But is it impossible?
I've not birded much in Guangdong villages in summer (not at all in fact), but they were very common in villages in Wuyuan, Jiangxi when I was there recently.
However, that is quite a way to the north I know.
Mike Turnbull.
PS more plausibly but in a similar vein, I believe I had a (Chinese) Blackbird yesterday near my home in Po Lo Che, Sai Kung, seen with naked eye as it flew along in front of my car for c 40 m on a quiet side road parallel to Hiram's Highway next to the WSD installation. Breeding locally perhaps?