Lady MacDuff also refers to herself as the "most diminuitive of birds" that would fight the "Owl" MacBeth to the death in order to protect her young. We know that a mother bird would fight to the death in reality to protect her chicklings and this is what Lady MacDuff was alluding to after she had found out that MacBeth may try to kill her and her children to get MacDuff to return.
Both stories also deal with the human connection to the animal kingdom. The description of the boys on the island gets increasingly naturalistic as they lose civilization. They leave their clothing behind and begin to behave like pack animals, seeking to attack prey and feed rather than adhere to order. In Macbeth, Shakespeare uses animal imagery throughout the play to demonstrate that the desire to conquer is the barbaric part of human nature. Lady Macbeth refers to the serpent and the raven, for example, when discussing the plot to murder King Duncan.
While the ambition for power is a theme shared by the play and the novel, and Jack and Macbeth both become corrupted by their desire for power, the two stories end differently. Order is restored in both cases: in Macbeth, through his death in a battle with Macduff definitively carrying on stage the head of the dead Macbeth, but in Lord of the Flies the arrival of a ship interrupts a battle and saves Ralph’s life. Macbeth is more optimistic: the tragic hero learns his lesson before he dies, and we know goodness will rule. In Lord of the Flies, we are not so sure, for when the naval officer looks away from Ralph’s tears and out at sea, Golding seems to suggest that the violence the boys lived is a fundamental part of human interaction that will not go away.
A major theme to Macbeth is that blind ambition is bad and will only result in destruction. In Lord of the Flies, we also see how ambition, especially the drive for power, can cause corruption. Jack becomes more and more savage with the more power he has over the boys. Before the boys are rescued in the final pages of the book, Jack is so savage that he wants to kill anyone who opposes him, namely Ralph. Macbeth became so corrupted by power once he had it, he was willing to do anything to hang on to that power including killing Macduff's family.