Data Zone
Justification of Red List category
This forest-dependent species is listed as Near Threatened because it is suspected to be undergoing a moderately rapid decline (15-25% over ten years) owing to the extensive loss of lowland forests from large areas of the Sundaic lowlands.
Population justification
The global population size of this species has not been quantified, but it is relatively common (Wells 2007, Eaton et al. 2021, eBird 2024) in remaining tracts of lowland forest, which remain widespread, although much reduced in extent compared to three generations ago. Accordingly, its global population size is likely to be relatively large.
Trend justification
No direct population trend data are available for this species, however remote sensing data are considered a suitable proxy for this forest-dependent species. Over the past ten years, forest cover within its range was reduced by c. 14-18% (Global Forest Watch [2024], based on data from Hansen et al. [2013] and methods therein). This species is commonest at lower elevations, where rates have been most rapid, and the species may be additionally impacted by forest degradation and fragmentation. Accordingly, rates of population reduction may be slightly higher than remote sensing data alone indicate; the rate of population reduction for the past three generations is set at 15-25%.
Ixidia cyaniventris is confined to the Sundaic lowlands, from south Tenasserim, Myanmar, peninsular Thailand, Sabah, Sarawak and Peninsular Malaysia, Kalimantan and Sumatra, Indonesia and Brunei (BirdLife International 2001). It is locally fairly common to common in suitable habitat. It is considered extinct in Singapore, having last been observed in 1949.
This species occurs in broadleaved evergreen forest in the lowlands, although it may be commoner in hill forest to 1,400 m (Eaton et al. 2021). It generally avoids plantations or other non-native woodlands, although it does occur in tall secondary forest or logged forest, provided that some high canopy cover remains (del Hoyo et al. 2005).
The chief threat to this species is forest loss, which has been especially rapid in the Greater Sundaic bioregion due to timber extraction and the proliferation of plantations (chiefly oil-palm and rubber). These threats are thought to have driven declines of 15-25% over the past ten years. Forest fires associated with climate change may become more frequent over time, adding an additional pressure to this species including in protected areas. This species has been reported as used in trade at a low prevalence, being found in two of the seven trade datasets evaluated (Donald et al. 2024).
Conservation Actions Underway
This species occurs in numerous protected areas across its range, which safeguard it from more precipitous rates of population decline. No specific measure is known.
Conservation Actions Proposed
Continue to monitor rates of population decline using habitat extent as a proxy. Protect more areas of lowland forest. Instigate longer-term monitoring at some sites to determine whether there are additional threats to habitat loss.
Text account compilers
Berryman, A., Richardson, L.
Recommended citation
BirdLife International (2024) Species factsheet: Grey-bellied Bulbul Ixidia cyaniventris. Downloaded from
https://datazone.birdlife.org/species/factsheet/grey-bellied-bulbul-ixidia-cyaniventris on 22/11/2024.
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 22/11/2024.