In this scene from the very beginning of “Life in the Iron Mills,” the narrator uses anthropomorphism to link the image of a woebegone canary to the idea of impoverished mill-workers. In addition to being an affecting image, it’s also an important part of the short story’s frame narrative:
Smoke everywhere! A dirty canary chirps desolately in a cage beside me. Its dream of green fields and sunshine is a very old dream,—almost worn out, I think.
“Life in the Iron Mills” begins and ends from a slightly different perspective than the bulk of the writing. The narrator “frames” the story of Hugh, Deb, and the Kerl-woman’s statue as part of a larger commentary on the brutality and injustice of industrial life in 1800s America. The frame story structure allows the narrator—who exists outside the primary narrative—to reflect on the conditions caused by the mill and places like it. In moments like this description of a canary, the narrator can draw analogies between their “real” world and the stories they recount about the mill workers. By adding this layer of removal, Davis increases the emotional impact of the story for the reader, while also providing a good deal of context and narrative commentary to guide them.
In this passage in particular, Davis uses anthropomorphism to attribute the human-like emotions of desolation and longing to a canary the narrator owns. By suggesting the bird has dreams of “green fields and sunshine,” the narrator implies that it’s pining for its natural habitat, one that’s very different from the smoggy mill town. In so doing, they also show that the canary's innate instincts for freedom are being suppressed by its environment. This, in turn, reflects the fact that the workers' desires for a better life are stifled by the mills. The canary's hope being "almost worn out" mirrors the waning hope of the mill town's inhabitants. Like the canary, they are trapped in an environment that’s actively hurting them physically and emotionally.