Noun
A species of warbler, Acrocephalus scirpaceus, family Acrocephalidae, native to Eurasia and Africa. [from 18th c.]
Any of various similar Old World birds of the same genus, especially great reed warbler (A. arundinaceus) and clamorous reed warbler (A. stentoreus).
Source: en.wiktionary.orgThe best match is the Nauru reed warbler ; the annañ might have been an undescribed subspecies of that species, or a distant but related species of reed warbler. Source: Internet