Data Zone
Justification of Red List category
This partridge has a disjunct distribution in lowland forest where conversion of forest to agriculture is rapid and on-going, and trapping pressure is prevalent. An apparent range contraction in the past two to three decades appears to leave it close to being extant in Malaysia only, although it is assumed to still be present in cross-border forests in Thailand. The subspecies T. c. atjenensis of Sumatra is likely to have become extinct during the last century. A rapid population reduction is suspected at a rate that likely slightly exceeds the rate of tree cover loss within the restricted elevation, which is 32% over the past three generations. The rate of population reduction is highly likely to continue to exceed 30% over the following three generations unless there is a sudden slowdown in the rate of habitat conversion. It is therefore classified as Vulnerable.
The total population is also now likely to be small and comprised of isolated subpopulations inferred to be undergoing continuing population declines. There is an overdue need for a range-wide sampling survey to generate a reliable population estimate, and for ongoing monitoring at key sites throughout the range.
Population justification
The global population has previously been judged to number fewer than 10,000 mature individuals (BirdLife International 2001, Madge and McGowan 2002), based on expert opinion of the plausible numbers in each section of the range. This figure may be too low, given the extent of protected forests within Malaysia where there are expected to be secure populations. However there is evidence of a large population reduction, inferred from the lack of recent records from historically occupied sites, and a corresponding large reduction in the extent of occurrence.
The population on Sumatra (subspecies T. c. atjenensis) is considered likely to be very small indeed if it persists at all. Boakes et al. (2018) found only two published records, the most recent in 1939, and considered that it was probably extinct. Recent records mentioned by Eaton et al. (2016) are unconfirmed (J. A. Eaton in litt. 2021) and may be erroneous.
In Thailand, there are similarly few recent records and the species appears to now be restricted to the far south: there do not appear to be any records from Krabi Province since those of Robson (1990a,b) or any further north (GBIF.org 2021). There is assumed to be a population in Hala-Bala Wildlife Sanctuary (D. L. Yong in litt. 2013, J. A. Eaton in litt. 2013), but there are no records. This area is contiguous with the Ulu Muda and Pedu Forest Reserves in Malaysia, where the species is regularly recorded despite some hunting pressure: suggesting that as with other members of the genus the species has some resilience to hunting (J. A. Eaton in litt. 2013). The species is also recorded, though infrequently, from several other protected forests (including Taman Negara National Park [GBIF.org 2021] but most of the habitat is unsuitable for the species) and recreational forests, though the species does not appear to be recorded in plantations.
Generally the species appears to be infrequently recorded, suggesting that its density is lower than that of congeners. Over the range, forest cover loss has been rapid over the past three generations. Total tree cover loss within the elevation range of the species is estimated at c. 32% forest cover loss over the three generation period 2006-2020 (Global Forest Watch 2021). The species is also suspected to be impacted by hunting in parts of the range, although this may have only minor population impacts (J. A. Eaton in litt. 2013).
Trend justification
There are no direct data on population trends in the species. However, within the suitable elevation range of the species between 2001 and 2020 there has been a loss of 36% of the estimated extent of forest cover present in 2000 (Global Forest Watch 2021). This rate of loss has been increasing over this period, with the largest annual losses (exceeding 200,000 km2) occurring in 2014, 2016 and 2017. For the most recent three-generation period for which forest loss data is available, 31.5% of the adjusted total extent of forest in 2006 had been lost by 2020 (Global Forest Watch 2021). The species is highly forest dependent. While it has been reported from degraded forest in parts of the range (Madge & McGowan 2002), almost all records are from relatively large contiguous forest areas, and it is likely that it occurs at much higher densities in undisturbed forest than in logged forest. Equally, although there are records of the species persisting in areas with known hunting pressure, hunting is believed to suppress densities and the fragmentation of the habitat within the range is likely to have exposed a greater proportion of the population to trapping. Given the apparent rapid range retraction from central southern Thailand to the border with Myanmar, and the apparent extinction from Sumatra (Boakes et al. 2018) coupled with the rapid loss of forest cover within the range, a continuing decline in range and number of mature individuals is inferred. The rate of population reduction may exceed that indicated by the tree cover loss alone over the past three decades, and is placed in the band of 30-49% reduction over the past three generations (14 years).
The species has a disjunct Sundaic distribution ranging (race charltonii) from southern Thailand, through Peninsular Malaysia and was present (race atjenensis) in two isolated areas (Aceh and South Sumatra) of Sumatra, Indonesia (BirdLife International 2001). The occurrence of the species in Myanmar is uncertain: there have been no records in recent decades despite considerable survey effort in the Tanintharyi region (Nay Myo Shwe, M. Grindley, Thiri Dae We Aung in litt. 2021). The only historical record is an observation dated 1922 via the GalliForm dataset (Boakes et al. 2020, GBIF.org 2021, Newcastle University 2020).
It may be extinct on Sumatra. The only records are an 1848 specimen from Aceh and a 1939 specimen from southern Sumatra. No more recent records were located by Boakes et al. (2020) and there are none in the GBIF database (GBIF.org. 2021). While Eaton et al. (2016) mention 'few recent records on Sumatra', none have been confirmed (J. A. Eaton in litt. 2021).
In Thailand the species is now believed to be restricted to the large forest areas close to or crossing the border with Malaysia. Some records are from degraded forest sites in south Thailand so it may have some tolerance of disturbed forest (Madge & McGowan 2002), however the species appears to have contracted in range considerably since the 1990s, when it was still present in Krabi Province (Robson 1990a,b) and these records may have been of a subpopulation heading to extinction. The rapid contraction and disjunct range appears to be a result of the species requirement for extreme lowlands (<300 m) and closed-canopy forest. This gives the species an extremely narrow elevational range, which overlaps entirely with the suitable conditions for oil palm agriculture. The approximate extent of forest (i.e. excluding plantations [Harris et al. 2018]) within this elevational band with records of the species in adjoining patches is c. 8,200 km2, although not all of this area may be occupied.
This species inhabits lowland forest largely below 300 m above sea level; there are records from disturbed and bamboo-dominated secondary forest (BirdLife International 2001, Madge and McGowan 2002, del Hoyo et al. 2020). It is typically found in flat, plains-level, closed-canopy forest. As such, the species has a very narrow elevational range and is restricted to a habitat also suitable for agriculture, and which has consequently suffered rapid conversion in recent decades.
Forest destruction in the Sundaic lowlands of Indonesia and Malaysia has been extensive and 36% of tree cover has been lost from suitable elevations within the range of the species between 2001 and 2020 (Global Forest Watch 2021). Most habitat has been converted to plantations, predominately oil palm (Harris et al. 2018). However forests have also been targeted for timber and the increased severity and frequency of forest fires within the range has accelerated the rate of forest loss since 2000. The rate of forest loss has been relatively consistent over the past ten years at a higher level than in the first ten years of the 2000s. The rate is unlikely to decrease in the near term within the elevation range of concern.
Trapping for food and for the cage-bird trade is also suspected to be reducing densities across much of the range. Species within the genus appear to be able to withstand relatively high trapping pressure (J. W. Duckworth in litt. 2013), but the degree to which that is applicable to the present species is unclear, especially when the range appears to be more fragmented and accessible than that of congeners. The relatively low frequency of reports in comparison to congeners also indicates that the species may occur at lower densities and have a lower tolerance of disturbance, or this may simply reflect the more rapid rate of habitat loss and degradation affecting the species.
Conservation Actions Underway
None is known. The species occurs in multiple protected areas in Malaysia and is assumed to occur in protected areas contiguous with these in Thailand, although this may not be the case. It was covered in the initial conservation action plan for partridges in 1995 (McGowan et al. 1995).
26-32 cm. Boldly-marked partridge with chestnut collar and tawny ear-patch. Similar spp. A. tonkinensis has narrower chestnut collar and smaller, tawny-stained white ear-patch with black spots. A. graydoni has dirty-white ear coverts. From Bar-backed Partridge A. brunneopectus by plainer upperside, heavy black breast markings, greenish to yellowish-green legs and distinctive ear-patch and collar. From extralimital Scaly-breasted and Annam Partridges A. merlini by chestnut ear-patch and collar. Voice Similar to Scaly-breasted (see Annam).
Text account compilers
Martin, R.
Contributors
Yong, D., Mahood, S., Eaton, J., Taylor, J., Symes, A., Benstead, P. & Duckworth, W.
Recommended citation
BirdLife International (2024) Species factsheet: Chestnut-necklaced Partridge Tropicoperdix charltonii. Downloaded from
https://datazone.birdlife.org/species/factsheet/chestnut-necklaced-partridge-tropicoperdix-charltonii on 20/12/2024.
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 20/12/2024.