Current view: Data table and detailed info
Taxonomic note
Previously lumped as C. banyumas with C. whitei and C. montanus (del Hoyo and Collar 2016), but those species now split following Eaton et al. (2016) and specimen examination. Differs from C. whitei by its broad black chin vs narrow or none in male (1); continuously russet underparts vs only throat/breast (belly/vent whitish) in both sexes (3); markedly greyer vs olive-brown upperparts in female (2); greater wing length (unmeasured, but at least 1); evidently different voice (Gwee et al. 2019) (not assessed, but at least 1). For differences from C. montanus, see that species. Has been considered conspecific with C. lemprieri; songs rather similar, and separation based mainly on plumage. Until recently considered conspecific with C. magnirostris, which proves to be vocally rather close to present species. Subspecies mardii, described from Panaitan I, off Java, sometimes recognised. Two subspecies recognised.
Taxonomic source(s)
Handbook of the Birds of the World and BirdLife International. 2022. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 7. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v7_Dec22.zip.
IUCN Red List criteria met and history
Red List criteria met
Red List history
| Migratory status |
not a migrant |
Forest dependency |
high |
| Land-mass type |
|
Average mass |
- |
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.
Country/territory distribution
Important Bird and Biodiversity Areas (IBA)
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 23/11/2024.
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 23/11/2024.
