Explain how the author creates the tone in "The Scarlet Ibis."

James Hurst's short story, "The Scarlet Ibis," is a wonderful work from which to explore tone. In literature, tone refers to the attitude a writer has toward their subject. It is conveyed primarily through diction (word choice) and style.
The tone of "The Scarlet Ibis" is nostalgic, wistful, sad, and, at times, heart-warming. James Hurst sets the tone right from the start. Consider the opening two paragraphs:

It was in the clove of seasons, summer was dead but autumn had not yet been born, that the ibis lit in the bleeding tree. The flower garden was strained with rotting brown magnolia petals and ironweeds grew rank amid the purple phlox. The five o'clocks by the chimney still marked time, but the oriole nest in the elm was untenanted and rocked back and forth like an empty cradle. The last graveyard flowers were blooming, and their smell drifted across the cotton field and through every room of our house, speaking softy the names of our dead.
It's strange that all this is still so clear to me, now that summer has long since fled and time has had its way. A grindstone stands where the bleeding tree stood, just outside the kitchen door, and now if an oriole sings in the elm, its song seems to die up in the leaves, a silvery dust. The flower garden is prim, the house a gleaming white, and the pale fence across the yard stands straight and spruce. But sometimes (like right now), as I sit in the cool, green-draped parlor, the grindstone begins to turn, and time with all its changes is ground away—and I remember Doodle.

The first paragraph is filled with imagery that foreshadows the tragic ending of this story. Hurst describes "rotting brown magnolia petals" and ironweeds that have grown rank. He gives readers an image of an empty bird's nest and compares it to an empty cradle. This all sets a tone of loss, sadness, and remembrance.
In the second paragraph, Hurst becomes nostalgic. "The grindstone begins to turn, and time with all its changes is ground away—and I remember Doodle." 
In the lines that follow this, Hurst's tone changes to a fond remembering as the narrator describes some heart-warming times with his brother. Consider the words of the next paragraph: "Doodle was just about the craziest brother a boy ever had." He goes on to say he wasn't crazy-crazy, but a nice crazy. This shows that he is remembering his brother with fondness. He goes on to describe happy times with Doodle. He develops the tone through dialogue and description. In the following quote, Brother, who narrates Hurst's story, describes how his brother got the nickname Doodle.

"Crawling backward made him look like a doodlebug, so I began to call him Doodle, and in time even Mama and Daddy thought it was a better name than William Armstrong."

In my opinion, one of the most compelling things about this story is the imagery, and it certainly helps to set the tone. One of the great images of this story is when the scarlet ibis lands in the bleeding tree. The image of the bright red bird dying in a tree whose sap is the color of blood sets a tone of loss and sadness. Then, Hurst uses a metaphor in the last lines of the story to refer to his dead brother as his "fallen scarlet ibis," with the image of the red bloodstain down his chest. There is also vivid imagery when Brother shows Doodle his casket, which is made of mahogany wood and covered with Paris green (an insecticide).
Brother narrates throughout the story that he was motivated to push his brother out of pride, and his word choice shows that he feels responsible for the loss of his brother.