In "The Scarlet Ibis," how does James Hurst use literary elements to portray the theme?

It is absolutely clear that one of the key literary elements that are used by the author is symbolism, and in particular, the way that the scarlet ibis in the story comes to symbolise Doodle. Note how the ibis possesses unique physical attributes, it only appears in the family's life briefly and it struggles to survive, finally dying. These are all elements that create a link between the scarlet ibis and Doodle.

Doodle himself seems to identify incredibly strongly with the scarlet ibis, choosing to forsake his favourite dessert to bury it even though, for him, to dig up a hole is a very complicated and time-consuming procedure. It is clear that he is impacted greatly by the appearance of the scarlet ibis and its death. At the end of the story, too, the narrator, Doodle's older brother, describes Doodle's body in a way that is very reminiscent of the body of the scarlet ibis:

He lay very awkwardly, with his head thrown far back, malign his vermilion neck appear unusually long and slim. His little legs, bent sharply at the knees, had never before seemed so fragile, so thin.

This is enough for the narrator to close his story with the image of his grief over his "fallen scarlet ibis" as he recognises his guilt and involvement in the death of his dear brother. Attempts to try and change others, especially when motivated by pride, are shown to cause pain and despair.