Parrot| About Parrot| Knowledge About Parrot| NaturWild
Parrots, also known
as psittacines are birds of the roughly
398 species in 92 genera comprising the order Psittaciformes found mostly in tropical and subtropical regions. The order
is subdivided into three superfamilies: the Psittacoidea ("true"
parrots), the Cacatuoidea (cockatoos), and the Strigopoidea (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 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 colored, and some
are multi-colored. Most parrots exhibit little or no sexual dimorphism in
the visual spectrum. 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 specialized 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 speech enhances their popularity
as pets. Trapping wild parrots for the pet trade, as well
as for 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 are 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.
Taxonomy
Origins and evolution
Psittaciform diversity in
South America and Australasia suggest that the order may have
evolved in Gondwana, centered in Australasia. The scarcity of parrots
in the fossil record, however, presents difficulties in confirming the
hypothesis. There is currently a higher amount of fossil remains from the
northern hemisphere in the early Cenozoic. Molecular studies suggest that
parrots evolved approximately 59 million years ago (Mya) (range
66–51 Mya) in Gondwana. The three major clades of Neotropical parrots originated
about 50 Mya (range 57–41 Mya).
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 generally assumed that
the Psittaciformes were present during the Cretaceous–Paleogene extinction
event (K-Pg extinction), 66 mya. They were probably generalized arboreal birds and did not have the specialized crushing bills of modern species. The genomic analysis provides strong evidence that parrots are the sister group of passerines,
forming the clade Psittacopasserae, which is the sister group of the falcons.
The first uncontroversial
parrot fossils date to tropical Eocene Europe around 50 mya.
Initially, a Moravian 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.
Numerous challenges are found in studying wild parrots, as they
are difficult to catch, and once caught, they are difficult to mark. Most wild
bird studies rely on banding or wing tagging, but parrots chew off
such attachments. Parrots also tend to range widely, and consequently, many
gaps occur in the knowledge of their behavior. Some parrots have a strong, direct
flight. Most species spend much of their time perched or climbing in tree
canopies. They often use their bills for climbing by gripping or hooking on
branches and other supports. On the ground, parrots often walk with a rolling
gait.
Diet
The diet of parrots consists of seeds, fruit, nectar, pollen, buds,
and sometimes arthropods and other animal prey. The most important of
these for most true parrots and cockatoos are seeds; the large and powerful
bill has evolved to open and consume tough seeds. All true parrots, except
the Pesquet's parrot, employ the same method to obtain the seed from the
husk; the seed is held between the mandibles and the lower mandible crushes the
husk, whereupon the seed is rotated in the bill and the remaining husk is
removed. They may use their foot sometimes to hold large seeds in place.
Parrots are granivores rather than seed dispersers, and in many
cases where they are seen consuming fruit, they are only eating the fruit
to get at the seed. As seeds often have poisons that protect them,
parrots carefully remove seed coats and other chemically defended fruit parts
prior to ingestion. Many species in the Americas, Africa, and Papua New Guinea
consume clay, which releases minerals and absorbs toxic compounds from the
gut.
Geographical range and body size predominantly explain the diet
composition of Neotropical parrots rather than phylogeny.
Lories, lorikeets, hanging parrots, and swift parrots are
primarily nectar and pollen consumers and have tongues
with brush tips to collect them, as well as some specialized gut adaptations.
Many other species also consume nectar when it becomes available.
Some parrot species prey on animals, especially invertebrate
larvae. Golden-winged parakeets prey on water snails, the
New Zealand kea can, though uncommonly, hunts adult sheep, and
the Antipodes parakeet, another New Zealand parrot, enters the burrows of
nesting grey-backed storm petrels and kills the incubating adults. Some
cockatoos and the New Zealand kaka excavate branches and wood to feed
on grubs; the bulk of the yellow-tailed black cockatoo's diet is made up
of insects.
Some extinct parrots had carnivorous diets. Pseudasturids were
probably cuckoo- or puffbird-like insectivores, while messelasturids were raptor-like
carnivores.
Breeding
With few exceptions, parrots are monogamous breeders
who nest in cavities and hold no territories other than their nesting
sites. The pair bonds of the parrots and cockatoos are strong
and a pair remains close during the nonbreeding season, even if they join
larger flocks. As with many birds, pair bond formation is preceded by courtship
displays; these are relatively simple in the case of cockatoos. In Psittacidae
parrots' common breeding displays, usually undertaken by the male, include
slow, deliberate steps known as a "parade" or "stately
walk" and the "eye-blaze", where the pupil of the eye constricts
to reveal the edge of the iris. Allopreening is used by the pair to
help maintain the bond. Cooperative breeding, where birds other than the
breeding pair help raise the young and is common in some bird families, is
extremely rare in parrots and has only unambiguously been demonstrated in
the El Oro parakeet and the golden parakeet (which may also
exhibit polygamous, or group breeding, behavior with multiple females
contributing to the clutch).
Only the monk parakeet and five species of lovebirds build
nests in trees, and three Australian and New Zealand ground parrots nest
on the ground. All other parrots and cockatoos nest in cavities, either tree
hollows or cavities dug into cliffs, banks, or the ground. The use of holes in
cliffs is more common in the Americas. Many species use termite nests,
possibly to reduce the conspicuousness of the nesting site or to create a
favorable microclimate. In most cases, both parents participate in
the nest excavation. The length of the burrow varies with species but is
usually between 0.5 and 2 m (1.6 and 6.6 ft) in length. The nests of
cockatoos are often lined with sticks, wood chips, and other plant material. In
the larger species of parrots and cockatoos, the availability of nesting
hollows may be limited, leading to intense competition for them both within the
species and between species, as well as with other bird families. The intensity
of this competition can limit breeding success in some cases. Hollows
created artificially by arborists have proven successful in boosting breeding
rates in these areas. Some species are colonial, with the burrowing
parrot nesting in colonies up to 70,000 strong. Coloniality is not as
common in parrots as might be expected, possibly because most species adopt old
cavities rather than excavate their own.
The eggs of parrots are white. In most species, the female
undertakes all the incubation, although incubation is shared in cockatoos,
the blue lorikeet, and the vernal hanging parrot. The female remains
in the nest for almost all of the incubation period and is fed both by the male
and during short breaks. Incubation varies from 17 to 35 days, with larger
species having longer incubation periods. The newly born young are altricial,
either lacking feathers or with sparse white down. The young spend three
weeks to four months in the nest, depending on species, and may receive
parental care for several months thereafter.
As typical of K-selected species, the macaws and other larger parrot species have low reproductive rates. They require several years to reach maturity, produce one or very few young per year, and do not necessarily breed every year.
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