The mountain bluebird (Sialia currucoides) is a medium-sized bird weighing about 30 g (1.1 oz) with a length from 16–20 cm (6.3–7.9 in). They have light underbellies and black eyes. Adult males have thin bills and are bright turquoise-blue and somewhat lighter underneath. Adult females have duller blue wings and tail, grey breast, grey crown, throat and back. In fresh fall plumage, the female's throat and breast are tinged with red-orange, brownish near the flank contrasting with white tail underparts. Their call is a thin 'few'; while their song is warbled high 'chur chur'. It is the state bird of Idaho and Nevada. It is an omnivore and it can live 6 to 10 years in the wild. It eats spiders, grasshoppers, flies and other insects, and small fruits. The mountain bluebird is a relative of the eastern and western bluebirds.
Mountain Bluebirds are fairly common, but populations declined by about 26% between 1966 and 2014, according to the North American Breeding Bird Survey. Partners in Flight estimates the global breeding population of 4.6 million, with 80% spending some part of the year in the U.S., 20% breeding in Canada, and 31% wintering in Mexico. The species rates an 8 out of 20 on the Continental Concern Score. 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.