Itys

In Greek mythology, Itys was the son of Procne and Tereus. Tereus loved his wife's sister, Philomela. He raped her, cut her tongue out and held her captive so she could never tell anyone. Philomela wove a tapestry that told her story and gave it to Procne. In revenge, Procne killed her son by Tereus, Itys, and fed him to Tereus unknowingly. Tereus tried to kill the sisters but all three were changed into birds: Tereus was a hoopoe; Philomela was a swallow; Procne was a nightingale whose song is a song of mourning for her son Itys. The names "Philomela" and "Procne" are sometimes used in literature to refer to a nightingale, though only the latter is mythologically correct.

Ovid VI, 636