I saw two adults & a juvenile at LV on May 30th. They were feeding in the fields near Yin Kong, and I saw them later in the valley further to the north.
This was the first time I'd seen this family party at LV - although I'd made several visits in April/May. In fact, the last White-cheeked Starling I'd seen there before May 30 was a single bird bathing with Red-billed Starlings on March 17th.
So I'd agree with Tony that they didn't breed in LV itself and - although they may have bred nearby - it's difficult to say quite how "local" they really are.
david
