching and guarding the new site against intruders. This process may take any where from two days to more than a week.

Soon after completing the nest, the female lays one egg each day until the clutch, usually with four to six eggs, is complete. Occasionally there are up to eight eggs in a clutch.

Unique characteristics

When elevated perches are not available, the Mountain Bluebird, unlike other members of the thrush family, will obtain most of its food by hovering in the air a metre or more above the ground in a hawk-like manner, as it searches the earth below for food.

Ages and Stages

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Sounds of a bluebird

Mountain Bluebird (song)
Mountain Bluebird (song)
Mountain Bluebird (call)