This is the biggest starling in Hong Kong, and is easily identified both with a broad black collar on its neck and it has a patch of yellow naked skin on its face. It is of course the BLACK-COLLARED STARLING 黑領椋鳥 . Gracupica nigricollis
This bird is gregarious and very noisy when roosting communally, with lots argy bargy like in the photos below, taken from my rooftop.
Establishing the pecking order...er, literally.
