The Pale-throated Wren-babbler (Spelaeornis kinneari) had been listed as Vulnerable since 2011, until it was downlisted in 2017 to Near Threatened (BirdLife International 2018) because of the recognition of potential range extensions, and a change to the use of Minimum Convex Polygons for measuring a species’s Extent of Occurrence (see IUCN 2001, 2012, Joppa et al. 2016). These meant that it was no longer considered to meet the threshold range size for listing as Vulnerable.
The extension of the species’s range appears, however, to have been erroneous as it assumed that the species occurs throughout the entire Hoang Lien Son range and included an uncertain record from Guangxi, China (S. Mahood in litt. 2017). In particular, this record from Guangxi should probably not have been included as the original paper identified the sighting as Long-tailed Wren-babbler (Spelaeornis chocolatinus) (Shing et al. 2006). This was prior to the splitting of this taxon into S. chocolatinus, S. kinneari, S. oatesi and S. reptatus (S. Mahood in litt. 2017), and with no further sub-identification, the individuals seen by Shing et al. (2006) may not actually represent this taxon; and could represent an undescribed species (S. Mahood in litt. 2017).
As such, we are in the process of re-mapping the species’s distribution and have provisionally reassessed the species here against all criteria.
Criterion A – The species inhabits forest habitats (see Collar and Robson 2018) and so is considered to be declining as a result of habitat loss and degradation within its range. The rate of forest loss has been estimated to be 0.1% per annum between 2000 and 2012, or 1.5% over three generations (c.13 years) (Tracewski et al. 2016, Ł. Tracewski unpublished data). This may be used as a very rough proxy for the rate of population decline, although this does include areas of mapped range that are now being removed from BirdLife’s map. However, based on this evidence it is still very unlikely that the rate of population decline would approach the threshold for Vulnerable (declines of 30% over three generations).
Criterion B – With the removal of areas where the species is not definitely known to occur (in particular in Guangxi – see above) from the species’s map, the Extent of Occurrence (EOO) and Area of Occupancy (AOO) values will be lower than currently held – considerably so in the case of the EOO. These values need to be recalculated per IUCN guidelines, and work is underway to do this. Preliminary results suggest that the EOO will fall beneath the threshold for Vulnerable (20,000km2), and potentially could approach or meet the threshold for Endangered (5,000km2).
From our current listing we consider habitat loss and degradation within the species’s range to be resulting in continuing declines in AOO, area/quality of habitat and population size, fulfilling sub-criterion b(ii,iii,v).
At the moment, the species is not considered to be severely fragmented, but is listed as occurring at only a very limited number of locations (6-10). Given the rate of deforestation shown above, it may actually be that the number of locations* where the species is found is higher than this current estimate. However, the data for Tracewski et al. (2016) only comes from between 2000 and 2012, and it has been noted that there has been an increase in disturbance and habitat clearance around Fan Si Pan due to developments for tourism (J. Pilgrim in litt. 2016), as well as more generally in northern Vietnam with an expansion in cardamom growing (J. Pilgrim in litt. 2011). Therefore, for now, the number of locations will be retained in the range 6-10, but this may need to be revised upwards in the future if the impacts of habitat loss don’t prove to be as far reaching as currently feared. Thus it would fulfil the condition for listing as Vulnerable for sub-criterion a.
The species is not thought to undergo extreme fluctuations, so it does not meet the conditions for listing under sub-criterion c. Thus, pending updated EOO and AOO values, the species likely will warrant listing as Vulnerable at least under criterion B1ab(ii,iii,v).
Criterion C – While the species is considered to be in decline due to habitat loss and degradation, the population size of this species has not been quantified, but is thought to be locally common (Collar and Robson 2018). Based on population density estimates of other members of the Timaliidae though, it is unlikely that the species would meet the threshold for consideration as Vulnerable under this criterion, and it is uncertain whether it would even approach this threshold. Therefore, given this uncertainty it is proposed that the species does not warrant listing under this criterion.
Criterion D – The population size of this species is likely too large, and its range is not restricted enough to warrant listing as threatened under this criterion.
Criterion E – To the best of our knowledge there has been no quantitative analysis of extinction risk carried out for this species. Therefore, it cannot be assessed against this criterion.
Therefore, it is proposed that the species be listed as Vulnerable at least under criterion B1ab(ii,iii,v) pending updated EOO and AOO values.
Comments on this proposal are welcome, though please note that this topic is not designed to be a general discussion about the ecology of the species, rather a discussion of the species’s Red List status. Therefore, please make sure your comments are about the proposed listing.
*Note that 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, 2012).
BirdLife International. 2018. Species factsheet: Spelaeornis kinneari. Downloaded from http://www.birdlife.org on 15/02/2018.
Collar, N.; Robson, C. 2018. Pale-throated Wren-babbler (Spelaeornis kinneari). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/59468 on 15 February 2018).
IUCN. 2001. IUCN Red List Categories and Criteria: Version 3.1. Gland, Switzerland and Cambridge, UK: IUCN Species Survival Commission.
IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN.
Joppa, L. N.; Butchart, S. H. M.; Hoffmann, M.; Bachman, S. P.; Akçakaya, H. R.; Moat, J. F.; Böhm, M.; Holland, R. A.; Newton, A.; Polidoro, B.; Hughes, A. 2016. Impact of alternative metrics on estimates of extent of occurrence for extinction risk assessment. Conservation Biology 30: 362-370.
Shing, L. K.; Lau, M. W.-N.; Fellowes, J. R.; Lok, C. B. P. 2006. Forest bird fauna of South China: notes on current distribution and status. Forktail 22: 23-38.
Tracewski, Ł.; Butchart, S. H. M.; Di Marco, M.; Ficetola, G. F.; Rondinini, C.; Symes, A.; Wheatley, H.; Beresford, A. E.; Buchanan, G. M. 2016. Toward quantification of the impact of 21st-century deforestation on the extinction risk of terrestrial vertebrates. Conservation Biology 30: 1070-1079.