Justification of Red List Category
The species is considered to have become extinct prior to the 1981 volcanic eruption on Pagan, though this rather destroyed hopes of the species persisting to the current day. Surveys in the 1970s, 1980s, in 2000 and in 2010 all failed to find any trace of the species.
On Pagan virtually all vegetative ground cover was effectively removed at certain periods during the 20th century through a variety of agents including human development, introduced feral ungulates and finally a volcanic eruption in 1981 (Reichel et al. 1992). However, there had not been any records for some time prior to this, with reports of reed-warblers being present by D. Aldan and J. Sablan into at least the 1960s (Reichel et al. 1992) appearing to be the last observations. Unsuccessful searches took place in the late 1970s (Tenorio and Associates 1979), between 1983 and 1989 (Reichel et al. 1992), in 1999 and 2000 (Division of Fish and Wildlife 2000) and in June 2010 (Marshall and Amidon 2010). The volcanic eruptions in 1981 appear to mark a full stop to the possibility of the species persisting, as all herbaceous and virtually all woody vegetation was destroyed in the last known site, around the upper lake (Reichel et al. 1992).
This species is historically known from Pagan in the Northern Mariana Islands (to USA). It probably went extinct in the early 1970s.
It was almost exclusively found in freshwater wetland and wetland edge vegetation (Engbring et al. 1982, Reichel et al. 1992, USFWS 1998).
Text account compilers
Benstead, P., Bird, J., Calvert, R., Khwaja, N., Mahood, S., O'Brien, A., Stattersfield, A., Derhé, M., Symes, A., Wright, L & Martin, R
Camp, R., Dutson, G., Freifeld, H., Saunders, A., Radley, P., Mosher, S., Amidon, F. & Gourley, J.
BirdLife International (2017) Species factsheet: Acrocephalus yamashinae. Downloaded from http://www.birdlife.org on 19/10/2017. Recommended citation for factsheets for more than one species: BirdLife International (2017) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/10/2017.