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.
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 at Kadoorie Farm. ill be posting more on that later.
I went to the butterfly garden at Kadoorie Farm in late October this year and found that two males were having a dispute over territory, with mid-air fighting. The following photos were extremely difficult to capture, and please excuse the quality, but I think it shows this behaviour, and also the damage they inflict on each other.
clickon the images below for a larger view of the fight