Duke was his father who is at the beginning.
Duke was James's father. He was shown at the beginning, but James doesn't know where is the eagle. They know the eagle was a dangerous animal and the eagle was flying everywhere in the sky. When Duke doesn't know where is the eagle. The eagle comes and eats Duke but James is about to cry so sad. Elizabeth comes and says "Hello, James." and he sees his mother named Elizabeth.
Duke is a blue gooball that he is James's father.