Justification of Red List category
Tree cover loss through conversion of forest to agriculture (particularly for oil palm plantations) is estimated at 14-18% over the past ten years, and with further impacts from degradation the the species is suspected to be undergoing a moderately rapid population reduction. The majority of the loss has taken place within the lowlands, within the preferred elevational range of the species. Overall, the population is suspected to have undergone a rapid recent reduction approaching 30% over ten years, hence is assessed as Near Threatened. This reduction will continue unless there is a significant reduction in both the rate of habitat conversion within the range of the species, or until the majority of the population becomes restricted to more secure protected areas.
The global population size has not been quantified but is believed to be large given the range and frequency of records in suitable habitat. Cyornis umbratilis is a forest-dependent species and appears to occur only in primary forest (eBird 2022). Within its range, the rate of forest conversion to plantations, primarily oil palm, has been rapid over the past few decades (per Global Forest Watch 2022). There are recent records from remaining forested areas across the range, however the extent of suitable habitat is now considerably smaller than three generations ago. Where habitat is secure the species continues to be regularly observed (eBird 2022), though observing the species away from protected areas is becoming increasingly difficult. In Thailand, all recent records are from (/the vicinity of) the Hala Bala Wildlife Sanctuary (Treesucon and Limparungpatthanakij 2018, eBird 2022) and the population there must be relatively small. Almost all records in Malaysia now come from protected areas or forest concessions, and the population is thought to be declining rapidly in lowland Indonesia, although here (especially in Kalimantan), there are large tracts of suitable habitat remaining. Forest loss is much lower in Brunei, where impacts on the species may be much less severe and much of the forest here is likely to be suitable for this species. Overall, the population is considered highly unlikely to meet or approach he threshold for listing as threatened (<10,000 mature individuals).
The species is commonest in the undergrowth of intact primary lowland forest. Consequently the population impact of forest cover loss is expected to be equal to or greater than the rate of loss. In the 10 years to 2021, forest cover in this species' range was reduced by 14–18%, depending on the forest cover thresholds set (Global Forest Watch 2022, based on data from Hansen et al.  and methods disclosed therein). This value does not account for the impact of forest degradation, hence the population rate of reduction from habitat loss is likely to be greater than this. Similarly, since the species is most regularly encountered in low-lying forest (eBird 2022), where losses are greater, the overall rate of population reduction is suspected to be equivalent to c.15-29% over the last ten years. This rate is also precautionarily projected over the next ten years, although beyond that rates of loss may slow as the percentage area of forest outside protected areas diminishes.
Cyornis umbratilis is restricted to the Sundaic lowlands, occurring in peninsular Thailand; Sabah, Sarawak and peninsular Malaysia; Kalimantan and Sumatra (including offshore islands), Indonesia, and Brunei.
It occurs in lowland primary and secondary broadleaved forests. Breeding has been recorded between January and August, with one nest described as a cup-shaped structure concealed inside a large Macaranga leaf (Yong and Lim 2008).
Forest destruction in the Sundaic lowlands of Indonesia and Malaysia has been extensive, for timber and conversion to agriculture. In particular the rapid expansion of oil palm has driven the conversion of the majority of remaining lowland forest in the region. Between 2011 and 2021, tree cover was reduced in its range by 14-18% (Global Forest Watch 2022, based on data from Hansen et al.  and methods disclosed therein). Most of this loss has occurred within the lowlands, where the highest densities of the species would be expected. Moreover, the impact of forest degradation will have added to rates of decline. Associated with the forest loss has been an increase in fire frequency, extent and severity, particularly during strong El Nino events (as in 1998).
Conservation Actions Underway
No species-specific actions are known but a number of protected areas lie within its range.
Text account compilers
Westrip, J.R.S., Bird, J., Butchart, S., Berryman, A., Khwaja, N.
BirdLife International (2024) Species factsheet: Cyornis umbratilis. Downloaded from https://datazone.birdlife.org/species/factsheet/grey-chested-jungle-flycatcher-cyornis-umbratilis on 01/03/2024.
Recommended citation for factsheets for more than one species: BirdLife International (2024) IUCN Red List for birds. Downloaded from https://datazone.birdlife.org on 01/03/2024.