Polyneices is being compared to an eagle.
Polyneices means "manifold strife" or "much strife." He was the son of Oedipus and Jocasta and the younger brother of Eteocles. When his father, Oedipus, was discovered to have murdered his father and married his mother, he was expelled from Thebes,enabling his sons Eteocles and Polynices to rule. As a result of a curse put on them by their father Oedipus, the two sons did not share the rule peacefully and consenquently, passed away killing each other in battle for control over Thebes.