Data Zone
Justification of Red List category
For a long time this species was considered one of Asia's greatest avian enigmas, known from just a single specimen collected between 1843 and 1848, at an unknown locality somewhere in southern Borneo. It was rediscovered in 2020, more than 170 years after the holotype was collected. It has since been found at several sites in eastern South Kalimantan, Indonesia, where it appears to be tied to forest on limestone karst, in a relatively small area east of the Meratus Range. Despite its small range, the perceived extinction risk is relatively low given its preference (and indeed dependence) on rugged forests which are not easily exploited. Nonetheless, there is evidence of some degradation by quarrying and localised subsistence timber extraction. Accordingly, it is evaluated as Near Threatened.
Population justification
For more than 170 years, this species was known from only a single specimen (Butchart et al. 2005, Collar 2014). By some authors it was even posited to be extinct (Clements 1991). It was rediscovered in 2020 (Akbar et al. 2020), and later found to be relatively common in areas of limestone karst in south-east Borneo (Kalimantan) (Akbar et al. 2021, 2022; eBird 2023). While its population size has not been estimated, the area of limestone karst is not large, and the species may have a relatively small population size.
Trend justification
The majority of habitat suitable for this species' lies in rugged and untouched limestone forest. Although Akbar et al. (2021) expressed concern about land conversion into oil palm plantations, this is almost never achieved on karst habitats and remote sensing data indicate minimal forest cover loss in suitable habitat in its range (Global Forest Watch 2023, based on data from Hansen et al. [2013]); while there may additionally be localised degradation of limestone forests, these are likely to be causing only marginal declines. A more conspicuous threat, however, is that of quarrying/mining, with evidence from remote sensing data (Google Earth 2023) that at least one area of suitable habitat has been mostly destroyed. Akbar et al. (2021) also identify trapping as a potential threat, although this is so far considered hypothetical, with no evidence yet of the species in markets, and acknowledgement that babblers are generally not targeted. Considering all mentioned threats together, it is precautionarily suspected that this species is declining; while the rate of this is not estimated, it is thought to be only very slow. Nonetheless, monitoring of remote sensing and market data should continue to ensure that threats do not become more acute, and rates of decline accelerate.
Endemic to Kalimantan, Indonesia (Indonesian Borneo). Known for more than 170 years from just a single specimen collected between 1843 and 1848 with unknown provenance, but strongly suspected to be from Kalimantan Selatan (see Collar 2014). Rediscovered in 2020 from Kotabaru Regency, Kalimantan Selatan (Akbar et al. 2020, 2021) and since found to occur on several areas of neighbouring limestone karst (to which the species appears confined). Currently the species is known from limestone karsts east of the Meratus Range, in Kalimantan Selatan, but another, larger, area of exposed limestone karst in Kalimantan Timur remains unexplored and may feasibly host this species. Such a discovery would considerably reduce this species' perceived extinction risk.
Confined to forest on limestone karst (Akbar et al. 2020, 2021, 2022). All observations have been on karst hill formations (<500 m) east of the Meratus Range, in areas replete with vertical cliffs and exposed limestone formations (crevices, caves etc.) (Akbar et al. 2022).
Identifying the threats facing this species was previously rendered nearly impossible given uncertainty over its range and habitat needs. However, this has now partially been elucidated (Akbar et al. 2021, 2022). While the species has a small range, most habitat within it currently seems secure with little evidence, according to remote sensing data (Global Forest Watch 2023) of degradation or outright loss over the past two decades. However, there is some evidence of quarrying in areas the species probably once occupied (but have now been totally cleared of forest), such that this probably is an ongoing threat causing slow but substantial declines given the species' assumed low abundance. There may also be some localised forest degradation due to timber removal and, given the dryness of the forest, fires may represent an increasing risk. Akbar et al. (2021) expressed concern that, given high trapping rates in Kalimantan and western Indonesia more broadly, this species may become threatened by bird trapping. However, there is no evidence of this species in the cagebird trade and babblers generally are not targeted. Therefore if this species is being trapped, it is probably at only a very low level.
Conservation Actions Underway
None of this species' (small) occupied range lies in a protected area (UNEP-WCMC and IUCN 2024).
Conservation Actions Proposed
Protect some of this species' habitat and work with local communities to prevent timber extraction that may be harmful to this species. Survey areas of limestone further north in East Kalimantan to see if the species occurs there. Determine the population size. Continue to monitor quarrying and forest cover loss using remote sensing tools.
16 cm. Drab, forest-dwelling babbler. Grey head with black supercilia joining above bill. Brown upperparts, wings and tail, becoming warmer on rump and undertail. Rest of underparts greyish-white, white throat. Stout, pale pinkish legs. Voice Described for the first time by Akbar et al. (2022): unusually for a Malacocincla, this species duets. The typical song is a loud and varied series of strophes lasting 8-10 seconds, with a pitch between 1-4 kHz. The authors described the most common pattern of strophes as: Pyoo-wiIT PII Pyuu chuu.
Text account compilers
Berryman, A.
Contributors
Collar, N., Crosby, M., Taylor, J., Davidson, P., Symes, A., Tobias, J., Pilgrim, J., Mahood, S. & Benstead, P.
Recommended citation
BirdLife International (2024) Species factsheet: Black-browed Babbler Malacocincla perspicillata. Downloaded from
https://datazone.birdlife.org/species/factsheet/black-browed-babbler-malacocincla-perspicillata on 24/11/2024.
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 24/11/2024.