Brown-Capped Rosy Finch The brown-capped rosy finch is another endemic bird, and has the smallest range of the three American species of rosy finch. Only found high in the mountains, it breeds above timberline. Nests are usually in crevices with plenty of shade. Mountain Bluebird The powder-blue male mountain bluebird is considered one of the most beautiful birds in the West, according to Denver Audubon. The birds may nest in tree hollows, holes in cliffs or dirt banks. During winter, mountain bluebirds gather in large flocks, sometimes by the hundreds. Violet-Green Swallow Although the violet-green swallow might look like a tree swallow, the bird’s green back and purple tail mark it as this passerine species. Its habitat runs along the West Coast from Alaska to Mexico, extending as far east as Montana and Texas.