What do the hunter and the white heron symbolize in “A White Heron?"
There is definitely a dichotomy or a binary opposition set up here between culture and nature. This opposition is also suggestive of the town and country duality. The White Heron represents nature. The White Heron is in its natural habitat. The hunter is the intruder. While he is polite, his presence and action threaten the purity and sanctity of nature and the world where the White Heron is not threatened.
This is why it is significant that Sylvia refuses to tell the hunter where the bird is. Initially, she wants to please the hunter. She is also lured by the promise of money. This lure of material wealth and/or possessions is often linked with notions of city (and town) life as opposed to country life which is more often associated with notions of simplicity and nature. In the end, Sylvia proves to be more like the White Heron than the hunter. She sides with nature in this choice between material culture and the natural world.
She was just thinking how long it seemed since she first came to the farm a year ago, and wondering if everything went on in the noisy town just the same as when she was there, the thought of the great red−faced boy who used to chase and frighten her made her hurry along the path to escape from the shadow of the trees.
Note that, early in the story, Sylvia "had to hunt" for her cow. The author uses the word "hunt" but when Sylvia "hunts" she is playing a game with the cow, treating the cow like a playmate (like a person). Thus, Sylvia looks at nature's creatures as her equals. The hunter hunts to kill and make a profit. Sylvia has a kinship with nature and the animals that overrides her desire to please the hunter or to make money. She feels like a part of nature:
She was not often in the woods so late as this, and it made her feel as if she were a part of the gray shadows and the moving leaves.