That’s a Mountain Bluebird, as seen by West Seattle photographer Mark Wangerin. He tells WSB, “Although rare on this side of the mountains, a few have been seen west of the Cascades in the past few weeks. There are 3 (all males) along the Duwamish by South Park. What a treat! I was going to go east of the mountains this week searching for them.” They are “the most migratory of the bluebirds,” Seattle Audubon explains here.
West Seattle, Washington