The Title sympathy makes me think the story is going to to be about someone doing an act of forgiveness for someone.
The poem is about how this man feels bad for this bird that is trapped in this cage and feels like the bird and him have similar feelings of pain.
This poor bird hes just like me What should I do :(
"I know why the bird sings!" Meaning the main character has some kind of connection with the bird and it's feelings.
Throughout the poem the author brought a sad vibe to the poem and that attitude doesn't change.
In he poem the person in speaking in the poem never changes and there is no real attitude change the whole poem is generally sad.
At the beginning of the poem I thought the poem was going to be about a guy that had forgiven someone just by reading the title. It turns out that I was completely wrong that the poem is about some guy that has sympathy toward this bird in a cage because he feels as if they have similar feelings.