|At Melaka Zoo, Malaysia|
P. a. aterrimus
|Australian Palm Cockatoo range (in red)|
The Palm Cockatoo (Probosciger aterrimus), also known as the Goliath Cockatoo, is a large smoky-grey or black parrot of the cockatoo family. It is the only member of the subfamily Microglossinae and the only member of the monotypic genus, Probosciger. Its unique position within the cockatoo family has been confirmed by molecular studies.
The Palm Cockatoo was originally described by German naturalist Gmelin in 1788. Its specific name, aterrimus, is the Latin superlative adjective for ater, "black", hence it means "very black" or "blackest". It is the earliest offshoot from the ancestors of what have become the cockatoo family.
The Palm Cockatoo is 55 to 60 cm (22 to 24 in) in length and weighs 910–1,200 g (2.01–2.6 lb). It may be the largest cockatoo species and largest parrot in Australia, although large races of Yellow-tailed Black Cockatoos and Sulphur-crested Cockatoos broadly overlap in size. It is a distinctive bird with a large crest and has one of the largest bills of any parrots (only the Hyacinth Macaw's is larger). This powerful bill enables Palm Cockatoos not only to eat very hard nuts and seeds, but it also enables males to break off thick (~1") sticks from live trees to use for a drumming display (Wood 1984). The male has a larger beak than the female. The bill is unusual as the lower and upper mandibles do not meet for much of its length, allowing the tongue to hold a nut against the top mandible while the lower mandible works to open it. The Palm Cockatoo also has a distinctive red cheek patch that changes colour when the bird is alarmed or excited.
Distribution and habitat
The Palm Cockatoo is distributed in rainforests and woodlands of New Guinea island in Indonesia and Papua New Guinea, and far northern Queensland, Australia. It can still be found near Sorong, West Papua, Indonesia, where sometimes seen in trees along the roads.
This species normally does not appear in large numbers. They are not known to flock feed like many of the cockatoo species. Usually only one to six individuals will be observed feeding together at one time. As with other large birds both parents care for young so seeing a breeding pair is not unusual. If these birds do congregate it will usually happen in open woodland just after sunrise or along the rainforest edge before returning to individual roost for the night.
The Palm Cockatoo has a large and complex vocal repertoire, including many whistles and even a "hello" call that sounds surprisingly human-like.
There are distinct dialects throughout the species' range. It has a unique territorial display where the bird (typically the male) drums with a large (i.e. up to 1" diameter, 15 cm long) stick or seed-pod against a dead bough or tree, creating a loud noise that can be heard up to 100 m away. After drumming, the male occasionally strips the drum-tool into small pieces to line the nest.. Although this drumming behaviour was discovered over two decades ago (in 1984 by G.A. Wood), the reason why palm cockatoos drum is still a mystery. One reason could be that females can assess the durability of the nesting hollow by the resonance of the drumming. Another possibility could be that males drum to mark their territory against other males. The Palm Cockatoo is an unusual bird, being an ancient species and one of the few bird species known to use tools.
Palm Cockatoos only lay one egg every second year and have one of the lowest breeding success rates reported for any species of parrot. Off-setting this is their very long life-span. A male commenced breeding at 29 in Taronga Zoo in Sydney, and a female at the London Zoo was 40 when she laid her first egg in 1966. There is anecdotal evidence of a Palm Cockatoo reaching 80 or 90 years of age in an Australian zoo, although the oldest confirmed individual was aged 56 in London Zoo in 2000. Although longevity of captive birds is known, it is still unknown how long palm cockatoos live in the wild. Breeding takes place inside tree hollows that look like standing pipes. Fires play an important role in the destruction and creation of nest hollows. Fires allow the colonisation of microorganisms and termites, which enter the tree and start hollowing out the inside. Cyclones are important in the final stage of nest hollow development.
The Palm Cockatoo is often observed feeding during the early hours of the day on a diet that consists mostly of wild growing Pandanus palm fruit and nuts from the Kanari tree, Canarium australasicum. They have also been seen eating fruit from Darwin Stringybark Eucalyptus tetradonta and Nonda tree as well as seeds from the Cocky apple tree, Beach almond and Black Bean tree. In early captive situations pet owners would either feed dog kibble or generic bird seed mixture while zoos would give them "monkey biscuits." As their nutritional needs became more apparent over the years owners have shifted to specially formulated "manufactured diet" pellets along with a wide variety of treats like peanuts, pecans, Brazil nuts, pine nuts, sunflower seeds, oranges, apples, grapes, pomegranate, bananas, sweet potatoes, carrots, beets, broccoli and kale. Many zoos will still give them monkey biscuits to broaden their diet.
The Palm Cockatoo is still relatively common in Cape York, but is threatened there by habitat destruction, particularly due to bauxite mining around Weipa and altered fire regimes elsewhere. Palm Cockatoos are hunted in New Guinea. This species is in high demand for the pet trade due to its unusual appearance. The Palm Cockatoo is currently evaluated as Least Concern on the IUCN Red List of Threatened Species. It is listed on Appendix I of CITES.
- BirdLife International (2012). "Probosciger aterrimus". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Brown DM, Toft CA (1999). "Molecular systematics and biogeography of the cockatoos (Psittaciformes: Cacatuidae)". Auk 116 (1): 141–57. ISSN 0004-8038.
- Forshaw (2006). plate 1.
- Indonesian Parrot Project
- Parrot Tag: Palm Cockatoo
- Australian Geographic
- Murphy S, Legge S, Heinsohn R (2003). "The breeding biology of palm cockatoos (Probosciger aterrimus): a case of a slow life history". Journal of Zoology 261: 327–39. doi:10.1017/S0952836903004175.
- Brouwer K, Jones M, King C, Schifter H (2000). "Longevity records for Psittaciformes in captivity". International Zoo Yearbook 37: 299–316. doi:10.1111/j.1748-1090.2000.tb00735.x.
- Nutritional Requirements of Adult Palm Cockatoos
- Murphy, S.A., Double M.C. and Legge S.M. (2007) The phylogeography of palm cockatoos, Probosciger aterrimus, in the dynamic Australo-Papuan region. Journal of Biogeography 34: 1534–1545.
- Murphy, S.A. and Legge S.M. (2007) The gradual loss and episodic creation of Palm Cockatoo (Probosciger aterrimus) nest-trees in a fire- and cyclone-prone habitat. Emu 107: 1–6.
- Forshaw, Joseph M. (2006). Parrots of the World; an Identification Guide. Illustrated by Frank Knight. Princeton University Press. ISBN 0-691-09251-6.
- BirdLife Species Factsheet
- The Palm Cockatoo Research Project.
- Royal Society for the Protection of Birds (RSPB) website – Threats to wild bird populations
- CITES website search page
- Oriental Bird Images: Palm Cockatoo Selected photos
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