Out of interest, how do you identify this as a
baicalensis White Wagtail? My understanding was that
baicalensis is a pale-backed race (i.e. similar to
ocularis), whereas these birds seem to me to be fairly dark-backed (more similar to the colour of a female
leucopsis).
Of course, the head pattern does not fit with
leucopsis, showing much too black, but surely the darker ear-coverts also do not fit very well for
baicalensis? This photo suggests that
baicalensis not only has a somewhat different head pattern, but also suggests that it shows more grey on the flanks than the Po Toi birds seem to show:
http://nomadicjourneys.com/press ... e=inline&id=369
I would be interested to hear some feedback. I am not trying to say these birds are definitely not
baicalensis - certainly it is a feasible migrant to Hong Kong - but I am slightly puzzled that they do not fit with my expectations for that subspecies. Geoff's suggestion that they seem to be associating with
leucopsis also seems intriguing (OK, so that may just be due to them associating with the most similar bird they can find, but it's not something I notice with e.g.
ocularis and
leucopsis).
