Do you want to compare Birdy with Sif? Discover the powers, weakness & weapons of Birdy and Sif from Birdy Biography and Sif Biography. Find out all about Birdy and Sif.# Check out how is Birdy unique and distinct from Sif. Discover their love interest, sidekicks, family tree and the movies and games list in which Birdy and Sif have appeared. Find out everything about them here!