One way that Doodle and the ibis are similar is that they both meet their tragic fates alone. Despite the time he spends helping his brother learn to walk and prepare for school, the narrator ultimately succumbs to his “streak of cruelty” and leaves Doodle behind in the storm. Similarly, the ibis is separated from its flock and meets its demise in an unlikely space. Even the narrator muses on the bird’s unusual fate:

How many miles had it traveled to die like this, in our yard, beneath the bleeding tree?

Similarly, Doodle works hard with his brother to improve his mobility and catch up to the other children’s development. Yet, when the storm poses a challenge that the boys did not anticipate, Doodle’s brother surpasses him simply because he can. The ibis’s fate represents the natural order in which some animals do not survive; however, Doodle’s thoughtfulness and compassion—shown throughout the story as he admires nature’s beauty, tags along with his moody brother, and volunteers to bury the ibis—is meant to remind the reader that humans can differ from this natural order in their behavior. While both Doodle and the ibis die alone in this story, their symbolic connection reminds the reader that humans are able to help one another when situations are complicated and that no one has to face their struggles alone.

Both the scarlet ibis and Doodle demonstrate great strength and tenacity. The bird has flown far from its origins in the tropics, perhaps driven by a need to explore more of the natural world than what exists near its home. Like the bird, Doodle is driven to explore nature despite his parents' early protests that he not exert himself too much. He and his brother thus spend much of their time in the "cool greenness of Old Woman Swamp." Both the bird and Doodle defy expectations, accomplishing greater physical feats than are expected of them.

Yet they also prove similar in their outcomes. Though the bird navigates itself all the way to North Carolina, the journey proves too much for its body. Exhausted from its effort, its wings hang loosely at its sides as it tries to maintain its position in the tree where Doodle finds it. Likewise, Doodle is unable to maintain a pace with his brother as they attempt to outrun the storm in the ending. When he gets out of the boat, the narrator notes that Doodle looks "tired" as he collapses into the mud. His fall is similar to the fall of the scarlet ibis, a final predictor that his physical struggles have become too much to bear.

Neither the scarlet ibis nor Doodle are well-suited for their environments. The bird has migrated beyond the realms of a habitat which is well-suited to supports its unique physical needs. Doodle has physical challenges which set him apart from the world around him. Though he attempts to be the brother the narrator wishes him to be, Doodle's physical challenges prove incompatible with that environment; he dies as his body succumbs to the environmental stresses which it is not capable of overcoming.

In James Hurst's poignant story of two brothers who compete against time, there are similarities between Doodle and the scarlet ibis.

The brother is six years old when Doodle is born in a caul, an amniotic membrane that encloses his tiny body. It is a membrane not unlike the transparent protein membranes of a bird's egg from which the ibis emerges. Later in the narrative, when the scarlet ibis lands in the bleeding tree, he perches in a precarious position, trying to flutter his wings in an uncoordinated manner. Suddenly, he becomes unable to hold himself up, and the bird falls to the ground. In death, its legs are crossed and its thin feet curved.

After rowing their boat ashore against the tide, Doodle is unable to run as fast as his angry and disappointed brother who hurries ahead in a storm. Although he tries to keep up with his brother, much like the poor bird, Doodle collapses, with his knees drawn up to hold his head. When the angry brother calms himself and turns back for Doodle, he finds his brother in a similar position as the collapsed bird, and he knows Doodle is dead: 

He had been bleeding from the mouth, and his neck and the front of his shirt were stained with a brilliant red.

The brother screams against the noise of the storm, throwing himself to the ground above Doodle. After lying there and crying for a long time, he gathers his brother in his arms.

I lay there crying, sheltering my fallen scarlet ibis from the heresy of rain.

Both Doodle and the scarlet ibis are too delicate for worldly storms.

Doodle and the Scarlet Ibis are similar in that both are rare and fragile beings.  Beautiful in their own way, yet oddly different and unusual.  The Ibis is red and in the end Doodle is left in a twisted pose similar to the Ibis and he, too, is red with blood.

The bird and Doodie are both different.
They are both rare.
They are both out of place, and fighting environments that are hostile to them.
They both die.
Both are red (the bird is red; Doodie bleeds).
Doodie "floats" above the expectations of others as the bird flies over head.