Nature and technology paired in one program: Merce Cunningham’s Beach Birds (1991) and BIPED (1999). Beach Birds draws on deep observation of that serene species of the eastern coast, Laughing Gulls. As for BIPED, “The dance gives me the feeling of switching channels on the TV,” Cunningham said, and there is something vacuum tube about this dark and eerie dance, choreographed with computer software. These are must-sees by master Merce. —L.J.