When does a snake "dance"?

Snake's "dance" - there are two occasions when a snake will "dance' both connected with the mating season. In the first case the dancing partners are both male and their performance appears to be a form of aggression designed to impress the female. The second occasion is a nuptial dance between male and female. First the snakes pursue each other and coil together. Then the couple raise their necks and heads as if forming the shape of the letter U. During the dance, which may last an hour, the male rubs its chin against the female's neck. The nuptial dance occurs mainly among European snakes, but the males dance of aggression is to be seen all over the world especially among rattlesnakes, adders and cobras.