Later in the film , Walter starts to question whether he is man , which he was believed to be his entire life , or actually a Muppet , which was why he always felt a strong connection towards them . This emotion eventually leads him to sing the Academy Award - winning song , `` Man or Muppet '' , where the human version of Walter is portrayed by actor Jim Parsons . The scene is pivotal to the character 's arc as it resolves Walter 's internal issues with himself . The character 's solo act of whistling in the telethon 's finale was performed by musician Andrew Bird . At the conclusion of the film , Walter deduces that he is a Muppet , adopts whistling as his sole talent and joins the group as their newest member .

Question: who did the whistling in the muppet movie
Answer: Andrew Bird