Ovid's Metamorphoses preserves a specific myth episode in which Calliope is not merely invoked but takes an active, competitive role: the contest between the nine Muses and the nine daughters of the mortal king Pierus, arrogant sisters who challenged the Muses to a singing match on Mount Helicon and were, on losing, transformed into chattering magpies for their presumption. Calliope is named as the Muse chosen to sing on behalf of her sisters, and the song she performs within Ovid's poem, an extended account of the abduction of Proserpina by the god of the underworld and Ceres's grief-stricken search for her, is one of the most celebrated set pieces in the entire Metamorphoses, a poem within the poem attributed specifically to Calliope's own voice rather than to Ovid's narrator directly.
The episode does more than showcase Calliope's mastery of epic song; it stages a contest between divine and mortal artistry with real stakes, since the Pierides are utterly transformed and silenced for daring to compete, a caution to any mortal poet tempted to measure their own gift against the goddesses who were traditionally credited with the whole of poetic inspiration. That Calliope herself is given the victory over rival singers, judged and confirmed by a panel of nymphs within Ovid's story, marks one of the few surviving moments where an individual Muse, rather than the nine collectively, performs and is judged on her own account, giving her a rare active role beyond the genealogical and patronage functions that otherwise define her.