Yes, it is an early record. The previous earliest was on 20th August 2013, according to the 2013 HKBR.
I have heard of a few very early sightings so far this year - it seems migration has started earlier than usual for some reason.
Welcome to HKBWS Forum 香港觀鳥會討論區 (http://hkbws.org.hk/BBS/)
Image Attachment: aug_17_15_1.JPG (17/08/2015 22:40, 154.01 KB) / Download count 530