Data Zone
Justification of Red List category
Although this species has an extremely large range, there is evidence from parts of the range (especially Australia) that it is in severe decline. While large areas of unspoilt habitat remain on New Guinea, this species is long-lived and extremely slow to breed, such that even small magnitudes of habitat loss and degradation, and hunting, are thought to cause moderate declines. Over the next three generations (47 years), the population is suspected to decline by 20–29%. Accordingly, it is listed as Near Threatened.
Population justification
The global population size has not previously been accurately estimated but it remains regularly observed through its range (eBird 2022). In Australia, the endemic taxon macgillivrayi is reliably estimated to number 1,800-2,600 mature individuals, with a best estimate of c.2,200 (Heinsohn et al. 2021). Robust population data on the other three recognised subspecies are lacking, although nest densities of 0.8/km2 were recorded in Papua New Guinea (Igag et al. 2019), equivalent to c.1.6 mature individuals/km2. Across the range (excluding Cape York, Australia, for which other data are available), there is a large area of ostensibly suitable habitat, amounting to c.400,000–500,000 km2 of forest depending on the tree cover percentage used (per Global Forest Watch 2022, based on data from Hansen et al. [2013] and methods disclosed therein). Assuming the densities collated at a single site in Papua New Guinea are representative for elsewhere in New Guinea (including satellites), and that only a percentage (arbitrarily set here to 40–80%) of the range is occupied, the population is estimated to number c.260,000–640,000 mature individuals.
Trend justification
This species is inferred to be in decline due to a plethora of threats across its range.
Although it represents only a small portion of the global population, the most robust data are available from Australia, where data are consistent in demonstrating the species is likely to be in severe decline (Heinsohn et al. 2009, 2021; Keighley et al. 2021). Over a slightly longer three-generation timeframe than that used here (49 vs 47 years), Keighley et al. (2021) used population viability analysis to predict a 46.7-94.5% future decline in the meta-population, and a 74.2–93.8% decline in the Iron/McIllwraith population; the authors favoured models that ultimately predicted more precise declines of 55.1–55.6% and 80.3–82.9% respectively. The principal cause of these declines is habitat loss (caused by clearing for bauxite mining), a changing fire regime, competition with Cacatua galerita and increasing storm severity/frequency (Heinsohn et al. 2021); however, none of these threats are thought to be impacting populations in New Guinea, where >95% of the population resides.
In New Guinea, the chief threats are habitat loss and trapping for the pet trade. Between 2000 and 2021, habitat loss in the non-Australian part of the species' range amounted to c.5%, equivalent to c.10-11% over three generations. However, this accelerated from 2014 to a rate equivalent to 14% over three generations and there is concern this could accelerate further if patterns observed in Indonesian Borneo over the last three decades are mirrored (Gaveau et al. 2021). Moreover, this species has bespoke nesting requirements, apparently favouring deep hollows with an open-skyward facing entrance (Igag et al. 2019), that may be heavily impacted by selective logging, a key threat in New Guinea's lowlands (Testolin et al. 2016) that is not accurately detectable using remote sensing data. The impact of trapping for the pet trade remains similarly unquantified, but both local (Pangau-Adam and Noske 2010) and international (Sy 2010) trade of this species has been documented. Although large areas of habitat remain impenetrable to local trappers, ongoing fragmentation and increasing accessibility via road infrastructure (Gaveau et al. 2021) are likely to make this an accelerating threat. This species breeds extremely slowly, producing only a single egg in any clutch and, at one site in Papua New Guinea, was estimated to nest only once every six years (Igag et al. 2019). Consequently, even low rates of trapping are likely to have a substantial impact on the population, especially if mature breeding adults are targeted. Evaluating the available data, the species is suspected to decline by 20–29% in the next three generations (47 years; Bird et al. 2020).
This species is found in Australia and New Guinea (West Papua, Indonesia and Papua New Guinea). In Australia, subspecies macgillivrayi is confined to the northern Cape York Peninsula, from Pormpuraaw on the west coast to Princess Charlotte Bay on the east. In New Guinea, it is widespread and tolerant of degraded forest habitats, mostly in the lowlands and foothills but occasionally up to 1,350 m.
This is a forest-dependent species, which is nevertheless tolerant of degradation. It occurs in the lowlands up to 1,350 m on New Guinea, but is commonest below 750 m (Juniper and Parr 1998). In Australia, it inhabits closed forest, but occurs at the highest densities in open woodland (Heinsohn et al. 2021).
In Australia, nest hollow availability appears to be the main constraint on abundance and is affected primarily by fire regime which both creates and destroys hollow and also affects the rate of spread of rainforest hollows are at a lower density (Heinsohn et al. 2021). Hollow abundance is also affected by the clearance of woodland for bauxite mining (TSSC 2015), cyclones and competition with Sulphur-crested Cockatoos Cacatua galerita, which may have increased near Weipa (TSSC 2015). Elsewhere (in New Guinea), the chief threats are forest loss to make way for urban areas and plantations, as well as selective timber extraction.
Trapping for pet trade is an ongoing threat and may accelerate as areas of forest become more accessible due to increasing road infrastructure. The impact of trapping for trade remains unquantified and poorly understood, but both local (Pangau-Adam and Noske 2010) and international (Sy 2010) trade of this species has been documented. Large areas of the species' range in New Guinea, however, lie in areas unlikely to be accessible to trappers. Nonetheless, this species breeds extremely slowly (Igag et al. 2019) and any trapping, especially of adults, is likely to have significant local impacts. Locally, the species may be killed for food and/or ornamentation.
Conservation Actions Underway
Listed in CITES Appendix I. In Australia, the Iron Range and Jardine River populations are already encompassed in a protected area (Heinsohn et al. 2021) and the species is nationally protected. In New Guinea the species is presumed to occur in many Protected Management Areas (PMAs) and Conservation Areas (CAs).
Conservation Actions Proposed
In Australia, Heinsohn et al. (2021) listed four research actions needed: (1) improve information on longevity, survival, other demographic parameters and movement ecology and ascertain the causes of low reproductive success; (2) identify optimal fire management regimes; (3) trial artificial breeding hollows in mining rehabilitation areas; and (4) investigate the impacts...[of]...habitat disturbance events. Some of these apply also to the much larger New Guinea population, although here there is a more basic need to understand the key threats impacting on the species, particularly the extent to which trapping is ongoing and driving population declines. In New Guinea remote sensing data should also be used to monitor the scale of forest cover loss over time; because this species has dependence on large, old trees, this will need to be reinforced by ground-truthing surveys. Investigate the scale and trend of trade globally, particularly those thought to have originated from New Guinea. Enforce the species' CITES Appendix I listing and monitor trade, and the extent of its impact on wild populations. In both countries, but particularly Australia, there is a need to implement habitat management strategies that restore degraded habitats, including (in Australia) the restoration of habitat after mining.
Text account compilers
Berryman, A.
Contributors
Butchart, S., Ekstrom, J. & Harding, M.
Recommended citation
BirdLife International (2024) Species factsheet: Palm Cockatoo Probosciger aterrimus. Downloaded from
https://datazone.birdlife.org/species/factsheet/palm-cockatoo-probosciger-aterrimus on 20/12/2024.
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 20/12/2024.