Interesting findings
Finding No 1:
The differentiation between white-winged and black tern was depicted on P189 of Encyclopedia of European Birds as follows:
" These two species can be told apart very easily in summer plumage, however, because as its name suggests, the White -winged has prominent white wing coverts. Even during the winter, whereas the Black Tern has a consistent black cap, the head markings of its white-winged relative are reduced to pale black streaks extending back behind the eye, with an isolated black spot on each side of the head behind the eye."
Based on the above way of differentiation, the photo taken should be a white-winged rather than black tern.
Finding No 2:
According to P.104 of A Checklist on the Classification and Distribution of the Birds of China(Second Edition)with ZHENG Guangmei as Chief Editor, Black Tern was found in Hong Kong as well. So even if a Black Tern was found in Hong Kong, it was not a Hong Kong First. What a mystery!!! Who was the person who had found the Hong Kong First Black Tern and when was that??????
Looking forward to hearing any expert advice.
