Recall that these are seen in our area (California) as migrants during the winter months. Well, in California there are populations that do what is called "vertical migration": migrating from high elevations to low elevations in winter. In spring they return to the high elevations to nest. This young bird is this year youngster in moult into adult plumage. At this stage only the tail (rectrics), and wing(remiges) feathers are adult. Remember that this little bird usually has a solid black head, when we see them in winter. That will happen in the second moult. Taken at 7000 feet; Green Horn summit.
