Justification of Red List Category
This cockatoo has suffered an extremely rapid population decline (>80% over three generations), owing to unsustainable trapping for the cagebird trade. This has been exacerbated by ongoing forest loss. It is assessed as Critically Endangered. Future rates of population reduction are suspected to be lower, as the bulk of the population is now restricted to protected areas.
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.
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.
This species is endemic to Timor-Leste and Indonesia, where it was formerly common throughout Nusa Tenggara (from Bali to Timor), on Sulawesi and its satellite islands, and the Masalembu Islands (in the Java Sea). It has undergone a dramatic decline, which is still ongoing, particularly in the last quarter of the 20th century, such that it is now extinct on many islands and close to extinction on most others. Formerly widespread throughout Sulawesi, it is now confined to a small population in South-east Sulawesi province, one island in Central Sulawesi, and three satellite islands to the south (O’Connell et al. 2020; A. Reuleaux in litt. 2021; Eaton et al. 2021); there have been no records from Buton since 2009 (Martin et al. 2012; T. Martin in litt. 2021). Subspecies djampeana occurs on the Flores Sea islands. Extinct on a number of islands in Nusa Tenggara (Lesser Sundas) on which it formerly occurred, but persists on some, with notable populations on Timor (both West Timor and Timor-Leste), and the Flores and Sumbawa island-groups (including a sizeable population, of c.1,100 individuals, on Komodo). Local information suggests that the species was extirpated from Masalembu Island in 1987, owing largely to the trapping and killing of birds that accompanied the exploration of the archipelago in the late 1980s (Nandika et al. 2009). It is likely extirpated from Lombok (F. Verbelen in litt. 2012). Only 17-22 of subspecies abbotti are estimated to persist (A. Reuleaux in litt. 2021) and this population is on the verge of extinction.
A feral population of several hundred birds exists in Hong Kong, China and Singapore (W. Duckworth in litt. 2020), outside of the species's natural range.
This species inhabits forest (including evergreen, moist deciduous, monsoon and semi-evergreen), forest edge, scrub and agriculture up to 500 m on Sulawesi, and 800 m (sometimes 1,500 m) in Nusa Tenggara. Previously thought to be heavily dependent on closed-canopy primary forest, on Sulawesi it is a bird of forest savanna and more open habitats and does not occur in primary forest (Anon. 2012). It nests in tree cavities with specific requirements, tending to use a chink in the trunk or branch, or a pre-existing nest-hole made by another species, often in dead, snagged or rotting trees (Nandika et al. 2009). On Masakabing Island, observations suggest that the species's favoured foods include male fruits of Artocarpus communis, fruit and flowers of Cocos nucifera (coconut palm), young leaves and flowers of Ceiba petandra, mangroves, and male flowers of Brassus sudaica, with consumption of the fruit, flowers and seeds of at least six other species observed (Metz et al. 2009). Nesting has been observed in C. nucifera, A. communis, C. petandra, Tamarindus indica and Avicennia spp. (Nandika et al. 2009).
Its precipitous decline is almost entirely attributable to unsustainable exploitation for internal and international trade. Although exports effectively became illegal in 1994, poor enforcement and monitoring enabled trapping to continue (Collar et al. 2001). Illegal trapping continued in many area including Rawa Aopa Watumohai National Park, Buton and Kadatua islands (Anon. 2012), where populations are now either much-depleted or extirpated entirely (A. Reuleaux in litt. 2021; T. Martin in litt. 2021). Large-scale logging and conversion of forest to agriculture across its range has exacerbated the decline and this is set to continue. 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. Although this species is adaptable to land conversion, it still requires large trees with substantial hollows for breeding, thus is affected detrimentally by the removal of old growth forest. On the Flores Sea islands, agricultural conversion is considered the principal threat, while hunting for food, not the pet trade, was identified as a likely threat (Bashari and Arndt 2016). Juvenile Komodo Dragons Varanus komodensis pose a threat to nestlings on Komodo (Nandika and Agustina 2012). Competition for cavity nest sites with other parrots and owls in large trees (those targeted by logging activities) leads to low productivity in C. citrinocristata (Walker et al. 2005) and may affect this species given its similar ecology. On the smaller islands of Roti, Alor and Pantar, capacity for the enforcement of hunting and trading regulations is low (F. Verbelen in litt. 2012).
Conservation and Research Actions Underway
CITES Appendix I (2005). A cooperative recovery plan was developed and adopted, and an update was prepared in 2012 (D. Mulyawati in litt. 2012). This species (along with C. citrinocristata, which is legislatively current treated as a subspecies of C. sulphurea) has become a national priority in Indonesia for increasing its population by the Ministy of Forestry and Environment (H. Bashari in litt. 2016). A recent census of all subspecies to estimate population sizes was recently undertaken (A. Reuleaux in litt. 2021). Conservation efforts have mostly been limited to legal protection, including the creation of protected areas (e.g., National Parks) to control trade and safeguard populations. Populations occur in several protected areas, including on Sulawesi and Timor-Leste (A. Reuleaux in litt. 2021). In protected areas on Sulawesi nests have been protected from predators by removing overhanging vegetation and fitting plastic collars around the trunks of nesting trees (Waugh 2013). The most important population in Komodo National Park is currently well-protected and stable thanks to intensive protection (Reuleaux et al. 2020).
Moratoria on international trade are in place, although it is likely that a large proportion of the trade is domestic. The World Parrot Trust, alongside the Nature Conservation Agency has promoted broader community engagement, including leaving field guides and binoculars to encourage parrot watching and ecotourism, as well as encouraging local involvement in birding trips. Following surveys in 2008 and 2009, the Indonesian Parrot Project and Konservasi Kakatua Indonesia initiated meetings with community leaders and villagers on Masakambing and Masalembu, as well as the local military and police, to raise awareness and garner support for the species's conservation (Metz et al. 2009). A conservation-awareness-pride programme has also begun to engage both adults and school children of the Masalembu Archipelago (Metz et al. 2009; Nandika et al. 2009) and in south-east Sulawesi (Anon. 2012). A 'village regulation' was drafted to make it illegal to trap, own or transport the species, and to initiate measures to reduce habitat destruction and employ a former village head to monitor and protect nests and study the species (Nandika et al. 2009, 2020). This locally-mediated zero-trapping policy has allowed the tiny population remaining to increase by nearly threefold in 12 years (Nandika et al. 2020). Similar community-based regulations have been put in place by the Moronone community in Sulawesi, where four village members have been hired as Forest Wardens (Anon. 2012). The wardens protect the species against poachers and carry out monitoring activities (Waugh 2013). The species's pest status may be tackled by the planting of crops to compensate for losses and to act as a 'sacrifice crop', for instance sunflower fields are used to attract the species away from other crops (Waugh 2013). Mangrove restoration is also being used to increase available nesting habitat (Waugh 2013).
Conservation and Research Actions Proposed
Monitor the population trends of each subspecies with regular surveys and identify critical areas for protection. Treat each taxon as a separate unit of conservation concern (Collar and Marsden 2014). Strengthen control, law enforcement and monitoring of trade and establish greater management of captive populations. In particular, subspecies sulphurea and abbotti are both estimated to number <100 mature individuals (Reuleaux et al. in prep.) and are in urgent need of continued and intensified action. Despite the species's inclusion on CITES I and protection in national law, away from Komodo National Park trapping for the pet trade continues with declines noted in almost all other populations (A. Reuleaux in litt. 2021); improving law enforcement in designated protected areas and other key areas for trade including ports, markets, etc. is therefore critical. Widespread community-based conservation initiatives should be promoted. For instance in Central Sulawesi a population persists on a tiny island with only five families, hence work to protect the species must involve all of these (Nandika and Agustina 2012; Nandika et al. 2012). Community engagement programmes for children and adults should begin on other islands where the species is found (Nandika and Agustina 2012). Recommendations made specifically for the protection of the species in Komodo National Park were to conduct annual monitoring, maintain regular patrols, raise awareness in local communities and study human activities and impacts within the park (Imansyah et al. 2005; Benstead 2006). Conduct ecological research to clarify options for its management and conservation. Additional targets should be to study the abundance and distribution of nest holes and water sources. Remote sensing data should continue to be used to monitor forest loss in this species's range. Providing artificial water sources near nest locations, i.e. water ponds, is essential for the species on Komodo Island and protecting nests from juvenile Komodo Dragons on Komodo may also be necessary (Nandika and Agustina 2012). Global trade in wild-caught Yellow-crested Cockatoos was banned in 2002; however, the sale of captive-bred birds is still permitted. A recent approach of distinguishing between wild-caught and captive bred birds using stable isotope analysis (Anderssen et al. 2021) advocated its use as a forensic tool in monitoring and combatting illegal trade. There are several populations in captivity in Europe: subspecies should be kept separate as isolated conservation units and populations need precautionary management.
33-35 cm. Medium-sized, white cockatoo. All-white, but for long, forward-curling yellow crest, yellow ear-coverts and yellow under-surfaces to wings and tail. Black bill, bluish, bare eye-ring and grey feet. Similar spp. Sulphur-crested Cockatoo C. galerita is much larger and has white skin around eye. Voice Loud and very raucous. Often gives single harsh screech but also sweeter whistles and squeaky notes.
Text account compilers
Berryman, A., Fernando, E., Martin, R.
Bashari, B., Duckworth, W., Halaouate, M., Imansyah, J., Kelly, D., Lehmberg, T., Martin, T., Mauro, I., Mulyawati, D., Prawiradilaga, D., Reuleaux, A., Trainor, C. & Verbelen, F.
BirdLife International (2023) Species factsheet: Cacatua sulphurea. Downloaded from http://www.birdlife.org on 01/04/2023. Recommended citation for factsheets for more than one species: BirdLife International (2023) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 01/04/2023.