Justification of Red List Category
This widespread species is listed as Near Threatened because it is suspected to be in moderately rapid decline as a result of habitat destruction and degradation across its range. It is apparently a successful colonist of some secondary habitats, suggesting that the population decline is not more rapid.
The global population size has not been quantified, but the species is described as generally uncommon to fairly common, although common in Borneo and extinct in Singapore (del Hoyo et al. 2007, Wells 2007, Eaton et al. 2021).
Despite the ability of this species to persist in degraded forest habitats, it is intolerant of oil palm plantations and there are indications that populations in fragmented secondary forest may be unable to persist long term. Remote-sensing data indicate rates of forest loss approximating 15% over three generations. Because of additional, unquantified fragmentation impacts, it is here tentatively suspected to be undergoing a decline of 15-25% in three generations (13.2 years).
Stachyris nigricollis occurs in the Sundaic lowlands, from peninsular Thailand, Sabah, Sarawak and Peninsular Malaysia, Kalimantan and Sumatra, Indonesia and Brunei. It is uncommon throughout this range. It formerly occurred on Singapore, where it has been extinct since the early 1970s at least (D. L. Yong in litt. 2011).
This species occurs in primary and secondary evergreen forest, including freshwater and peat swamp forest, from the lowlands to 1,400 m. In the Thai-Malay Peninsula, it appears to be confined to lowland forest below 600 m, with a preference for plains-level forest (Wells 2007). Although it can persist in logged forests (Hamer et al. 2015, D. Edwards in litt. 2020, Collar & Robson 2020), it requires luxuriant lower-storey growth (Edwards et al. 2011, D. Edwards in litt. 2021) and its extinction from Singapore suggests it may be unable to persist in secondary forest fragments in the long term (Castelletta et al. 2000). In a comparative study of understorey babblers in the Sundaic region, Styring et al. (2016) found densities of 1.7 individuals/ha in continuous natural forest, 2.8 individuals/ha in logged native forest fragments and mature plantations, and 1.9 individuals/ha in young (<5 years old) plantations, but none were found in oil palm plantations. However, in Peninsular Malaysia, the species was not found in heavily degraded and disturbed forest or plantations (Peh et al. 2011, Posa 2011). Rates of deforestation have been rapid within the range, and much of this has been absolute clearance and replacement with unsuitable oil palm.
Rates of forest loss in the Sundaic lowlands have been extremely rapid (Global Forest Watch 2021), owing partly to the escalation of illegal logging and land conversion, with deliberate targeting of all remaining stands of valuable timber including those inside protected areas. Forest fires have also had a damaging effect (particularly in 1997-1998). As this species persists in secondary and logged forests, and plantations however, it may not be under immediate threat from selective logging and may be relatively secure in areas where habitat clearance is incomplete. However, it appears to be intolerant of the oil palm plantations that proliferate the Sundaic region, and there are indications that it may not persist long-term in fragmented patches of secondary forest.
Conservation Actions Underway
The species occurs in many protected areas, including; Taman Negara and Panti Forest Reserve (Peninsular Malaysia; D. L. Yong in litt. 2011), Similajau National Park (Sarawak), Tanjung Puting National Park (Southern Kalimantan), and Gunung Leuser, Bukit Tigapuluh and Way Kambas National Parks (Sumatra) (Collar & Robson 2020).
Conservation Actions Proposed
Conduct ecological studies to improve understanding of its precise habitat requirements and response to fragmentation. Monitor population trends and rates of habitat loss across the range. Effectively protect significant areas of suitable forest at key sites, in both strictly protected areas and community-led multiple use areas.
Text account compilers
Berryman, A., Fernando, E.
Benstead, P., Derhé, M., Duckworth, W., Edwards, D., Gilroy, J., Mahood, S., Taylor, J. & Yong, D.
BirdLife International (2022) Species factsheet: Stachyris nigricollis. Downloaded from http://www.birdlife.org on 11/08/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 11/08/2022.