What inference can you draw from the text to explain why the bird hurts himself in this way?

From the text, we can infer that the caged bird is desperate and filled with despair. The author also illustrates the way in which the bird beats its wings against the bars of the cage, personifying the bars as cruel. In line 10 & 11, the speaker confirms the bird's desire, citing that after beating its wings against the bars of the cage, the bird is forced to retreat to its perch "when he fein would be on the bough a-swing".