The Motif of the story is the color red, as you can see in the picture below the author uses it plenty of times. This is no coincidence the author uses it the symbolize death and blood.
The main theme of this story is that pride and selfishness can get in the way of love. In the cartoon below the older brother is pushing Doodle to the max but not because he loves him its because he wants a "normal" brother.
The Imagery in the story is the scarlet ibis because it is out of its place in North Carolina just how Doodle is in the world. The cartoon below demonstrates the time when Doodle realizes that him and the scarlet ibis are alike.