Data Zone
Justification of Red List category
This species is very poorly known and there are only a handful of modern records from two mountains in Java. However there are unconfirmed reports from widely separated additional sites and the species is noted to be highly inconspicuous. Plausible bounds of the population therefore range from a very small number of mature individuals that may be as few as 250 mature individuals to a large population that would exceed the population size threshold for listing as threatened or Near Threatened.
There is a slow rate of ongoing forest loss and degradation, such that a slow rate of decline is suspected. However, the species has also been recorded in domestic trade in Java, which represents an unquantified level of threat from which a continuing decline can be inferred.
As such, and with no information to judge current population size more accurately the species could be assessed within any category from Critically Endangered under C2a(ii) (if the population is restricted to the very small numbers from two adjacent sites suggested by confirmed records, coupled with a continuing decline inferred from the observed capture for trade) through to Least Concern (if the population is thinly spread throughout the whole of Java and therefore large, and any suspected rate of decline does not exceed or approach 30% in three generations).
As such, at present this elusive and poorly known species is assessed as Data Deficient. It is a high priority for further research.
Population justification
The global population size has not been quantified. Weeklong ornithological surveys across 27 sites on nine mountains in West-Central Java between 2018 and 2020 found Javan Oriole at 4 sites and 2 mountains with a mean encounter rate of 0.51 groups/hour (range = 0.19 to 0.74 where present; C. Devenish, A.R. Junaid and S. Marsden in litt. 2020).
Javan Oriole is restricted to mid elevation forest on Java, Indonesia, with the very few modern records all from West-Central Java (B. van Balen in litt. 2018, 2020; J. Eaton in litt, 2018, 2020; Jihad in litt. 2016; C. Devenish, A.R. Junaid and S. Marsden in litt. 2020). While it may still occur in East Java, numerous surveys and expeditions have not recorded the species (e.g. Mittermeier et al. 2014, van Balen in litt. 2020). .
Confirmed records come from evergreen hill and montane forests between c. 900 m and 1400 m, with an unconfirmed sighting at 1,800 m (Jihad in litt. 2018). A pair has been observed to join a mixed-species foraging group, but is typically high in the canopy and calls infrequently with simple and easily missed vocalisations (B. van Balen in litt. 2020). The song is only delivered during the breeding season (B. van Balen in litt. 2020).
The species is known from few widely separated areas of montane forest in west Java, where there is a slow rate of deforestation and forest degradation ongoing. Over the ten years to 2019 approximately 1.5% of tree cover with 75% canopy cover was lost from within the species’s range (Global Forest Watch 2020).
The prevalence of song bird trapping across Java is such that it would be a great surprise that this species would not be trapped if located, and indeed two records of the species in markets have been observed (in Sukabumi between September 2017 and April 2018 and Cicurug in January 2018, J. Bielby in litt. 2020). The paucity of records from market inventories is highly likely to be a reflection on both the rarity and inconspicuous habits of the species (B. van Balen in litt. 2020).
Conservation Actions Underway
Recent records are all from within protected areas, in fact the entire extent of remaining potential habitat is within protected areas.
Conservation Actions Proposed
There is a need for targeted surveys to confirm the current presence of the species within additional protected areas, prioritising East and Central Java. This can adopt the same methodology as the survey effort carried out between 2018-2020 by Burung Indonesia/Manchester Metropolitan University, and this should be repeated at regular intervals to establish trends in encounter rates for this and the whole suite of Javan montane forest birds.
Further collaboration with the Indonesian government is required to find a mechanism to allow meaningful regular monitoring of species, numbers and prices within major bird markets in Java. It is important to ensure that this taxon is recognised by all parties monitoring international trade and that it is likewise included in lists 'zero quota' species (for which any take from the wild is illegal) in national legislation. Investigate the feasibility of a subsidy approach for trading 'safe' species, such as those for which the vast majority of birds traded are derived from captive-bred stock, and conversely developing a list of 'red-flag' species (including Javan Oriole) for which discovery of birds for sale will lead to immediate sanction.
Text account compilers
Martin, R.
Contributors
Beilby, J., Devenish, C., Eaton, J., Junaid, A., Marsden, S., Sulfani Udin, J. & van Balen, B.S.
Recommended citation
BirdLife International (2024) Species factsheet: Javan Oriole Oriolus cruentus. Downloaded from
https://datazone.birdlife.org/species/factsheet/javan-oriole-oriolus-cruentus on 22/12/2024.
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 22/12/2024.