In fresh fall plumage, the female's throat and breast are tinged with red-orange which is brownish near the flank, contrasting with white tail underparts.

The mountain bluebird was formally described in 1798 by the German ornithologist Johann Matthäus Bechstein and given the name Motacilla s. Sylvia currucoides.

In fresh fall plumage, the female's throat and breast are brownish near the flank, contrasting with white tail underparts.

Although mountain bluebirds can be found in some states year-round, their range is expansive — they generally migrate south to Mexico in the winter and north into western Canada and even Alaska in the summer.

Depending on the time of year, they may be ubiquitous in mountain environments like grasslands or landscapes of sagebrush, where trees and shrubs are fairly spread out.

[12] Mountain bluebirds are cavity nesters and can become very partial to a nest box, especially if they have successfully raised a clutch.

The threats of predation for those that dwell in nesting boxes are mostly from house cats, raccoons, and the parasitic blowfly, Apaulina stalia.

[16] Mountain bluebirds are fairly common, but populations declined by about 26% between 1966 and 2014, according to the North American Breeding Bird Survey.

These bluebirds benefited from the westward spread of logging and grazing in the late nineteenth and early twentieth centuries, when the clearing of forest created open habitat for foraging.

The subsequent waning of these industries, coupled with the deliberate suppression of wildfires, led to a dwindling of open acreage in the West and the decline of the species.

Mountain, Western, and more recently Eastern bluebirds compete for nest boxes where their ranges overlap.

[18] The combined effect of decreased baseline and increased acute corticosterone may reduce the fitness of these birds by making them susceptible to inflammation and disease.

Female bluebirds that leave the nest more frequently expose their eggs to fluctuations in incubation time and temperature.