Data Zone
Justification of Red List category
This recently recognised species was formerly common across the island of Java, but demand for the Indonesian songbird trade has resulted in a precipitous decline over the past 20 years. The species is now confined to only a handful of localities, all of which are at risk of extirpation with trappers having proven their ability at other sites to remove all individuals from a locality in a short period of time. Remarkably, the population in captivity likely numbers in the tens of thousands, while the wild population is now suspected to number fewer than 1,000, and maybe much lower. Over the past ten years, the population is suspected of having declined by more than 80% and with demand for the species still high, there is a significant chance the species will become extinct in the near-future. For these reasons, it is listed as Critically Endangered.
Population justification
The population has not been quantified, but may now be small. Although formerly described as one of the commonest flycatchers on the island (MacKinnon 1988), its population appears to have been greatly reduced and it is now very difficult to find in the wild (F. Rheindt in litt. 2020, J. Eaton in litt. 2022). During the 'Big Month' citizen science event, conducted in January 2020, wherein 22,054 checklists were generated, it was recorded just three times in two squares (2 x 2 km) (Squires et al. 2021).
Trend justification
The population is thought to be in rapid decline. Historically, this species was not rare on Java, with MacKinnon (1988) describing it as one of the commonest flycatchers on the island. Since then, the species is known to have disappeared from many sites due to trapping for the cagebird trade; Marshall et al. (2020) estimated that 98,134 ± 48,988 individuals are kept in captivity on Java, but very few now seem to persist in the wild (F. Rheindt in litt. 2020, Eaton et al. 2021, J. Eaton in litt. 2022). During the 'Big Month' citizen science event, conducted in January 2020, wherein 22,054 checklists were generated and more than 70% of island tetrads received some survey effort, it was recorded just three times in two squares (2 x 2 km) [Squires et al. 2021]. Van Balen (1999) found it to occur at 14/20 (70%) of study sites surveyed 1985-1995, but it has been recorded at only two of these sites since 2016, despite all having received some degree of search effort during this time ('Big Month' data [Squires et al. 2021], eBird 2022).
Anecdotally, one site that hosted four males in 2012 and at least one individual in 2015, is no longer occupied, while the species appears to have also disappeared (with 0 records 2018-2022) from a locality that had 12 singing males in 2005 (J. Eaton in litt. 2022, eBird 2022).
Such declines are also reflected in Indonesia's songbird markets. Extensive surveys of Jakarta's three largest markets found 23 individuals in six shops in July 2014 (Chng et al. 2015), but a repeat effort in July 2019 found only three across three stalls (J. Eaton in litt. 2022). This drop is thought to reflect a genuine reduction in wild populations rather than a fall in demand, since numbers of similar species across the two time periods remained relatively stable. Similarly, only three were recorded in two large markets on Bali in 2017-2018, although comparative historic data for this market are lacking (Chng et al. 2018).
Determining a rate of decline for this species is difficult owing to the paucity of historic baseline data. However, observational, distributional and market data are congruent with a very rapid decline over the past ten years. Consequently, the population is suspected of having declined 60-90% between 2012 and 2022, with a precautionary best estimate of 80-90%. Resolving a future rate of decline is even more challenging with market demands ever-changing and incomplete contemporary distribution and population size data. However, it is noted that this species' preference for more accessible forests at lower elevations (<1,300 m) renders all remaining populations vulnerable to trapping, such that very rapid future declines are eminently plausible.
The species is endemic to Java, Indonesia, where two rather weakly defined subspecies are recognised: C. b. banyumas in Central and East Java, and C. b. ligus in West Java.
It is a forest specialist, occupying primary and secondary broadleaf forests with a predilection for ravines and bamboo thickets. It occurs to 1,300 m (Eaton et al. 2021).
Historically, this species was impacted by habitat loss and fragmentation, although remote sensing data (Global Forest Watch 2022) indicate that over the past three generations this has been minimal, and forest cover on Java may have actually increased. More recently, capture for the songbird trade has been the principal threat for this species (Eaton et al. 2015) and is thought to have driven extremely rapid declines in the wild population.
Conservation Actions Underway
Despite its status as a Critically Endangered species, this species has received little conservation attention, principally owed to its previous treatment as a subspecies of the more widespread C. whitei. More recently, a project in Yogykarta employed ex-poachers to farm coffee, with the present species able to persist and breed in shade-grown coffee plantations. Farmers who successfully found nests were financially rewarded and the monitoring of nests was compensated for (see Taufiqurrahman et al. 2019).
Conservation Actions Proposed
There is an urgent need to quantify the population size and identify sites the species is still present. Sites where the species is found need to be protected and, where possible, birds to be monitored. Include in legislation to make the trade in this species illegal. Consider a reintroduction project.
Text account compilers
Berryman, A.
Contributors
Akbar, P., Eaton, J. & Rheindt, F.
Recommended citation
BirdLife International (2024) Species factsheet: Javan Blue Flycatcher Cyornis banyumas. Downloaded from
https://datazone.birdlife.org/species/factsheet/javan-blue-flycatcher-cyornis-banyumas on 23/12/2024.
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 23/12/2024.