Songfacts®:

• Like many of the songs penned by Sia, this is an extended metaphor (check out David Guetta's, "Titanium," Rihanna's, "Diamonds" and Britney Spears' "Perfume"). In this instance, Sia is singing about stepping out from an abusive relationship in which she felt like a caged bird.
• Sia penned the song with Adele's "Hello" collaborator Greg Kurstin. Like This is Acting's lead single, "Alive," it was pitched for Adele's 25 album, but rejected.
  
  Adele apparently turned down "Bird" because she thought it sounded more like a Sia song.
• This song is a great example of Sia's belief in beauty over perfection: "I don't care if I sing off-key."
  
  Some songwriters aim for flawless execution, but Sia is more about the passion of the performance.
• Sia sang this on the November 7, 2015 episode of Saturday Night Live, her second turn as musical guest that year. In all of her performances, she wore a wig covering her face, and for this one she also wore an enormous bow. While she sang, the Japanese dancer Mina Nishimura did a kinetic interpretation of the song on stage.
  
  Donald Trump, who was the guest host, got a sneak peek at the dance during rehearsal and liked what he saw. "He gave me such compliments," Nishimura told The New York Times. "He said, 'Oh my God, you're so excellent and wonderful.' He seemed like a very generous person."
• Sia and Kurstin originally wrote this for the movie Pitch Perfect 2. She recalled to Rolling Stone: "They rejected it and took another song of ours called 'Flashlight.' That become a big thing through the movie, but I could not believe they rejected 'Bird Set Free' because to me it was such a big, anthemic, fun, sing-along-in-the-car song. I felt seller's remorse. I had grief. I feel connected to that song."