Acrocephalus

The Acrocephalus warblers are small, insectivorous passerine birds belonging to the genus Acrocephalus. Formerly in the paraphyletic Old World warbler assemblage, they are now separated as the namesake of the marsh- and tree-warbler family Acrocephalidae. They are sometimes called marsh-warblers or reed-warblers, but this invites confusion with Marsh Warbler and Reed Warbler proper, especially in North America where it is common to use lower case for bird species.

These are rather drab brownish warblers usually associated with marshes or other wetlands. Some are streaked, others plain. Many species are migratory.

Many species have a flat head profile, which gives rise to the group's scientific name.

Species breeding in temperate regions are strongly migratory.

The most enigmatic species of the genus, the Large-billed Reed-warbler (A. orinus), was rediscovered in Thailand on March, 2006. It was only found once before, in 1867. It was found also in a remote corner of Afghanistan in the Summer 2009.

List of species in taxonomic order

 * Basra Reed-Warbler, Acrocephalus griseldis
 * Lesser Swamp-Warbler, Acrocephalus gracilirostris
 * Greater Swamp-Warbler, Acrocephalus rufescens
 * Cape Verde Swamp-Warbler / Cape Verde Warbler, Acrocephalus brevipennis
 * Madagascan Warbler / Madagascan Swamp-Warbler, Acrocephalus newtoni
 * Rodrigues Warbler, Acrocephalus rodericanus
 * Seychelles Warbler, Acrocephalus sechellensis
 * Great Reed-Warbler, Acrocephalus arundinaceus
 * Oriental Reed-Warbler, Acrocephalus orientalis
 * Clamorous Reed-Warbler, Acrocephalus stentoreus
 * Nightingale Reed-Warbler, Acrocephalus luscinius
 * Saipan Reed-Warbler, Acrocephalus hiwae
 * Australian Reed-Warbler, Acrocephalus australis
 * Aguiguan Reed-Warbler, Acrocephalus nijoi – doubtfully distinct; extinct (c.1997)
 * Carolinian Reed-Warbler, Acrocephalus syrinx
 * Kiritimati Reed-Warbler / Bokikokiko, Acrocephalus aequinoctialis
 * Southern Marquesan Reed-Warbler, Acrocephalus mendanae
 * Pagan Reed-Warbler, Acrocephalus yamashinae – doubtfully distinct; extinct (1970s)
 * Nauru Reed-Warbler, Acrocephalus rehsei
 * Millerbird, Acrocephalus familiaris
 * Pitcairn Reed-Warbler, Acrocephalus vaughani
 * Henderson Reed-Warbler, Acrocephalus taiti
 * Cook Reed-Warbler, Acrocephalus kerearako
 * Rimatara Reed-Warbler, Acrocephalus rimitarae
 * Garrett's Reed-Warbler, Acrocephalus musae – extinct
 * Tahiti Reed-Warbler, Acrocephalus caffer
 * Moorea Reed-Warbler, Acrocephalus longirostris – extinct
 * Northern Marquesan Reed-Warbler, Acrocephalus percernis
 * Tuamotu Reed-Warbler, Acrocephalus atyphus
 * Mangareva Reed-Warbler, Acrocephalus astrolabii – extinct (mid-19th century?)

Fragmentary fossil remains from the Late Miocene (about 11 mya) of Rudabánya (NE Hungary) show some apomorphies typical of this genus (Bernor et al. 2002). Given its rather early age (most Passerida genera are not known until the Pliocene), it is not too certain that it is correctly placed here, but it is highly likely to belong to the Acrocephalidae at the least.