Editing Cockatoo (section)

==Behaviour==

[[File:Parrot - Henry Stacy Marks - 9078-2048x1994.jpg|thumb|Watercolour and gouache sketch by [[Henry Stacy Marks]]]]

Cockatoos are [[diurnality|diurnal]] and require daylight to find their food.<ref name = "HBW"/> They are not early risers, instead waiting until the sun has warmed their roosting sites before feeding. All species are generally highly social and roost, forage and travel in colourful and noisy [[flock (birds)|flocks]]. These vary in size depending on availability of food; in times of plenty, flocks are small and number a hundred birds or less, while in droughts or other times of adversity, they may swell up to contain thousands or even tens of thousands of birds; one record from the [[Kimberley (Western Australia)|Kimberley]] noted a flock of 32,000 [[little corella]]s. Species that inhabit open country form larger flocks than those of forested areas.<ref name=Cam126>{{Harvnb|Cameron|2007|p=126}}.</ref>

Some species require roosting sites that are located near drinking sites; other species travel great distances between the roosting and feeding sites.<ref>{{Cite journal|title=Roosting of the Sulphur-Crested Cockatoo ''Cacatua galerita''|journal=Emu|year=1996|last=Lindenmayer|first=DB|author2=Pope MP|author3=Cunningham RB|author4=Donnelly CF|author5=Nix HA|volume=96|issue=3|pages=209–12 |doi=10.1071/MU9960209|bibcode=1996EmuAO..96..209L }}</ref> Cockatoos have several characteristic methods of bathing; they may hang upside down or fly about in the rain or flutter in wet leaves in the canopy.<ref name=Forshaw110>{{harvnb|Forshaw|Cooper|1978|p=110}}</ref> Cockatoos have a preferred "footedness" analogous to human handedness. Most species are left-footed with 87–100% of individuals using their left feet to eat, but a few species favor their right foot.<ref>{{cite journal|url=http://escholarship.org/uc/item/9h15z1vr#page-4|title=Laterality in Animals|last=Rogers|first=Lesley J.|date=1 January 1989|journal=International Journal of Comparative Psychology|volume=3|issue=1|doi=10.46867/C48W2Q |s2cid=53355461 |access-date=27 March 2018|archive-date=7 March 2018|archive-url=https://web.archive.org/web/20180307152436/https://escholarship.org/uc/item/9h15z1vr#page-4|url-status=live|doi-access=free}}</ref>

===Breeding===
[[File:Umbrella cockatoo chicks 31l07.JPG|right|thumb|Hand-reared [[white cockatoo]] chicks bred for sale as pets.|alt=Two pink-skinned chicks sparsely covered with incompletely formed whitish feathers standing in a plastic bowl. The pre-feathers are round and pointed and are pinkish towards the base fading to white at the tips]]
Cockatoos are [[monogamy in animals|monogamous]] breeders, with [[pair bond]]s that can last many years. Many birds pair up in flocks before they reach sexual maturity and delay breeding for a year at least. Females breed for the first time anywhere from three to seven years of age and males are often older. Sexual maturity is delayed so birds can develop the skills for raising and parenting young, which is prolonged compared with other birds; the young of some species remain with their parents for up to a year.<ref name=Cam1434>{{Harvnb|Cameron|2007|pp=143–44}}.</ref><!-- ref cites all previous segment --> Cockatoos may also display [[philopatry|site fidelity]], returning to the same nesting sites in consecutive years.<ref name="Palm">{{Cite journal|vauthors=Murphy S, Legge S, Heinsohn R |title=The breeding biology of palm cockatoos (''Probosciger aterrimus''): a case of a slow life history|journal=Journal of Zoology|year=2003|volume=261|pages=327–39|doi=10.1017/S0952836903004175|issue=4|citeseerx=10.1.1.475.7031}}</ref> Courtship is generally simple, particularly for established pairs, with the black cockatoos alone engaging in [[Nuptial gift|courtship feeding]]. Established pairs do engage in preening [[Social grooming|each other]], but all forms of courtship drop off after [[avian incubation|incubation]] begins, possibly due to the strength of the pair-bond.<ref>{{Cite journal|title=The function of displays in the breeding of the White-tailed Black Cockatoo|journal=Emu|year=1974|first=DA|last=Saunders |volume=74|issue=1|pages=43–46 |doi=10.1071/MU974043|bibcode=1974EmuAO..74...43S }}</ref>

Like most parrots, the cockatoos are cavity [[bird nest|nesters]], nesting in holes in trees,<ref>{{Cite journal|title=Nesting habitat of the glossy black-cockatoo in central New South Wales |journal=Biological Conservation|year= 2006| first=M|last =Cameron| volume=127 |issue=4|pages=402–10 |doi=10.1016/j.biocon.2005.08.019|bibcode=2006BCons.127..402C }}</ref> which they are unable to excavate themselves.<ref name=Cam129>{{Harvnb|Cameron|2007|p=129}}</ref> These hollows are formed from decay or destruction of wood by branches breaking off, fungi or insects such as termites or even [[woodpecker]]s where their ranges overlap.<ref name=Cam130>{{Harvnb|Cameron|2007|p=130}}</ref> In many places these holes are scarce and the source of competition, both with other members of the same species and with other species and types of animal.<ref>{{Cite journal|title= Overlap and competition for nest holes among eclectus parrots, palm cockatoos and sulphur-crested cockatoos|journal=Australian Journal of Zoology|first=R|last= Heinsohn|author2=Murphy S|author3=Legge S |volume=51|issue=1|pages=81–94 |doi=10.1071/ZO02003|year= 2003}}</ref> In general, cockatoos choose hollows only a little larger than themselves, hence different-sized species nest in holes of corresponding (and different) sizes. If given the opportunity, cockatoos prefer nesting over {{convert|7|or|8|m|ft}} above the ground<ref name=Cam130/> and close to water and food.<ref name=Cam131>{{Harvnb|Cameron|2007|p=131}}.</ref>

The nesting hollows are lined with sticks, wood chips and branches with leaves. The eggs of cockatoos are oval and initially white, as their location makes camouflage unnecessary.<ref name=Cam137>{{Harvnb|Cameron|2007|p=137}}.</ref> However, they do become discoloured over the course of incubation. They range in size from {{convert|55|x|37|mm|abbr=on}} in the palm and red-tailed black cockatoos, to {{convert|26|x|19|mm|abbr=on}} in the cockatiel.<ref name=Cam137/> [[Clutch (eggs)|Clutch]] size varies within the family, with the palm cockatoo and some other larger cockatoos laying only a single egg and the smaller species laying anywhere between two and eight eggs. Food supply also plays a role in [[avian clutch size|clutch size]].<ref name=Cam138>{{Harvnb|Cameron|2007|p=138}}</ref><!-- refs previous two sentences --> Some species can lay a second clutch if the first fails.<ref name=Cam139>{{Harvnb|Cameron|2007|p=139}}</ref> Around 20% of eggs laid are infertile.<ref name=Cam147>{{Harvnb|Cameron|2007|p=147}}.</ref> The cockatoos' incubation and brooding responsibilities may either be undertaken by the female alone in the case of the black cockatoos or shared amongst the sexes as happens in the other species. In the case of the black cockatoos, the female is provisioned by the male several times a day. The young of all species are born covered in yellowish down, bar the palm cockatoo, whose young are born naked.<ref name=Cam1394>{{Harvnb|Cameron|2007|pp=139–40}}.</ref> Cockatoo incubation times are dependent on species size, with the smaller cockatiels having a period of around 20&nbsp;days and the larger Carnaby's black cockatoo incubating its eggs for up to 29&nbsp;days.<ref name="HBW"/>

The [[Nestling#Parental care and fledging|nestling]] period also varies by species size, with larger species having longer nestling periods. It is also affected by season and environmental factors and by competition with siblings in species with clutch sizes greater than one. Much of what is known about the nestling period of some species is dependent on aviary studies&nbsp;– aviary cockatiels can [[fledge]] after 5&nbsp;weeks and the large palm cockatoos after 11&nbsp;weeks.<ref name="HBW"/> During this period, the young become covered in juvenile plumage while remaining in the hollow. Wings and tail feathers are slow to grow initially but more rapid as the primary feathers appear. Nestlings quickly reach about 80–90% of adult weight about two-thirds of the time through this period, plateauing before they leave the hollow; they fledge at this weight with wing and tail feathers still to grow a little before reaching adult dimensions.<ref name=Cam141>{{Harvnb|Cameron|2007|p=141}}.</ref> Growth rate of the young, as well as numbers fledged, are adversely impacted by reduced food supply and poor weather conditions.<ref name=Cam143>{{Harvnb|Cameron|2007|p=143}}.</ref>

===Diet and feeding===
[[File:Cacatua tenuirostris -Joondalup-8-3c.jpg|left|thumb|Wild [[long-billed corella]]s in [[Perth]]. The bird on the right is using its long beak to dig for food in short grass.|alt=Two mainly white-plumaged cockatoos on what appears to be a lawn. One cockatoo is standing upright and has a long upper mandible and orange-pink feathers its face and chest. The other cockatoo has its head in the grass with its bill not visible.]]
Cockatoos are versatile feeders and consume a range of mainly vegetable food items. Seeds form a large part of the diet of all species; these are opened with their large and powerful bills. The galahs, corellas and some of the black cockatoos feed primarily on the ground; others feed mostly in trees.<ref name = "HBW"/><!-- this ref cites previous two sentences --> The ground-feeding species tend to forage in flocks, which form tight, squabbling groups where seeds are concentrated and dispersed lines where food is more sparsely distributed;<ref name=Cam1189>{{Harvnb|Cameron|2007|pp=118–9}}.</ref> they also prefer open areas where visibility is good. The [[western corella|western]] and long-billed corellas have elongated bills to excavate tubers and roots and the pink cockatoo walks in a circle around the doublegee (''[[Emex australis]]'') to twist out and remove the underground parts.<ref name=Cam113>{{Harvnb|Cameron|2007|p=113}}.</ref><!-- this ref cites previous two sentences -->

Many species forage for food in the canopy of trees, taking advantage of [[serotiny]] (the storage of a large supply of seed in cones or gumnuts by plant genera such as ''[[Eucalyptus]]'', ''[[Banksia]]'' and ''[[Hakea]]''), a natural feature of the Australian landscape in dryer regions. These woody fruiting bodies are inaccessible to many species and harvested in the main by parrots, cockatoos and rodents in more tropical regions. The larger cones can be opened by the large bills of cockatoos but are too strong for smaller animals.<ref name=Cam1167>{{Harvnb|Cameron|2007|pp=116–7}}.</ref> Many nuts and fruits lie on the end of small branches which are unable to support the weight of the foraging cockatoo, which instead bends the branch towards itself and holds it with its foot.<ref name=Cam114>{{Harvnb|Cameron|2007|p=114}}.</ref>

While some cockatoos are generalists taking a wide range of foods, others are specialists. The glossy black cockatoo specialises in the cones of trees of the genus ''[[Allocasuarina]]'', preferring a single species, ''[[Allocasuarina verticillata|A. verticillata]]''. It holds the cones in its foot and shreds them with its powerful bill before removing the seeds with its tongue.<ref>{{Cite journal|title=Food value and tree selection by Glossy Black-Cockatoos ''Calyptorhynchus lathami''|journal=Austral Ecology|year=2001|first=GM|last=Crowley|author2=Garnett S|volume=26|issue=1|pages=116–26|doi=10.1046/j.1442-9993.2001.01093.x|doi-broken-date=3 December 2024 }}</ref> Some species take large numbers of insects, particularly when breeding; in fact the bulk of the [[yellow-tailed black cockatoo]]'s diet is made up of insects. The large bill is used in order to extract grubs and larvae from rotting wood. The amount of time cockatoos have to spend foraging varies with the season.<ref name=Cam114/> During times of plenty they may need to feed for only a few hours in the day, in the morning and evening, then spend the rest of the day roosting or preening in trees, but during the winter most of the day may be spent foraging. The birds have increased nutritional requirements during the breeding season, so they spend more time foraging for food during this time. Cockatoos have large [[crop (anatomy)|crops]], which allow them to store and digest food for some time after retiring to a tree.<ref name=Cam1223>{{Harvnb|Cameron|2007|pp=122–23}}.</ref><!-- this ref cites previous three sentences -->

===Predators and threats===
The [[peregrine falcon]] and [[little eagle]] have been reported taking galahs and the [[wedge-tailed eagle]] has been observed killing a sulphur-crested cockatoo.<ref name=Forshaw29/> Eggs and nestlings are vulnerable to many hazards. Various species of monitor lizard (''[[Varanus]]'') are able to climb trees and enter hollows. Other predators recorded include the [[spotted wood owl]] on Rasa Island in the Philippines; the [[Morelia amethistina|amethystine python]], [[black butcherbird]] and rodents including the [[giant white-tailed rat]]<ref>{{Cite journal|last=Wood GA|year=1987|title=Further field observations of the Palm Cockatoo ''Probosciger aterrimus'' in the Cape York Peninsula, Queensland|journal=Corella|volume=12|issue=2|pages=48–52|url=http://www.aainsects.com.au/Pdf-papers-aainsects/Bird/bird-Cacat-3.pdf|access-date=17 December 2009|archive-date=21 September 2016|archive-url=https://web.archive.org/web/20160921140624/http://www.aainsects.com.au/Pdf-papers-aainsects/Bird/bird-Cacat-3.pdf|url-status=dead}}</ref> in Cape York; and [[common brushtail possum|brushtail possum]] on Kangaroo Island. Furthermore, galahs and little corellas competing for nesting space with the glossy black cockatoo on Kangaroo Island have been recorded killing nestlings of the latter species there. Severe storms may also flood hollows drowning the young and termite or borer activity may lead to the internal collapse of nests.<ref name=Cam149>{{Harvnb|Cameron|2007|p=149}}.</ref><!-- cites all para-->

Like other parrots, cockatoos can be afflicted by [[psittacine beak and feather disease]] (PBFD). The viral infection causes feather loss and beak malformation and reduces the bird's overall immunity. Particularly prevalent in sulphur-crested cockatoos, little corellas and galahs, it has been recorded in 14 species of cockatoo to date. Although unlikely to significantly impact on large, healthy populations of birds in the wild, PBFD may pose a high risk to smaller stressed populations.<ref name="gov">{{cite web|url=http://fedlaw.gov.au/ComLaw/Legislation/LegislativeInstrument1.nsf/previewlodgmentattachments/81FCCCA0AB589760CA25718E00044623/$file/F2005L02255.htm |archive-url=https://web.archive.org/web/20110706142728/http://fedlaw.gov.au/ComLaw/Legislation/LegislativeInstrument1.nsf/previewlodgmentattachments/81FCCCA0AB589760CA25718E00044623/%24file/F2005L02255.htm |archive-date=6 July 2011 |title=Threat Abatement Plan for Psittacine Beak and Feather Disease Affecting Endangered Psittacine Species |last=Borthwick |first=David |date=May 2005 |website=Department of the Environment and Heritage website |publisher=Department of the Environment and Heritage, Commonwealth of Australia |access-date=7 December 2009 |url-status=dead }}</ref>

A [[white cockatoo]] and a sulphur-crested cockatoo were found to be infected with the protozoon ''[[Haemoproteus]]'' and another sulphur-crested cockatoo had the [[malaria]] parasite ''[[Plasmodium]]'' on analysis of faecal samples at Almuñecar ornithological garden in [[Granada]] in Spain.<ref name=VP09>{{Cite journal|last=Cordon|first=GP|author2=Hitos Prados A |author3=Romero D |author4=Sánchez Moreno M |author5=Pontes A |author6=Osuna A |author7=Rosales MJ |year=2009|title=Intestinal and haematic parasitism in the birds of the Almunecar (Granada, Spain) ornithological garden|journal=Veterinary Parasitology|volume=165|pmid=19682800|issue=3–4|pages=361–66|doi=10.1016/j.vetpar.2009.07.027}}</ref> Like amazon parrots and macaws, cockatoos frequently develop cloacal [[papilloma]]s. The relationship with malignancy is unknown, as is the cause, although a parrot [[Papillomaviridae|papilloma virus]] has been isolated from a [[grey parrot]] with the condition.<ref>{{cite conference |vauthors=Stedman NL, Latimer KS, Rakich PM |title=Cloacal papillomas in psittacine birds: A retrospective histopathologic review |book-title=Proceedings of International Virtual Conferences in Veterinary Medicine: Diseases of Psittacine Birds |year=1998 |journal=International Virtual Conferences in Veterinary Medicine |publisher=College of Veterinary Medicine, University of Georgia |location=Athens, GA |url=http://www.vet.uga.edu/vpp/archives/ivcvm/1998/stedman/index.php |access-date=1 March 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110720084405/http://www.vet.uga.edu/vpp/archives/ivcvm/1998/stedman/index.php |archive-date=20 July 2011 |df=dmy-all }}</ref>

===Social learning===
Cockatoos have been shown to learn new skills through social interaction. In [[New South Wales]], researchers and [[citizen scientists]] were able to track the spread of  lid-flipping skills as cockatoos learned from each other to open garbage bins. Bin-opening spread more quickly to neighbouring suburbs than suburbs further away. In addition, birds in different areas developed their own variants for accomplishing the complex task.<ref name="Conroy">{{cite news |last1=Conroy |first1=Gemma |last2=Swanston |first2=Tim |title=Cockies are learning how to bust into bins and their skills are spreading across suburbia |url=https://www.abc.net.au/news/science/2021-07-23/cockatoos-open-wheelie-bin-lid-social-learning-suburbs/100306786 |access-date=24 February 2022 |work=ABC News |date=22 July 2021 |language=en-AU}}</ref><ref name="Klump">{{cite journal |last1=Klump |first1=Barbara C. |last2=Martin |first2=John M. |last3=Wild |first3=Sonja |last4=Hörsch |first4=Jana K. |last5=Major |first5=Richard E. |last6=Aplin |first6=Lucy M. |title=Innovation and geographic spread of a complex foraging culture in an urban parrot |journal=Science |date=23 July 2021 |volume=373 |issue=6553 |pages=456–460 |doi=10.1126/science.abe7808 |pmid=34437121 |bibcode=2021Sci...373..456K |s2cid=236179560 |url=https://www.science.org/doi/full/10.1126/science.abe7808 |access-date=24 February 2022 |language=EN}}</ref>