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

Taxonomic note
Closely related to C. galerita and C. ophthalmica. Previous recognised taxon included subspecies citrinocristata (del Hoyo & Collar 2014), but this now split as Citron-crested Cockatoo (which see). Subspecies abbotti strikingly large (except in bill size) (3), with small, pale brownish-yellow ear-covert patch (2). Subspecies djampeana and occidentalis generally regarded as synonyms of nominate subspecies and parvula, respectively, but new evaluation indicates real morphological differences and even possible subspecific division within djampeana (Collar & Marsden 2014). Five subspecies recognized.

Taxonomic source(s)
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: http://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip.

Red List criteria met

Critically Endangered	Endangered	Vulnerable
A2bcd+4bcd	A2bcd+4bcd	A2bcd+3bcd+4bcd

Red List history

Year	Category	Criteria
2021	Critically Endangered	A2bcd+4bcd

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

	Estimate	Data quality
Extent of Occurrence breeding/resident (km2)	965,000	medium
Number of locations	15-100	-
Severely Fragmented		-

	Value	Data quality	Derivation	Year of estimate
No. of mature individuals	1200-2000	medium	estimated	2019
Population trend	decreasing	poor	inferred	-
Decline (3 years/1 generation past)		-	-	-
Decline (5 years/1 generation past)		-	-	-
Decline (10 years/1 generation past)		-	-	-
Decline (10 years/3 generation future)	30-49	-	-	-
Decline (10 years/3 generation past and future)	80-90	-	-	-
Number of subpopulations	10-100	-	-	-
Percentage in largest subpopulation	1-89	-	-	-
Generation length (yrs)	14.3	-	-	-

Population justification: A recent estimation of the population of each subspecies produced as a result of intensive surveys throughout the species's range between 2016 and 2019 (Reuleaux et al. in prep.) suggests the following: nominate, on Sulawesi and its satellites, 27-105 individuals; parvula, on Timor, Rote, Semau, 430-990 individuals; paulandrewi, Tukangbesi islands, 81-170 individuals; djampeana, Flores Sea islands, 61-156 individuals; occidentalis, Nusa Penida and Lombok-Alor (although extinct on many islands), 1,200-1,700 individuals; and abbotti, 17-22 individuals. In total, the population is estimated to number 1,800-3,140, or 1,200-2,000 mature individuals, with the best estimate near the higher end of the range. This total is suspected to be only a small percentage of that present three generations ago, when the species was still widespread throughout Sulawesi and large numbers still occurred throughout the Lesser Sundas. The rate of reduction over this time is suspected to have been between 80-90%. Future declines are likely to be at a far slower rate as the majority of the population is now concentrated in protected areas, but trapping continues and there are several islands at imminent risk of losing their remaining few individuals.

Trend justification: This species has declined extremely rapidly owing to international trade in the species and to a lesser extent the widespread deforestation within its range. The size of its population before the rapid trade rise is poorly understood, but that >5,000 were imported to Singapore annually throughout the 1980s (Cahill et al. 2006) is strongly indicative of a population formerly substantially greater than the contemporary estimation of 1,200-2,000 birds, especially when considering large numbers were probably lost in transit before making it to Singapore (A. Reuleaux in litt. 2021). However, internal and international trade is thought to continue (e.g. Andersson et al. 2021). The species has become extinct on a number of islands in Nusa Tengarra, and other populations have been decimated. For example, nominate sulphurea persists on Sulawesi with a much-diminished population of c.50 birds in South-east Sulawesi province, having formerly been widespread across the island. Similarly, subspecies abbotti persists with just 17-22 birds left.
Over the last three generations (since 1978), the population is suspected to have decline by 80-90%. Declines were also documented even where trade was not so obvious, such as on Komodo where a rapid decline was reported up to 2005 (Imansyah et al. 2016). The population on Komodo (comprising c.1,100 individuals, c.35% of the global population) is now believed to be stable thanks to protections in Komodo National Park (Reuleaux et al. 2020), such that future declines of the global population are estimated to be slower. However, the current and future rate of forest cover loss in the current occupied and probably occupied range (based on the estimated mean annual rate over the most recent five years, per Global Forest Watch 2021) is projected to be 16.1% over three generations. Consequently, even if trapping is successfully halted in the remnant populations, it is inferred that the population will continue to decline due to the species’s dependence on large trees for nesting. The species is therefore projected to decline over 30-49% over the next three generations. However, any declines in the Komodo population would likely see this rate increase once again, and from a much smaller starting population.

Country/Territory	Presence	Origin	Resident	Breeding	Non-breeding	Passage
China (mainland)	extant	introduced	yes
Hong Kong (China)	extant	introduced	yes
Indonesia	extant	native	yes
Singapore	extant	introduced	yes
Timor-Leste	extant	native	yes

Country/Territory	IBA Name

Habitat (level 1)	Habitat (level 2)	Importance	Occurrence
Artificial/Terrestrial	Arable Land	suitable	non-breeding
Artificial/Terrestrial	Plantations	suitable	resident
Forest	Subtropical/Tropical Dry	major	resident
Forest	Subtropical/Tropical Mangrove Vegetation Above High Tide Level	suitable	resident
Forest	Subtropical/Tropical Moist Lowland	major	resident
Shrubland	Subtropical/Tropical Dry	suitable	resident
Shrubland	Subtropical/Tropical Moist	suitable	resident
Altitude	0 - 1000 m	Occasional altitudinal limits

Threat (level 1)	Threat (level 2)	Impact and Stresses
Agriculture & aquaculture	Annual & perennial non-timber crops - Shifting agriculture	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Agriculture & aquaculture	Livestock farming & ranching - Agro-industry grazing, ranching or farming	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Ecosystem degradation, Ecosystem conversion
Biological resource use	Hunting & trapping terrestrial animals - Intentional use (species is the target)	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Very Rapid Declines		High Impact: 8
		Stresses Species mortality
Biological resource use	Hunting & trapping terrestrial animals - Persecution/control	Timing		Scope		Severity		Impact
		Past, Unlikely to Return		Minority (<50%)		Slow, Significant Declines		Past Impact
		Stresses Species mortality
Biological resource use	Logging & wood harvesting - Unintentional effects: (subsistence/small scale) [harvest]	Timing		Scope		Severity		Impact
		Ongoing		Majority (50-90%)		Slow, Significant Declines		Medium Impact: 6
		Stresses Ecosystem degradation
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Unspecified species	Timing		Scope		Severity		Impact
		Ongoing		Unknown		Negligible declines		Unknown
		Stresses Competition, Reduced reproductive success
Invasive and other problematic species, genes & diseases	Problematic native species/diseases - Varanus komodoensis	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Slow, Significant Declines		Low Impact: 5
		Stresses Species mortality
Pollution	Agricultural & forestry effluents - Herbicides and pesticides	Timing		Scope		Severity		Impact
		Ongoing		Minority (<50%)		Unknown		Unknown
		Stresses Ecosystem degradation

Purpose	Primary form used	Life stage used	Source	Scale	Level	Timing
Food - human	-	-			non-trivial	recent
Pets/display animals, horticulture	-	-		international	non-trivial	recent

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Recommended citation
BirdLife International (2023) Species factsheet: Cacatua sulphurea. Downloaded from http://datazone.birdlife.org/species/factsheet/yellow-crested-cockatoo-cacatua-sulphurea on 06/06/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://datazone.birdlife.org on 06/06/2023.