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 Origin of Birds the reptile." He also finds the eyes of birds and reptiles to be remarkably similar, especially the development of the lens, as well as the ear, which reveals a much wider gap between the Sauropsida and mammals than with birds. He describes the sexual organs of birds and reptiles to likewise be structurally similar, and finds that while most species of male bird have lost the penis to reduce weight, those that retain it bear remarkable similarities to extant reptiles. He writes that secondary sexual characteristics are also similar between birds and reptiles, with both groups frequently utilizing bright colors