• Summary
• Text account
• Data table and detailed info
• Distribution map
• Reference and further resources

Taxonomic note

Previously treated as Arborophila graydoni (del Hoyo & Collar 2014) but moved to Tropicoperdix following Chen et al. (2015, 2018). Formerly included within A. charltonii along with T. tonkinensis following Sibley and Monroe (1990, 1993). Differs in its plain dirty white vs plain tawny-buff ear-coverts (2); absence of a distinct black upper necklace from the lower throat around below the ear-coverts (2); much darker, richer chestnut on upper breast with black vs greyish-brown lower breast feathers, more narrowly, evenly and distinctly barred with buff (3); belly with darker rufous and rufous-chestnut coloration (ns1); and darker upperparts (ns1). It differs from T. chloropus in its absence of buff-tan band around lower throat/upper breast (3); upper breast and neck-sides rich chestnut vs dingy grey-brown (3); lower breast more boldly barred (2); remaining underparts two shades darker (ns2); and darker upperparts (ns1). Differences from T. tonkinensis are indicated under that species. Monotypic.

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A. and Fishpool, L.D.C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 1: Non-passerines. Lynx Edicions BirdLife International, Barcelona, Spain and Cambridge, UK.
Handbook of the Birds of the World and BirdLife International. 2021. Handbook of the Birds of the World and BirdLife International digital checklist of the birds of the world. Version 6. Available at: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
-	-	-

Red List history

Year	Category	Criteria
2021	Near Threatened	A2c+3c+4c
2017	Least Concern
2016	Least Concern
2014	Least Concern
2012	Not Recognised
2008	Not Recognised
2004	Not Recognised
2000	Not Recognised
1994	Not Recognised
1988	Not Recognised

Migratory status	not a migrant	Forest dependency	high
Land-mass type		Average mass	-

	Estimate	Data quality
Extent of Occurrence (breeding/resident)	62,900 km2	medium
Severely fragmented?	no	-

	Estimate	Data quality	Derivation	Year of estimate
Population size	unknown	-	-	-
Population trend	decreasing	poor	inferred	2009-2022
Rate of change over the past 10 years/3 generations (longer of the two periods)	21-29%	-	-	-
Rate of change over the future 10 years/3 generations (longer of the two periods)	10-25%	-	-	-
Rate of change over the past & future 10 years/3 generations (longer of the two periods)	20-29%	-	-	-
Generation length	4.6 years	-	-	-

Population justification: The global population size has not been quantified. The current extent of potentially suitable habitat is approximately 29,000 km², though this includes a large extent of habitat close to the upper limit of the elevation utilised by the species, where densities may be low. A further 25,000 km² within this elevation range has already been converted to plantations (Harris et al. 2018). In the remaining habitat that is suitable, the species is still commonly encountered, and is tolerant of logging and is recorded in secondary forest (D. L. Yong in litt. 2021), suggesting that the overall population size remains large. However, the population is suspected to be undergoing a moderately rapid to rapid population decline from the rate of tree cover loss within the range of this forest-dependent species, which exceeds 20% and may approach 30% over the past three generations (Global Forest Watch 2021).

Trend justification: Within the range of the species habitat conversion, primarily for oil palm, has proceeded exceptionally rapidly in the past two decades. Verma et al. (2020) found that of the species they studied across Sundaland, this one had the greatest increase in the the proportion of the range impacted by human activity over the period 2000-2015. While the range of the species is more extensive than the distribution extent that was considered for that study, the growth of human footprint on the species has certainly been swift. Absolute tree cover loss within the suitable elevational range has been 26.3% over the 14 years (three generations) from 2006 to 2020, when using the forest cover estimate for 2000 corrected for loss prior to 2006 as a baseline (Global Forest Watch 2021). Using the forest cover estimate for 2010, the total loss to 2020 has been 16.1%, equivalent to a loss of 20.9% of tree cover within the suitable elevational range of the species over three generations (Global Forest Watch 2021).

Country/Territory	Presence	Origin	Resident	Breeding visitor	Non-breeding visitor	Passage migrant
Malaysia	extant	native	yes

Country/Territory	IBA Name
Malaysia	Danum Valley Conservation Area
Malaysia	Kinabatangan floodplain
Malaysia	Maliau Basin Conservation Area
Malaysia	Tabin Wildlife Reserve

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Forest	Subtropical/Tropical Moist Lowland	major	resident
Altitude	0 - 500 m	Occasional altitudinal limits	(max) 800 m

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Agro-industry farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Rapid Declines		Medium Impact: 6
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Wood & pulp plantations - Agro-industry plantations	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Logging & wood harvesting - Unintentional effects: (large scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation

Purpose	Scale
Pets/display animals, horticulture	international

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Recommended citation
BirdLife International (2024) Species factsheet: Sabah Partridge Tropicoperdix graydoni. Downloaded from https://datazone.birdlife.org/species/factsheet/sabah-partridge-tropicoperdix-graydoni on 27/12/2024.
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 27/12/2024.