Identifying juvenile large Gulls in HK is one of most difficult area that need to be studied. Author: badesc Time: 14/01/2013 00:51
Most difficult and thereby very interesting ;-).
This bird, however, does not appear to be a Slaty-backed Gull. Therefore, it would have to show different contrast on the underwing: primaries and secundaries should be pale, contrasting with the darker underwing coverts. For example: http://www.hkbws.org.hk/BBS/viewthread.php?tid=15932.
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