Birds are everywhere in Sula, and they are often associated with specific characters. When we meet Rochelle, she wears a "canary-yellow dress" and has the "glare of a canary" (1920.40-3.41). And we already know that a "plague of robins" (1937.1) arrives in Medallion just before Sula does. Birds invoke the idea of flight, which makes sense when we consider that Cecile and Sula both flee at some point in the story. And robins are often associated with the spring, the season of rebirth and growth. Although Sula brings with her a lot of pain and destruction, we learn that her presence also generates a renewed sense of purpose in the Bottom, even if it is directed against her.
We can again turn to Rochelle and Sula for this one. When Nel meets Rochelle, she notices that she smells like gardenias. Sula has a birthmark shaped like a rose, and "The Rose Tattoo" is the source of the novel's epigraph. These particular flowers are beautiful and fragrant, even intoxicating. Rochelle intoxicates the young Nel, and Sula intoxicates the many men around her. These characters are also a little dangerous in that they disrupt the lives of the people they encounter. But the thing about flowers is, once they're picked, they don't live for very long. Just as the flower's beauty is fleeting, so too is the presence of both of these women in the novel.
Fire appears throughout the novel and results in the deaths of Hannah and Plum. There are many possible meanings of fire, one of which is the idea that it is cleansing. When Eva douses Plum in kerosene (before the fire, but still applicable we think), he feels like he's undergoing "Some kind of baptism, some kind of blessing" (1921.49). And when Hannah dies in a fire, it's possible that this somehow cleanses Sula of a mother who is at best indifferent and at worst admits to not liking her daughter.
Water is often associated with death in the novel. For Sula (and Nel, to a lesser degree), it represents Chicken's horrible drowning. Fire might be a cleansing force, but water engulfs and consumes the young boy. Water doesn't comfort Sula but rather agitates and upsets her because of her responsibility for Chicken's death. At the end of the novel, one of the townspeople who die in the tunnel slides and hits the ice below.