Mountain Bluebird
Sialia currucoides
The mountain bluebird is 15.5–18 cm (6.1–7.1 in) in length, weighs 24–37 g (0.85–1.31 oz), and has a wingspan of 11.0-14.2 in (28-36 cm). It is sexually dimorphic in the color of the plumage but the sexes are similar in size. An adult male is bright turquoise-blue above and somewhat lighter blue underneath but with a white lower belly. An adult female has duller blue wings and tail, grey breast, grey crown, throat and back. In fresh fall plumage, the female's throat and breast are brownish near the flank, contrasting with white tail underparts.
ID text from Wikipedia, CC BY-SA 4.0
Western Bluebird
Sialia mexicana
The western bluebird is a small stocky bird with a length of 15 to 18 cm (5.9 to 7.1 in). The adult male is bright blue on top and on the throat with an orange breast and sides, a brownish patch on back, and a gray belly and undertail coverts. The adult female has a duller blue body, wings, and tail, a gray throat, a dull orange breast, and a gray belly and undertail coverts. Both sexes have a thin straight bill with a fairly short tail. Immature birds have duller colors than the adults, and have spots on their chest and back.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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