The striped feather extends straight up from the dancer's head, nearly doubling her height. As she moves, it moves in response, bending like a reed in the wind, rippling like an eel. In Chinese opera, pheasant tail feathers, called ling zi and usually worn in pairs, identify a warrior character. The plumes aren't just decorative; their waving and quivering express mood and emotion. But in "Birdy," by Taiwanese contemporary dance company Hung Dance, the feathers take on more functions.