The wren is a tiny brown bird, although it is heavier, less slim, than the even smaller gold-crest. An adult wren will weigh about the same as a £1 coin. For such a small bird the wren has an astonishingly loud song. In fact, per unit weight, it sings at ten times the power of a crowing cockerel. Bronze Wren-on-Chest Sculpture by Steve Langford (cast by Wildlife in Bronze).