Grief and Loss is Swamplandia!’s most overt theme, and it emerges within the first few pages of the narrative. Readers learn that Hilola Bigtree, mother to siblings Ava, Osceola, and Kiwi, has recently died of cancer, unexpectedly and at a young age. Learning to cope with the loss of their mother will become an important process for the Bigtree family, and each of the children will handle Hilola’s death in their own way. Ava, the novel’s protagonist and an introspective 13-year-old, will ruminate over memories of her mother, and ultimately learn how to incorporate her mother’s advice into her everyday decisions and life choices. Her sister Osceola will experience melancholia and will turn to spiritualism and the occult in an effort to remain in contact with Hilola. Kiwi, although not as grief-prone as his sisters, will still experience pangs of sadness, but will, more so than anyone in his family, understand how to move on.

Ava narrates much of the novel, and the reader thus has access to her perspective more so than that of her siblings. She is a solitary, reflective child, and at the beginning of the novel she is still reeling from the loss of her mother.