Birnam Wood is heavily influenced by Shakespeare’s play The Tragedy of Macbeth (1623). The first and most obvious influence is the title and name of the organization, which in Macbeth refers to the forest outside Macbeth’s castle and one of the prophecies that he dramatically misunderstands. It states that he will not be vanquished until the trees of the wood come to fight him, which he arrogantly interprets as impossible. Much like Macbeth, Lemoine assumes that Birnam Wood is no threat, as it’s small, poor, and insignificant. Misinterpreting and misjudging Birnam Wood contributes to the downfall of both characters.

Another similarity is the idea of open-source information misleading people. In an interview, Eleanor Catton refers to the witches’ prophecies in Macbeth as “open-source information” rather than magical predictions. If Macbeth had carefully considered the predictions, the two big surprises in the play wouldn’t have happened. It’s not hidden information that an invading army will choose the surrounding wood for cover, or that Macduff was born by cesarean (and hence kills Macbeth—Macbeth believes that he cannot be killed by any man born of a woman). Macbeth had access to those facts. Catton’s characters use and interpret open-source information such as property descriptions, online biographies, news articles, cellphone data, and tracking apps to suit their own purposes.