Current view: Data table and detailed info
Taxonomic note
Previously considered a subspecies of C. sulphurea. Collar & Marsden (2014) used the Tobias criteria to evaluate the taxonomic status of the subspecies citrinocristata from Sumba of the Yellow-crested Cockatoo Cacatua sulphurea. They found that it met the criteria (scoring 7) against every other taxon except C. s. parvula, against which it scored only 6 as a result of the latter’s surprisingly long tail (by comparison with other Wallacean yellow-crests). This may have been a case of an overly strict application of the criteria, and the decision was ignored by Eaton et al. (2016) who readily split the ‘Sumba Cockatoo’. With the further disclosure that fledgling citrinocristata have black bills and fledgling sulphurea of all known forms have pale bills, we have further evidence of a distinction between Sumba birds and the others, we reverse the decision in Collar & Marsden (2014) to keep citrinocristata lumped and now regard it as a full species. Monotypic.
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: https://datazone.birdlife.org/userfiles/file/Species/Taxonomy/HBW-BirdLife_Checklist_v6_Dec21.zip.
IUCN Red List criteria met and history
Red List criteria met
Red List history
| Migratory status |
not a migrant |
Forest dependency |
does not normally occur in forest |
| Land-mass type |
|
Average mass |
- |
Population justification: Due to previously being recorded only as a subspecies of Yellow-crested Cockatoo C. sulphurea, numbers of traded individuals of this subspecies are not precisely known, but it was estimated that in 1989 1,350-3,000 individuals were being exported from the island annually (Marsden 1995). In the 1980s two surveys took place with the aim of determining a harvest quota (PHPA/LIPI/BirdLife International 1998). In early 1986, a density of 8 birds per km2 were recorded, and a population estimate of 12,000 individuals derived, while in 1989 the equivalent values were 1.8 birds per km2 and 2,700 individuals (PHPA/LIPI/BirdLife International 1998). The total population was estimated at 3,200 in 1992 based on a density of 2.2 (plus or minus 1.1) individuals per km2 in forest patches (1,080 km2) and around 800 elsewhere (Jones et al. 1995). Marsden (1995), placed the total population in 1992 at between 1,150 to 2,644 individuals. In 1989, the number of individuals being exported annually was estimated at between 1,350 and 3,000 (Marsden 1995), while CITES reported exports averaged 1,600 per year in 1991-1992 (WCMC, unpub. data collated from CITES annual reports, per Cahill et al. 2006). Consequently the species was considered to be at exceedingly high risk of extinction (Jones et al. 1995, BirdLife International 2001). From these values, it appears that the annual rate of decline exceeded 10% during the 1980s, and the total population reduction over this period exceeded 80%, which if it had been sustained would have led to the extinction of the species in under three generations. In 1992 and 1993, local decrees banned the trapping and transport of cockatoos on west Sumba and then east Sumba, and subsequently a zero quota for Indonesia was imposed for Cacatua sulphurea (sensu lato) in 1994. In 2002, densities in key forest patches had doubled from those in 1992 (Cahill et al. 2006), and the population outside of National Parks was estimated at 229-1,195 individuals (Persulessy et al. 2003). Overall, using equivalent area values to 1992 the population was likely between 2,000 and 5,200 individuals in 2002. The population has recently (2016-2019) been reassessed. The absolute minimum population size derived from direct observation of birds was 286 with a best value of 1,200 individuals extrapolated from sightings across the forest areas, while density estimate extrapolation indicated a tentative population size of 2,000 individuals, though this requires further evaluation of the assumptions of the extrapolation (A. Reuleaux in litt. 2021). The population is therefore estimated to number 800-1,320 mature individuals, which is suspected to still represent a reduction of greater than 80% over the past three generations.
Trend justification: Over the last three generations (1978-2021), the population of C. citriocristata is estimated to have declined rapidly. Population estimates from the late 1980s and early 1990s vary. Independently comparing the contemporary population estimate of c.2000 individuals (per A. Reuleaux in litt. 2021) to estimates of 12,000 individuals in 1986 (PHPA/LIPI/BirdLife International 1998) and 4,000 individuals in 1992 (Jones et al. 1995) suggests a decline rate equivalent to c.65-90% over three generations. Given the estimate of 1,350-3,000 birds being exported annually from Sumba in 1989 (Marsden 1995), and the substantially more abundant population size this implies, the rate of decline is suspected to be at the higher end of the 65-90% range. It is therefore suspected to have undergone a decline >80% over the past three generations (43 years). In recent years, this population decline has slowed. In 2002, densities in key forest patches had doubled from those in 1992 (Cahill et al. 2006), and the population outside of National Parks was estimated at 229-1,195 individuals (Persulessy et al. 2003). Overall, using equivalent area values to 1992 the population was likely between 2,000 and 5,200 individuals in 2002, suggesting that the population had stabilised or increased. The most recent population estimate however, of c.1,200-2,000 individuals in 2019 (per A. Reuleaux in litt. 2021) suggests that the population never recovered, and has plausibly declined slightly since. Recent reports of increased trapping (per A. Reuleaux in litt. 2021), including in protected areas, suggest that the species may be in decline once again but this requires confirmation with further surveys. Forest loss on Sumba is also accelerating: average annual forest cover loss averaged over the most recent 5 years (2016-2020) has been 0.8% (Global Forest Watch 2021), equivalent to a 34% reduction over three generations. The species is dependent on large trees for nest sites, and these trees are lost at a disproportionately rapid rate in comparison to general forest cover loss as the tree species are used for building or boat construction (Bashari 2013). Even if the slow declines of the population since 1992 continues, the scale of the reduction is sufficient that the rate of reduction will continue to meet thresholds for listing as Critically Endangered for several years to come. If trapping intensity does continue to increase, the species will no doubt be severely impacted within a few years once again, from a much lower population starting population.
Country/territory distribution
Important Bird and Biodiversity Areas (IBA)
Recommended citation
BirdLife International (2024) Species factsheet: Citron-crested Cockatoo Cacatua citrinocristata. Downloaded from
https://datazone.birdlife.org/species/factsheet/citron-crested-cockatoo-cacatua-citrinocristata on 23/11/2024.
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 23/11/2024.
