Archived 2010-2011 topics: White-throated Wren-babbler (Rimator pasquieri): uplist to Endangered?

White-throated Wren-babbler Rimator pasqiueri is restricted to the Hoang Lien mountains of north-west Vietnam, where it has only ever been found at three sites, however it is currently classified as Least Concern as its population, trend and range have not been suspected to approach the thresholds for classification as Vulnerable.

In recent years it has become apparent that the species is likely to be threatened. Although its altitudinal range limits are poorly known, it has only been found in forest between 1,950 and 2,500 m elevation. However, it may undertake altitudinal migrations and only occupy higher elevations for part of the year, because it was not found above 2,000 m elevation during the only winter survey, and all other records (which were all above 2,000 m elevation) have been made during the spring. Despite much searching in forest where the understory has been replaced with cardamom plantations, it has only been found in forest with an intact, natural understory of dense Arundinaria sp. bamboo.

If it has been undergoing a population decline of >30% over the past 10 years owing to ongoing forest loss and clearance of forest understory for cardamom then the species would warrant uplisting to VU (under criterion A2c). Expansion of cardamom cultivation continues at a very fast (but unquantified) pace within its range, both outside and within protected areas. Furthermore, it may qualify for EN (under criterion B1a+b[i,ii,iii,iv,v]) because its Extent of Occurrence (assuming an altitudinal range of 1,950-2,500 m) is less than 5,000 km2 (see attached draft map within which area indicated totals c1,500 km2), and there is likely to be a continuing decline in its extent of occurrence, area of occupancy, the area, extent and quality of habitat, the number of locations and subpopulations and the number of mature individuals; and, it is currently known with certainty from less than five locations (currently three, with records in the last five years from only one). If it were able to be calculated, its AOO is likely to be much smaller, because cardamom cultivation is so widespread. In addition, if it were an altitudinal migrant, then suitable habitat would be much less in extent.

Searches at one location where it was recorded up to 2004 have failed to find either the species, or suitable habitat, in the last two years. In 2011 construction work will begin on a hydropower dam at the only site where it has been recorded which still has extensive dense Arundinaria sp. bamboo in the understory. Although this project will impact very little forest directly, the building of an access road will facilitate the development of cardamom cultivation at that site.

Comments and information on the species likely rate of recent population decline, the extent of its range, and the degree to which its habitat is fragmented would be welcome.

Draft map showing potential range of White-throated Wren-babbler assuming it is restricted to 1,950-2,500 m (areas outside of this altitudinal band are shown as partially greyed-out)

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2 Responses to Archived 2010-2011 topics: White-throated Wren-babbler (Rimator pasquieri): uplist to Endangered?

  1. Simon Mahood says:

    This species is clearly in trouble and is a priority for research. It is much more threatened than Pale-throated Wren-babbler and fits the criteria for Endangered. I strongly recommend uplisting it to EN.

  2. John Pilgrim says:

    The extent and rate of forest loss in north-west Vietnam and the explosion of cardamom cultivation over the last five years have made it clear that this species is threatened from the time it was split. In recent visits to the Hoang Lien Son, it has been very difficult to find any intact understorey – it is all cleared and underplanted with cardamom. In protected areas this happens with the support or tacit acceptance of authorities.

    Exact rate of decline of this species’ habitat could be quantified by remote sensing. However, even if the EOO proves to be larger than currently known (e.g. owing to larger altitudinal range), the fact remains that it will be less than 5,000 km2 and the species’ habitat is undergoing a continuing decline in its area, extent and quality. It seems without doubt that this species is Endangered.

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