Common chiffchaff one of the first avian signs that spring has returned. Its call is a "hweet", less disyllabic than the "hooeet" of the willow warbler or "hu-it" of the western Bonelli's warbler. The song differs from that of the Iberian chiffchaff, which has a shorter . However, mixed singers occur in the hybridisation zone and elsewhere, and can be difficult to allocate to species. When not singing, the common chiffchaff can be difficult to distinguish from other leaf warblers with greenish upperparts and whitish underparts, particularly the willow warbler. However, that species has a longer primary projection, a sleeker, brighter appearance
A Photographic Guide to the Birds of Indonesia Berkeley Books Pte Ltd. The second edition involved a total revamp of the material; a new checklist was used on the basis of "The Clements Checklist of Birds of the World 6th Edition" from 2007. This list has 1,605 bird species for Indonesia, while the 1992 list had 1,534. It also uses the ‘buntings last’ sequence which means that the Indonesian book now uses the same sequence as the companion volume "A Photographic Guide to the Birds of Southeast Asia". However, while "Southeast Asia" came out in 2012 with just a new cover and imprint, "Indonesia" came out that year