How does the poet use symbolism in the poem, Thirteen Ways of Looking at a Blackbird?

The poet uses the presence of the blackbird as a symbol for the passage of time. Throughout the verse the blackbird’s presence and impending absence are marked by the narrator. The bird’s movements are juxtaposed to the stillness of the landscape and are seemingly implicated in the natural rhythms of the world itself, as the twelfth canto indicates: “The river is moving. / The blackbird must be flying” (12). The blackbird is both a stark outlier in a stillness, a black emblem etched on white snow, as well as a marker of a sentience and an order other than a human-derived one.