There are two species of Birdwings in Hong Kong, and these are the only two butterfly species protected by law; they are the Common Birdwing and Golden Birdwing, which are visually very similar.
These images were shot in Fanling just a few weeks ago .
The images below were shot last year in Kadoorie farm.
They are the largest butterflies in Hong Kong (hence the name), and both have large wingspans, of 12-16cm. Probably the best place to see them (and a place where both species are present) is at Kadoorie Farm. They also have a spectacular caterpillar which i have also found and photographed also at Kadoorie Farm.
I went to the butterfly garden at Kadoorie Farm on May 3rd 2018, to give a quick instruction on capturing insects in flight (which was hard, as it was overcast) and took the following photos of the Birdwing in flight.