Published on July 13, 2016
Parrots, also known as psittacines /ˈsɪtəsaɪnz/, are birds of the roughly 393 species in 92 genera that make up the order Psittaciformes, found in most tropical and subtropical regions. The order is subdivided into three superfamilies: the Psittacoidea (“true” parrots), the Cacatuoidea (cockatoos), and the Strigopoidea (New Zealand parrots).Parrots have a generally pantropical distribution with several species inhabiting temperate regions in the Southern Hemisphere, as well. The greatest diversity of parrots is in South America and Australasia.
Characteristic features of parrots include a strong, curved bill, an upright stance, strong legs, and clawed zygodactyl feet. Many parrots are vividly coloured, and some are multi-coloured. Most parrots exhibit little or no sexual dimorphism. They form the most variably sized bird order in terms of length.
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 fruits. Almost all parrots nest in tree hollows (or nest boxes in captivity), and lay white eggs from which hatch altricial (helpless) young.
Parrots, along with ravens, crows, jays, and magpies, are among the most intelligent birds, and the ability of some species to imitate human voices enhances their popularity as pets. Some parrots are intelligent and talk at the level of a four-to-five year old human. 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 birds. 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.
Psittaciform diversity in South America and Australasia suggests that the order may have evolved in Gondwanaland, centred in Australasia. The scarcity of parrots in the fossil record, however, presents difficulties in confirming the hypothesis. Molecular studies suggest that parrots evolved approximately 59 Mya (range 66–51 Mya) in Gondwanaland. The three major clades of Neotropical parrots originated about 50 Ma (range 57–41 Ma).
A single 15 mm (0.6 in) 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 now generally assumed that the Psittaciformes, or their common ancestors with several related bird orders, were present somewhere in the world around the Cretaceous–Paleogene extinction event (K-Pg extinction), some 66 Mya. If so, they probably had not evolved their morphological autapomorphies yet, but were generalised arboreal birds, roughly similar (though not necessarily closely related) to today’s potoos or frogmouths (see also Palaeopsittacus below). Though these birds (Cypselomorphae) are a phylogenetically challenging group, they seem at least closer to the parrot ancestors than, for example, the modern aquatic birds (Aequornithes). The combined evidence supported the hypothesis of Psittaciformes being “near passerines”, i.e. the mostly land-living birds that emerged in close proximity to the K-Pg extinction. Indeed, analysis of transposable element insertions observed in the genomes of passerines and parrots, but not in the genomes of other birds, provides strong evidence that parrots are the sister group of passerines, forming a clade Psittacopasserae, to the exclusion of the next closest group, the falcons.
Europe is the origin of the first undeniable parrot fossils, which date from about 50 Mya. The climate there and then was tropical, consistent with the Paleocene-Eocene thermal maximum. Initially, a neoavian named Mopsitta tanta, uncovered in Denmark’s Early Eocene Fur Formation and dated to 54 Mya, was assigned to the Psittaciformes; it was described from a single humerus. However, the rather nondescript bone is not unequivocally psittaciform, and more recently it was pointed out that it may rather belong to a newly discovered ibis of the genus Rhynchaeites, whose fossil legs were found in the same deposits.
Fossil skull of a presumed parrot relative from the Eocene Green River Formation in Wyoming
Fossils assignable to Psittaciformes (though not yet the present-day parrots) date from slightly later in the Eocene, starting around 50 Mya. Several fairly complete skeletons of parrot-like birds have been found in England and Germany. Some uncertainty remains, but on the whole it seems more likely that these are not direct ancestors of the modern parrots, but related lineages that evolved in the Northern Hemisphere and have since died out. These are probably not “missing links” between ancestral and modern parrots, but rather psittaciform lineages that evolved parallel to true parrots and cockatoos and had their own peculiar autapomorphies:
Parrots are found on all tropical and subtropical continents and regions including Australia and Oceania, South Asia, Southeast Asia, Central America, South America, and Africa. Some Caribbean and Pacific islands are home to endemic species. By far the greatest number of parrot species come from Australasia and South America. The lories and lorikeets range from Sulawesi and the Philippines in the north to Australia and across the Pacific as far as French Polynesia, with the greatest diversity being found in and around New Guinea. The subfamily Arinae encompasses all the neotropical parrots, including the amazons, macaws, and conures, and ranges from northern Mexico and the Bahamas to Tierra del Fuego in the southern tip of South America. The pygmy parrots, tribe Micropsittini, form a small genus restricted to New Guinea. The superfamily Strigopoidea contains three living species of aberrant parrots from New Zealand. The broad-tailed parrots, subfamily Platycercinae, are restricted to Australia, New Zealand, and the Pacific islands as far eastwards as Fiji. The true parrot superfamily, Psittacoidea, includes a range of species from Australia and New Guinea to South Asia and Africa. The centre of cockatoo biodiversity is Australia and New Guinea, although some species reach the Solomon Islands (and one formerly occurred in New Caledonia), Wallacea and the Philippines.
Several parrots inhabit the cool, temperate regions of South America and New Zealand. One, the Carolina parakeet, lived in temperate North America, but was hunted to extinction in the early 20th century. Many parrots have been introduced to areas with temperate climates, and have established stable populations in parts of the United States (including New York City), the United Kingdom, Belgium and Spain, as well as in Greece.
Few parrots are wholly sedentary or fully migratory. Most fall somewhere between the two extremes, making poorly understood regional movements, with some adopting an entirely nomadic lifestyle.