Justification of Red List Category
This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be stable, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified, but it is not believed to approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
The global population size has not been quantified, but the species is reported to be scarce throughout much of its range (del Hoyo et al. 1999), however it is unobtrusive and likely to be more common than records suggest.
The population is suspected to be stable in the absence of evidence for any declines or substantial threats.
B. javensis occurs from Myanmar to Java, Indonesia, including Thailand, Laos, Cambodia, Viet Nam, Peninsular Malaysia, Philippines (Busuanga, Culion and Palawan (Kennedy et al. 2000), Sumatra (and the Riau Archipelago), Java, East Malaysia, Brunei Darussalam and Kalimantan (and Banggi island) (del Hoyo et al. 1999, Holyoak 2001). Generally considered uncommon throughout this range, and the population on Java is particularly scarce (del Hoyo et al. 1999, Kennedy et al. 2000, Holyoak 2001, Mann 2008), but it is likely to be under-recorded throughout (del Hoyo et al. 1999).
Typically found in dense lowland evergreen forest (del Hoyo et al. 1999, Robson 2008), but also occurs in heavily-degraded habitat, including town parks, plantations and secondary forest including very young secondary growth and forest edge (J. W. Duckworth, J. Eaton and D. L. Yong in litt. 2013). Also occurs locally in mixed deciduous forest in Thailand and also in tree-rich scrub on Java but always where there is dense undergrowth (del Hoyo et al. 1999, Holyoak 2001). Mostly found in the lowlands, up to around 800 m in northern Thailand and c. 550 m. in Peninsular Malaysia, but from sea level up to 1,600 m. in Java (Holyoak 2001) and 2,150 m. in E Java (del Hoyo et al. 1999). B. javansis is nocturnal like most frogmouths, resting on branches (often in pairs) generally close to the ground in thick undergrowth during the day (Holyoak 2001). Nests with eggs have been observed in February-March in Peninsular Malaysia, and nests with nestlings in July on the Philippines (Holyoak 2001).
Text account compilers
Butchart, S., Ekstrom, J., Martin, R, Taylor, J. & Symes, A.
Yong, D., Eaton, J., Duckworth, J.W., Pilgrim, J. & Goes, F.
BirdLife International (2019) Species factsheet: Batrachostomus javensis. Downloaded from http://www.birdlife.org on 14/11/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 14/11/2019.