Utente:Panjabi/Prove

Come leggere il tassobox Giraffa
Stato di conservazione
Rischio minimo[1]
Classificazione scientifica
Dominio	Eukaryota
Regno	Animalia
Phylum	Chordata
Classe	Mammalia
Ordine	Artiodactyla
Famiglia	Giraffidae
Genere	Giraffa Brisson, 1762
Specie	G. camelopardalis
Nomenclatura binomiale
Giraffa camelopardalis (Linnaeus, 1758)
Areale

La giraffa (Giraffa camelopardalis Linnaeus, 1758) è un mammifero artiodattilo africano; è il più alto animale terrestre vivente, nonché il ruminante di maggiori dimensioni. Il suo nome scientifico si riferisce al suo aspetto simile a un cammello e alle macchie colorate che ne ornano il manto. È facilmente riconoscibile per il collo e le zampe estremamente lunghi, per i suoi ossiconi simili a corna e la caratteristica colorazione. Misura 5-6 m di altezza, mentre il peso varia dai circa 1600 kg per i maschi ai circa 830 kg per le femmine. Appartiene alla famiglia dei Giraffidi, così come il suo unico parente attuale, l'okapi. Se ne riconoscono nove sottospecie, che differiscono tra loro per la colorazione del mantello.

L'areale della giraffa, piuttosto frammentato, si estende dal Ciad, a nord, fino al Sudafrica, a sud, e dal Niger, a ovest, fino alla Somalia, a est. Le giraffe vivono generalmente nelle savane, nelle praterie e nelle boscaglie aperte. Si nutrono soprattutto di foglie di acacia, che brucano ad altezze non raggiungibili dalla maggior parte degli altri erbivori. Loro unici nemici naturali sono i leoni, ma i piccoli possono cadere vittima anche di leopardi, iene macchiate e licaoni. Gli esemplari adulti non stringono stretti rapporti sociali con i conspecifici, ma possono raggrupparsi in aggregazioni libere con altri esemplari che si spostano nella stessa direzione. I maschi stabiliscono gerarchie sociali attraverso il cosiddetto necking, cioè combattimenti nei quali il collo viene impiegato come arma. Solo ai maschi dominanti è consentito accoppiarsi con le femmine, che sono le uniche a prendersi cura dell'allevamento dei piccoli.

Per il suo aspetto peculiare, la giraffa ha affascinato uomini di varie culture, sia antiche che moderne, e compare spesso in pitture, libri e cartoni animati. Sebbene sulla Lista dell'Unione Internazionale per la Conservazione della Natura (IUCN) venga classificata tra le specie a basso rischio, è scomparsa da molte zone del suo areale originario, e alcune sottospecie sono a rischio di estinzione. Tuttavia, le giraffe sono presenti in numerosi parchi nazionali e riserve di caccia.

Etimologia

Il nome «giraffa» trae origine dalla parola araba zarafa (زرافة), forse derivata a sua volta da un termine africano^[2]. Tale parola è stata tradotta come «[colei che] cammina veloce»^[3]. Nel Medioevo la specie era nota anche come jarraf, ziraph e gerfauntz^[2]. È possibile che il termine derivi dal nome con il quale l'animale è noto in lingua somala, Geri^[4]. Il nome italiano giraffa risale agli anni '90 del XVI secolo^[2]. La forma inglese Giraffe, invece, derivata dal francese girafe, risale al 1600 circa^[2]. Il nome specifico camelopardalis è il termine con il quale l'animale era noto in latino^[5].

Kameelperd è anche il nome con cui la specie è nota in lingua afrikaans^[6]. Tra gli altri nomi africani con cui viene indicato l'animale ricordiamo Ekorii (ateso), Kanyiet (elgon), Nduida (gikuyu), Tiga (kalenjin e luo), Ndwiya (kamba), Nudululu (kihehe), Ntegha (kinyaturu), Ondere (lugbara), Etiika (luhya), Kuri (ma'di), Oloodo-kirragata od Olchangito-oodo (maasai), Lenywa (meru), Hori (pare), Lment (samburu) e Twiga (swahili e altre lingue minori) nell'Africa orientale^[7]; e Tutwa (lozi), Nthutlwa (shangaan), Indlulamitsi (siswati), Thutlwa (sotho), Thuda (venda) e Ndlulamithi (zulu) nell'Africa meridionale^[6].

Taxonomy and evolution

 

Mounted Shansitherium skeleton from the Beijing Museum of Natural History

The giraffe is one of only two living species of the family Giraffidae, the other being the okapi. The family was once much more extensive, with over 10 fossil genera described. Giraffids first arose 8 million years ago (mya) in south-central Europe during the Miocene epoch. The superfamily Giraffoidea, together with the family Antilocapridae (whose only extant species is the pronghorn), evolved from the extinct family Palaeomerycidae.^[8] The earliest known giraffid was the deer-like Climacoceras.

While the progressive elongation of the neck and limbs can be found throughout the giraffid lineage, it became more pronounced in genera such as Giraffokeryx, Palaeotragus (possible ancestor of the okapi), Samotherium and Bohlinia.^[8] Bohlinia entered China and northern India in response to climate change. From here, the genus Giraffa evolved and, around 7 mya, entered Africa. Further climate changes caused the extinction of the Asian giraffes, while the African ones survived and radiated into several new species. G. camelopardalis arose around 1 mya in eastern Africa during the Pleistocene.^[8] Some biologists suggest that the modern giraffe descended from G. jumae;^[9] others find G. gracilis a more likely candidate.^[8] It is believed that the main driver for the evolution of the giraffes was the change from extensive forests to more open habitats, which began 8 mya.^[8] Some researchers have hypothesized that this new habitat with a different diet, including Acacia, may have exposed giraffe ancestors to toxins that caused higher mutation rates and a higher rate of evolution.^[10]

The giraffe was one of the many species first described by Carl Linnaeus in 1758. He gave it the binomial name Cervus camelopardalis. Morten Thrane Brünnich classified the genus Giraffa in 1772.^[11] In the early 19th century, Jean-Baptiste Lamarck believed that the giraffe's long neck was an "acquired characteristic", developed as generations of ancestral giraffes strived to reach the leaves of tall trees.^[12] This theory was eventually rejected, and scientists now believe that the giraffe's neck arose through Darwinian natural selection—that ancestral giraffes with long necks thereby had a competitive advantage that better enabled them to reproduce and pass on their genes.^[12]

Subspecies

 

"Approximate geographic ranges, fur patterns and phylogenetic relationships between some giraffe subspecies based on mitochondrial DNA sequences. Colored dots on the map represent sampling localities. The phylogenetic tree is a maximum-likelihood phylogram based on samples from 266 giraffes. Asterisks along branches correspond to node values of more than 90 percent bootstrap support. Stars at branch tips identify paraphyletic haplotypes found in Maasai and Reticulated giraffes".^[13]

Up to nine subspecies of giraffe are recognized (with population estimates Template:As of):

• G. c. camelopardalis,^[14] the nominate subspecies, is known as the Nubian giraffe. It is found in eastern South Sudan and south-western Ethiopia. Fewer than 250 are thought to remain in the wild, although this number is uncertain.^[15] It is rare in captivity, although a group is kept at Al Ain Zoo in the United Arab Emirates.^[16] In 2003, this group numbered 14.^[17]
• G. c. reticulata,^[14] known as the reticulated^[14] or Somali giraffe, is native to north-eastern Kenya, southern Ethiopia and Somalia. It is estimated that no more than 5,000 remain in the wild,^[15] and based on International Species Information System records, more than 450 are kept in zoos.^[18]
• G. c. angolensis, the Angolan or Namibian giraffe, is found in northern Namibia, south-western Zambia, Botswana and western Zimbabwe. A 2009 genetic study on this subspecies suggests that the northern Namib Desert and Etosha National Park populations form a separate subspecies.^[19] It is estimated that no more than 20,000 remain in the wild;^[15] and approximately 20 are kept in zoos.^[18]
• G. c. antiquorum,^[14] the Kordofan giraffe, has a distribution which includes southern Chad, the Central African Republic, northern Cameroon and north-eastern DR Congo. Populations in Cameroon were formerly included in G. c. peralta, but this was incorrect.^[20] No more than 3,000 are believed to remain in the wild.^[15] Considerable confusion has existed over the status of this subspecies and G. c. peralta in zoos. In 2007 it was shown that all alleged G. c. peralta in European zoos were, in fact, G. c. antiquorum.^[20] With this correction approximately 65 are kept in zoos.^[18]
• G. c. tippelskirchi,^[14] known as the Masai^[14] or Kilimanjaro giraffe, can be found in central and southern Kenya and in Tanzania. It is estimated that no more than 40,000 remain in the wild,^[15] and approximately 100 are kept in zoos.^[18]
• G. c. rothschildi^[14] is known variously as the Rothschild,^[14] Baringo or Ugandan giraffe. Its range includes parts of Uganda and Kenya.^[21] Its presence in South Sudan is uncertain.^[22] Fewer than 700 are believed to remain in the wild,^[15] and more than 450 are kept in zoos.^[18]
• G. c. giraffa, the South African giraffe, is found in northern South Africa, southern Botswana, southern Zimbabwe and south-western Mozambique. It is estimated that no more than 12,000 remain in the wild,^[15] and approximately 45 are kept in zoos.^[18]
• G. c. thornicrofti,^[14] called the Thornicroft^[14] or Rhodesian giraffe, is restricted to the Luangwa Valley in eastern Zambia. No more than 1,500 remain in the wild,^[15] with none kept in zoos.^[18]
• G. c. peralta,^[14] commonly known as the West African,^[14] Niger or Nigerian giraffe,^[23] is endemic to south-western Niger.^[21] Fewer than 220 individuals remain in the wild.^[15] Giraffes in Cameroon were formerly believed to belong to this subspecies, but are actually G. c. antiquorum.^[20] This error resulted in some confusion over its status in zoos, but in 2007 it was established that all "G. c. peralta" kept in European zoos actually are G. c. antiquorum.^[20]

 

The endangered West African giraffe

Giraffe subspecies are distinguished by their coat patterns. The reticulated and Masai giraffe represent two extremes of giraffe patch shapes. The former has neatly shaped patches while the latter has jagged ones.^[24] There are also differences in the width of the lines separating the patches. The West African giraffe has thick lines while the Nubian and reticulated giraffe have thin ones.^[7]321–22 The former also has a lighter coat pelage than other subspecies.^[7]322

A 2007 study on the genetics of six subspecies—the West African, Rothschild, reticulated, Masai, Angolan and South African giraffe—suggests that they may in fact be separate species. The study deduced from genetic drift in nuclear and mitochondrial DNA (mtDNA) that giraffes from these populations are reproductively isolated and rarely interbreed, even though no natural obstacles block their mutual access.^[13] This includes adjacent populations of Rothschild, reticulated and Masai giraffes. The Masai giraffe may also consist of a few species separated by the Rift Valley. Reticulated and Masai giraffes have the highest mtDNA diversity, which is consistent with the fact that giraffes originated in eastern Africa. Populations further north evolved from the former while those to the south evolved from the latter. Giraffes appear to select mates of the same coat type, which are imprinted on them as calves.^[13] The implications of these findings for the conservation of giraffes were summarised by David Brown, lead author of the study, who told BBC News: "Lumping all giraffes into one species obscures the reality that some kinds of giraffe are on the brink. Some of these populations number only a few hundred individuals and need immediate protection."^[25]

The West African giraffe is more closely related to the Rothchild and reticulated giraffe than to the Kordofan giraffe. Its ancestor may have migrated from eastern to northern Africa and then to its current range with the development of the Sahara desert. At its largest, Lake Chad may have acted as a barrier between West African and Kordofan giraffes during the Holocene.^[20]

Appearance and anatomy

Altri progetti

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Closeup of the head of a giraffe at the Melbourne Zoo

 

Giraffe skeleton on display at the Museum of Osteology, Oklahoma City, Oklahoma

Fully grown giraffes stand 5–6 m (16–20 ft) tall, with males taller than females.^[11] The average weight is 1 600 kg (3 500 lb) for an adult male and 830 kg (1 830 lb) for an adult female.^[26] Despite its long neck and legs, the giraffe's body is relatively short.^[27]66 Located at both sides of the head, the giraffe's large, bulging eyes give it good all-round vision from its great height.^[28]25 Giraffes see in color^[28]26 and their senses of hearing and smell are also sharp.^[12] The animal can close its muscular nostrils to protect against sandstorms and ants.^[28]27 The giraffe's prehensile tongue is about 50 cm (20 in) long. It is purplish-black in color, perhaps to protect against sunburn, and is useful for grasping foliage as well as for grooming and cleaning the animal's nose.^[28]27 The upper lip of the giraffe is also prehensile and useful when foraging. The lips, tongue and inside of the mouth are covered in papillae to protect against thorns.^[11]

(video) A pair of giraffes at Tobu Zoo, in Saitama, Japan.

The coat has dark blotches or patches (which can be orange, chestnut, brown or nearly black on color^[12]) separated by light hair (usually white or cream in color^[12]). Male giraffes become darker as they age.^[24] The coat pattern serves as camouflage, allowing it to blend in the light and shade patterns of savanna woodlands.^[8][14] The skin underneath the dark areas may serve as windows for thermoregulation, being sites for complex blood vessel systems and large sweat glands.^[29] Each individual giraffe has a unique coat pattern.^[24] The skin of a giraffe is mostly gray.^[26] It is also thick and allows them to run through thorn bush without being punctured.^[28]34 Their fur may serve as a chemical defence, as it is full of parasite repellents that give the animal a characteristic scent. There are at least eleven main aromatic chemicals in the fur, although indole and 3-methylindole are responsible for most of the smell. Because the males have a stronger odor than the females, it is suspected that it also has a sexual function.^[30] Along the animal's neck is a mane made of short, erect hairs.^[11] The 1 m (3,3 ft) tail ends in a long, dark tuft of hair and is used as a defense against insects.^[28]36

Skull and ossicones

Both sexes have prominent horn-like structures called ossicones, which are formed from ossified cartilage, covered in skin and fused to the skull at the parietal bones.^[24] Being vascularized, the ossicones may have a role in thermoregulation.^[29] Ossicones are also used in combat between males.^[31] Appearance is a reliable guide to the sex or age of a giraffe: the ossicones of females and young are thin and display tufts of hair on top, whereas those of adult males end in knobs and tend to be bald on top.^[24] There is also a median lump, which is more prominent in males, at the front of the skull.^[11] Males develop calcium deposits that form bumps on their skulls as they age.^[12] A giraffe's skull is lightened by multiple sinuses.^[27]70 However, as males age, their skulls become heavier and more club-like, helping them become more dominant in combat.^[24] The upper jaw has a grooved palate and lacks front teeth.^[28]26 The giraffe's molars have a rougher surface than those of some other mammals.^[28]27

Legs, locomotion and posture

The front and back legs of a giraffe are approximately the same length. The radius and ulna of the front legs are articulated by the carpus, which, while structurally equivalent to the human wrist, functions as a knee.^[32] The foot of the giraffe reaches a diameter of 30 cm (12 in), and the hoof is 15 cm (5,9 in) high in males and 10 cm (3,9 in) in females.^[28]36 The rear of each hoof is low and the fetlock is close to the ground, allowing the foot to support the animal's weight.^[11] Giraffes lack dewclaws and interdigital glands. The giraffe's pelvis, though relatively short, has an ilium that is outspread at the upper ends.^[11]

A giraffe has only two gaits: walking and galloping. Walking is done by moving the legs on one side of the body at the same time, then doing the same on the other side.^[24] When galloping, the hind legs move around the front legs before the latter move forward,^[12] and the tail will curl up.^[24] The animal relies on the forward and backward motions of its head and neck to maintain balance and the counter momentum while galloping.^[7]327–29 The giraffe can reach a sprint speed of up to 60 km/h (37 mph),^[33] and can sustain 50 km/h (31 mph) for several kilometers.^[34]

A giraffe rests by lying with its body on top of its folded legs.^[7]329 To lie down, the animal kneels on its front legs and then lowers the rest of its body. To get back up, it first gets on its knees and spreads its hind legs to raise its hindquarters. It then straightens its front legs. With each step, the animal swings its head.^[28]31 The giraffe sleeps intermittently around 4.6 hours per day, mostly at night.^[35] It usually sleeps lying down, however, standing sleeps have been recorded, particularly in older individuals. Intermittent short "deep sleep" phases while lying are characterized by the giraffe bending its neck backwards and resting its head on the hip or thigh, a position believed to indicate paradoxical sleep.^[35] If the giraffe wants to bend down to drink, it either spreads its front legs or bends its knees.^[24] Giraffes would probably not be competent swimmers as their long legs would be highly cumbersome in the water,^[36] although they could possibly float.^[37] When swimming, the thorax would be weighed down by the front legs, making it difficult for the animal to move its neck and legs in harmony^[36][37] or keep its head above the surface.^[36]

Neck

 

An adult male giraffe feeding high up on an acacia

The giraffe has an extremely elongated neck, which can be up to 2 m (6 ft 7 in) in length, accounting for much of the animal's vertical height.^[28]29 The long neck results from a disproportionate lengthening of the cervical vertebrae, not from the addition of more vertebrae. Each cervical vertebra is over 28 cm (11 in) long.^[27]71 They comprise 52–54 percent of the length of the giraffe's vertebral column, compared with the 27–33 percent typical of similar large ungulates, including the giraffe’s closest living relative, the okapi.^[10] This elongation largely takes place after birth, as giraffe mothers would have a difficult time giving birth to young with the same neck proportions as adults.^[38] The giraffe's head and neck are held up by large muscles and a nuchal ligament, which are anchored by long dorsal spines on the anterior thoracic vertebrae, giving the animal a hump.^[11]

The giraffe's neck vertebrae have ball and socket joints.^[27]71 In particular, the atlas–axis joint (C1 and C2) allows the animal to tilt its head vertically and reach more branches with the tongue.^[28]29 The point of articulation between the cervical and thoracic vertebrae of giraffes is shifted to lie between the first and second thoracic vertebrae (T1 and T2), unlike most other ruminants where the articulation is between the seventh cervical vertebra (C7) and T1.^[10][38] This allows C7 to contribute directly to increased neck length and has given rise to the suggestion that T1 is actually C8, and that giraffes have added an extra cervical vertebra.^[39] However, this proposition is not generally accepted, as T1 has other morphological features, such as an articulating rib, deemed diagnostic of thoracic vertebrae, and because exceptions to the mammalian limit of seven cervical vertebrae are generally characterized by increased neurological anomalies and maladies.^[10]

There are two main hypotheses regarding the evolutionary origin and maintenance of elongation in giraffe necks.^[31] The "competing browsers hypothesis" was originally suggested by Charles Darwin and only challenged recently. It suggests that competitive pressure from smaller browsers, such as kudu, steenbok and impala, encouraged the elongation of the neck, as it enabled giraffes to reach food that competitors could not. This advantage is real, as giraffes can and do feed up to 4,5 m (15 ft) high, while even quite large competitors, such as kudu, can only feed up to about 2 m (6 ft 7 in) high.^[40] There is also research suggesting that browsing competition is intense at lower levels, and giraffes feed more efficiently (gaining more leaf biomass with each mouthful) high in the canopy.^[41][42] However, scientists disagree about just how much time giraffes spend feeding at levels beyond the reach of other browsers,^{[9][31][40][43]} and a 2010 study found that adult giraffes with longer necks actually suffered higher mortality rates under drought conditions than their shorter-necked counterparts. This study suggests that maintaining a longer neck requires more nutrients, which puts longer-necked giraffes at risk during a food shortage.^[44]

The other main theory, the sexual selection hypothesis, proposes that the long necks evolved as a secondary sexual characteristic, giving males an advantage in "necking" contests (see below) to establish dominance and obtain access to sexually receptive females.^[9] In support of this theory, necks are longer and heavier for males than females of the same age,^[9][31] and the former do not employ other forms of combat.^[9] However, one objection is that it fails to explain why female giraffes also have long necks.^[45]

Internal systems

 

Giraffe bending down to drink. The animal's rete mirabile prevents excess blood flow to the brain when the neck is lowered.

In mammals, the left recurrent laryngeal nerve is longer than the right; in the giraffe it is over 30 cm (12 in) longer. These nerves are longer in the giraffe than in any other living animal;^[46] the left nerve is over 2 m (6 ft 7 in) long.^[47] Each nerve cell in this path begins in the brainstem and passes down the neck along the vagus nerve, then branches off into the recurrent laryngeal nerve which passes back up the neck to the larynx. Thus, these nerve cells have a length of nearly 5 m (16 ft) in the largest giraffes.^[46] The structure of a giraffe's brain resembles that of domestic cattle.^[28]31 The shape of the skeleton gives the giraffe a small lung volume relative to its mass.^[48] Its long neck gives it a large amount of dead space, in spite of its narrow windpipe. These factors increase the resistance to airflow. Nevertheless, the animal can still supply enough oxygen to its tissues.^[48]

The circulatory system of the giraffe has several adaptations for its great height. Its heart, which can weigh more than 25 lb (11 kg) and measures about 2 ft (61 cm) long, must generate approximately double the blood pressure required for a human to maintain blood flow to the brain.^[12] Giraffes have unusually high heart rates for their size, at 150 beats per minute.^[27]76 In the upper neck, the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head.^[14] The jugular veins also contain several (most commonly seven) valves to prevent blood flowing back into the head from the inferior vena cava and right atrium while the head is lowered.^[49] Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). To solve this problem, the skin of the lower legs is thick and tight; preventing too much blood from pouring into them.^[14]

Giraffes have oesophageal muscles that are unusually strong to allow regurgitation of food from the stomach up the neck and into the mouth for rumination.^[27]78 They have four chambered stomachs, as in all ruminants, and the first chamber has adapted to their specialized diet.^[11] The giraffe's intestines measure up to 80 m (260 ft) in length^[11] and have a relatively small ratio of small to large intestine.^[50] The liver of the giraffe is small and compact.^[27]76 A gallbladder is generally present during fetal life, but it may disappear before birth.^[11][51][52]

Behavior and ecology

Habitat and feeding

 

Giraffe extending its tongue to feed. Its tongue, lips and palate are tough enough to deal with sharp thorns in trees.

Giraffes usually inhabit savannas, grasslands and open woodlands. They prefer Acacia, Commiphora, Combretum and open Terminalia woodlands over denser environments like Brachystegia woodlands.^[7]322 The Angolan giraffe can be found in desert environments.^[53] Giraffes browse on the twigs of trees, preferring trees of genera Acacia, Commiphora and Terminalia,^[3] which are important sources of calcium and protein to sustain the giraffe's growth rate.^[8] They also feed on shrubs, grass and fruit.^[7]324 A giraffe eats around 34 kg (75 lb) of foliage daily.^[24] When stressed, giraffes may chew the bark off branches. Although herbivorous, the giraffe has been known to visit carcasses and lick dried meat off bones.^[7]325

During the wet season, food is abundant and giraffes are more spread out, while during the dry season, they gather around the remaining evergreen trees and bushes.^[3] Mothers tend to feed in open areas, presumably to make it easier to detect predators, although this may reduce their feeding efficiency.^[43] As a ruminant, the giraffe first chews its food, then swallows it for processing and then visibly passes the half-digested cud up the neck and back into the mouth to chew again.^[27]78-79 It is common for a giraffe to salivate while feeding.^[28]27 The giraffe requires less food than many other herbivores, because the foliage it eats has more concentrated nutrients and it has a more efficient digestive system.^[3] The animal's feces come in the form of small pellets.^[11] When it has access to water, a giraffe drinks at intervals no longer than three days.^[24]

Giraffes have a great effect on the trees that they feed on, delaying the growth of young trees for some years and giving "waistlines" to trees that are too tall.^[24] Feeding is at its highest during the first and last hours of daytime. Between these hours, giraffes mostly stand and ruminate. Rumination is the dominant activity during the night, when it is mostly done lying down.^[24]

 

Male giraffe mounting a female. Only dominant males are generally able to mate.

Social life and breeding habits

While giraffes are usually found in groups, the composition of these groups tends to be open and ever-changing.^[54] They have few strong social bonds, and aggregations usually change members every few hours. For research purposes, a "group" has been defined as "a collection of individuals that are less than a kilometre apart and moving in the same general direction."^[55] The number of giraffes in a group can range up to 32 individuals.^[54] The most stable giraffe groups are those made of mothers and their young,^[55] which can last weeks or months.^[56] Social cohesion in these groups is maintained by the bonds formed between calves.^[7]330^[55] Mixed-sex groups made of adult females and young males are also known to occur.^[55] Subadult males are particularly social and will engage in playfights. However, as they get older males become more solitary.^[56] Giraffes are not territorial,^[11] but they have home ranges.^[24] Male giraffes occasionally wander far from areas that they normally frequent.^[7]329

Reproduction is broadly polygamous: a few older males mate with the fertile females. Male giraffes assess female fertility by tasting the female's urine to detect estrus, in a multi-step process known as the Flehmen response.^[55][56] Males prefer young adult females over juveniles and older adults.^[55] Once an estrous female is detected, the male will attempt to court her. When courting, dominant males will keep subordinate ones at bay.^[56] During copulation, the male stands on its hind legs with its head held up and its front legs resting on the female's sides.^[24]

Although generally quiet and non-vocal, giraffes have been heard to communicate using various sounds. During courtship, males emit loud coughs.^[24] Females call their young by bellowing. Calves will emit snorts, bleats, mooing and mewing sounds. Giraffes also snore, hiss, moan and make flute-like sounds,^[24] and they communicate over long distances using infrasound.^[57]

Birthing and parental care

 

Mother giraffe and calves feeding. It is mostly the females that raise young, and they may gather in nursery herds.

Giraffe gestation lasts 400–460 days, after which a single calf is normally born, although twins occur on rare occasions.^[58] The mother gives birth standing up. The calf emerges head and front legs first, having broken through the fetal membranes, and falls to the ground, severing the umbilical cord.^[11] The mother then grooms the newborn and helps it stand up.^[28]40 A newborn giraffe is about 1,8 m (6 ft) tall. Within a few hours of birth, the calf can run around and is almost indistinguishable from a one-week-old. However, for the first 1–3 weeks, it spends most of its time hiding;^[59] its coat pattern providing camouflage. The ossicones, which have lain flat while it was in the womb, become erect within a few days.^[24]

Mothers with calves will gather in nursery herds, moving or browsing together. Mothers in such a group may sometimes leave their calves with one female while they forage and drink elsewhere. This is known as a "calving pool".^[59] Adult males play almost no role in raising the young,^[7]337 although they appear to have friendly interactions.^[55] Calves are at risk of predation, and a mother giraffe will stand over her calf and kick at an approaching predator.^[24] Females watching calving pools will only alert their own young if they detect a disturbance, although the others will take notice and follow.^[59] The bond a mother shares with her calf varies, though it can last until her next calving.^[59] Likewise, calves may suckle for only a month^[7]335 or as long as a year.^[24][56] Females become sexually mature when they are four years old, while males become mature at four or five years. However, males must wait until they are at least seven years old to gain the opportunity to mate.^[24][28]40

Necking

 

Male giraffes will engage in necking to establish dominance.

Male giraffes use their necks as weapons in combat, a behavior known as "necking". Necking is used to establish dominance and males that win necking bouts have greater reproductive success.^[9] This behavior occurs at low or high intensity. In low intensity necking, the combatants rub and lean against each other. The male that can hold itself more erect wins the bout.^[24] In high intensity necking, the combatants will spread their front legs and swing their necks at each other, attempting to land blows with their ossicones. The contestants will try to dodge each other's blows and then get ready to counter. The power of a blow depends on the weight of the skull and the arc of the swing.^[24] A necking duel can last more than half an hour, depending on how well matched the combatants are.^[7]331

After a duel, it is common for two male giraffes to caress and court each other, leading up to mounting and climax. Such interactions between males have been found to be more frequent than heterosexual coupling.^[60] In one study, up to 94 percent of observed mounting incidents took place between males. The proportion of same-sex activities varied from 30–75 percent. Only one percent of same-sex mounting incidents occurred between females.^[61]

Mortality and health

 

Lioness seen with adult giraffe kill

Giraffes have an unusually long lifespan compared to other ruminants,^[62] up to 25 years in the wild.^[14] Because of their size, eyesight and powerful kicks, adult giraffes are usually not subject to predation.^[24] However, they can fall prey to lions and are regular prey for them in Kruger National Park.^[63] Nile crocodiles can also be a threat to giraffes when they bend down to drink.^[28]31 Calves are much more vulnerable than adults, and are additionally preyed on by leopards, spotted hyenas and wild dogs.^[12] A quarter to a half of giraffe calves reach adulthood.

Some parasites feed on giraffes. They are often hosts for ticks, especially in the area around the genitals, which has thinner skin than other areas.^[11] Tick species that commonly feed on giraffes are those of genera Hyalomma, Amblyomma and Rhipicephalus. Giraffes may rely on red-billed and yellow-billed oxpeckers to clean them of ticks and alert them to danger. Giraffes host numerous species of internal parasite and are susceptible to various diseases. They were victims of the (now eradicated) viral illness rinderpest.^[11]

Relationship with humans

Cultural significance

 

Bushman rock art in Namibia depicting a giraffe

Humans have interacted with giraffes for millennia. The Bushmen of southern Africa have medicine dances named after some animals; the giraffe dance is performed to treat head ailments.^[64] How the giraffe got its height has been the subject of various African folktales,^[9] including one from eastern Africa which explains that the giraffe grew tall from eating too many magic herbs.^[65] Giraffes were depicted in art throughout the African continent, including that of the Kiffians, Egyptians and Meroë Nubians.^[28]45–47 The Kiffians were responsible for a life-size rock engraving of two giraffes that has been called the "world's largest rock art petroglyph".^[28]45^[66] The Egyptians gave the giraffe its own hieroglyph, named 'sr' in Old Egyptian and 'mmy' in later periods.^[28]49 They also kept giraffes as pets and shipped them around the Mediterranean.^[28]48–49

 

Painting of a giraffe imported to China during the Ming Dynasty

The giraffe was also known to the Greeks and Romans, who believed that it was an unnatural hybrid of a camel and a leopard and called it camelopardalis.^[28]50 The giraffe was among the many animals collected and displayed by the Romans. The first one in Rome was brought in by Julius Caesar in 46 BC and exhibited to the public.^[28]52 With the fall of the Roman Empire, the housing of giraffes in Europe declined.^[28]54 During the Middle Ages, giraffes were only known to Europeans through contact with the Arabs, who revered the giraffe for its peculiar appearance.^[12]

In 1414, a giraffe was shipped from Malindi to Bengal. It was then taken to China by explorer Zheng He and placed in a Ming Dynasty zoo. The animal was a source of fascination for the Chinese people, who associated it with the mythical Qilin.^[28]56 The Medici giraffe was a giraffe presented to Lorenzo de' Medici in 1486. It caused a great stir on its arrival in Florence,^[67] being reputedly the first living giraffe to be seen in Italy since antiquity. Another famous giraffe was brought from Egypt to Paris in the early 19th century. A sensation, the giraffe was the subject of numerous memorabilia or "giraffanalia".^[28]81

Giraffes continue to have a presence in modern culture. Salvador Dalí depicted them with conflagrated manes in some of his surrealist paintings. Dali considered the giraffe to be a symbol of masculinity, and a flaming giraffe was meant to be a "masculine cosmic apocalyptic monster".^[28]123 Several children's books feature the giraffe, including David A. Ufer's The Giraffe Who Was Afraid of Heights, Giles Andreae's Giraffes Can't Dance and Roald Dahl's The Giraffe and the Pelly and Me. Giraffes have appeared in animated films, as minor characters in Disney's The Lion King and Dumbo, and in more prominent roles in The Wild and in the Madagascar films. Sophie the Giraffe has been a popular teether since 1961. Another famous fictional giraffe is the Toys "R" Us mascot Geoffrey the Giraffe.^[28]127 The giraffe is also the national animal of Tanzania.^[68]

The giraffe has also been used for some scientific experiments and discoveries. Scientists have looked at the properties of giraffe skin when developing suits for astronauts and fighter pilots.^[27]76 This is because the people in these professions are in danger of passing out if blood rushes to their legs. Computer scientists have modeled the coat patterns of several subspecies using reaction–diffusion mechanisms.^[69] The constellation of Camelopardalis, introduced in the seventeenth century, depicts a giraffe.^[28]119–20

Exploitation and conservation status

 

Giraffe killed by tribesmen in the early 20th century

Giraffes were probably common targets for hunters throughout Africa.^[7]337 Different parts of their bodies were used for different purposes.^[11] Their meat was used for food. The tail hairs served as flyswatters, bracelets, necklaces and thread.^[7]337^[11] Shields, sandals and drums were made using the skin, and the strings of musical instruments were from the tendons.^[11] The smoke from burning giraffe skins was used by the medicine men of Buganda to treat nose bleeds.^[7]337 In the 19th Century, European explorers begin hunting them for sport.^[28]129 Habitat destruction has hurt the giraffe, too: in the Sahel, the need for firewood and grazing room for livestock has led to deforestation. Normally, giraffes can coexist with livestock, since they do not directly compete with them.^[14]

The giraffe species as a whole is assessed as Least Concern from a conservation perspective by the IUCN, as it is still numerous. However, giraffes have been extirpated from much of their historic range including Eritrea, Guinea, Mauritania and Senegal. They may also have disappeared from Angola, Mali, and Nigeria, but have been introduced to Rwanda and Swaziland.^[21] Two subspecies, the West African giraffe and the Rothschild giraffe, have been classified as Endangered,^[22][23] as wild populations of each of them number in the hundreds.^[15] In 1997, Jonathan Kingdon suggested that the Nubian giraffe was the most threatened of all giraffes;^[3] Template:As of, it may number fewer than 250, although this estimate is uncertain.^[15] Private game reserves have contributed to the preservation of giraffe populations in southern Africa.^[14] Giraffe Manor is a popular hotel in Nairobi which also serves a sanctuary for Rothschild's giraffes.^[70] The giraffe is a protected species in most of its range. In 1999, it was estimated that over 140,000 giraffes existed in the wild, but estimates in 2010 indicate that fewer than 80,000 remain.^[15]

Come leggere il tassobox Psittaciformi [71]
Agapornis roseicollis
Classificazione scientifica
Regno	Animalia
Phylum	Chordata
Classe	Aves
Ordine	Psittaciformes Wagler, 1830
Famiglie
Cacatuidae Psittacidae Strigopidae

 

Un'ara gialloblu mentre mangia la noce che tiene con un piede.

Gli Psittaciformi ^[72] (Psittaciformes ^[73][74] Wagler, 1830) sono un ordine di uccelli che comprende circa 372 specie di pappagalli suddivise in 86 generi; vivono soprattutto nelle regioni calde e tropicali. L'ordine viene suddiviso in tre famiglie: gli Psittacidi (pappagalli «veri»), i Cacatuidi (cacatua) e gli Strigopidi (pappagalli della Nuova Zelanda) ^[75] . Generalmente i pappagalli hanno una distribuzione pantropicale, ma alcune specie si incontrano anche nelle regioni temperate dell'Emisfero Australe. La maggiore diversità di specie si incontra in Sudamerica ed Australasia.

Tra i più importanti aspetti che caratterizzano i pappagalli vi sono il robusto becco ricurvo, la posizione eretta che mantengono quando sono appollaiati, le zampe robuste e i piedi zigodattili muniti di forti unghie. La maggior parte delle specie hanno un colore prevalentemente verde, spesso unito ad altri colori brillanti, ma altre sono variopinte. I cacatua variano in colorazione dal bianco al nero ed esibiscono una cresta mobile di penne sulla sommità della testa. In quasi tutti i pappagalli il dimorfismo sessuale è scarso o assente. Per quanto riguarda la lunghezza hanno le dimensioni più variabili tra tutti gli uccelli.

L'alimentazione dei pappagalli è composta soprattutto da semi, noci, frutta, gemme e altre sostanze vegetali. Poche specie mangiano anche ratti e vermi e i Lorini sono specializzati nel mangiare nettare dei fiori e frutti morbidi. Quasi tutti i pappagalli nidificano nelle cavità degli alberi (o, in cattività, nelle scatole-nido) e depongono uova bianche da cui sgusciano piccoli inetti.

I pappagalli, insieme a corvi, cornacchie, ghiandaie e gazze, sono tra gli uccelli più intelligenti e l'abilità di alcune specie nell'imitare la voce umana li ha resi molto popolari come animali domestici. La cattura di esemplari selvatici per il mercato degli animali da compagnia, la caccia, la deforestazione e la compezione con le specie invasive ha notevolmente diminuito il numero dei pappagalli selvatici e questi animali stanno tuttora subendo uno sfruttamento da parte dell'uomo maggiore di quello di ogni altro gruppo di uccelli ^[76] . Le recenti misure di conservazione volte a proteggere l'habitat di alcune tra le più importanti specie di pappagallo sono servite anche a proteggere molte specie meno note che vivono nello stesso ecosistema ^[77] .

Evoluzione e sistematica

Origini ed evoluzione

Le ricerche che cercano di svelare l'origine dei pappagalli sono tuttora in corso. La maggiore diversità di specie che si incontra in Sudamerica ed Australasia sembra indicare che l'ordine degli Psittaciformi abbia avuto origine nel Gondwana, con centro di diffusione in Australasia ^[78] . La scarsità dei resti fossili di uccello, tuttavia, rende molto difficile valutare la certezza di questa ipotesi.

Si ritiene che il più antico fossile di pappagallo, risalente al Cretaceo superiore (circa 70 milioni di anni fa), sia un singolo frammento, lungo 1002 mm, del ramo inferiore di un grosso becco ritrovato nei depositi della Formazione di Lance Creek nella Contea di Niobrara (Wyoming) ^[79] . Vari studiosi, tuttavia, ritengono con certezza che questo fossile non appartenga a un uccello, ma ad un teropode cenagnatide o ad un altro dinosauro non-aviario munito di un becco simile a quello di un uccello ^[80][81] .

Al giorno d'oggi si ritiene generalmente che gli Psittaciformi o gli antenati che hanno in comune con altri uccelli fossero già presenti al periodo della scomparsa dei dinosauri, circa 65 milioni di anni fa. Se fosse così, i pappagalli probabilmente non sono creature che svilupparono autapomorfie morfologiche, ma i discendenti di uccelli arboricoli generalisti abbastanza simili (ma non necessariamente imparentati) ai nittibi e ai bocca di rana odierni.

Il luogo di origine dei primi pappagalli fossili è l'Europa. Il reperto più antico è un osso alare di Mopsitta tanta scoperto in Danimarca e risalente a 54 milioni di anni fa ^[82] . All'epoca la regione aveva un clima tropicale dovuto al cosiddetto «Massimo Termico Paleocene-Eocene».

Fossili di età successiva risalgono all'Eocene, periodo iniziato circa 50 milioni di anni fa. Alcuni fossili quasi completi di uccelli simili a pappagalli sono stati rinvenuti in Inghilterra e Germania ^[83] . Sembra più probabile, però, che questi fossili non appartengano ai diretti antenati dei pappagalli moderni, ma piuttosto a linee evolutive loro imparentate che si evolvettero nell'Emisfero Boreale e scomparvero senza lasciare discendenti. Probabilmente non sono quindi «anelli mancanti» tra pappagalli ancestrali e moderni, ma piuttosto linee di Psittaciformi che si evolvettero parallelamente ai pappagalli veri e ai cacatua, sviluppando le loro peculiari autapomorfie:

• Psittacopes (Eocene inferiore/medio di Geiseltal, Germania) – forma basale?
• Serudaptus – pseudasturide o psittacide?
• Pseudasturidae (o più correttamente Halcyornithidae)
  • Pseudasturides- in passato Pseudastur
• Vastanavidae
  • Vastanavis (Eocene inferiore di Vastan, India)
• Quercypsittidae
  • Quercypsitta (Eocene superiore)

 

Le penne di un'amazzone testagialla. Le componenti blu della colorazione verde sono dovute alla diffusione della luce, mentre quelle verdi sono dovute ad un pigmento.

I più antichi resti fossili di pappagalli moderni risalgono a circa 23-20 milioni di anni fa e provengono anch'essi dall'Europa. I resti fossili successivi - di nuovo di provenienza europea - consistono di ossa chiaramente attribuibili a pappagalli di tipo moderno. Per quanto riguarda questo periodo l'Emisfero Australe non è così ricco di fossili come quello boreale e i primi fossili attribuibili a pappagalli risalgono solo al Miocene inferiore o medio, circa 20 milioni di anni fa. A questo periodo, tuttavia, risale già una mascella superiore fossile indistinguibile da quella dei moderni cacatua. In passato si ritenevano risalenti al Miocene anche altri resti fossili che successivamente sono stati datati più correttamente a 5 milioni di anni fa.

Tra i pappagalli fossili chiaramente attribuili agli Psittacidi o ai loro diretti antenati ricordiamo:

• Archaeopsittacus (Oligocene superiore/Miocene inferiore)
• Xenopsitta (Miocene inferiore della Repubblica Ceca)
• Psittacidae gen. e spp. indet. (Miocene inferiore/medio di Otago, Nuova Zelanda) - varie specie
• Bavaripsitta (Miocene medio di Steinberg, Germania)
• Psittacidae gen. e sp. indet. (Miocene medio della Francia) - erroneamente attribuito a Pararallus dispar, comprende Psittacus lartetianus

I seguenti fossili del Paleogene, invece, sembra non appartengano agli Psittaciformi:

• Palaeopsittacus (Miocene inferiore/medio dell'Europa nord-occidentale) - un caprimulgiforme (podargide?) o un quercypsittide?
• Precursor (Eocene inferiore) – una vera chimera, forse uno pseudasturide o uno psittacide
• Pulchrapollia (Eocene inferiore) – comprende il cosiddetto Primobucco olsoni - uno psittaciforme (pseudasturide o psittacide)?

Filogenesi

 

Il kaka, una delle tre specie attuali di Strigopidi.

La filogenesi dei pappagalli è ancora sotto esame. La classificazione qua presente è quella ritenuta attualmente più valida, ma studi successivi potrebbero apportarvi delle modifiche. Proprio per questo motivo non va considerata una stesura definitiva.

Gli Psittaciformi comprendono tre linee evolutive principali: gli Strigopidi, gli Psittacidi (pappagalli veri) e i Cacatuidi (cacatua). In passato gli Strigopidi erano ritenuti un gruppo di Psittacidi, ma studi più recenti sembrano indicare che queste specie originarie della Nuova Zelanda vadano poste alla base dell'albero filogenetico dei pappagalli, ben distanti sia dagli Psittacidi che dai Cacatuidi ^[78][84][85] .

Anche i Cacatuidi sono piuttosto diversi dagli Psittacidi: presentano una cresta mobile sulla testa, una diversa disposizione delle arterie carotidi, una cistifellea e alcune differenze nelle ossa del cranio; sono inoltre privi delle cosiddette penne «a testura Dick» che, negli Psittacidi, diffondono la luce in maniera tale da produrre i tipici colori vibranti tipici di molti pappagalli. Le penne colorate con alti livelli di psittacofulvina resistono meglio di quelle bianche agli attacchi del batterio Bacillus licheniformis ^[86] .

In passato i lorichetti venivano classificati in una terza famiglia, i Loriidi ^[87] , ma gli studi sul DNA hanno dimostrato che sono Psittacidi a tutti gli effetti, strettamente imparentati con i pappagalli dei fichi (due dei tre generi che costituiscono la tribù dei Cyclopsittacini della sottofamiglia degli Psittacini) e il pappagallino ondulato (tribù dei Melopsittacini della sottofamiglia dei Platicercini) ^[78][84][85] .

Sistematica

La seguente classificazione indica le varie sottofamiglie degli Psittaciformi. I dati molecolari sembrano indicare che alcune di esse costituiscano famiglie vere e proprie, ma una corretta sistematica è ancora da definire.

 

Un lorichetto arcobaleno della sottospecie moluccanus appollaiato sul recinto di un giardino in Australia.

 

Lo scheletro di un pappagallo.

Famiglia Strigopidae: pappagalli della Nuova Zelanda

• Tribù Nestorini: 1 genere con solo 2 specie viventi, il kea e il kaka della Nuova Zelanda;
• Tribù Strigopini: il kakapo della Nuova Zelanda, incapace di volare e gravemente minacciato.

Famiglia Cacatuidae: cacatua

• Sottofamiglia Microglossinae;
• Sottofamiglia Calyptorhynchinae: cacatua neri;
• Sottofamiglia Cacatuinae: cacatua bianchi.

Famiglia Psittacidae: pappagalli veri

• Sottofamiglia Arinae: pappagalli neotropicali, circa 160 specie suddivise in circa 30 generi. Probabilmente 2 linee evolutive distinte ^[84][88] ;
• Sottofamiglia Loriinae: circa una dozzina di generi con circa 50 specie di lorichetti e lori, originari soprattutto della Nuova Guinea, ma diffusi anche in Australia, Indonesia e nelle isole del Pacifico meridionale;
• Sottofamiglia Micropsittinae: 6 specie di pappagalli pigmei, appartenenti tutte ad un unico genere;
• Sottofamiglia Psittacinae
  • Tribù Cyclopsittacini: pappagalli dei fichi, 3 generi, tutti originari della Nuova Guinea o delle isole vicine;
  • Tribù Polytelini: tre generi originari dell'Australia e della Wallacea che in passato venivano classificati tra i pappagalli dalla coda larga;
  • Tribù Psittrichadini: un'unica specie, il pappagallo di Pesquet;
  • Tribù Psittacini: pappagalli afrotropicali, circa una dozzina di specie suddivise in 3 generi;
  • Tribù Psittaculini: pappagalli psittaculini paleotropicali, circa 70 specie viventi suddivise in 12 generi diffuse dall'India all'Australasia.
• Subfamiglia Platycercinae: pappagalli dalla coda larga; circa 30 specie in una dozzina di generi
  • Tribù Melopsittacini: un genere con una sola specie, il pappagallino ondulato;
  • Tribù Neophemini: due piccoli generi di pappagalli;
  • Tribù Pezoporini: un genere di pappagalli con due specie piuttosto diverse tra loro;
  • Tribù Platycercini: roselle e loro simili; circa 20 specie suddivise in 8 generi.

Other lists

• A list of all parrots sortable by common or binomial name, about 350 species.
  • Taxonomic list of Cacatuidae species, 21 species in 7 genera
  • Taxonomic list of true parrots which provides the sequence of Psittacidae genera and species following a traditional two-subfamily approach, as in the taxobox above, about 330 species.
  • List of Strigopidae
• List of macaws
• List of Amazon parrots
• List of Aratinga parakeets

Distribuzione

 

Quasi tutte le specie di pappagallo sono tropicali, ma alcune specie, come questo parrocchetto australe, si spingono molto all'interno delle zone temperate.

I pappagalli vivono nelle zone tropicali e subtropicali di tutti i continenti, essendo diffusi in Australia e isole del Pacifico, Asia meridionale, Sud-est asiatico, regioni meridionali del Nordamerica, Sudamerica e Africa. Alcune isole dei Caraibi e del Pacifico ospitano specie endemiche. Di gran lunga la maggiore diversità di specie si incontra in Australasia e Sudamerica. I lori e i lorichetti sono diffusi in un'area che da Sulawesi e Filippine si spinge fino all'Australia e alla Polinesia francese; il maggior numero di specie si incontra in Nuova Guinea e nelle aree circostanti. La sottofamiglia degli Arini, comprendente tutti i pappagalli neotropicali, tra cui amazzoni, ara e conuri, è distribuita dal Messico settentrionale e dalle Bahamas fino alla Terra del Fuoco, all'estremità meridionale del Sudamerica. I pappagalli pigmei, che costituiscono la sottofamiglia dei Micropsittini, appartengono tutti a un unico genere limitato alla Nuova Guinea. La sottofamiglia dei Nestorini è costituita da tre specie aberranti tutte originarie della Nuova Zelanda. I pappagalli dalla coda larga della sottofamiglia dei Platycercini sono ristretti ad Australia, Nuova Zelanda e isole del Pacifico (fino alle Figi). L'ultima sottofamiglia di pappagalli veri, gli Psittacini, occupa un vastissimo areale che da Australia e Nuova Guinea si spinge fino all'Asia meridionale e all'Africa. Il maggior numero di specie di cacatua vive in Australia e Nuova Guinea, ma alcune vivono anche nelle Isole Salomone, in Indonesia e alle Filippine (una specie estinta in passato viveva anche in Nuova Caledonia ^[89] ).

Alcune specie di pappagallo si spingono nelle fredde regioni temperate del Sudamerica e della Nuova Zelanda. Una specie, il parrocchetto della Carolina, viveva nelle regioni temperate del Nordamerica, ma venne cacciata fino alla sua totale scomparsa agli inizi del XX secolo. Numerose specie sono state introdotte in aree dal clima temperato e al giorno d'oggi si incontrano popolazioni stabili in alcuni Stati degli Stati Uniti, in Regno Unito e Spagna ^[90][91] .

Sebbene alcune specie di pappagallo siano sedentarie o perfino migratrici, la maggior parte di esse effettua brevi spostamenti stagionali e alcune hanno perfino adottato uno stile di vita nomade ^[92] .

Morfologia

 

Il cacatua nero lucente mostra il becco robusto, i piedi artigliati e gli occhi in posizione laterale tipici di tutti i pappagalli

Le specie attuali variano in dimensione dal pappagallo pigmeo facciacamoscio di meno di 10 g di peso e 8 cm di lunghezza all'ara giacinto di 1 m di lunghezza e al kakapo di 4 kg di peso. Tra le varie famiglie, quella degli Strigopidi comprende tre specie di notevoli dimensioni, così come quella dei cacatua. I pappagalli psittacidi, invece, variano moltissimo in dimensioni a seconda delle specie.

La principale caratteristica fisica che caratterizza maggiormente i pappagalli è il robusto becco largo e ricurvo. Il ramo superiore, dall'estremità appuntita, è prominente e ricurvo all'ingiù. Non è fuso alle ossa del cranio e così è in grado di muoversi indipendentemente, permettendo a questi uccelli di mordere esercitando una notevole pressione. Il ramo inferiore è più corto ed ha un margine tagliente molto affilato che poggia contro la porzione piatta del ramo superiore in modo simile ad un incudine. I pappagalli che si nutrono di semi hanno una lingua robusta che permette loro di manipolare i semi o le noci nel becco in posizione tale che le mandibole possano applicare meglio la loro pressione. La testa è grande e gli occhi sono posizionati lateralmente; la visione binoculare, quindi, è molto limitata, ma quella periferica aumenta notevolmente.

Le specie di cacatua hanno una cresta di penne mobili sulla sommità della testa che può essere sollevata e abbassata a piacere. Tale cresta non è presente in nessun'altra specie di pappagallo, ma i lorichetti del Pacifico dei generi Vini e Phigys sono in grado di arruffare le penne della corona e della nuca. Il colore predominante del piumaggio dei pappagalli è il verde, ma la maggior parte delle specie presenta anche piccole quantità di penne rosse o di altro colore. I cacatua costituiscono l'unica eccezione, poiché durante la loro storia evolutiva hanno perso completamente il colore verde e azzurro del piumaggio e ora sono generalmente bianchi o neri con alcune zone rosse, rosa o gialle. Tra i pappagalli non è presente un notevole dimorfismo sessuale, ma vi sono comunque alcune eccezioni, prima tra tutte il pappagallo eclettico.

Comportamento

Studiare i pappagalli in natura presenta notevoli difficoltà, poiché sono difficili da catturare e una volta presi è molto difficile anche riuscirli a marcare. Gran parte delle ricerche svolte su uccelli selvatici si basano sull'applicazione di anelli (o bande) alle zampe o di targhette alle ali, ma i pappagalli tendono a toglierseli poco dopo ^[92] ; inoltre, si spostano su areali molto vasti. Di conseguenza sono tuttora presenti moltre lacune per quanto riguarda la conoscenza del loro comportamento.

I pappagalli hanno un volo sostenuto e diretto. La maggior parte delle specie trascorre gran parte del tempo appollaiata sui rami della volta della foresta. Spesso utilizzano il becco per arrampicarsi o appendersi a rami o ad altri supporti. Al suolo camminano solitamente con passo ondeggiante.

Dieta

Un cacatua nero codagialla utilizza il becco robusto per cercare delle larve.

La dieta dei pappagalli è costituita da semi, frutta, nettare, polline, gemme e, talvolta, insetti, ad esempio blatte, e altri piccoli animali. Senza dubbio, però, i componenti fondamentali della dieta dei pappagalli veri e dei cacatua sono i semi. L'evoluzione di becchi grandi e potenti può essere interpratata principalmente come un adattamento per aprire e mangiare i semi. Tutti i pappagalli veri, a eccezione del pappagallo di Pesquet, utilizzano lo stesso metodo per liberare i semi dal guscio: tengono il seme tra le mandibole e con quella inferiore frantumano il guscio; quindi il seme viene fatto ruotare nel becco e il guscio rimanente viene rimosso ^[92] . Per tenere fermi i semi più grossi i pappagalli talvolta utilizzano anche un piede. I pappagalli sono soprattutto razziatori di semi e non loro dispersori; in molti casi alcune specie sono state viste mangiare dei frutti solamente per poter arrivare al seme. Dato che spesso i semi sviluppano un qualche veleno per proteggersi, i pappagalli sono in grado di rimuovere l'involucro e altre parti tossiche del frutto prima di ingerirlo. Molte specie delle Americhe, dell'Africa e della Nuova Guinea consumano argilla, utile sia per rilasciare sali minerali che per assorbire sostanze tossiche all'interno del tubo digerente ^[93] .

 

Pappagalli che leccano argilla in Ecuador. Il consumo di questa sostanza neutralizza le tossine contenute nella loro dieta.

I lori e i lorichetti, il pappagallo di Latham e il pappagallo acrobata delle Filippine si nutrono soprattutto di nettare e polline e sono dotati di lingue dall'estremità a spazzola con cui raccolgono queste particolari fonti di cibo; inoltre il loro apparato digerente ha sviluppato particolari adattamenti per assorbire queste sostanze ^[94] . Il nettare, tuttavia, quando è disponibile, viene consumato anche da molte altre specie.

Oltre che di semi e fiori, alcuni pappagalli si nutrono anche di animali. Il parrocchetto alidorate cattura chiocciole acquatiche e il famoso kea della Nuova Zelanda è in grado di uccidere giovani petrelli e perfino di attaccare e uccidere indirettamente pecore adulte ^[95] . Un altro pappagallo neozelandese, il parrocchetto delle Antipodi, si introduce nelle tane degli uccelli delle tempeste dorsogrigio per uccidere gli adulti che covano le uova ^[96] . Alcuni cacatua e il kaka scavano cavità nei rami e nel legno per trovare larve.

Breeding

Although there are a few exceptions, parrots are monogamous breeders which nest in cavities and hold no territories other than their nesting sites.^[92][97] The pair bonds of the parrots and cockatoos are strong and the pair will remain close even during the non-breeding 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.^[92] Allopreening is used by the pair to help maintain the bond. Cooperative breeding, where birds other than the breeding pair help the pair raise the young and is common in some bird families, is extremely rare in parrots, and has only unambiguously been demonstrated in the Golden Parakeet (which may also exhibit polyamorous or group breeding system with multiple females contributing to the clutch).^[98]

 

The vast majority of parrots are, like this Blue-winged Parrotlet, cavity nesters.

Only the Monk Parakeet and five species of Agapornis lovebird build nests in trees,^[99] 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 will use termite nests, possibly as it reduces the conspicuousness of the nesting site or because it creates favourable microclimates.^[100] In most cases both parents will participate in the nest excavation. The length of the burrow varies with species, but is usually between 0.5–2 m in length. The nests of cockatoos are often lined with sticks, wood chips and other plant material. In the larger species of parrot and cockatoo the availability of nesting holes can be limited and this can lead 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.^[101][102] Some species are colonial, with the Burrowing Parrot nesting in colonies up to 70,000 strong.^[103] Coloniality is not as common in parrots as might be expected, possibly because most species adopt old cavities rather than excavate their own.^[104]

The eggs of parrots are white. In most species the female undertakes all the incubation, although incubation is shared for 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 the larger species have the longer incubation periods. The newly born young are altricial, either lacking feathers or with sparse white down. The young spend anything from three weeks to four months in the nest, depending on species, and may receive parental care for up to further months thereafter.^[105]

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 sometimes do not breed every year at all.

Intelligence and learning

 

Sun Parakeet demonstrating parrots' puzzle-solving skills

Studies with captive birds have given insight into which birds are the most intelligent. While parrots have the distinction of being able to mimic human speech, studies with the African Grey Parrot have shown that some are able to associate words with their meanings and form simple sentences (see Alex and N'kisi). Along with crows, ravens, and jays (family Corvidae), parrots are considered the most intelligent of birds. The brain-to body size ratio of psittacines and corvines is actually comparable to that of higher primates.^[106] One argument against the supposed intelligent capabilities of bird species is that birds have a relatively small cerebral cortex, which is the part of the brain considered to be the main area of intelligence in other animals. However, it seems that birds use a different part of their brain, the medio-rostral neostriatum / hyperstriatum ventrale, as the seat of their intelligence. Not surprisingly, research has shown that these species tend to have the largest hyperstriata, and Dr. Harvey J. Karten, a neuroscientist at University of California, San Diego who has studied the physiology of birds, discovered that the lower part of the avian brain is functionally similar to that in humans. Not only have parrots demonstrated intelligence through scientific testing of their language using ability, but some species of parrot such as the Kea are also highly skilled at using tools and solving puzzles.^[107]

Learning in early life is apparently important to all parrots, and much of that learning is social learning. Social interactions are often practised with siblings, and in several species creches are formed with several broods, and these as well are important for learning social skills. Foraging behaviour is generally learnt from parents, and can be a very protracted affair. Supra-generalists and specialists are generally independent of their parents much quicker than partly specialised species which may have to learn skills over a long period of time as various resources become seasonally available. Play forms a large part of learning in parrots; it can be solitary, and related to motor skills, or social. Species may engage in play fights or wild flights to practice predator evasion. An absence of stimuli can retard the development of young birds, as demonstrated by a group of Vasa Parrots kept in tiny cages with domesticated chickens from the age of 3 months; at 9 months these birds still behaved in the same way as 3 month olds, but had adopted some chicken behaviour.^[92] In a similar fashion captive birds in zoo collections or pets can, if deprived of stimuli, develop stereotyped behaviours and harmful behaviours like self plucking. Aviculturists working with parrots have identified the need for environmental enrichment to keep parrots stimulated.

Sound imitation and speech

  Lo stesso argomento in dettaglio: Talking bird.

  Lo stesso argomento in dettaglio: Animal language.

Video of an Orange-winged Amazon saying "Hello" having been prompted by some people

Many species can imitate human speech or other sounds. A study by Irene Pepperberg suggested a high learning ability in an African Grey Parrot named Alex. Alex was trained to use words to identify objects, describe them, count them, and even answer complex questions such as "How many red squares?" with over 80% accuracy. N'kisi, another African grey, has been shown to have a vocabulary of approximately a thousand words, and has displayed an ability to invent as well as use words in context and in the correct tense.

Parrots do not have vocal cords, so sound is accomplished by expelling air across the mouth of the bifurcated trachea. Different sounds are produced by changing the depth and shape of trachea. African Grey Parrots of all subspecies are known for their superior ability to imitate sounds and human speech. This ability has made them prized as pets from ancient time to the present. In the Masnavi, a writing by Rumi of Persia, AD 1250, the author talks about an ancient method for training parrots to speak.

Although most parrot species are able to imitate, some of the Amazon parrots are generally regarded as the next-best imitators and speakers of the parrot world.

The question of why birds imitate remains open, but those that do often score very high on tests designed to measure problem solving ability. Wild African Grey Parrots have been observed imitating other birds.^[108] Most other wild parrots have not been observed imitating other species.

Relationship with humans

Humans and parrots have a complicated relationship. Economically they can be beneficial to communities as sources of income from the pet trade and are highly marketable tourism draws and symbols. But some species are also economically important pests, particularly some cockatoo species in Australia. Some parrots have also benefited from human changes to the environment in some instances, and have expanded their ranges alongside agricultural activity, but many species have declined as well.

It is possible to devote careers to parrots. Zoos and aquariums employ keepers to care for and shape the behavior of parrots. Some veterinarians who specialize in avian medicine will treat parrots exclusively. Biologists study parrot populations in the wild and help to conserve wild populations. Aviculturalists breed and sell parrots for the pet trade.

Tens of millions of parrots have been removed from the wild, and parrots have been traded in greater numbers and for far longer than any other group of wild animals.^[109] Many parrot species are still threatened by this trade as well as habitat loss, predation by introduced species, and hunting for food or feathers. Some parrot species are agricultural pests,^[110] eating fruits, grains, and other crops, but parrots can also benefit economies through birdwatching based ecotourism.^[111]

Pets

 

Pet Cuban Amazons in Cuba

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Parrots are popular as pets due to their sociable and affectionate nature, intelligence, bright colours, and ability to imitate human voices. The domesticated Budgerigar, a small parrot, is the most popular of all pet bird species. In 1992 the newspaper USA Today published that there were 11 million pet birds in the United States alone,^[112] many of them parrots. Europeans kept birds matching the description of the Rose-ringed Parakeet (or called the ring-necked parrot), documented particularly in a first century account by Pliny the Elder.^[113] As they have been prized for thousands of years for their beauty and ability to talk, they have also often been misunderstood. For example, author Wolfgang de Grahl discusses in his 1987 book "The Grey Parrot," that some importers allowed parrots to drink only coffee while they were being shipped by boat considering pure water to be detrimental and believing that their actions would increase survival rates during shipping. (Nowadays it is commonly accepted that the caffeine in coffee is toxic to birds).

Pet parrots may be kept in a cage or aviary; though generally, tame parrots should be allowed out regularly on a stand or gym. Depending on locality, parrots may be either wild caught or be captive bred, though in most areas without native parrots, pet parrots are captive bred.

Parrot species that are commonly kept as pets include conures, macaws, Amazons, cockatoos, African Greys, lovebirds, cockatiels, budgerigars, eclectus, Caiques, parakeets, Pionus and Poicephalus. Species vary in their temperament, noise level, talking ability, cuddliness with people, and care needs, although how a parrot has been raised usually greatly affects its personality.

Parrots can make excellent companion animals, and can form close, affectionate bonds with their owners. However they invariably require an enormous amount of attention, care and intellectual stimulation to thrive, akin to that required by a three year old child, which many people find themselves unable to provide in the long term.^[114] Parrots that are bred for pets may be hand fed or otherwise accustomed to interacting with people from a young age to help ensure they will be tame and trusting. However, parrots are not low maintenance pets; they require feeding, grooming, veterinary care, training, environmental enrichment through the provision of toys, exercise, and social interaction (with other parrots or humans) for good health. Some large parrot species, including large cockatoos, Amazons, and macaws, have very long lifespans with 80 years being reported and record ages of over one hundred. Small parrots, such as lovebirds, hanging parrots, and budgies have shorter life spans of up to 15–20 years. Some parrot species can be quite loud, and many of the larger parrots can be destructive and require a very large cage, and a regular supply of new toys, branches, or other items to chew up. The intelligence of parrots means they are quick to learn tricks and other behaviors—both good and bad—that will get them what they want, such as attention or treats.

The popularity, longevity, and intelligence of many of the larger species of pet parrots has led to many of these birds being re-homed during the course of their long lifespans.

A common problem is that large parrot species which are cuddly and gentle as juveniles will mature into intelligent, complex, often demanding adults that can outlive their owners. Due to these problems, and the fact that homeless parrots are not euthanized like dogs and cats, parrot adoption centers and sanctuaries are becoming more common.

Zoos

 

Scarlet Macaw riding a tricycle at a show in Spain

Parrot species are found in most zoos, and a few zoos participate in breeding and conservation programs. Some zoos have organised displays of trained parrots and other birds doing tricks.

Trade

 

10,000 Hyacinth Macaws were taken from the wild for the pet trade in the 1980s.^[115]

The popularity of parrots as pets has led to a thriving—and often illegal—trade in the birds, and some species are now threatened with extinction. A combination of trapping of wild birds and damage to parrot habitats makes survival difficult or even impossible for some species of parrot. Importation of wild caught parrots into the US and Europe is illegal.

The trade continues unabated in some countries. A report published in January 2007 presents a clear picture of the wild-caught parrot trade in Mexico, stating: "The majority of parrots captured in Mexico stay in the country for the domestic trade. A small percentage of this capture, 4% to 14%, is smuggled into the USA."^[116] In the early 1980s an American college student who worked his way through school smuggling parrots across the Rio Grande put his contraband Mexican birds in a cage on an inflatable raft and floated with them across the international river to the U.S. side where a partner would be waiting.^[117]

The scale of the problem can be seen in the Tony Silva case of 1996, in which a parrot expert and former director at Tenerife's Loro Parque (Europe's largest parrot park) was jailed in the United States for 82 months and fined $100,000 for smuggling Hyacinth Macaws.^[118] (Such birds command a very high price). The case led to calls for greater protection and control over trade in the birds. Different nations have different methods of handling internal and international trade. Australia has banned the export of its native birds since 1960. The United States protects its only native parrot through its Endangered Species Act, and protects other nations' birds through its Wild Bird Conservation Act. Following years of campaigning by hundreds of NGOs and outbreaks of avian flu, in July 2007, the European Union halted the importation of all wild birds with a permanent ban on their import. Prior to an earlier temporary ban started in late October 2005, the EU was importing approximately two million live birds a year, about 90% of the international market: hundreds of thousands of these were parrots. There are no national laws protecting feral parrot populations in the U.S. Mexico has a licensing system for capturing and selling native birds (though the laws are not well enforced).

Culture

 

Moche Parrot. 200 A.D. Larco Museum Collection Lima, Peru

Parrots have featured in human writings, story, art, humor, religion and music for thousands of years. From the Roman poet Ovid's "The Dead Parrot"(Latin), (English) to Monty Python's Dead Parrot Sketch millennia later, parrots have existed in the consciousness of many cultures. Recent books about parrots in human culture include Parrot Culture.^[119]

In ancient times and currently parrot feathers have been used in ceremonies, and for decoration. The "idea" of the parrot has been used to represent the human condition in medieval literature such as the bestiary. They also have a long history as pets.

In Polynesian legend as current in the Marquesas Islands, the hero Laka/Aka is mentioned as having undertaken a long and dangerous voyage to Aotona in what are now the Cook Islands, to obtain the highly prized feathers of a red parrot as gifts for his son and daughter. On the voyage a hundred out of his 140 rowers died of hunger on their way, but the survivors reached Aotona and captured enough parrots to fill 140 bags with their feathers.^[120] By at least some versions, the feathers were plucked off living parrots without killing them.^[121]

Currently parrots feature in many media. There are magazines devoted to parrots as pets, and to the conservation of parrots (PsittaScene). Fictional films include Paulie, and documentaries include The Wild Parrots of Telegraph Hill.

Parrots have also been considered sacred. The Moche people of ancient Peru worshipped birds and often depicted parrots in their art.^[122]

Parrots are used as symbols of nations and nationalism. A parrot is found on the flag of Dominica. The St. Vincent parrot is the national bird of St. Vincent and the Grenadines, a Caribbean nation.

Parrots are popular in Buddhist scripture and there are many writings about them. For example, Amitābha once changed itself into a parrot to aid in converting people. Another old story tells how after a forest caught fire, the parrot was so concerned it carried water to try and put out the flames. The ruler of heaven was so moved upon seeing the parrot's act, that he sent rain to put out the fire. In Chinese Buddhist iconography, a parrot is sometimes depicted hovering on the upper right side Guan Yin clasping a pearl or prayer beads in its beak.

Sayings about parrots colour the modern English language. The verb "parroting" can be found in the dictionary, and means "to repeat by rote." There are also clichés, such as the British saying "sick as a parrot."

Feral populations

  Lo stesso argomento in dettaglio: Feral parrots.

 

Feral Red-masked Parakeets in San Francisco. The population is the subject of the book and film, The Wild Parrots of Telegraph Hill.

Escaped parrots of several species have become established in the wild outside their natural ranges and in some cases outside the natural range of parrots. Among the earliest instances were pet Red Shining-parrots from Fiji which established a population on the islands of southern Tonga. These introductions were prehistoric and Red-shining Parrots were recorded in Tonga by Captain Cook in the 1770s.^[89] Escapees first began breeding in cities in California, Texas and Florida in the 1950s (with unproven earlier claims dating back to the 1920s in Texas and Florida).^[90] They have proved surprisingly hardy in adapting to conditions in Europe and North America. They sometimes even multiply to the point of becoming a nuisance or pest, and a threat to local ecosystems, and control measures have been used on some feral populations.^[123]

Threats and conservation

 

A mounted specimen of the Carolina Parakeet, which was hunted to extinction

 

Community-based conservation has helped arrest the decline of the endangered Ouvea Parakeet.

A large number of parrot species are in decline, and several species are now extinct. Of the 350 or so living species of parrot 130 species are listed as near threatened or worse by the IUCN.^[124] There are numerous reasons for the decline of so many species, the principal threats being habitat loss and degradation, hunting, and for certain species, wild-bird trade. Parrots are persecuted for a number of reasons; in some areas they may (or have been) hunted for food, for feathers, and as agricultural pests. For a time, Argentina offered a bounty on Monk Parakeets (an agricultural pest), resulting in hundred of thousands of birds being killed, though apparently this did not greatly affect the overall population.^[125] Capture for the pet trade is a threat to many of the rarer or slower to breed species. Habitat loss or degradation, most often for agriculture, is a threat to numerous parrot species. Parrots, being cavity nesters, are vulnerable to the loss of nesting sites and to competition with introduced species for those sites. The loss of old trees is particularly a problem in some areas, particularly in Australia where suitable nesting trees may be many hundreds of years old. Many parrot species occur only on islands and are vulnerable to introduced species such as rats and cats, as they lack the appropriate anti-predator behaviours needed to deal with mammalian predators. Controlling such predators can help in maintaining or increasing the numbers of endangered species.^[126] Insular species, which have small populations in restricted habitat, are also vulnerable to physical threats such as hurricanes and volcanic eruptions.

There are many active conservation groups whose goal is the conservation of wild parrot populations. One of the largest includes the World Parrot Trust,^[127] an international organization. The group gives assistance to worthwhile projects as well as producing a magazine^[128] and raising funds through donations and memberships, often from pet parrot owners. They state they have helped conservation work in 22 countries. On a smaller scale local parrot clubs will raise money to donate to a cause of conservation. Zoo and wildlife centers usually provide public education, to change habits that cause damage to wild populations. Recent conservation measures to conserve the habitats of some of the high-profile charismatic parrot species has also protected many of the less charismatic species living in the ecosystem.^[77] A popular attraction that many zoos now employ is a feeding station for lories and lorikeets, where visitors feed small parrots with cups of liquid food. This is usually done in association with educational signs and lecture.

Several projects aimed specifically at parrot conservation have met with success. Translocation of vulnerable Kakapo, followed by intensive management and supplementary feeding, has increased the population from 50 individuals to 123.^[129] In New Caledonia the Ouvea Parakeet was threatened by trapping for the pet trade and loss of habitat. Community based conservation, which eliminated the threat of poaching, has allowed the population to increase from around 600 birds in 1993 to over 2000 birds in 2009.^[130]

At present the IUCN recognises 19 species of parrot as extinct since 1600 (the date used to denote modern extinctions).^[131] This does not include species like the New Caledonian Lorikeet which has not been officially seen for 100 years yet is still listed as critically endangered.

Trade, export and import of all wild-caught parrots is regulated and only permitted under special licensed circumstances in countries party to CITES, the Convention on the International Trade in Endangered Species, that came into force in 1975 to regulate the international trade of all endangered wild caught animal and plant species. In 1975, 24 parrot species were included on Appendix I of CITES, thus prohibiting commercial international trade in these birds. Since that initial listing, continued threats from international trade have lead CITES to add an additional 32 parrot varieties to Appendix I, including nine in the last four years.^[132] All the other parrot species are protected on Appendix II of CITES. In addition, individual countries may have laws to regulate trade in certain species.

References

Notes

1. ^ (EN) Hoffmann, M. & Mallon, D. 2010, Panjabi/Prove, su IUCN Red List of Threatened Species, Versione 2020.2, IUCN, 2020.
2. Giraffe, su etymonline.com, Online Etymology Dictionary. URL consultato il 1º novembre 2011.
3. Kingdon, J., The Kingdon Field Guide to African Mammals, Academic Press, 1997, pp. 339–44, ISBN 0-12-408355-2.
4. ^ Peust, C., Semito-Hamitic Festschrift for A.B. Dolgopolsky and H. Jungraithmayr, Reimer, 2009, pp. 257–60, ISBN 3-496-02810-6.
5. ^ camelopardalis, su perseus.tufts.edu, A Latin Dictionary, Perseus Digital Library. URL consultato il 23 novembre 2011.
6. Walker, C., Signs of the Wild, Struik, 1997, p. 142, ISBN 1-86825-896-3.
7. Kingdon, J., East African Mammals: An Atlas of Evolution in Africa, Volume 3, Part B: Large Mammals, University Of Chicago Press, 1988, pp. 313–37, ISBN 0-226-43722-1.
8. Mitchell, G.; Skinner, J. D., On the origin, evolution and phylogeny of giraffes Giraffa camelopardalis (PDF), in Transactions of the Royal Society of South Africa, vol. 58, n. 1, 2003, pp. 51–73, DOI:10.1080/00359190309519935.
9. Simmons, R. E.; Scheepers, L., Winning by a Neck: Sexual Selection in the Evolution of Giraffe (PDF), in The American Naturalist, vol. 148, n. 5, 1996, pp. 771–86, DOI:10.1086/285955.
10. L. N. Badlangana, Adams, J. W.; Manger P. R., The giraffe (Giraffa camelopardalis) cervical vertebral column: A heuristic example in understanding evolutionary processes?, in Zoological Journal of the Linnean Society, vol. 155, n. 3, 2009, pp. 736–57, DOI:10.1111/j.1096-3642.2008.00458.x.
11. Dagg, A. I., Giraffa camelopardalis (PDF), in Mammalian Species, vol. 5, n. 5, 1971, pp. 1–8, DOI:10.2307/3503830.
12. Prothero, D. R.; Schoch, R. M., Horns, Tusks, and Flippers: The Evolution of Hoofed Mammals, Johns Hopkins University Press, 2003, pp. 67–72, ISBN 0-8018-7135-2.
13. Brown, D. M.; Brenneman R. A.; Koepfli, K-P.; Pollinger, J. P.; Milá, B.; Georgiadis, N. J.; Louis Jr., E. E.; Grether, G. F.; Jacobs, D. K.; Wayne R. K., Extensive population genetic structure in the giraffe, in BMC Biology, vol. 5, n. 1, 2007, DOI:10.1186/1741-7007-5-57.
14. Pellow, R. A., The Encyclopedia of Mammals, a cura di MacDonald, D, 2nd, Oxford University Press, 2001, pp. 520–27, ISBN 0-7607-1969-1.
15. Giraffe – The Facts: Current giraffe status?, su giraffeconservation.org, Giraffe Conservation Foundation. URL consultato il 21 dicembre 2010.
16. ^ Exhibits, su awpr.ae, Al Ain Zoo, 25 febbraio 2003. URL consultato il 21 novembre 2011.
17. ^ Nubian giraffe born in Al Ain zoo, su uaeinteract.com, UAE Interact. URL consultato il 21 dicembre 2010.
18. Giraffa, su app.isis.org, ISIS, 2010. URL consultato il 4 novembre 2010.
19. ^ Brenneman, R. A.; Louis, E. E. Jr; Fennessy, J., Genetic structure of two populations of the Namibian giraffe, Giraffa camelopardalis angolensis, in African Journal of Ecology, vol. 47, n. 4, 2009, pp. 720–28, DOI:10.1111/j.1365-2028.2009.01078.x.
20. Hassanin, A.; Ropiquet, A.; Gourmand, B-L.; Chardonnet, B.; Rigoulet, J., Mitochondrial DNA variability in Giraffa camelopardalis: consequences for taxonomy, phylogeography and conservation of giraffes in West and central Africa, in Comptes Rendus Biologies, vol. 330, n. 3, 2007, pp. 173–83, DOI:10.1016/j.crvi.2007.02.008.
21. Errore nelle note: Errore nell'uso del marcatore <ref>: non è stato indicato alcun testo per il marcatore iucn
22. Template:IUCN2008
23. Template:IUCN2008
24. Estes, R., The Behavior Guide to African Mammals: including Hoofed Mammals, Carnivores, Primates, University of California Press, 1992, pp. 202–07, ISBN 0-520-08085-8.
25. ^ Lever, A-M., Not one but 'six giraffe species', BBC News, 21 dicembre 2007. URL consultato il 4 marzo 2009.
26. Skinner, J. D.; Smithers, R. H. M., The mammals of the southern African subregion, University of Pretoria, 1990, pp. 616–20, ISBN 0-521-84418-5.
27. Swaby, S., Mammal Anatomy: An Illustrated Guide, a cura di Harris, T., Marshall Cavendish Corporation, 2010, pp. 64–84, ISBN 0-7614-7882-5.
28. Williams, E., Giraffe, Reaktion Books, 2011, ISBN 1-86189-764-2.
29. Mitchell, G.; Skinner, J.D., Giraffe thermoregulation: a review, in Transactions of the Royal Society of South Africa: Proceedings of a Colloquium on Adaptations in Desert Fauna and Flora, vol. 59, n. 2, 2004, pp. 49–57, DOI:10.1080/00359190409519170.
30. ^ Wood, W. F.; Weldon, P. J., The scent of the reticulated giraffe (Giraffa camelopardalis reticulata), in Biochemical Systematics and Ecology, vol. 30, n. 10, 2002, pp. 913–17, DOI:10.1016/S0305-1978(02)00037-6.
31. R. E. Simmons, Altwegg, R., Necks-for-sex or competing browsers? A critique of ideas on the evolution of giraffe, in Journal of Zoology, vol. 282, n. 1, 2010, pp. 6–12, DOI:10.1111/j.1469-7998.2010.00711.x.
32. ^ MacClintock, D.; Mochi, U., A natural history of giraffes, Scribner, 1973, p. 30, ISBN 0-684-13239-7.
33. ^ T Garland, Janis, C. M., Does metatarsal/femur ratio predict maximal running speed in cursorial mammals? (PDF), in Journal of Zoology, vol. 229, n. 1, 1993, pp. 133–51, DOI:10.1111/j.1469-7998.1993.tb02626.x.
34. ^ Rafferty, John. P, Grazers (Britannica Guide to Predators and Prey), Britannica Educational Publishing, 2011, p. 194, ISBN 1-61530-336-7.
35. Tobler, I.; Schwierin, B., Behavioural sleep in the giraffe (Giraffa camelopardalis) in a zoological garden, in Journal of Sleep Research, vol. 5, n. 1, 1996, pp. 21–32, DOI:10.1046/j.1365-2869.1996.00010.x.
36. Henderson, D. M.; Naish, D., Predicting the buoyancy, equilibrium and potential swimming ability of giraffes by computational analysis, in Journal of Theoretical Biology, vol. 265, n. 2, 2010, pp. 151–59, DOI:10.1016/j.jtbi.2010.04.007.
37. Template:Cite magazine
38. S. J. Van Sittert, Skinner, J. D.; Mitchell, G., From fetus to adult – An allometric analysis of the giraffe vertebral column, in Journal of Experimental Zoology Part B Molecular and Developmental Evolution, 314B, n. 6, 2010, pp. 469–79, DOI:10.1002/jez.b.21353.
39. ^ Solounias, N., The remarkable anatomy of the giraffe's neck (PDF), in Journal of Zoology, vol. 247, n. 2, 1999, pp. 257–68, DOI:10.1111/j.1469-7998.1999.tb00989.x.
40. J. T. du Toit, Feeding-height stratification among African browsing ruminants (PDF), in African Journal of Ecology, vol. 28, n. 1, 1990, pp. 55–62, DOI:10.1111/j.1365-2028.1990.tb01136.x.
41. ^ Cameron, E. Z.; du Toit, J. T., Winning by a Neck: Tall Giraffes Avoid Competing with Shorter Browsers (PDF), in American Naturalist, vol. 169, n. 1, 2007, pp. 130–35, DOI:10.1086/509940.
42. ^ Woolnough, A. P.; du Toit, J. T., Vertical zonation of browse quality in tree canopies exposed to a size-structured guild of African browsing ungulates (PDF), in Oecologia, vol. 129, n. 1, 2001, pp. 585–90, DOI:10.1007/s004420100771.
43. Young, T. P.; Isbell, L. A., Sex differences in giraffe feeding ecology: energetic and social constraints (PDF), in Ethology, vol. 87, 1–2, 1991, pp. 79–89, DOI:10.1111/j.1439-0310.1991.tb01190.x.
44. ^ Mitchell, G.; van Sittert, S.; Skinner, J. D., The demography of giraffe deaths in a drought, in Transactions of the Royal Society of South Africa, vol. 65, n. 3, 2010, pp. 165–68, DOI:10.1080/0035919X.2010.509153.
45. ^ Mitchell, G.; van Sittert, S. J.; Skinner, J. D., Sexual selection is not the origin of long necks in giraffes, in Journal of Zoology, vol. 278, n. 4, 2009, pp. 281–86, DOI:10.1111/j.1469-7998.2009.00573.x.
46. Wedel, M. J., A monument of inefficiency: the presumed course of the recurrent laryngeal nerve in sauropod dinosaurs (PDF), in Acta Palaeontologica Polonica, vol. 57, n. 2, 2012, pp. 251–56, DOI:10.4202/app.2011.0019.
47. ^ Harrison, D. F. N., The Anatomy and Physiology of the Mammalian Larynx, Cambridge University Press, 1995, p. 165, ISBN 0-521-45321-6.
48. Skinner, J. D.; Mitchell, G., Lung volumes in giraffes, Giraffa camelopardalis, in Comparative Biochemistry and Physiology – Part A: Molecular & Integrative Physiology, vol. 158, n. 1, 2011, pp. 72–78, DOI:10.1016/j.cbpa.2010.09.003.
49. ^ Mitchell, G.; van Sittert, S. J.; Skinner, J. D., The structure and function of giraffe jugular vein valves, in South African Journal of Wildlife Research, vol. 39, n. 2, 2009, pp. 175–80, DOI:10.3957/056.039.0210.
50. ^ Pérez, W.; Lima, M.; Clauss, M., Gross anatomy of the intestine in the giraffe (Giraffa camelopardalis), in Anatomia, Histologia, Embryologia, vol. 38, n. 6, 2009, pp. 432–35, DOI:10.1111/j.1439-0264.2009.00965.x.
51. ^ Cave, A. J. E., On the liver and gall-bladder of the Giraffe, in Proceedings of the Zoological Society of London, vol. 120, n. 2, 1950, pp. 381–93, DOI:10.1111/j.1096-3642.1950.tb00956.x.
52. ^ <571::AID-JEMT3>3.0.CO;2-I Comparative morphology of the gallbladder and biliary tract in vertebrates: variation in structure, homology in function and gallstones, in Microscopy Research and Technique, vol. 38, n. 6, 1997, pp. 571–79, DOI:10.1002/(SICI)1097-0029(19970915)38:6<571::AID-JEMT3>3.0.CO;2-I.
53. ^ Template:Cite thesis
54. van der Jeugd, H. P; Prins, H. H. T., Movements and group structure of giraffe (Giraffa camelopardalis) in Lake Manyara National Park, Tanzania (PDF), in Journal of Zoology, vol. 251, n. 1, 2000, pp. 15–21, DOI:10.1111/j.1469-7998.2000.tb00588.x.
55. Pratt D. M.; Anderson V. H., Giraffe social behavior, in Journal of Natural History, vol. 19, n. 4, 1985, pp. 771–81, DOI:10.1080/00222938500770471.
56. Leuthold, B. M., Social organization and behaviour of giraffe in Tsavo East National Park, in African Journal of Ecology, vol. 17, n. 1, 1979, pp. 19–34, DOI:10.1111/j.1365-2028.1979.tb00453.x.
57. ^ Silent Sentinels?, su pbs.org, PBS online – Nature. URL consultato il 21 dicembre 2011.
58. ^ Mammal Guide – Giraffe, su animal.discovery.com, Animal Planet. URL consultato il 7 marzo 2009.
59. Langman, V. A., Cow-calf relationships in giraffe (Giraffa camelopardalis giraffa), in Zeitschrift fur Tierpsychologie, vol. 43, n. 3, 1977, pp. 264–86. doi:10.1111/j.1439-0310.1977.tb00074.x
60. ^ Coe, M. J., 'Necking' behavior in the giraffe, in Journal of Zoology, vol. 151, n. 2, 1967, pp. 313–21, DOI:10.1111/j.1469-7998.1967.tb02117.x.
61. ^ Bagemihl, B., Biological Exuberance: Animal Homosexuality and Natural Diversity, St. Martin's Press, 1999, pp. 391–93, ISBN 0-312-19239-8.
62. ^ Müller, D.W.; Zerbe, P; Codron, D; Clauss, M; Hatt, J.M., A long life among ruminants: giraffids and other special cases, in Schweizer Archiv für Tierheilkunde, vol. 153, n. 11, 2011, pp. 515–519, DOI:10.1024/0036-7281/a000263.
63. ^ Owen-Smith, N.; Mills, M. G., Predator-prey size relationships in an African large-mammal food web, in Journal of Animal Ecology, vol. 77, n. 1, 2008, pp. 173–83, DOI:10.1111/j.1365-2656.2007.01314.x.
64. ^ Ross, K., Okavango: jewel of the Kalahari, Struik, 2003, p. 168, ISBN 1-86872-729-7.
65. ^ Greaves, N.; Clement, R., When Hippo Was Hairy: And Other Tales from Africa, Struik, 2000, pp. 86–88, ISBN 1-86872-456-5.
66. ^ The Dabous Giraffe rock art petrograph, su bradshawfoundation.com, The Bradshaw Foundation. URL consultato il 6 novembre 2011.
67. ^ Ringmar, E., Audience for a Giraffe: European Expansionism and the Quest for the Exotic, in Journal of World History, vol. 17, n. 4, 2006, pp. 353–97, DOI:10.1353/jwh.2006.0060.
68. ^ Knappert, J, East Africa: Kenya, Tanzania & Uganda, Vikas Publishing House, 1987, p. 57, ISBN 0-7069-2822-9.
69. ^ Walter, M.; Fournier, A.; Menevaux, D., Integrating shape and pattern in mammalian models in SIGGRAPH '01 (PDF), in Proceedings of the 28th annual conference on Computer graphics and interactive techniques, 2001, pp. 317–26, DOI:10.1145/383259.383294.
70. ^ Lord. M, Outlandish Outposts: Giraffe Manor in Kenya, su forbes.com, 11 gennaio 2012. URL consultato il 4 aprile 2012.
71. ^ David M. Waterhouse, Parrots in a nutshell: The fossil record of Psittaciformes (Aves), in Historical Biology, vol. 18, n. 2, 2006, pp. 223–234, DOI:10.1080/08912960600641224.
72. ^ Zoological Nomenclature Resource: Psittaciformes (Version 9.013), su zoonomen.net, www.zoonomen.net, 29 dicembre 2008.
73. ^ Psittacine, in American Heritage Dictionary of the English Language, Fourth Edition, Houghton Mifflin Company, 2000. URL consultato il 9 settembre 2007 (archiviato dall'url originale il 27 agosto 2007).
74. ^ Psittacine, in Merriam-Webster Online Dictionary, Merriam-Webster, Inc. URL consultato il 9 settembre 2007.
75. ^ Christidis L, Boles WE, Systematics and Taxonomy of Australian Birds, Canberra, CSIRO Publishing, 2008, p. 200, ISBN 9780643065116.
76. ^ Snyder, N; McGowan, P; Gilardi, J; & A Grajal (2000), Parrots: Status Survey and Conservation Action Plan, 2000-2004. Chapter 1. vii. IUCN ISBN 2-8317-0504-5. Chapter 1. vii.
77. Snyder, N; McGowan, P; Gilardi, J; & A Grajal (2000), Parrots: Status Survey and Conservation Action Plan, 2000-2004. Chapter 1. vii. IUCN ISBN 2-8317-0504-5. Chapter 2. page 12.
78. T.F. Wright, Schirtzinger E. E., Matsumoto T., Eberhard J. R., Graves G. R., Sanchez J. J., Capelli S., Muller H., Scharpegge J., Chambers G. K. & Fleischer R. C., A Multilocus Molecular Phylogeny of the Parrots (Psittaciformes): Support for a Gondwanan Origin during the Cretaceous, in Mol Biol Evol, vol. 25, n. 10, 2008, pp. 2141–2156, DOI:10.1093/molbev/msn160.
79. ^ Stidham T. (1998) "A lower jaw from a Cretaceous parrot" Nature 396: 29–30
80. ^ Dyke GJ, Mayr G. (1999) "Did parrots exist in the Cretaceous period?" Nature 399: 317–318
81. ^ Waterhouse DM. (2006) "Parrots in a nutshell: The fossil record of Psittaciformes (Aves)" Historical Biology 18(2): 227–238
82. ^ Waterhouse, D.M., Lindow, B.E.K.; Zelenkov, N.; Dyke, G.J., Two new fossil parrots (Psittaciformes) from the Lower Eocene Fur Formation of Denmark, in Palaeontology, vol. 51, 2008, pp. 575–582, DOI:10.1111/j.1475-4983.2008.00777.x.
83. ^ Dyke GJ, Cooper JH (2000) "A new psittaciform bird from the London clay (Lower Eocene) of England" Palaeontology 43: 271–285
84. RS de Kloet, de Kloet SR, The evolution of the spindlin gene in birds: Sequence analysis of an intron of the spindlin W and Z gene reveals four major divisions of the Psittaciformes., in Molecular Phylogenetics and Evolution, vol. 36, n. 3, 2005, pp. 706–721, DOI:10.1016/j.ympev.2005.03.013.
85. M Tokita, Kiyoshi T and Armstrong KN, Evolution of craniofacial novelty in parrots through developmental modularity and heterochrony., in Evolution & Development, vol. 9, n. 6, 2007, pp. 590–601, DOI:10.1111/j.1525-142X.2007.00199.x.
86. ^ Edward H. Burtt, Max R. Schroeder, Lauren A. Smith, Jenna E. Sroka, Kevin J. McGraw (2010): Colourful parrot feathers resist bacterial degradation, Biology Letters, The Royal Society, doi:10.1098/rsbl.2010.0716.
87. ^ Forshaw, Joseph M. & Cooper, William T. (1978): Parrots of the World (2nd ed). Landsdowne Editions, Melbourne Australia ISBN 0-7018-0690-7
88. ^ Y. Miyaki, Parrot evolution and paleogeographical events: Mitochondrial DNA evidence (PDF), in Molecular Biology and Evolution, vol. 15, n. 5, 1998, pp. 544–551.
89. Steadman D, (2006). Extinction and Biogeography in Tropical Pacific Birds, University of Chicago Press. ISBN 978-0-226-77142-7 pp.342–351
90. Butler C (2005) "Feral Parrots in the Continental United States and United Kingdom: Past, Present, and Future" Journal of Avian Medicine and Surgery 19(2): 142–149
91. ^ Daniel Sol, Santos, David M. ; Feria, Elías & Jordi Clavell, Habitat Selection by the Monk Parakeet during Colonization of a New Area in Spain, in Condor, vol. 99, n. 1, 1997, pp. 39–46, DOI:10.2307/1370222.
92. Collar N (1997) "Family Psittacidae (Parrots)" in Handbook of the Birds of the World Volume 4; Sandgrouse to Cuckoos (eds del Hoyo J, Elliott A, Sargatal J) Lynx Edicions:Barcelona. ISBN 84-87334-22-9
93. ^ Diamond, J (1999). "Evolutionary biology: Dirty eating for healthy living" Nature 400(6740): 120–121
94. ^ Gartrell B, Jones S, Brereton R & Astheimer L (2000) "Morphological Adaptations to Nectarivory of the Alimentary Tract of the Swift Parrot Lathamus discolor". Emu 100(4) 274–279
95. ^ Kea – Mountain Parrot, NHNZ. (1 hour documentary)
96. ^ Terry Greene, Aspects of the ecology of Antipodes Island Parakeet (Cyanoramphus unicolor) and Reischek's Parakeet (C. novaezelandiae hochstetten) on Antipodes Island (PDF), in Notornis, vol. 46, n. 2, Ornithological Society of New Zealand, 1999 November/December, pp. 301–310.
97. ^ Rowley I(1997) "Family Cacatuidae (Cockatoos)" in Handbook of the Birds of the World Volume 4; Sandgrouse to Cuckoos (eds del Hoyo J, Elliott A, Sargatal J) Lynx Edicions:Barcelona. ISBN 84-87334-22-9
98. ^ David C. Oren, Novaes, Fernando, Observations on the golden parakeet Aratinga guarouba in Northern Brazil, in Biological Conservation, vol. 36, n. 4, 1986, pp. 329–337, DOI:10.1016/0006-3207(86)90008-X.
99. ^ Eberhard J (1998) "Evolution of nest-building behavior in Agapornis parrots" Auk 115(2): 455–464
100. ^ Tania Sanchez-Martinez, Katherine Renton, Availability and selection of arboreal termitaria as nest-sites by Orange-fronted Parakeets Aratinga canicularis in conserved and modified landscapes in Mexico, in Ibis, vol. 151, n. 2, 2009, pp. 311–320, DOI:10.1111/j.1474-919X.2009.00911.x.
101. ^ Robert Heinsohn, Murphy, Stephen & Legge, Sarah, Overlap and competition for nest holes among eclectus parrots, palm cockatoos and sulphur-crested cockatoos, in Australian Journal of Zoology, vol. 51, n. 1, 2003, pp. 81–94, DOI:10.1071/ZO02003.
102. ^ A Pell, Tidemann, C, The impact of two exotic hollow-nesting birds on two native parrots in savannah and woodland in eastern Australia, in Biological Conservation, vol. 79, n. 2, 1997, pp. 145–153, DOI:10.1016/S0006-3207(96)00112-7.
103. ^ Masello, J; Pagnossin, M; Sommer, C & P Quillfeldt (2006) "Population size, provisioning frequency, flock size and foraging range at the largest known colony of Psittaciformes: the Burrowing Parrots of the north-eastern Patagonian coastal cliffs" Emu 106 (1): 69–79 DOI: 10.1071/MU04047
104. ^ Jessica Eberhard, [0240:CAATEO2.0.CO;2 Cavity adoption and the evolution of coloniality in cavity-nesting birds], in Condor, vol. 104, n. 2, 2002, pp. 240–247, DOI:10.1650/0010-5422(2002)104[0240:CAATEO]2.0.CO;2.
105. ^ Forshaw, Joseph, Encyclopaedia of Animals: Birds, a cura di Forshaw, Joseph, London, Merehurst Press, 1991, pp. 118–124, ISBN 1-85391-186-0.
106. ^ Andrew Iwaniuk, This Bird Is No Airhead, Natural Sciences and Engineering Research Council of Canada, 9 febbraio 2004. URL consultato il 9 settembre 2007.
107. ^ Mike Beynon, Who's a clever bird, then?, BBC News, April 2000. URL consultato il 9 settembre 2007.
108. ^ A Cruickshank, Gautier, J & Chappuis, C, Vocal mimicry in wild African Grey Parrots Psittacus erithacus, in Ibis, vol. 135, n. 3, 1993, pp. 293–299, DOI:10.1111/j.1474-919X.1993.tb02846.x.
109. ^ IUCN, Status Survey and Conservation Action Plan, 2000–2004, Parrots, Foreword
110. ^ Warburton, L. S. & M. R. Perrin (2006) "The Black-cheeked Lovebird (Agapornis nigrigenis) as an agricultural pest in Zambia" Emu 106 (4): 321–328 DOI: 10.1071/MU04037
111. ^ Christian, C; Potts, T; Burnett, G & T Lacher Jr. (1999) "Parrot Conservation and Ecotourism in the Windward Islands". Journal of Biogeography 23 (3): 387–393
112. ^ Sam Ward, USA Snapshots: Most Popular Pets, su pqasb.pqarchiver.com, USA Today, 21 dicembre 1992. URL consultato il 6 settembre 2009.
113. ^ Parrot, su bestiary.ca, The Medieval Bestiary, 13 febbraio 2008.
114. ^ The National Parrot Sanctuary - Europe's Only Dedicated Parrot Zoo
115. ^ BirdLife International (2004). Anodorhynchus hyacinthinus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 27 August 2007.
116. ^ Stopping the Illegal Mexican Parrot Trade, su defenders.org, Defenders of Wildlife. URL consultato il 23 December 2007.
117. ^ Miller, Tom. On the Border: Portraits of America's Southwestern Frontier, p. 94–100.
118. ^ Jason Lowther, Crime and Punishment in the Wildlife Trade (PDF), World Wildlife Federation, 5 agosto 2002. URL consultato il 9 settembre 2007.
119. ^ Bruce Boehrer, Parrot Culture, Philadelphia, University of Pennsylvania Press, 2004, ISBN 978-0-8122-3793-1.
120. ^ :*R.D. Craig, Dictionary of Polynesian Mythology (Greenwood Press: New York, 1989), 6.; E.S.C. Handy, Marquesan Legends (Bernice P. Bishop Museum Press: Honolulu, 1930), 130–1
121. ^ Aka's Voyage for Red Feathers (Marquesas Islands)
122. ^ Berrin, Katherine & Larco Museum. The Spirit of Ancient Peru:Treasures from the Museo Arqueológico Rafael Larco Herrera. New York: Thames and Hudson, 1997.
123. ^ Department of Conservation, DOC's work with rainbow lorikeet, su doc.govt.nz, 2008. URL consultato il 14 luglio 2008.
124. ^ IUCN Red List of Threatened Species, su iucnredlist.org, IUCN, 2006. URL consultato il 31 August 2007.
125. ^ Campbell, T. S., The Monk Parakeet, su invasions.bio.utk.edu, The Institute for Biological Invasions, December 2000.
126. ^ Ron Moorhouse, Terry Greene, Peter Dilks, Ralph Powlesland, Les Moran, Genevieve Taylor, Alan Jones, Jaap Knegtmans, Dave Wills, Moira Pryde, Ian Fraser, Andrew August and Claude August (2002) "Control of introduced mammalian predators improves kaka Nestor meridionalis breeding success: reversing the decline of a threatened New Zealand parrot". Biological Conservation 110 (1): 33–44
127. ^ Current homepage, su parrots.org, The World Parrot Trust.
128. ^ Our publications: PsittaScene Magazine, su parrots.org, World Parrot Trust.
129. ^ Kakapo Recovery Programme, Then and Now, in Kakapo Recovery Programme, 2010. URL consultato il 1º April 2010.
130. ^ Nicholas Barré, Theuerkauf, Jörn; Verfaille, Ludovic ; Primot, Pierre and Maurice Saoumoé, Exponential population increase in the endangered Ouvéa Parakeet (Eunymphicus uvaeensis) after community-based protection from nest poaching, in Journal of Ornithology, vol. 151, 2010, p. 695, DOI:10.1007/s10336-010-0499-7.
131. ^ IUCN (2007). "2007 IUCN Red List of Threatened Species" . Downloaded on 14 July 2008.
132. ^ A group of 226 non-governmental organisations, The European Union Wild Bird Declaration (PDF), su birdsareforwatching.org, www.birdsareforwatching.org, 19 maggio 2005.