It has been argued that The Birds has suffered more than any other Aristophanic play from over-interpretation by scholars. Political allegory featured prominently in 19th century interpretations: Cloudcuckooland could be identified with the Sicilian Expedition as an over-ambitious scheme, Athenians could then be identified with the birds, and their enemies with the Olympian gods. The 20th century has also come up with allegorical interpretations—for example, Pisthetaerus has been interpreted as a metaphor for Alcibiades. Cloudcuckooland has been understood by some scholars as a comic representation of an ideal polis and it has also been understood as a cautionary example of a polis gone wrong; according to yet another view, however, the play is nothing more than escapist entertainment.
The friendship between Pisthetaerus and Euelpides is realistically portrayed in spite of the unreality of their adventure. The keynote of their friendship is good-humoured teasing of each other for one another's failings (e.g. lines 54-5, 86–91, 336–42) and the proof of their friendship is the ease with which they work together in difficult situations, largely due to Euelpides' willingness to concede the initiative and leadership to Pisthetaerus. The father-son relationship between Philocleon and Bdelycleon in The Wasps and the husband-wife relationship between Cinesias and Myrrine in Lysistrata are other examples of Aristophanes' ability to depict humanity convincingly in the most unconvincing settings imaginable.
Toynbee, in his Study of History, argues for a link between The Birds and the New Testament. Here are significant examples of correspondence:
- Both Pisthetaerus and Jesus are deified human beings.
- Cloudcuckooland is synonymous with the Kingdom of Heaven, as they are both idealized heavenly cities.
- The example given in Matthew 6:26 of birds that make their living without reaping or gathering is echoed from a conversation between Euelpides and Hoopoe, in lines 155-61. Another connection is a fragment of Musonius.
- The Christian imagery of the Dove as the Holy Spirit is derived from its use as the emblem of the "heavenly love" of Aphrodite Urania.
He believes that the New Testament was influenced by a literary tradition that began with Aristophanes. The major difference is that Aristophanes presents these ideas as comic fantasy, while the New Testament treats them as profoundly serious revelation. More information can be found in Annex 1 of V. C I (d) 11, pp. 346 – 364, Volume VI of the unabridged Study of History.