Birds played an important role in Indo-European religion, used for divination by augurs, and according to a suggestion by Walter Burkert, these customs may have their roots in the Paleolithic when during the Ice Age, early humans used to look for carrion by observing birds.
From the Renaissance, it was the inspiration for some magical a priori languages, in particular musical languages. Whistled languages based or constructed on or articulated natural languages used in some cultures are sometimes also referred to, and compared with, the language of the birds.
According to Apollonius Rhodius, the figurehead of Jason's ship, the Argo, was built of oak from the sacred grove at Dodona and could speak the language of birds. The language of birds in Greek mythology may be attained by magical means. Democritus, Anaximander, Apollonius of Tyana, Tiresias, Melampus and Aesopus were all said to have understood the birds.
According to several Norse sagas, dragons' blood gives its drinker the power to understand the speech of birds.
In Celtic mythology, birds usually represent prophetic knowledge or bloodshed (especially crows). Morrigan adopted the shape of a bird to warn the Brown Bull. Echoing stories of the Edda and the Mabinogion, Richard Wagner's Siegfried understands the birds after he tasted Fafner's blood.
The concept is also known from many folk tales (including Welsh, Russian, German, Estonian, Greek), where usually the protagonist is granted the gift of understanding the language of the birds either by some magical transformation, or as a reward for some good deed by the king of birds. The birds then inform or warn the hero about some danger or hidden treasure.
In Sufism, the language of birds is a mystical language of angels. The Conference of the Birds (mantiq at-tair) is a mystical poem of 4647 verses by the 12th century Persian poet Farid ud-Din Attar .
Francis of Assisi is said to have preached to the birds.
In the Talmud (Louis Ginzberg, Legends of the Bible, 1909), Solomon's proverbial wisdom was due to his being granted understanding of the language of birds by God.
In Kabbalah, Renaissance magic, and alchemy, the language of the birds was considered a secret and perfect language and the key to perfect knowledge, sometimes also called the langue verte, or green language (Jean Julien Fulcanelli, Heinrich Cornelius Agrippa de occulta philosophia).
In medieval France, the language of the birds (la langue des oiseaux) was a secret language of the Troubadours, connected with the Tarot, allegedly based on puns and symbolism drawn from homophony, e. g. an inn called au lion d'or "the Golden Lion" is allegedly "code" for au lit on dort "in the bed one sleeps"  (note that this particular pun cannot be medieval, since final t was pronounced until Middle French, c.f. e.g. the 14th century loanword bonnet).
Compare also the rather comical and satirical Birds of Aristophanes and Parliament of Fowls by Chaucer.
"The language of the birds" (Die Sprache der Vögel) is a 1991 German movie. Jean Sibelius composed a wedding march titled "The language of the birds" in 1911. The children's book author Rafe Martin has written "The Language of Birds" as an adaptation of a Russian folk tale; it was made into a children's opera by composer John Kennedy.
In Egyptian Arabic, hieroglyphic writing is called "the alphabet of the birds". In Ancient Egyptian itself, the hieroglyphic form of writing was given the name medu-netjer ("words of the gods" or "divine language").
- Animal Symbolism in Celtic Mythology, by Lars Noodén (1992)
- Davidson, H.R. Ellis. Myths and Symbols in Pagan Europe: Early Scandinavian and Celtic Religions. Syracuse University Press: Syracuse, NY, USA, 1988.
- Richard Khaitzine, La Langue des Oiseaux - Quand ésotérisme et littérature se rencontrent 
- Rene Guenon, The Language of the Birds, Australia's Sufi Magazine "The Treasure" 2 (1998).
- LE VERLAN DES OISEAUX (The Verlan of the Birds) Collection "Pommes Pirates Papillons", Poèmes de Michel Besnier. Illustrations de Boiry, Editions Møtus (in French)
- Definition of Verlan English (in French)