The sounds of birds are a common source for refrains in poetry and song. They are well suited to this role: they are easy to sing, they are meaningless (more or less), which is no disadvantage in a refrain, and they are repetitive. Refrains based on bird-song are found in Medieval troubadour lyric and in German Minnesang. English poets of the Elizabethan period also used bird-song refrains, for example in a lyric from Thomas Nashe's Summer's Last Will and Testament, which dates from 1592. 1