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Probosciger aterrimuspalm cockatoo

By Justine Zingsheim

Geographic Range

Palm cockatoos are found in the Australasian region, including New Guinea, the Cape York Peninsula (Northern Australia), Aru Islands, West Irian, Misool Isle (Western Papuan Islands) and other islands. There are three subspecies, P. a. atterimus, found in the Misool Isles, Aru Islands, and Northern Australia, P. a. goliath, the largest of the subspecies, found in Western Irian and the Papuan Islands, and finally P. a. stenolopus, in New Guinea and Western Irian. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

Habitat

Palm cockatoos are found in rainforests, including gallery forests, forest edges, monsoon woodlands, eucalypt and paperbark woodlands, partly cleared areas, and dense savannas. They choose large trees for nesting and roosting. During the day they roost near food or water sources and at night roost in or near a nest tree. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Range elevation
    1300 (high) m
    4265.09 (high) ft
  • Average elevation
    below 750 m
    ft

Physical Description

Palm cockatoos are the largest of all parrots, ranging from 49 to 68 cm in height. They weigh 500 to 1100 g, with females ranging from 500 to 950 g and males ranging from 540 to 1100 g. Wing length is around 35.1 cm, tail length 23.8 cm, bill length 9.1 cm, and tarsus length averages 3.5 cm.

Palm cockatoos are almost all black with a 15 cm erectile crest on their head. Their beaks never close completely, always revealing a bit of their black-tipped red tongues. This partly open mouth makes it easier for the birds to hold nuts in their mouth and crack them at the same time. Their strong mandibles are used for cracking nuts and are larger in males than in females. Their legs are grey/black with few feathers on their thighs and their red facial markings are their most distinguished characteristic. Their cheek skin changes color based on their health or level of stress so when highly stressed the skin will change color to a pink/beige, while when highly excited the skin changes to yellow. In young birds, the underfeathers are lined with a pale yellow and in very young birds (under 18 months old), the tip of the bill and the eye ring are white. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Sexual Dimorphism
  • male larger
  • Range mass
    500 to 1100 g
    17.62 to 38.77 oz
  • Range length
    49 to 68 cm
    19.29 to 26.77 in
  • Range wingspan
    70 to 100 cm
    27.56 to 39.37 in

Reproduction

During mating the male and female approach each other with wings extended. Before mating the male makes loud whistles and bows several times during which the skin on the face will usually become a deep red. Sometimes the male will also bang a stick against a tree while calling out, as a territorial gesture near the nesting sight. Palm cockatoos are monogamous and stay together for life. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; Silverstein, et al., 2003)

The mating season varies with local climate, but is usually from August to January. Palm cockatoos cannot excavate their own nesting cavities. Instead they use previously hollowed cavities in large trees, such as palms. Their nesting holes tend to be about 1 m in depth and 25 to 60 cm in diameter are are lined with a pile of broken twigs at the bottom, upon which the egg rests. The same site is often used year after year. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

Palm cockatoos lay one egg per clutch, which is incubated for 30 to 33 days. The newly hatched young are naked and helpless. They take 100 to 110 days to fledge, the longest period to fledging of any parrot species. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

After leaving the nest, the young bird is dependent on the parents for at least another 6 weeks because of its inability to fly. After this, the young bird will be independent, but will stay relatively close to the parents until the next breeding season, whereupon the parents evict the previous year's young from their territory. Young birds are estimated to reach sexual maturity at 7 to 8 years old. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Breeding interval
    Palm cockatoos breed once yearly.
  • Breeding season
    The breeding season usually occurs between the months of August and January, but varies with local climate.
  • Average eggs per season
    1
  • Range time to hatching
    30 to 35 days
  • Range fledging age
    100 to 110 days
  • Range time to independence
    142 to 152 days
  • Range age at sexual or reproductive maturity (female)
    7 to 8 years
  • Range age at sexual or reproductive maturity (male)
    7 to 8 years

Although both parents participate in incubation, females incubate the egg more than males and males spend more of their time foraging for food. After hatching, chicks are brooded mostly by females. Males also brood the young, but are mainly responsible for finding food. After the chick leaves the nest, both parents provide food and protection for it until it is fully independent. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Parental Investment
  • altricial
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-weaning/fledging
    • provisioning
      • male
    • protecting
      • male
      • female
  • pre-independence
    • provisioning
      • male
      • female
    • protecting
      • male
      • female
  • post-independence association with parents

Lifespan/Longevity

The lifespan of wild palm cockatoos is not well known. Other cockatoo species live from 40 to 60 years in the wild. Captive cockatoos may live to more than 100 years old. ("Animal Bytes: Cockatoo", 2006)

  • Average lifespan
    Status: captivity
    56.3 years
    AnAge

Behavior

Wild and captive birds behavior differently. Captive birds may develop compulsive behaviors, such as feather picking. They can also mimic human sounds and language. Wild palm cockatoos are bold and will accept food from humans and raid bird feeders. When food sources become low, they have been known to chew up decks and side paneling on homes.

Palm cockatoos can be found alone, in pairs, and in larger groups. They spend a lot of their time high in the forest canopy or flying between roosting and foraging areas. They often feed in large groups, where one "sentinel" bird will watch out for predators. If a predator or any other threat should appear, the “sentinel” gives an alarm cry to alert the rest of the flock. They are highly social, gathering in groups early in the day in favorite locations where they spend time preening and interacting. In rainy conditions they can be found hanging upside down with their wings and tails stretched out, as if taking a bath. ("Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006; Rauzon, 2001)

Home Range

Palm cockatoos sometimes remain quite close to their nesting sites, but can travel long distances in search of food or water. Their territory includes several possible trees for nesting sites. They will visit these sites throughout the year for various reasons, increasing the frequency of these visits during the breeding season. ("Fact Sheets: Palm Cockatoo", 2006; Silverstein, et al., 2003)

Communication and Perception

Palm cockatoos are one of the loudest parrot species, making loud whistling calls. The most common call heard is the contact call which is a disyllabic whistle. When they are alarmed they produce a sharp, harsh screech. Other calls include grunts, mournful/wailing cries, whistles, and screeches. Another way they communicate is by stomping noisily on a perch, using sticks or nuts to drum against the tree, sometimes up to 200 times. This is usually used to advertise territorial boundaries. Their cheeks will change color with mood, stress, and health. They also use their erectile crest to communicate mood. ("Animal Bytes: Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Other Communication Modes
  • mimicry

Food Habits

Palm cockatoos mainly eat leaf buds, seeds, and fruits. They sometimes also eat insects and their larvae. They forage primarily in the forest canopy, but may also forage on the forest floor for fallen fruits and seeds. They crush seeds and hard fruits with their sharp, strong mandibles. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

  • Animal Foods
  • insects
  • Plant Foods
  • leaves
  • seeds, grains, and nuts
  • fruit

Predation

Confirmed reports of predation on palm cockatoos was not found. However, common brushtail possums steal eggs from glossy black cockatoo nests, a close relative of palm cockatoos. Egg predation was found to greatly reduce the population size of the glossy black cockatoos. Arboreal snakes are also potential nest predators. Large birds of prey may take adults.

Competition between cockatoo species for nesting sites is high, and may result in egg or nestling death when cockatoo individuals fight over a nest. ("Threatened Species - South Australian Glossy Black-Cockatoo - A Gradual Recovery", 2006; Filardi and Tewksbury, 2005)

Ecosystem Roles

Palm cockatoos aid in the dispersal of seeds for many fruit-bearing trees. Many plant species have evolved methods to attract large, frugivorous birds to further enhance the probability of seed dispersal. (Filardi and Tewksbury, 2005; Heinsohn, et al., 2003)

  • Ecosystem Impact
  • disperses seeds

Economic Importance for Humans: Positive

Palm cockatoos are sometimes kept as pets or in zoos because people enjoy the intelligence, sociality, and vocal dexterity of parrots. Unfortunately, trade in cockatoos sometimes harms wild populations. ("Fact Sheets: Palm Cockatoo", 2006)

Economic Importance for Humans: Negative

Because palm cockatoos take quickly to accepting food from humans, they are known to raid bird feeders. They may destroy wood decks and the paneling of houses. ("Animal Bytes: Cockatoo", 2006)

  • Negative Impacts
  • household pest

Conservation Status

Palm cockatoos are considered near threatened or low risk due to the destruction of habitat with logging and seasonal fires. Additionally, in the 1970s, keeping palm cockatoos as pets became quite popular, and since then they have been the object of hunting for the aviary trade with the most popular tactic of capture involving arrows covered in sticky resin. There are now laws that prohibit the export of any palm cockatoo without a permit. Unfortunately, many are still illegally exported and sold as pets, and they do not survive well in captivity. ("Fact Sheets: Palm Cockatoo", 2006; "Palm Cockatoo", 2006; "Parrots: Cockatoos", 2006)

Other Comments

Probosciger aterrimus, is derived from the Greek words "proboscis" which means nose and "gero" which means to carry. The specific name is from the Latin "aterrimus," meaning very black. ("Nature Feature (Probosciger aterrimus)", 2003)

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Justine Zingsheim (author), Kalamazoo College, Ann Fraser (editor, instructor), Kalamazoo College.

Glossary

Australian

Living in Australia, New Zealand, Tasmania, New Guinea and associated islands.

World Map

acoustic

uses sound to communicate

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

arboreal

Referring to an animal that lives in trees; tree-climbing.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

diurnal
  1. active during the day, 2. lasting for one day.
ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

frugivore

an animal that mainly eats fruit

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

mimicry

imitates a communication signal or appearance of another kind of organism

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

rainforest

rainforests, both temperate and tropical, are dominated by trees often forming a closed canopy with little light reaching the ground. Epiphytes and climbing plants are also abundant. Precipitation is typically not limiting, but may be somewhat seasonal.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

terrestrial

Living on the ground.

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

visual

uses sight to communicate

References

2006. "Animal Bytes: Cockatoo" (On-line). Zoological Society of San Diego. Accessed October 13, 2006 at http://www.sandiegozoo.org/animalbytes/t-cockatoo.html.

2006. "Fact Sheets: Palm Cockatoo" (On-line). Smithsonian National Zoological Park. Accessed September 30, 2006 at http://nationalzoo.si.edu/Animals/Birds/Facts/FactSheets/fact-palmcockatoo.cfm.

2003. "Nature Feature (Probosciger aterrimus)" (On-line). Accessed November 12, 2006 at http://www.australianstamp.com/coin-web/feature/nature/palmcock.htm.

2006. "Palm Cockatoo" (On-line). Honolulu Zoo. Accessed September 30, 2006 at http://www.honoluluzoo.org/palm_cockatoo.htm.

2006. "Parrots: Cockatoos" (On-line). Natural Encounters Inc. Accessed September 30, 2006 at http://www.naturalencounters.com/abby3a.html.

2006. "Threatened Species - South Australian Glossy Black-Cockatoo - A Gradual Recovery" (On-line). Biodiversity. Accessed November 11, 2006 at http://www.environment.sa.gov.au/biodiversity/glossyblack.html.

Filardi, C., J. Tewksbury. 2005. Ground-foraging palm cockatoos (Probosciger aterrimus) in lowland New Guinea: fruit flesh as a directed deterrent to seed predation?. Journal of Tropical Ecology, 21: 355-361. Accessed November 11, 2006 at http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=315507.

Heinsohn, R., S. Murphy, S. Legge. 2003. Overlap and competition for nest holes among eclectus parrots, palm cockatoos and sulphur-crested cockatoos. Australian Journal of Zoology, 51: 81–94. Accessed November 11, 2006 at http://publish.csiro.au/paper/ZO02003.htm.

Rauzon, M. 2001. Parrots Around the World. New York: Franklin Watts, a Division of Grolier Publishing.

Silverstein, A., V. Silverstein, L. Silverstein Nunn. 2003. Beautiful Birds. Brookfield, Connecticut: Twenty-First Century Books.

Taylor, M. 2006. "General Characteristics and Natural History" (On-line). Accessed November 09, 2006 at http://www.funnyfarmexotics.com/PALM/chapter1.htm.

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