The falcon's "pride of place" is the highest point of its flight, in reference to Duncan it suggests that he was rightfully there and Macbeth is traitorous. The owl, which usually catches mice on the ground, went up instead of down, and killed a falcon. Also, a falcon is a day creature, and a royal companion, while the owl is an untameable bird of night and death (connotations of this). Shakespeare includes this to present the dangers of regicide, showing how it was an unnatural act and so much so that it has made nature itself reverse. Mirrors Macbeth and Duncan.