Procne is a character from Greek mythology who was turned into a bird called a nightingale. She was the daughter of a king named Pandion, and she had a sister named Philomela.
One day, Procne's husband, Tereus, did a very bad thing. He raped Philomela and then cut out her tongue so she couldn't tell anyone. Philomela was imprisoned, but she managed to weave a message into a tapestry that revealed what had happened to her.
When Procne found out what had happened to her sister, she was very angry. She decided to get revenge on Tereus, so she killed their son and served him to Tereus for dinner. When Tereus found out, he chased Procne and Philomela, but the gods intervened and turned all three of them into birds.
Procne became a nightingale, while Philomela became a swallow. Tereus became a hoopoe bird. In this way, they were punished for their crimes and forever transformed into birds which sing and fly in the sky.