Budgerigar

The species is monotypic, meaning it is the only member of the genus Melopsittacus, which is the only genus in the Melopsittacini tribe.

The budgerigar is closely related to lories and the fig parrots.

The origin of the budgerigar's name is unclear. First recorded in 1805, budgerigars are popular pets around the world due to their small size, low cost, and ability to mimic human speech. They are likely the third most popular pet in the world, after the domesticated dog and cat. Budgies are nomadic flock parakeets that have been bred in captivity since the 19th century. In both captivity and the wild, budgerigars breed opportunistically and in pairs.

They are found wild throughout the drier parts of Australia, where they have survived harsh inland conditions for over five million years. Their success can be attributed to a nomadic lifestyle and their ability to breed while on the move.

Wild budgerigars average 18 cm (7 in) long, weigh 30–40 grams (1.1–1.4 oz), 30 cm (12 in) in wingspan, and display a light green body colour, while their mantles display pitch-black mantle markings (blackish in fledglings and immatures) edged in clear yellow undulations. The forehead and face is yellow in adults.

Prior to their adult plumage, young individuals have blackish stripes down to the cere in young individuals until around 3–4 months of age. They display small, iridescent blue-violet cheek patches and a series of three black spots across each side of their throat. The two outermost throat spots are situated at the base of each cheek patch. The tail is cobalt, and outside tail feathers display central yellow flashes. Their wings have greenish-black flight feathers and black coverts with yellow fringes along with central yellow flashes, which only become visible in flight or when the wings are outstretched. Bills are olive grey and legs blueish-grey, with zygodactyl toes.

In their natural Australian habitat, budgerigars are noticeably smaller than those in captivity. This particular parrot species has been bred in many other colours and shades in captivity (e.g. blue, grey, grey-green, pieds, violet, white, yellow-blue). Pet store individuals will commonly be blue, green, or yellow. Like most parrot species, budgerigar plumage fluoresces under ultraviolet light – a phenomenon possibly related to courtship and mate selection.

The colour of the cere (the area containing the nostrils) differs between the sexes, being a lavender/baby blue in males, pale brownish/white (non breeding) to brown (breeding) in females, and pink in immature birds of both sexes (usually of a more even purplish-pink colour in young males). Some female budgerigars develop brown cere only during breeding time, which later returns to the normal colour. Young females can often be identified by a subtle, chalky whiteness that starts around the nostrils. Males that are either albino, lutino, dark-eyed clear or recessive pied (Danish pied or harlequin) retain the immature purplish-pink cere colour for their entire lives.

Mature males usually have a cere of light to dark blue, but in some particular colour mutations it can be periwinkle, lavender, purplish or pink – including dark-eyed clears, Danish pieds (recessive pieds) and inos, which usually display much rounder heads. Female budgerigars display more dominant behaviour compared to males of the species and may act aggressively towards them.

Budgerigars have tetrachromatic colour vision, although all four classes of cone cells will not operate simultaneously unless under sunlight or a UV lamp. The ultraviolet spectrum brightens their feathers to attract mates. The throat spots in budgerigars reflect UV and can be used to distinguish individual birds. While ultraviolet light is essential to the good health of caged and pet birds, inadequate darkness or rest results in overstimulation.

All captive budgerigars are divided into two basic series of colours; namely, white-based (blue, grey and white) and yellow-based (green, grey-green and yellow). Presently, at least 32 primary mutations (including violet) occur, enabling hundreds of possible secondary mutations (stable combined primary mutations) and colour varieties (unstable combined mutations).