Grey parrot

Head of grey parrot

The grey parrot is a medium-sized, predominantly grey, black-billed parrot. Its typical weight is 400 g (0.88 lb), with an approximate length of 33 cm (13 in),[2] and a wingspan of 46–52 cm (18–20 in).[3] It has darker grey than its body over the head and both wings. The head and body feathers have slight white edges. The tail feathers are red.

Due to selection by parrot breeders, some grey parrots are partly or completely red.[4] Both sexes appear similar.[2] The colouration of juveniles is similar to that of adults, but typically, their eyes are dark grey to black, in comparison to the yellow irises around dark eyes of the adult birds,[5] and their undertail coverts are tinged with grey.[2] Adults weigh 418–526 g (0.922–1.160 lb).[6]

Grey parrots may live for 40–60 years in captivity, although their mean lifespan in the wild appears to be shorter — approximately 23 years.[3]

The grey parrot is native to equatorial Africa, including Angola, Cameroon, the Congo, Gabon, Ivory Coast, Ghana, Kenya, and Uganda. The species is found inside a range from Kenya to the eastern part of the Ivory Coast.[7][8] Current estimates for the global population are uncertain and range from 630,000 to 13 million birds. Populations are decreasing worldwide.[8] The species seems to favor dense forests, but can also be found at forest edges and in more open vegetation types, such as gallery and savanna forests.[1]

A population study published in 2015 found that the species had been ″virtually eliminated″ from Ghana with numbers declining 90 to 99% since 1992.[9] They were found in only 10 of 42 forested areas, and three roosts that once held 700–1200 birds each, now had only 18 in total. Local people mainly blamed the pet trade, and the felling of timber for the decline.[10] Populations are thought to be stable in Cameroon. In the Congo an estimated 15,000 are taken every year for the pet trade, from the eastern part of the country, although the annual quota is stated to be 5,000.[10]

The grey parrot has escaped or been deliberately released into Florida, USA, but no evidence indicates that the population is breeding naturally.[11]

The natural predators for this species include palm-nut vultures and a number of raptors. Monkeys target eggs and the young for food. Grey parrots in captivity have been observed to be susceptible to fungal infections, bacterial infections, nutritional insufficiency, malignant tumors, psittacine beak and feather disease, tapeworms, and blood-worms.[7][13]

Humans are by far the largest threat to wild grey populations. Between 1994 and 2003, more than 359,000 grey parrots were traded on the international market. Approximately 21% of the wild population was being harvested every year. Mortality rates are extremely high between the time they are captured and they reach market, ranging from 60–66%.[8] Mortality among imported birds is high.[15] This species also is hunted for its meat and for its parts, which are used in traditional medicines.[16] As a result of the extensive harvest of wild birds, in addition to habitat loss, this species is believed to be undergoing a rapid decline in the wild and therefore, has been rated as endangered by the International Union for Conservation of Nature.[1]

In October 2016, the Convention on the International Trade of Endangered Fauna and Flora (CITES) extended the highest level of protection to grey parrots by listing the species under Appendix 1, which bans global and domestic trade in the species.[17]

The species is common in captivity and regularly kept by humans as a companion parrot, prized for its ability to mimic human speech, which makes it one of the most popular avian pets.[1] An escaped pet in Japan was returned to his owner after repeating the owner's name and address.[18]

Skeleton

They are notorious for mimicking noises heard in their environment and using them tirelessly. They are highly intelligent birds, needing extensive behavioral and social enrichment as well as extensive attention in captivity or else they may become distressed. Feather plucking is a common symptom seen among such distressed grey parrots.[13] They also may be prone to behavioural problems due to their sensitive nature.[15] Social isolation hastens stress and aging.[19]Their ability to reproduce noises has led to them exercising their vocal abilities in front of humans; for example in the metal band Hatebeak.

Greys are highly social species and rely on a flock-type structure, even when raised in captivity. Because they are so dependent on the other birds within their flock, much of their speech and vocal ability is acquired through interaction with the humans with whom they reside.[20] Both wild and captive parrots have been shown to use contact calls, which allow them to interact with their flock mates and communicate information about their location, detection of predators, availability of food, and safety status. In addition, contact calls are used to form strong social bonds with their flock mates, or in the case of captive greys, with their human house mates. In captivity, African Grey parrots have been shown to display communicative competence, meaning they not only use human language correctly, but also in such a way that is appropriate for the social situation in which they are in. [21]

African grey parrots are highly intelligent and are considered by many to be one of the most intelligent species of psittacines. Many individuals have been shown to perform at the cognitive level of a four- to six-year-old child in some tasks. A number of studies have been conducted with African Greys, indicating a slew of higher level cognitive abilities. Experiments have shown that grey parrots can learn number sequences and can learn to associate human voices with the faces of the humans who create them.[22]

The American scientist Irene Pepperberg's work with Alex the parrot showed his ability to learn more than 100 words, differentiating between objects, colours, materials, and shapes.[23] Pepperberg spent several decades working with Alex, and wrote numerous scientific papers on experiments performed, indicating his advanced cognitive abilities. One such study found that Alex had the ability to add numbers as well as having a zero-like concept, similar to that of young children and apes.[24]

In addition to their striking cognitive abilities, grey parrots have been shown displaying altruistic behavior and concern for others. Researchers found that while blue-headed macaws were unlikely to share a nut with other members of their own species, grey parrots would actively give their conspecific partner a nut, even if it meant that they would not be able to get one themselves.[25] When the roles were reversed, their partners were overwhelmingly likely to return the favor, foregoing their own nut to their partners benefits. This indicates not only a display of selflessness but also an act of reciprocity.

Some research has shown that foot preference can be linked to the number of words a particular Grey parrot may know and use. Researchers found that African Grey parrots who prefer to use their right foot showed a marked increase in the number of words within their lexicon as compared to parrots who were left-footed.[26] Scientists postulate that parrots may have lateralization of brain function, much like mammals do.

Grey mutations occur naturally in the wild, such as the Blue Ino (albino), the Incomplete Ino, and the Blue varietals. The Blue Ino is all white. The Incomplete Ino has light pigmentation. The Blue has a white tail.

Breeders from South Africa, Australia, New Zealand, and Scandinavia have bred greys intensively since the 1800s. These bred varieties include the Red Pied, F2 Pied, Grizzles, Ino, Incomplete, Parino, Lutino, Cinnamon, and Red Factor. South African bird breeder Von van Antwerpen and New Zealand partner Jaco Bosman selected F2 Pieds and created the first Red Factor Greys. They are rare, may be predominantly red-pigmented, and vary in price depending upon the extent of the red plumage displayed.[27]

• Media related to Psittacus erithacus at Wikimedia Commons