Although there are a few exceptions, parrots are monogamous breeders which nest in cavities and hold no territories other than their nesting sites. 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.

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).


Only the Monk Parakeet and five species of Agapornis lovebird build nests in trees, and three Australian and New Zealand ground parrots nest on the ground.

All other parrots and cockatoos nest in cavities, either tree hollows or cavities dug into cliffs, banks or the ground. The use of holes in cliffs is more common in the Americas. many species will use termite nests, possibly as it reduces the conspicuousness of the nesting site or because it creates favourable microclimates.

In most cases both species 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. Some species are colonial, with the Burrowing Parrot nesting in colonies up to 70,000 strong. Coloniality is not as common in parrots as might be expected, possibly because most species adopt old cavities rather that excavate their own.

Extant species range in size from the Buff-faced Pygmy Parrot, at under 10 g (0.35 oz.) in weight and 8 cm (3.2 inches) in length, to the Hyacinth Macaw, at 1.0 meter (3.3 feet) in length, and the Kakapo, at 4.0 kg (8.8 lbs) in weight.


Amongst the families, the three Nestoridae species are all large parrots, and the cockatoos tend to be large birds as well. The Psittacidae parrots are far more variable, ranging the full spectrum of sizes shown by the family. The most obvious physical characteristic that characterises parrots is their strong, curved, broad bill.

The upper mandible is prominent, curves downward, and comes to a point. It is not fused to the skull, which allows it to move independently, and contributes to the tremendous biting pressure these birds are able to exert. The lower mandible is shorter, with a sharp, upward facing cutting edge, which moves against the flat portion of the upper mandible in an anvil-like fashion.

Seed eating parrots have a strong tongue which helps to manipulate seeds or position nuts in the bill so that the mandibles can apply an appropriate cracking force. The head is large, with eyes positioned sideways, which limits binocular vision, but greatly enhances peripheral vision. Cockatoo species have a mobile crest of feathers on the top of their heads which can be raised for display, and retracted.

No other parrots can do so, but the Pacific lorikeets in the genera Vini and Phigys are able to ruffle the feathers of the crown and nape. The predominant colour of plumage in parrots is green, though most species have some red or another colour in small quantities.

Cockatoos are the main exception to this, having lost the green and blue plumage colours in their evolutionary history they are now predominately black or white with some red, pink or yellow. Strong sexual dimorphism in plumage is not typical amongst the parrots, with some notable exceptions, the most striking being the Eclectus Parrot.