The robins can be seen as signifying a correlation between Sula and the irrepressible forces of nature.
Sula returns to Medallion in 1937, ten years after Nel’s wedding, and her presence in the town brings a new and invidious life to the town.
“Accompanied by a plague of robins, Sula came back to Medallion. The little yam-breasted birds were everywhere, exciting very small children away from their usual welcome into a vicious stoning.”
Where once there was a quiet distance between neighbors, between parents and their children and between wives and their husbands, Sula’s behavior inspires an almost violent closing of the guard.
The robins that arrive in town with Sula upon her return to Medallion are one of the numerous curious atmospheric elements in the novel. They are symbolically associated with Sula but are also part of a system of signs that function as a magical-realism motif, situating the action of the tale within a world defined by a specific relationship between man and the forces of the natural world.
“Nature was never askew—only inconvenient. Plague and drought were as ‘natural’ as springtime. If milk could curdle, God knows robins could fall. The purpose of evil was to survive it and they determined (without ever knowing they had made up their minds to do it) to survive floods, white people, tuberculosis, famine and ignorance.”
In this light, we can see the robins as an indication that Sula is a force of nature in her own right. She follows an inner truth, as her mother and grandmother also do, in ways that keep her out of step with cultural norms. She embraces the fact that she has an inner life and this self-embrace turns her into something of a cannon ball shot through the town of Medallion.
Sula breaks up marriages, sleeping with men only to cast them off. She puts her grandmother into a retirement home, which is against the code of the culture.
She turns everything upside down. And so, in her return to town she brings an inverted spring where new life is created in relationships across Medallion so as to defend them from destruction. People bond to protect themselves from Sula. She is a plague to be endured and, in the end, the people endure.
“In their world, aberrations were as much a part of nature as grace. It was not for them to expel or annihilate it. They would no more run Sula out of town than they would kill the robins that brought her back, for in their secret awareness of Him, He was not the God of three faces they sang about. They knew quite well that He had four, and that the fourth explained Sula.”
When Sula dies, winter strikes with a fury. The force that had beset Medallion and brought the people together in a protective unity is removed. The bonds begin to weaken and break. The changes that Sula had wrought in the town are undone.
As a person aligned with a personal nature and also with a sense of nature at large, in all its mysterious power, Sula functions as a social pressure on the rest of the town. This highlights the notion that many people in Medallion are probably out of touch with any internal sense of self. They think and act on a superficial level, mindful of gossip and local customs but unaware of the life that exists in them below the surface.
When Sula dies and the pressure she exerted on the town is gone, the inner life of the town that has been frozen over by years of rigorous denial comes bubbling up with the new year. The people find that, like Sula, they have an aimless, violent energy that needs to be expressed.
The “plague of robins” which accompanies Sula into town foreshadow the plague of deaths that will come later in the book. The four robins on the walk into Eva’s home symbolize the deaths of the residents of the house: Plum, Sula, Hannah, and Eva.
The plague of robins announces the return of Sula. She embodies an ill-spirited woman and prodigal daughter of the town Medallion. Morrison uses the birds as a foreshadowing effect of evil to come, while upholding Sula as an unnatural force of nature.
The robins allow Sula to be depicted as evil when in reality she has no say in what the robins do or when they come. The robins are viewed as a sign of evil and from there on since Sula is not liked by those at the bottom, others view her as evil. Such as when Shadrack tipped his hat at her and others believed that she was the devil.