The story of how the nightingale reed-warbler was extirpated from Guam, Pagan and Tinian is one echoed by many island species across the world. Human impact, through habitat destruction and the use of harmful insecticides (such as DDT), combined with natural factors, such as volcanic activity and widespread fires, are thought to be partially responsible (4) (5) (6) (9). However, the largest impact on the nightingale reed-warbler has been from the introduction of the brown tree snake (Boiga irregularis), believed to be responsible for the warbler’s final extirpation from Guam in 1969 (2) (4).
The other Mariana Islands receive virtually all their supplies from Guam and the brown tree snake is often a stowaway in cargo (10). As a result, a population of brown tree snakes has already been established on Saipan and there is a very high risk it will reach Alamagan and Aguijan (6). The brown tree snake, in combination with habitat loss for home building and tourism and the introduction of cats and rats, has led the Saipan population of nightingale reed-warblers to fall from 6,658 birds in 1982 to only 2,596 birds in 2007 (4) (6) (9). The much smaller Alamagan and Aguijan populations, estimated in 1997 to contain just 346 birds and up to 6 birds respectively, could easily be devastated by the arrival of the brown tree snake (4) (6) (9).