Parrots (order Psittaciformes), also known as psittacines () from the name of the type genus Psittacus, are birds with a strong curved beak, upright stance, and clawed feet. They are classified in four families that contain roughly 410 species in 101 genera, found mostly in tropical and subtropical regions. The four families are the Psittaculidae (Old World parrots), Psittacidae (African and New World parrots), Cacatuidae (cockatoos), and Strigopidae (New Zealand parrots). One-third of all parrot species are threatened by extinction, with a higher aggregate extinction risk (IUCN Red List Index) than any other comparable bird group. Parrots have a generally pantropical distribution with several species inhabiting temperate regions as well. The greatest diversity of parrots is in South America and Australasia.
Parrots, along with corvids (ravens, crows, jays, and magpies), are among the most intelligent birds, and the ability of some species to imitate human speech enhances their popularity as pets. They form the most variably sized bird order in terms of length; many are vividly coloured and some, multi-coloured. Most parrots exhibit little or no sexual dimorphism in the visual spectrum.
The most important components of most parrots' diets are seeds, nuts, fruit, buds, and other plant material. A few species sometimes eat animals and carrion, while the lories and lorikeets are specialised for feeding on floral nectar and soft fruit. Almost all parrots nest in tree hollows (or nest boxes in captivity), and lay white eggs from which hatch altricial (helpless) young.
Trapping wild parrots for the pet trade, as well as hunting, habitat loss, and competition from invasive species, has diminished wild populations, with parrots being subjected to more exploitation than any other group of wild birds. As of 2021, about 50 million parrots (half of all parrots) live in captivity, with the vast majority of these living as pets in people's homes. Measures taken to conserve the habitats of some high-profile charismatic species have also protected many of the less charismatic species living in the same ecosystems.
Parrots are the only creatures that display true tripedalism, using their necks and beaks as limbs with propulsive forces equal to or greater than those forces generated by the forelimbs of primates when climbing vertical surfaces. They can travel with cyclical tripedal gaits when climbing.Melody W. Young, Edwin Dickinson, Nicholas D. Flaim and Michael C. Granatosky (2022). Overcoming a 'forbidden phenotype': the parrot's head supports, propels and powers tripedal locomotion, Proceedings of the Royal Society B: Biological Sciences, 20220245, https://doi.org/10.1098/rspb.2022.0245
Taxonomy
Origins and evolution Psittaciform diversity in South America and Australasia suggests that the order may have evolved in Gondwana, centred in Australasia. The scarcity of parrots in the fossil record, however, presents difficulties in confirming the hypothesis. There is currently a higher number of fossil remains from the northern hemisphere in the early Cenozoic.Mayr, G. (2009). Paleogene fossil birds. Springer. Molecular studies suggest that parrots evolved approximately 59 million years ago (Mya) (range 66–51 Mya) in Gondwana. The Neotropical parrots are monophyletic, and the three major clades originated about 50 Mya (range 57–41 Mya).
A single fragment from a large lower bill (UCMP 143274), found in deposits from the Lance Creek Formation in Niobrara County, Wyoming, had been thought to be the oldest parrot fossil and is presumed to have originated from the Late Cretaceous period, which makes it about 70 million years old. However, other studies suggest that this fossil is not from a bird, but from a caenagnathid oviraptorosaur (a non-avian dinosaur with a birdlike beak), as several details of the fossil used to support its identity as a parrot are not actually exclusive to parrots, and it is dissimilar to the earliest-known unequivocal parrot fossils.
It is generally assumed that the Psittaciformes were present during the Cretaceous–Paleogene extinction event (K-Pg extinction), 66 mya. They were probably generalised arboreal birds, and did not have the specialised crushing bills of modern species. Genomic analysis provides strong evidence that parrots are the sister group of passerines, forming the clade Psittacopasserae, which is in turn the sister group of the falcons.
The first uncontroversial parrot fossils date to tropical Eocene Europe around 50 mya. Initially, a neoavian named Mopsitta tanta, uncovered in Denmark's Early Eocene Fur Formation and dated to 54 mya, was assigned to the Psittaciformes. However, the rather nondescript bone is not unequivocally psittaciform, and it may rather belong to the ibis genus Rhynchaeites, whose fossil legs were found in the same deposits.
Several fairly complete skeletons of parrot-like birds have been found in England and Germany. These are probably not transitional fossils between ancestral and modern parrots, but rather lineages that evolved parallel to true parrots and cockatoos: Psittacopes Serudaptus Halcyornithidae Cyrilavis Halcyornis Pulchrapollia Pseudasturides Vastanavidae Vastanavis Quercypsittidae Quercypsitta Messelasturidae Messelastur Tynskya The earliest records of modern parrots date to around 23–20 mya. The fossil record—mainly from Europe—consists of bones clearly recognisable as belonging to anatomically modern parrots. The Southern Hemisphere contains no known parrot-like remains earlier than the Early Miocene around 20 mya.
Etymology The name 'Psittaciformes' comes from the ancient Greek for parrot, (), whose origin is unclear. Ctesias (5th century BCE) recorded the name after the Indian name for a bird, most likely a parakeet (now placed in the genus Psittacula). Pliny the Elder (23/24–79 CE) in his Natural History (book 10, chapter 58) noted that the Indians called the bird "siptaces"; however, no matching Indian name has been traced. "Popinjay" is an older term for parrots, first used in English in the 1500s.
Phylogeny Molecular phylogenetic studies have shown that Psittaciformes form a monophyletic clade that is sister to the Passeriformes: The time calibrated phylogeny indicates that the Australaves diverged around 65 Ma (million years ago) and the Psittaciformes diverged from the Passeriformes around 62 Ma.
Most taxonomists now divide Psittaciformes into four families; Strigopidae (New Zealand parrots), Cacatuidae (Cockatoos), Psittacidae (African and New World parrots) and Psittaculidae (Old World parrots). In 2012, Leo Joseph and collaborators proposed that the parrots should be divided into six families. The New Zealand parrots in the genus Nestor were placed in a separate family Nestoridae and the two basal genera in the family Psittaculidae (Psittrichas and Coracopsis) were placed in a separate family Psittrichasidae. The two additional families have not been recognised by taxonomists involved in curating lists of world birds and instead only four families are recognised.
The following cladogram shows the phylogenetic relationships between the four families. The species numbers are taken from the list maintained by Frank Gill, Pamela Rasmussen and David Donsker on behalf of the International Ornithological Committee (IOC), now the International Ornithologists' Union.
The Psittaciformes comprise three main lineages; Strigopoidea, Cacatuoidea, and Psittacoidea. The Strigopoidea were considered part of the Psittacoidea, but are now placed at the base of the parrot tree next to the remaining members of the Psittacoidea, as well as all members of the Cacatuoidea. The Cacatuoidea are distinct from the rest of the order in having a movable head crest, a different arrangement of the carotid arteries, a gall bladder, differences in the skull bones, and in lacking the Dyck texture feathers that, in the Psittacidae, scatter light to produce the vibrant colours of many parrots. Colourful feathers with high levels of psittacofulvin resist the feather-degrading bacterium Bacillus licheniformis better than white ones. Lorikeets were previously regarded as a third family, Loriidae, but are now considered a tribe (Loriini) within the subfamily Loriinae in the family Psittaculidae. The two other tribes in the subfamily are the closely related fig parrots (two genera in the tribe Cyclopsittini) and budgerigar (tribe Melopsittacini).
Systematics
The order Psittaciformes consists of four families containing roughly 410 species belonging to 101 genera.
Superfamily Strigopoidea: New Zealand parrots Family Strigopidae Subfamily Nestorinae: two genera with two living (kea and New Zealand kākā) and several extinct species of the New Zealand region Subfamily Strigopinae: the flightless, critically endangered kākāpō of New Zealand Superfamily Cacatuoidea: cockatoos Family Cacatuidae Subfamily Nymphicinae: one genus with one species, the cockatiel. Subfamily Calyptorhynchinae: the black cockatoos Subfamily Cacatuinae Tribe Microglossini: one genus with one species, the black palm cockatoo Tribe Cacatuini: four genera of white, pink, and grey species Superfamily Psittacoidea: true parrots Family Psittacidae Subfamily Psittacinae: two African genera, Psittacus and Poicephalus Subfamily Arinae Tribe Arini: 18 genera Tribe Androglossini: seven genera. Family Psittaculidae Subfamily Psittrichasinae: two genera, Psittrichas (Pesquet's parrot), Coracopsis Subfamily Platycercinae Tribe Pezoporini: ground parrots and allies Tribe Platycercini: broad-tailed parrots Subfamily Psittacellinae: one genus (Psittacella) with several species Subfamily Loriinae Tribe Loriini: lories and lorikeets Tribe Melopsittacini: one genus with one species, the budgerigar Tribe Cyclopsittini: fig parrots Subfamily Agapornithinae: three genera Subfamily Psittaculinae Tribe Polytelini: three genera Tribe Psittaculini: Asian psittacines Tribe Micropsittini: pygmy parrots
Morphology
Living species range in size from the buff-faced pygmy parrot, at under in weight and in length, to the hyacinth macaw, at in length, and the kākāpō, at in weight. Among the superfamilies, the three extant Strigopoidea species are all large parrots, and the cockatoos tend to be large birds, as well. The Psittacoidea parrots are far more variable, ranging the full spectrum of sizes shown by the family.
The most obvious physical characteristic is the strong, curved, broad bill. The upper mandible is prominent, curves downward, and comes to a point. It is not fused to the skull, which allows it to move independently, and contributes to the tremendous biting pressure the birds are able to exert. A large macaw, for example, has a bite force of , close to that of a large dog. The lower mandible is shorter, with a sharp, upward-facing cutting edge, which moves against the flat part of the upper mandible in an anvil-like fashion. Touch receptors occur along the inner edges of the keratinised bill, which are collectively known as the "bill tip organ", allowing for highly dexterous manipulations. Seed-eating parrots have a strong tongue (containing similar touch receptors to those in the bill tip organ), which helps to manipulate seeds or position nuts in the bill so that the mandibles can apply an appropriate cracking force. The head is large, with eyes positioned high and laterally in the skull, so the visual field of parrots is unlike any other birds. Without turning its head, a parrot can see from just below its bill tip, all above its head, and quite far behind its head. Parrots also have quite a wide frontal binocular field for a bird, although this is nowhere near as large as primate binocular visual fields. Unlike humans, the vision of parrots is also sensitive to ultraviolet light.