The white-crowned sparrow must listen to and memorize other adult sparrow singing. It then copies the song it hears as well as it possibly can, then compare its own song with the one it memorized. If the sparrow doesn't hear the song at an early stage, then it can't memorize it and instead it creates it's own version of the song until it hears the adult song.
Let me know if this helped! :) Have a nice night Crissybraco5217!
