In the Old Man's dialogue in The Tragedy of Macbeth, what symbolizes King Duncan is (d.) a falcon.
In Macbeth, bird imagery is used to symbolize the characters but also to anticipate what is going to happen afterwards. In this dialogue, the Old Man reveals he feels disturbed due to a strange event: an owl has killed a falcon. While the falcon is generally associated to royalty and the day, the owl is linked to the night and mainly to death. In that way, the falcon comes to symbolize King Duncan, whom is murdered by Macbeth, the man that represents the owl.