The grey warbler is a small, grey and brown bird that eats mainly invertebrates and some small fruit. It has pale coloring on its face, throat, and breast and grows to around 11 cm in length. While the female incubates the eggs alone, the male defends the home territory, and stoats are a main threat, making it difficult for grey warblers to escape predation. Its predators include ferrets, stoats, weasels, and feral cats.