Lyric discussion by ChokingOnStars 

Cover art for Bird Song lyrics by Florence + the Machine

I think the song is about a woman who did something she deeply regrets (murder?). The bird being a manifestation of her guilt. She goes back and forth with this crushing guilt to the point it gets so bad she "broke its neck" possibly meaning she ended her guilt in a very permanent way.

My Interpretation
Negative
Subjective
Sadness
Guilt
Regret
Violence
Conflict
Resolution