Data Zone
Justification of Red List category
This species has a large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is suspected to be declining but the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size has not been quantified but is not believed approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Population justification
Fundamentally unknown. Qualitative descriptions of abundance on Borneo range from 'common and widespread' (Mann 2008) to 'uncommon' (Eaton et al. 2021), but these interpretations include also Bornean populations of O. xanthonotus (the two having only recently been separated as distinct species: Rheindt et al. 2022). On Palawan, described as 'fairly common' (Allen 2020). Citizen science data suggest that on both islands it is relatively common in lowland forest blocks (eBird 2023); while it appears able to persist in mature Acacia mangium and Albizia plantations, albeit at lower densities than in forest (Styring et al. 2011), there is no evidence that it can persist in even mature oil palm plantations (Koh and Wilkove 2008, Styring et al. 2011). While the population is not thought to be small (there remains a large amount of suitable habitat), it is thought to have considerably decreased over the past 20-30 years in response to large-scale conversion of land to oil palm plantations.
Trend justification
Undoubtedly declining in response to conversion of forest habitats to plantations, although this species is tolerant of some degradation, and declines are not thought to have exceeded 20% over the past three generations, and are unlikely to accelerate in the near future. According to remote sensing data, forest cover loss in this species range over the past three generations was equivalent to 14-19%, depending on the assumptions used (Global Forest Watch 2023, based on data from Hansen et al. [2013] and methods disclosed therein). This species is considered moderately forest-dependent, with most records from lowland forest, where it evidently occurs at the highest densities (Styring et al. 2011, eBird 2023). While the species occurs in Acacia mangium and Albizia plantations (Styring et al. 2011), a large proportion of land conversion in its range has been conversion to oil palm plantations, which this species does not occur in (Koh and Wilkove 2008, Styring et al. 2011). While the remote sensing data used here is insensitive to forest degradation, this is not thought to be a key threat to this species, which regularly occurs in forest edge and mature second growth. Consequently, over the past three generations (10.8 years: 2012-2023) O. consobrinus is suspected to have declined by 10-20%. This same rate is precautionarily assumed to occur over the next three generations, although thereafter rates of reduction may begin to slow, as an increasing percentage of this species' range will lie in protected areas.
Known from Sabah, Malaysia, Kalimantan, Indonesia (thus northern/eastern Borneo), and Palawan, the Philippines. The southern and western limit of its range (and where it surely comes into contact with O. xanthonotus) is unknown (Rheindt et al. 2022), including whether it occurs in Brunei. There are also no recent records from Culion (Allen 2020) and habitat there is severely degraded; accordingly, it is mapped there as only possibly extant.
This is a species principally of lowland forest, occurring in primary and tall secondary evergreen forest, edge and mature second growth, principally below 500 m, but with records extending up to c.1,200 m (Wells 2007, Mann 2008, Eaton et al. 2021).
The principal threat to this species is the conversion of forest to plantations, particularly oil palm, and the associated timber extraction. Both threats are thought to be causing slow declines (equivalent to 10-20% over three generations), although this species' tolerance of some habitat degradation buffers it from steeper declines.
Conservation Actions Underway
None is known specific to this species, but it occurs in numerous protected areas.
Conservation Actions Proposed
Research in more detail this species' habitat tolerances and, particularly, the impact of degradation. Advocate for more extensive protection of lowland forest areas in its range, to benefit it and other more threatened lowland Sundaic species.
Text account compilers
Berryman, A.
Recommended citation
BirdLife International (2024) Species factsheet: Ventriloquial Oriole Oriolus consobrinus. Downloaded from
https://datazone.birdlife.org/species/factsheet/ventriloquial-oriole-oriolus-consobrinus 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.