First found in this area by Sharon Hull on 14 November, this is an example of the race M. a. lugens which breeds in Japan and the Russian Far East. It is a rare but regular stray to Alaska (Aleutians) but very rare as a migrant and winter visitor to California. However there have been at least seven California White Wagtails this year. The subspecies lugens can be identified by a combination of dark eyeline and extensive white in its wings as seen here. This is a bird of particular interest to me, having written a research paper many years ago that temporarily resulted the AOU elevating this bird into a separate species called Black-backed Wagtail (M. lugens). Subsequent genetic work by Voelker (2002) found that lugens and ocularis were polyphyletic with respect to each other. I thought that would support them being separate species but Voelker said (in litt.) that they needed to be reciprocally monophyletic instead. Apparently Voelker follows the genealogical species concept. Reciprocal monophyly sounds awesome, but I have been advised that it is always just one sample away from being reversed.
Canon PowerShot SX70 HS