Justification of Red List Category
This species qualifies as Endangered because of the rapid loss of plains-level forest in Peninsular Malaysia (which shows no signs of slowing), on which this species is dependent. Its population is becoming increasingly fragmented, leaving it vulnerable to extinction debt processes and increasing access to forest for hunters.
The population size has been previously suggested to fall into the band 2,500-9,999 mature individuals, based on an assessment of known records, descriptions of abundance and range size. However there is no density estimate available for this species, and those of congeners (none of which are as tied to plains-level forest as this) range too widely to allow for an accurate inference. The area of suitable habitat was estimated by Savini et al. (2021) to be 5,205 km2, however their methodology excluded all patches <40 km2. Ascertaining this species' persistence in smaller forest patches should be considered a priority for research as well as developing new densities to allow for the producing of a new global population estimate.
Forest loss in Thai-Malay Peninsula's plains-level forest, to which this species is confined, has been extremely rapid and does not appear to be slowing. Global Forest Watch (2021) (using Hansen et al.  data and methods disclosed therein) data indicate that total forest cover loss within suitable elevations in the range of the species was 44-50% between 2000 and 2020, equivalent to 46-51% over three generations (20.7 years; Bird et al. 2020). Similarly, Savini et al. (2021) estimated using compositional analysis and GBIF (2019) data, that between 2000 and 2018, the area of suitable habitat declined by c.33%, equivalent to c.39% over three generations. The total area of patches >40 km2 in this species's range fell rapidly (by 84%) from c.32,500 km2 to c.5,200 km2 between 2000 and 2018 (Savini et al. 2021), indicating pervasive habitat fragmentation that is likely to leave the species vulnerable to disturbance and hunting; the latter is observed even in protected areas (J. Eaton in litt. 2022). Even in areas not specifically targeted by hunters, leg snares are commonly (and illegally) used by labourers of the logging industry (G. Davison in litt. 2022).
This species is highly forest dependent and occurs in only tall primary dipterocarp forest and occasionally mature secondary forest, but never in plantations, hence the loss of area of suitable habitat is suspect to be directly related to the rate of population reduction. Thus over the past three generations, the population is suspected to have declined by 40-60%. The rate of decline may be expected to increase in the future: average annual rates of forest loss have increased such that projecting the average annual rate for the past five years (2016-2020) results in 56-64% forest cover loss over the next three generations while future local extinctions in smaller habitat patches may be expected if populations prove unviable or easily impacted by hunting. The rate of decline over the next three generations is therefore suspected to be 60-70%.
Polyplectron malacense is endemic to Peninsular Malaysia and possibly southern peninsular Thailand. Reports of its occurrence in Sumatra have been refuted, and evidence for its occurrence in Myanmar is flawed (McGowan and Kirwan 2020). It is possibly already extinct in Thailand, and its range in Malaysia has contracted dramatically (Savini et al. 2021).
Polyplectron malacense is an extreme lowland specialist, resident in tall primary and secondary (including lightly logged) lowland dipterocarp forest, usually from just 15 to 80 m, and never above c.300 m (Wells 1999), on level or gently sloping ground.
The overriding threats are habitat loss, degradation and fragmentation as a result of large-scale clearance for plantations of oil-palm and to a lesser extent rubber and timber. The conversion of habitat is typically preceded by commercial logging, which targets all remaining stands of valuable timber, even within protected areas. Rates of plains-level forest loss in the Thai-Malay Peninsula have been extremely rapid: exceeding 50% over the past three generations. Remote sensing data (Global Forest Watch , using Hansen et al.  data and methods disclosed therein) and compositional analysis (Savini et al. 2021) and the associated impacts of degradation and increased access for hunting (Savini et al. 2021) are expected to have additive impacts on the rate of reduction for this strictly forest-dependent species. Hunting for food (and to a lesser extent sport and trade) poses an additional, more localised, threat.
Conservation Actions Underway
CITES Appendix II. Important populations occur in at least two protected areas, Taman Negara and Krau Wildlife Reserve, and further populations have been reported at Sungai Dusun Wildlife Reserve (Selangor) and a number of Forest Reserves that do not qualify as protected areas under wildlife legislation, including Pasoh (Negeri Sembilan).
Male 50-53.5 cm, female 40-45 cm. Rusty-brown, crested peacock-pheasant. Similar spp. Warmer brown than extralimital Grey Peacock-pheasant P. bicalcaratum, with greener ocelli, long, dark green-glossed crest, blacker crown and hindneck, darker ear-coverts (contrast with pale surround), orange-pink facial skin and plainer underparts. Female, smaller and shorter tailed, with very short crest, blacker and more pointed ocelli, indistinct paler scaling above, more uniform underparts and yellower facial skin. Voice Male territorial call is loud, slow, melancholy puu pwoii (second note more drawn and rising). Also, sudden explosive cackle, running to throaty clucks: tchi-tchi-tchao-tchao wuk-wuk-wuk-wuk-wuk.
Text account compilers
Davidson, P., Benstead, P., Berryman, A.
Aik, Y.C., Davison, G. & Eaton, J.
BirdLife International (2022) Species factsheet: Polyplectron malacense. Downloaded from http://www.birdlife.org on 07/10/2022. Recommended citation for factsheets for more than one species: BirdLife International (2022) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 07/10/2022.