What do birds symbolize in the novel, Miss Jane?

Birds are the dominant symbol throughout the entire novel, so much so that the cover of the novel is taken up by a single peacock. Wherever a character may be, the narration will frequently call attention to the birds that are in the environment, whether they may be irritably squawking or soothing somebody to sleep. In the closing scenes of the book, Dr. Thompson and Jane look at the doctor's flock of semi-wild peacocks and reflect that, in ways physical and spiritual, Jane herself is similar to birds.