Psittaciformes

Psittaciformes [sə‚tas·ə′fȯr‚mēz]

(vertebrate zoology)

The parrots, a monofamilial order of birds that exhibit zygodactylism and have a strong hooked bill.

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Psittaciformes 

an order of birds with a body length ranging from 9.5 cm to 1 m. The plumage, which is often brightly colored, is usually green, frequently mixed with red and deep blue. Species with black or gray plumage are relatively rare. The males and females usually have the same coloration. The bill is thick and high, and the culmen articulates with the frontal bones. The birds are able to crush very hard fruits with their bills; in addition, when they climb trees, they use their bills to grasp the branches. The feet have strong talons, and the first and fourth toes are turned backward. The birds fly rapidly. Some species, such as Pezoporus wallicus and the owl parrot (Strigops habroptilus), have lost the ability to fly.

The order Psittaciformes consists of a single family, which embraces 316 species. The birds are distributed in the subtropics and tropics of both hemispheres. In the Americas, their range extends from 40° N lat. to 54° S lat. The majority of species live on plains; a few penetrate high into the mountains, to elevations 3,600 m above sea level. The birds most commonly live in flocks. As a rule, they are arboreal, but some species inhabit open spaces.

The birds nest in tree hollows, termite nests, rock fissures, and cliffs; some nest on the ground. Only a few species line their nest with grass, which they carry in their bill or between the feathers of the upper tail coverts (Agapornis). The Argentinian Myiopsitta build colonial nests in trees, with divisions for each couple. A clutch contains one to 12 (most often two to five) white eggs, which are incubated for about three weeks. The young are born naked and blind.

Psittaciformes feed on fruits, seeds, buds, nectar, and, sometimes, insects. They are beneficial in distributing seeds and pollinating plants; however, some may seriously damage plantings and orchards. A number of species, including love birds, budgerigars (Melopsittacus undulatus), African gray parrots (Psittacus erithacus), and cockatoos, are popular pets owing to their decorative plumage and their ability to imitate various sounds, including human speech. They may be carriers of psittacosis, a serious disease that afflicts man.

REFERENCES

Zhizn’ zhivotnykn, vol. 5. Moscow, 1970.
Naturgeschichte der Vögel. Edited by R. Berndt and W. Meise. Stuttgart, 1962.
A New Dictionary of Birds. Edited by A. L. Thomson. London, 1964.

A. I. IVANOV