Due to the older brother's pride, he pushes Doodle past his breaking point trying to teach him how to walk.
The swimming, running, fighting, and climbing is all too much for Doodle. The older brother should stop, but he is ashamed of Doodle's disability. Once again, his pride causes him to proceed.
One day, the work is finally so strenuous that Doodle is forced to stop. The older brother's pride and selfishness causes him to run away from his younger sibling. Doodle tries to follow, but is hit by exhaustion, and dies underneath a tree.
There is a scarlet ibis that dies under a tree in the family's yard shortly before Doodle dies. The imagery of the bird has intense similarities to Doodle. They die in the same position, are both very rare, and Doodle has a deep connection with it.
Doodle has put off a reddish hue since the moment he's been born. Red is a color that represents anger, love, danger, or warning, all of which are emotions shown in this story. The scarlet ibis is also red. All these connections hint that death is about to come.
There are storms in this story that are also symbolic. The first storm that is mentioned led the scarlet ibis all the way from his far away home to the yard of the family, where it died. The second storm happened the night Doodle died of exhaustion. The storm can be looked at as representing the brother: the storm killed the ibis, and the brother caused the death of Doodle.