The Mountain Bluebird (Sialia currucoides) is a medium-sized bird weighing about 30 g (1.1 ounces) with a length from 16–20 cm (6.3–7.9 in). They have light underbellies and black eyes. Adult males have thin bills that are bright turquoise-blue and somewhat lighter beneath. 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. Call is a thin few; Song is warbled high chur chur.