Story of the gods
Aristophanes uses Aesop's tales of the beginning of creation and the gods on earth in order to show that the birds have first rights to be gods. This is a metaphor for how many use stories of mythology to create their actual authority in life on earth above others.
Feed in Gardens
Tereus says that in Birdland, "we feed in gardens on white sesame, myrtle-berries, poppies and bergamot." This is a metaphor for the sexual appetites of the men there as the flowers represent women and an unrestrained way of living.
The gods
The gods, Poseidon, Heracles and Triballians arrive and quickly concede both of Zeus' main sources of power in order that they would be able to receive sacrificial offerings and no longer starve. This is a metaphor that the gods need man in order to survive as much as man needs the gods.
Sovereignty
The Princess is said to be Zeus' greatest weapon, even greater than his lightning bolt. The Princess represents Zeus' sovereignty, which is a metaphor that love is actually the greatest ruling power.
Half-Transformed
Peisetaerus and Euelpides both are transformed into birds by Tereus. But, they are only partially transformed. This is a symbol that these are no longer men, and only half birds. Though they seek to escape one form to become another, they are only capable of going so far in their metamorphosis.
