The title of the chapter, “The birds of negative space,” is explained on this page.

Since “there are no birds in the Winter City,” S. dreams of a blackbird who is shot, but when it bleeds out, it becomes a “white, raven-shaped husk in a cold expanse of black.” Dorst’s use of negative space may hint at the concept of literary negative space. When you have enough clues, you can use process of elimination to find the truth. This blog post shares some examples of literary negative space in S.