Classification One of the most unexpected findings of phylogenomic studies of birds has been that Parrots (Psittaciformes) are the sister order of Passerines (Passeriformes).
Psittaciformes comprise roughly 372 species of parrots found in most tropical and subtropical regions. Strigopidae (New Zealand parrots) are a basal lineage which are sister to all other parrots. Cacatuidae (Cockatoos) have a movable head crest, and lack the feather texture which, in the Psittacidae ("True parrots"), scatters light and produces their contrasting colours. The upper mandible of parrot bill curves downward and is not fused to the skull. This feature allows it to move independently, and contributes to the tremendous biting pressure the birds are able to exert. In addition, there are touch receptors along the inner edges of the kerantinised bill, which allow for highly dextrous manipulations. Parrots eat mainly seeds, nuts, fruit, buds and other plant material.
Parrots are monogamous. Courtship and behaviour to maintain the pair bond may include vocalizations, bill-caressing, mutual preening, bowing, wing-raising, tail-spreading, and feeding of the mate. Almost all parrots nest in tree hollows and lay white eggs from which hatch altricial (helpless) young.
Parakeeet (Perruche in French) is a name for any one of a large number of unrelated small to medium sized species of parrot, that generally have long tail feathers.
Parrots, along with Corvidae (ravens, crows, jays and magpies), are among the most intelligent birds. While parrots are able to mimic human speech, studies with the Grey Parrots (Psittacus erythacus) Alex and N'kisi have suggested that some are able to associate words with their meanings and form simple sentences. The brain-to body size ratio of psittacines and corvines is actually comparable to that of higher primates. Although birds have a relatively small cerebral cortex, it has been contended that birds use a different part of the brain, the medio-rostral neostriatum / hyperstriatum ventrale, as the seat of their intelligence. In addition, some species of parrot such as the Kea are also highly skilled at using tools and solving puzzles.
Suh A et al (2011): Mezozoic retroposons reveal parrots as the closest living relative of passerine birds. nat Commun.2:443 doi :10.1038/ncomms 1448 (2011).