In the last line of the second to last paragraph in the story, the author writes,
"Sylvia cannot speak; she cannot tell the heron's secret and give its life away."
Sylvia's only friend, the pleasant young hunter who has come to her house in hopes of finding and shooting the great heron that inhabits the area, is going to leave, and has asked Sylvia to tell him where the heron can be found. Sylvia knows, but after much agonizing, finds that the loyalty she feels for the heron, as it represents the natural world, is greater than her longing for human contact. Sylvia cannot speak because to do so will be a betrayal of the heron and all she holds dear.
Sylvia had never been one to talk very much. Shy and retiring by nature, she is "a little maid who had tried to grow for eight years in a crowded manufacturing town," but she did not blossom until she came to live at her grandmother's farm. Having been overlooked in a "houseful of children," Sylvia is "afraid of folks," and has memories of a "great red-faced boy who used to chase and frighten her." On her grandmother's farm, she has no companions, and becomes very close to the animals and the land in compensation.
When the young hunter comes to her grandmother's house, Sylvia is at first intimidated, but then is drawn to him. There is within her a longing for human interaction which has never been fulfilled, and thus when she is faced with the choice between making her new friend happy or saving her beloved heron's life, the dilemma is agonizing. Looking deep within herself, Sylvia recognizes that, in the final analysis, her loyalty to the bird is greater than her love for the man, and so when she has one final chance to give the hunter what he wants, she remains silent, unable to speak the words that will mean death for her beloved heron and the world it represents.