There are many different aspects of style that could be selected to talk about, however one of the most interesting to my mind is the final paragraph that comes at the end of the story, when the narrator addresses Nature itself, appealing to it to confide in Sylvia, who has chosen companionship with Nature over companionship with her own kind. Note how this paragraph ends:
Were the birds better friends than their hunter might have been--who can tell? Whatever treasures were lost to her, woodlands and summertime, remember! Bring your gifts and graces and tell your secrets to this lonely country child!
This is actually an example of pathetic fallacy, which is the assumption that nature itself has human feeling and cares about the suffering of humans. The narrator addresses Nature, in the form of "woodlands and summertime," on behalf of Sylvia, who has sacrificed so much to protect the white heron. Sylvia, as the name suggests (it means "wood" or "forest"), is identified with nature throughout the novel, and if we examine the section where she climbs the tree to locate the white heron's nest, we see that the great tree is even shown to help her climb up. Thus perhaps it is not incongruous for the story to end with the narrator's appeal to Nature to be the friend to her that she has just sacrificed by refusing to divulge the location of the white heron's nest to the hunter.