A very small brown bird that frequently carries its short tail upright. At times it sings boldly from an exposed perch, while at others it behaves in a mouse-like way, slipping through brambles and dense undergrowth and easily going unnoticed. It prefers woodland with thick understory, as well as gardens, hedgerows in farmland, heathland, and even coastal cliffs. Far more often heard than seen, it delivers a loud, lively, musical song made up of trills and clear warbling phrases, repeated again and again. Sharp chipping calls can also reveal where it is hiding.