Common chiffchaff obvious wing bars; they include the willow, Bonelli's, wood and plain leaf warblers. The common chiffchaff has three still commonly accepted subspecies, together with some from the Iberian Peninsula, the Canary Islands, and the Caucasus which are now more often treated as full species. The common chiffchaff's English name is onomatopoeic, referring to the repetitive "chiff-chaff" song of the European subspecies. There are similar names in some other European languages, such as the Dutch "Tjiftjaf", the German "Zilpzalp" and Welsh "siff-saff". The binomial name is of Greek origin; "Phylloscopus" comes from "phyllon"/φυλλον, "leaf", and "skopeo"/σκοπεω, "to look at" or "to
The Life of Birds raven from raiding a nest by collectively raising an audible alarm. However, in an English wood, all species co-operate to warn each other surreptitiously of approaching danger. By contrast, a sunbittern is shown expanding its plumage to discourage a group of marauding hawks. The members of the finch family exemplify how colour aids recognition. Birds have excellent colour vision, and the feathers of many species react to ultraviolet light. Flocking birds, such as sparrows, also have a 'ranking system' that determines seniority. In Patagonia, Attenborough demonstrates the effectiveness of sound: he summons a Magellanic woodpecker by knocking on a tree.