Current view: Data table and detailed info
Taxonomic note
Pomatorhinus montanus and P. bornensis were previously lumped as P. montanus (Handbook of the Birds of the World and BirdLife International 2022) but are split on the basis of differences in plumage, vocalisations, habitat/elevation and behaviour (Eaton et al. 2016), although further work is needed to clarify and better understand these differences. Recent molecular studies reveal the complexity of Pomatorhinus taxonomy (Dong et al. 2010, Reddy and Moyle 2011), pointing to transfer of subspecies nuchalis, difficilis, klossi and “fastidiosus” of P. schisticeps to present species in one interpretation of evidence (Dickinson and Christidis 2014); however, these four forms differ so strongly in appearance, with longer bills, olive-brown vs bluish-grey crowns, olive-brown vs chestnut upperparts and unstreaked underparts, that their relationship with present species and status as conspecific require confirmation (independent species status might be appropriate). Two subspecies recognised.
Taxonomic source(s)
Handbook of the Birds of the World and BirdLife International. 2023. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 8. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v8_Dec23.zip.
IUCN Red List criteria met and history
Red List criteria met
Red List history
| Migratory status |
full migrant |
Forest dependency |
high |
| Land-mass type |
|
Average mass |
- |
Population justification: The population size of this species has not been estimated. The area of suitable habitat is large, however occupancy is demonstrably low (eBird 2023, Marsden et al. 2023) and there is strong evidence that the wild population size is (at least locally) being suppressed by intense trapping pressure (see Population Trend). Descriptively its abundance was revised from 'uncommon' (Eaton et al. 2016) to 'locally now rare' (Eaton et al. 2021), although in the absence of empirical data from which to produce a numerically derived estimate, the population size is set here to unknown. Determining this value should be considered a priority for future research.
Trend justification: Although not initially identified as a taxon at risk of extinction in Eaton et al. (2015), there is now evidence that this species has declined (potentially rapidly) over the past 1-2 decades in response to demand for the Indonesian songbird trade. Reviewing published market inventories, Collar and Wirth (2022) found no 'large numbers or [suggestion of] a sudden surge in the trade [of this species]'; however a comparison of Chng et al. (2015), who found 12 individuals in Jakarta's three markets (in 2014), with an equivalent survey undertake in 2019 (Anon. in litt. 2022), which found 174 birds across the same three markets, suggests that demand for this species may have increased rapidly. Using a web-scraping tool to mine data from online marketplace platforms, Okarda et al. (2022) found 42 listings of this species, indicating that this species is also widely traded online.
There is increasing evidence that demand for trade is causing ongoing declines in wild populations. The only empirical trend data available come from Marsden et al. (2023), who generated encounter rates for 12 mountains in West/Central Java and found the species to be rare, with an encounter rate of 0.06 (0.02-0.13) at occupied sites (n=4). Previous encounter rates are available for Gede–Pangrango (1981; 0.82), Puncak (1981; 0.90) and Slamet (1995; 1.05). Although neither Gede or Puncak were visited in the most recent surveys, the consistency of encounter rate between them (and with Slamet) suggest these are likely to have been representative values, and in any instance the rapid fall in encounter rate at Slamet fits the inferred trend of a potentially rapid fall in populations size. If the encounter rate is considered a reliable proxy for the rate of population trend, this would suggest a very rapid reduction (exceeding 80%) compared to 30-40 years ago. Given the rapid increase in demand for the species over the past 10 years (see above), much of this reduction is thought to have been recent. These data support other reports that the species has declined at some sites. At Gunung Gede, the species was encountered with regularity until c. 2016, after which it seems to have become scarcer, followed by near-total extirpation, with very few recent records despite intense effort (eBird 2023, J. Eaton in litt. 2023). Further east, the species appears to still be regularly encountered at several sites, although even at these there is weak evidence (eBird 2023) of an ongoing (but unquantifiable) decline in encounter rate over the past 5-6 years that is nonetheless likely to be at a shallower rate than sites surveyed further west. On Bali, the population trend (based on eBird 2023) appears to be relatively stable. Compiling an overall rate of decline is consequently difficult for P. montanus, and it must be considered that the most remote parts of its range are simultaneously those with the lowest trapping pressure and poorest ornithological survey effort. Following available data too strictly therefore risks overestimating the rate of decline. Nonetheless, a rapid rate of decline seems entirely possible with little of Java's forests considered truly remote from the intrusions of trappers, as demonstrated by the precipitous decline of other endemic bird species on the island (see, e.g., Eaton et al. 2015, Collar and Wirth 2022).
Overall, rates of decline over the past ten years could span a range of 20-60% given the immense uncertainties surrounding available data, and rates at individual sites may even span 0-100%. Evaluating all data available, rates of decline are thought most likely to fall into the band 30-49% over the past ten years and are also suspected to hit the same rate of decline between 2016 and 2026, and in the next ten years (thus meeting the threshold for Vulnerable A2, A3 and A4).
Country/territory distribution
Important Bird and Biodiversity Areas (IBA)
Recommended citation
BirdLife International (2024) Species factsheet: Javan Scimitar-babbler Pomatorhinus montanus. Downloaded from
https://datazone.birdlife.org/species/factsheet/javan-scimitar-babbler-pomatorhinus-montanus on 26/12/2024.
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 26/12/2024.
