These are wonderful shots of Common Rat Snake's mating display.
Apart from the Burmese Python(which is much fatter and very distinctively patterned), this is the only snake in HK which can be as long as a King Cobra. You can see in the first shot that the snakes flatten their necks, but the other way from a cobra.
I saw this display once at Mai Po in Pond 11 a few years ago, and more recently at Nam Chung, but it is not a common site in Hong Kong.
Cheers
Mike K
Mike KilburnVice Chairman, HKBWSChairman, Conservation Committee