I encountered this same Copperhead Racer 3 times in Con Dao Island Vietnam. 1) slithering at the edge of a small stream near a rice field. 2) swallowing a smaller snake near bushes at the same stream 3) in the rice field 15 meters from the stream. The last time I photographed its head close up before it fled for the stream. As I chased and photographed it full length and tried pinning it down gently with a stick for closer look, it turned and lunged with its upper body lifted high and its neck widened like a vertical flap. It made off into the stream. About 180cm long.