Kadoorie Farm and Botanical Gardens do a lot of good work for animal rescue in Hong Kong. This is a crested serpent eagle (Spilornis cheela), a medium-sized bird of prey, that has been at the farm for some time. she was called Shan, but has since passed away since these photos were taken.
These lovely birds have a large looking head with long feathers on the back of the head giving them a maned and crested appearance. The face is bare and yellow joining up with the - word for today: ceres (This is a waxy structure called a cere -from the Latin cera, which means "wax"- which covers the base of their bill. The cere is typically bare and often brightly colored).
Here is a juvenile...
You can also see the powerful feet are unfeathered and heavily scaled. They fly over the forest canopy on broad wings and can often heard calling with a loud, piercing and familiar three or two-note call.