This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2014.
Pitcairn Reed-warbler Acrocephalus vaughani is endemic to the tiny volcanic island of Pitcairn. It is currently classified as Endangered because it has a very small population which was believed to be continuing to decline, as a result of habitat degradation and predation by feral cats, which have recovered fairly quickly since control efforts. Although there has never been any detailed census of the species, anecdotal evidence suggests that it has remained relatively common on the island, with no obvious changes in numbers during the past 22 years (M. Brooke in litt. 2012). Predation by Pacific rats and feral cats is likely, but these have been present for many years and do not seem to be causing declines.
It would therefore seem appropriate to reclassify the species as Vulnerable under criterion D1 (having a total population of fewer than 1,000 mature individuals). If there was any evidence that the species was undergoing or predicted to undergo a continuing decline in its range or population it would most likely warrant uplisting to Critically Endangered (under which category it should have been listed previously).
Comments on the likelihood that the species is declining, and therefore whether it should be downlisted or uplisted, are welcomed.