In J.D. Salinger's novel, "The Catcher In The Rye," the ducks in the Central Park lagoon reveal a youthful side of Holden that the audience rarely sees. Holden, who is often grim, grumpy, and angry throughout the book, wonders what happens to the ducks in the winter once the Central Park pond freezes.
His concern over where the ducks go and his joy when they return represent a youthful curiosity and joyfulness in exploring other matters in a character who generally lacks these qualities in other parts of his life. The ducks also convey that change is cyclical rather than permanent. The fact that they return brings hopefulness to Holden as he deals with the death of his brother.