The overcast sky, fading light and rather diffuse color of the bird when seen from the front created some photographic challenges. At one point it flew to a perch within 15 feet of where I was standing, but with a network of high-contrast tree branches in the background, I could not get my camera to focus on the bird. The photos show here were all taken from many yards away with high zoom, and then cropped.
The normal range of the mountain bluebird is primarily the western mountain and plains states and up the western part of Canada into Alaska in the summer breeding season. Winters are spent in the southern part of that range and well south into Mexico. Normally it would not be closer to us than the western edge of the Dakotas.
For comparison, here (below) is the male eastern bluebird, which is the bluebird we normally see in this part of the country.