james4j

I took it at Long Valley yesterday afternoon.

ajohn

This is a white wagtail of the subspecies ocularis, a regular winter visitor to Hong Kong.
Note the obvious black eye-stripe, pale grey back and mostly dark wing coverts.

The lugens subspecies (a rare winter visitor, although with several records recently) has a similar eye-stripe, but the back is black (or very dark grey) and the wing coverts are pure white.

james4j

Thanks very much, John.