Data Zone
Justification of Red List category
This species, endemic to Java and Bali (Indonesia), is listed as Vulnerable. It is considered to be threatened with extinction because of capture for the cagebird trade, the only identified threat, which is suspected of having driven declines of c. 30–49% over the past ten years (2013–2023). This threat has driven even more severe declines in other species on Java, such that rates of decline must be urgently monitored.
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).
It is endemic to Java and Bali, Indonesia, where it is represented by two subspecies: (1) nominotypical montanus on several mountains in West and Central Java (Eaton et al. 2021, eBird 2023, Marsden et al. 2023); and (2) ottolanderi in East Java and Bali (Eaton et al. 2021, eBird 2023). An introduced population on Mt Rinjani, Lombok, originates from escapes.
Ii inhabits montane forest between 1,000 and 2,200 m. It occurs in small noisy groups of less than 10 birds (unlike P. bornensis, which typically occurs singly or in pairs) (Eaton et al. 2021).
The only threat identified for this species is capture for the pet trade, with no indication that the extent of forest cover in its range has decreased (Hansen et al. 2013, Global Forest Watch 2023). Although historically rare in market surveys (e.g., Chng et al. 2015), it has since become much more commonly observed in physical markets (Anon. in litt. 2022) and online (Okarda et al. 2022). Given this is the only identified threat, it is considered wholly responsible for the rapid declines observed in wild populations (Marsden et al. 2023). This trade is entirely (or mostly) domestic, with no indication that birds are leaving Indonesia.
Conservation Actions Underway
None is known. The Asian Songbird Trade Specialist Group (ASTSG) lists this species in Tier 1 (those they consider most threatened by trade) and has recommended that this bird be protected under Indonesian law. Because (almost?) all trade in this species is domestic, international policy instruments such as CITES would be ineffectual for this species. No captive birds are currently held in Indonesia (Collar and Wirth 2022).
Conservation Actions Needed
Continue to monitor population trends (sensu Marsden et al. 2023), preferably expanding these to East Java and Bali, from which robust population trends are currently lacking. Establish a captive breeding population in Indonesia if considered appropriate (Collar and Wirth 2022). Determine whether the introduced population on Lombok is having an impact on native species.
Text account compilers
Berryman, A.
Contributors
Eaton, J.
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.