In spring, male Adders perform a 'dance' during which they duel to fend off competition to mate. The 'dance' is in fact a test of strength and stamina, with each male trying to force the other to the ground. Ryan Greaves filmed this amazing Adder dance on the Downs. Ryan said "It was a dream come true encounter with a pair of dancing Adders. Had them wrestling at my feet for a good twenty minutes. The winner eventually curled up around the female who was sat nearby". https://sussexwildlifetrust.