Family Reed-warblers (Acrocephalidae)


Guam Reed-warbler (Acrocephalus luscinius)


French: Rousserolle rossignol German: Guamrohrsänger Spanish: Carricero de Guam
Other common names: Guam Warbler, Nightingale Reed-warbler (when lumped with A. hiwae, †A. nijoi, †A. yamashinae and †A. astrolabii)

Thryothorus luscinius

Quoy and Gaimard

, 1830,



Has sometimes been treated as conspecific with A. syrinx, and sometimes also with A. rehsei, but differed from both in distinctly larger size, much longer bill and song. Previously considered conspecific with †A. nijoi, †A. yamashinae and †A. astrolabii, while A. hiwae was often treated as a synonym of luscinius (sensu stricto); but all are now separated primarily on basis of comprehensive genetic data#R#R. Monotypic.


Guam, in S Mariana Is.

Restricted to freshwater wetland and wetland-edge vegetation, this species is thought to have succumbed to a combination of predation by the introduced brown tree-snake (Boiga irregularis), wetland destruction, pesticide use and major fires. The last sighting was in 1969, and searches in the 1970s and 1980s failed to find it#R#R#R#R.

Descriptive notes

18 cm; male average 35·9g, female average 32 g. Relatively large reed-warbler with very long bill, head plumage often dishevelled. Nominate race has yellow supercilium... read more


Song loud, melodic, varied and complex, of whistles, warbles and trills, long sustained, may... read more


Mosaics of elephant grass and tangan-tangan (Leucaena), also mangroves (Bruguiera... read more

Food and feeding

Information sparse. Diet probably mostly insects, lizards, also spiders (Araneae) and snails. Forages mainly on ground; gleans... read more


Peak periods in Jan–Mar and Jul–Sept. Monogamous. Nest built by female, a rather deep cup, two types distinguished, one tightly... read more



Status and conservation

CRITICALLY ENDANGERED. Restricted-range species: present in Mariana Islands EBA. Current population estimated at c. 3700 individuals, all of nominate race: 946 on Alamagan in... read more

Recommended citation

Dyrcz, A. & Sharpe, C.J. (2019). Guam Reed-warbler (Acrocephalus luscinius). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from on 21 May 2019).