The name Pierides has two ancient uses. It can refer to the Muses because Pieria in Macedonia was a major region of their birth and worship, and it can refer to the mortal daughters of Pierus who challenge them. This overlap is not accidental. The mortal sisters imitate the number and identity of the goddesses they oppose, turning a familiar poetic epithet into the name of artistic rivals.

Ovid gives the fullest surviving narrative. He calls their father Pierus of Pella, rich in lands, and their mother Euippe of Paeonia. Proud that they are nine in number, the sisters travel through Achaia and Haemonia to challenge the Muses of Helicon. The Roman poem invokes Lucina as the childbirth goddess whom Euippe calls upon nine times, a specifically Roman literary colouring rather than evidence for a Greek cult of Lucina in Macedonia.

The challengers propose territorial stakes. If the Muses lose, they must surrender the Heliconian springs associated with poetic inspiration, including Hippocrene and Aganippe. If the Pierides lose, the divine sisters will take the challengers' northern lands. Nymphs judge the performance, making the contest a formal trial of art rather than a spontaneous quarrel.

Ovid's leading Pierid chooses a provocative theme. She glorifies the enemies of the Olympians and narrates Typhoeus terrifying the gods into Egypt, where they hide in animal forms. Calliope answers for the Muses with a long song centred on Ceres and Proserpina, loss and recovery, and the spread of agriculture. The nymphs unanimously award the victory to the Muses.

Defeat is not yet the transformation. In Ovid the sisters continue to jeer, threaten and abuse the goddesses after the verdict. Feathers then grow from their bodies and their mouths harden into beaks. All nine become magpies, and their former verbal aggression survives as clamorous, imitative chatter. The punishment therefore answers not only the failed song but the refusal to accept judgement.

Antoninus Liberalis preserves a distinct Greek version attributed to Nicander. Pierus is an earth-born king of Emathia, his nine daughters form a rival chorus, and the contest takes place on Helicon. When the mortal sisters sing, everything grows dark and refuses to listen; when the Muses sing, heaven, stars, sea and rivers stand still while Helicon swells upward with delight. Pegasus stops the mountain's rise by striking the summit with his hoof.

The ending in Antoninus is different from Ovid's. The Muses transform the defeated sisters into nine different birds rather than nine magpies. The list includes birds such as the grebe, wryneck, kestrel, jay, greenfinch, goldfinch, duck and woodpecker, with the final bird name difficult to identify precisely. The two bird transformations should be kept as separate versions rather than combined into one catalogue.

Pausanias preserves yet another family tradition. He says some people believed Pierus had nine daughters with the same names as the Muses and even reassigned to them children normally called sons of the goddesses. This account does not reproduce Ovid's complete singing contest. It shows how thoroughly mortal and divine Pierides could overlap in ancient genealogy.