Data Zone
Justification of Red List category
This species is confined to the Saraburi Group Limestone Karst in central Thailand, where the area of suitable habitat amounts to less than 200 km2. Quarrying has proven a critical threat to this species, causing local extinctions historically and, with large areas of remaining suitable habitat gazetted as proposed quarrying areas, future declines are projected. As a consequence it is listed as Vulnerable.
Population justification
The population density of this species has not been directly estimated, however based on an assessment of known records and inferred densities (eBird 2022) and expert consultation (P. Round in litt. 2021), its density is believed to be no higher than that that of P. capistratum, which has been recorded occurring at c.23 mature individuals/km2 (Francis & Wells 2003), and may be substantially lower (P. Round in litt. 2021). Round et al. (2021) identified only 174 km2 of suitable habitat. Applying this density gives a total of 4,000 mature individuals. Accounting for uncertainties, the population is therefore estimated to number 2,500-6,000 mature individuals, with a best estimate of 2,500-4,000.
Trend justification
This species is inferred to be undergoing a slow, continuous decline because of quarrying for limestone in parts of its very limited range, a threat that has caused localised extinctions and is projected to do so in the future, with only 1.4% of the species' range formally protected in a national park (Round et al. 2021).
Turdinus calcicola is confined to the south-western part of north-east Thailand in forest associated with limestone, below 915 m (Collar and Robson 2016). It has a highly restricted range within the Permian limestone in the provinces of Saraburi, Lopburi and Nakhon Ratchasima (Round et al. 2021).
This species is found in forest associated with limestone, below 915 m (Collar & Robson 2016).
The principal threat to this species is quarrying for limestone, chiefly in Saraburi province. Round et al. (2021) estimated using satellite data and an ASTER global digital elevation model that the area of suitable habitat for this species fell from 184.85 km2 in 1980 to 174.07 km2 in 2020 because of quarrying, with this rate of decline increasing more recently. Further quarrying concessions cover an additional 23.23 km2 of suitable habitat for G. calcicola. As well as removing habitat, quarrying is likely to have additive impacts caused by access roads, noise and dust (Round et al. 2021). This species is also likely to be locally impacted by small-scale deforestation, mostly as a result of shifting agriculture and wood-collection.
Conservation Actions Underway
Occurs in one protected area: Khao Luuk Chang in Khao Yai National Park. Wat Khao Somphot and Khao Tham Erawan (both Buddhist monasteries) are designated as Non-Hunting Areas (NHAs) that together contain approximately 2.19 km2 of babbler habitat. Another 12.17 km2 of potential babbler habitat lies inside two other NHAs, Kaeng Khoi and Namtok Chet Sao Noi, although confirmation of the babbler's presence there is needed. It bears mention that NHA status does not necessarily confer protection (Round et al. 2021).
Conservation Actions Proposed
Conduct surveys to get a better idea of population size and trends estimates as well as a better understanding of the threats that affect this species. Protect areas of its remaining habitat.
Text account compilers
Berryman, A.
Contributors
Round, P.
Recommended citation
BirdLife International (2024) Species factsheet: Rufous Limestone-babbler Gypsophila calcicola. Downloaded from
https://datazone.birdlife.org/species/factsheet/rufous-limestone-babbler-gypsophila-calcicola on 22/12/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from
https://datazone.birdlife.org/species/search on 22/12/2024.