Data Zone
Justification of Red List category
Tree cover loss through conversion of forest to agriculture (particularly for oil palm plantations) is estimated at 17% over the past three generations, and with further impacts from degradation the the species is now suspected to be undergoing a moderately rapid to rapid population reduction over the past three generations. The majority of the loss has taken place within the lowlands, within the preferred elevational range of the species. In addition, trapping pressure on the species is thought to be high and it is a desirable bird in trade, with exploitation suspected to result in an additional 25% reduction over three generations. Overall, the population is suspected to have undergone a rapid recent reduction at a rate exceeding 30% over three generations, hence is assessed as Vulnerable. This reduction will continue unless there is a significant reduction in both the rate of habitat conversion and of wild bird trapping within the range of the species, or until the majority of the population becomes restricted to more secure protected areas.
Population justification
The global population size has not been quantified but is believed to be large given the range and frequency of records in suitable habitat. It is a forest-dependent species, although it can use degraded and secondary growth and is one of the more regularly observed South-East Asian galliformes (Madge and McGowan 2002). Within the range the rate of forest conversion to plantations, primarily oil palm, has been very rapid over the past few decades (Global Forest Watch 2021) and as such the population is inferred to be declining. There are recent records from remaining forested areas across the range, however the extent of suitable habitat is now considerably smaller than three generations ago. Where habitat is secure the species continues to be regularly observed (eBird 2021), though observing the species away from protected areas is becoming much more difficult. There are very few records from recent years in Thailand and the population here is now thought to be small. In Myanmar the loss of lowland forest has been rapid in the past decade, although populations on offshore protected islands such as Lampi Marine National Park may be secure. Almost all records in Malaysia now come from protected areas, and the population is thought to be declining rapidly in Indonesia. Forest loss is much lower in Brunei, where impacts on the species may be much less severe.
Absolute loss of forest cover has proceeded at a moderately rapid rate, with further population impacts assumed from degradation in forest remaining (Global Forest Watch 2021). On top of this it is suspected that the rate of additional population reduction due to hunting and trapping for the cage bird trade has been 25% over three generations (Symes et al. 2018). These two main threats the to species interact: where forest is fragmented, access increases and with it the extent of trapping pressure. As such the species is suspected to be suffering a rapid population reduction.
Trend justification
The species is more abundant in intact forest, consequently the population impact of forest cover loss is expected to be equal to or greater than the rate of loss. 17% of forest cover (with greater than 30% canopy cover) has been lost over the past three generations (14.1 years) (Global Forest Watch 2021). This value does not account for the impact of forest degradation, hence the population rate of reduction from habitat loss is likely to be greater than this. The impact of hunting and trapping for the cage bird trade was assessed using expert opinion in Symes et al. (2018), who concluded that it could be causing an additive reduction of 25% over three generations. These two main threats the to species interact: where forest is fragmented, access increases and with it the extent of trapping pressure. As such the species is suspected to be suffering a rapid population reduction.
Rollulus rouloul is confined to the Sundaic lowlands, where it is known from south Tenasserim, Myanmar, peninsular Thailand (where there are very few recent records), Sabah, Sarawak and Peninsular Malaysia, Brunei, and Kalimantan and Sumatra, Indonesia (BirdLife International 2001, eBird 2021). Forest loss within this range has been rapid over the past two decades and while the species is able to persist in selectively logged forest and can utilise early-stage regenerating forest it has undoubtedly declined and it appears likely that the range has been fragmented due to deforestation. At the northern edge of the range in Thailand there have apparently not been any records in Kaeng Krachan National Park for over a decade (Thaibirding.com 2020), although it is assumed to still occur in Hala Bala with continued presence noted in the contiguous Belum-Temengor Forest Complex in Malaysia (Chye 2010). Continued presence in the Krabi province is uncertain, previously the species was regularly seen at Khao Nor Chu Chi but there are no records from this part of Thailand in the past decade (GBIF 2021). The species does not occur on Singapore (Wells 1999), though there is a single historical specimen (GBIF 2021). Presence on Bangka and Belitung Islands off south east Sumatra is unclear: judged possibly extinct in 1989 (Holmes 1989) and apparently no recent records (GBIF 2021). There is also a record from eastern Thailand from 1934 (GBIF 2021): it is presumed the species no longer occurs in this area.
It occurs in broadleaved evergreen and dense primary lowland and hill forests and bamboo, largely in true lowlands, although there are records up to 1,300 m on Borneo (Mann 2008) and up to 1,550 m in Peninsular Malaysia (Wells 1999). Forages on the ground and appears to be associated with large frugivorous mammals, especially pigs (McGowan et al. 2020). Abundance is higher in more intact forest (Jati et al. 2018) and in some sites the species is not found outside of primary forest at all (Peh et al. 2005).
Forest destruction in the Sundaic lowlands of Indonesia and Malaysia has been extensive, for timber and conversion to agriculture. In particular the rapid expansion of oil palm has driven the conversion of the majority of remaining lowland forest in the region. 25% of tree cover within the range of the species has been lost between 2001-2019 (Global Forest Watch 2021), equivalent to 17.2% loss over three generations. Most of this loss has occurred within the lowlands, where the highest densities of the species would be expected. Moreover, the impact of forest degradation will have added to rates of decline. Associated with the forest loss have been an increase in fire frequency, extent and severity, particularly during strong El Nino events (as in 1998).
In addition the species has been frequently observed in trade, and rates of trapping are suspected to be high (Symes et al. 2018). The combination of loss of habitat and associated increase in the accessibility of remaining forest to trappers strongly indicates that the rate of decline in the species is likely to be faster than predicted from habitat loss and degradation alone (Symes et al. 2018).
While the species can use secondary growth and higher elevations, the extent of the threats is such that this species's population is likely to be declining rapidly.
Conservation Actions Underway
It occurs in a number of protected areas.
Text account compilers
Martin, R.
Contributors
Mahood, S.
Recommended citation
BirdLife International (2024) Species factsheet: Crested Partridge Rollulus rouloul. Downloaded from
https://datazone.birdlife.org/species/factsheet/crested-partridge-rollulus-rouloul 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.