This discussion was first published as part of the 2013 Red List update, but remains open for comment to enable reassessment in 2015.
Rusty Laughingthrush Garrulax poecilorhynchus is restricted to Taiwan (China). It is currently listed as Least Concern because it was not thought to approach the thresholds for Vulnerable under any of the IUCN Red List criteria. It was thought to have very large range, and hence did not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence [EOO] <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appeared to be decreasing, the decline was not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it was not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure).
However, recent mapping of this species’s range shows that its EOO is approximately 17,800km2. Also, its population is suspected to be in decline owing to on-going habitat destruction and fragmentation. If this information is confirmed, and the EOO of this species is <20,000km2, it is inferred to be in continuing decline owing to habitat loss, and it is found at ≤10 locations or severely fragmented, it would warrant uplisting to Vulnerable under criterion B1ab(i,ii,iii,v). If these thresholds were approached but not all met, uplisting to Near Threatened may be appropriate.
The term ‘location’ defines a geographically or ecologically distinct area in which a single threatening event can rapidly affect all individuals of the taxon present. The size of the location depends on the area covered by the threatening event and may include part of one or many subpopulations. Where a taxon is affected by more than one threatening event, location should be defined by considering the most serious plausible threat. (IUCN 2001). For example, where the most serious plausible threat is habitat loss, a location is an area where a single development project can eliminate or severely reduce the population. Where the most serious plausible threat is volcanic eruption, hurricane, tsunami, frequent flood or fire, locations may be defined by the previous or predicted extent of lava flows, storm paths, inundation, fire paths, etc.
Information is requested on the population size, trends and distribution of this species, the number of locations at which it occurs and the degree to which the population is fragmented.