The diary pages are a symbol for experiential learning and the limitations of learning from others’ written accounts. While reading about how others experience something that helps, Noah takes his newfound commitment to the Secret Zoo seriously because he found it himself and made his path there; Megan started his journey, but he did it himself. This commitment to doing better, being better, and learning through experience plays into one of the novel’s more significant themes—The Need to Conserve Nature.

Megan’s diary is also an important motif that helps drive the narrative action, particularly in the opening stages of the novel. They first appear in the novel’s Prologue, where she uses the diary to complete a brainstorming session because “she’d learned about brainstorming—scribbling down ideas as quickly as possible. Her teacher had said that it was a way to make sense of something that was difficult to figure out” (5). She uses her diary to record her zoo explorations and identify all the bizarre incidents she encounters there. When Noah finds her diary through the animals in the zoo, he only recovers three pages that guide him to Podgy the Penguin, who gets him into the Secret Zoo.