AppearanceWild budgerigars average 18 cm long, weigh 30–40 grams, 30 cm in wingspan, and display a light green body colour, while their mantles display pitch-black mantle markings 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 throats. 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. 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 upper half of their beaks is taller than the bottom half, covering the bottom when closed. The beak does not protrude much, due to the thick, fluffy feathers surrounding it, giving the appearance of a downward-pointing beak that lies flat against the face. The upper half acts as a long, smooth cover, while the bottom half is just about a half-sized cup-piece. These beaks allow the birds to eat plants, fruits, and vegetables.
The colour of the cere differs between the sexes, being royal blue in males, pale brown to white or brown in females, and pink in immatures of both sexes . 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 always retain the immature purplish-pink cere colour their entire lives.
It is usually easy to tell the sex of a budgerigar over six months old, mainly by the cere colours, but behaviours and head shape also help indicate sex. Veterinarians can determine the sex of a bird by invasive examination or samples of blood, feather, or eggshell.
Mature males usually have a cere of light to dark blue, but in some particular colour mutations it can be purplish to pink – including Dark-eyed Clears, Danish Pieds and Inos, which usually display much rounder heads. The behaviour of males can distinguish them from females. Males are typically cheerful, extroverted, highly flirtatious, peacefully social, and very vocal.
Female ceres are pinkish while immature. As they age, they move from being beigish or whitish outside breeding condition into brown in breeding condition and usually display flattened backs of heads . Females are typically highly dominant and more socially intolerant. This behavior is more pronounced around other females than with males.
Budgerigars have tetrachromatic colour vision, although all four classes of cone cells will not operate simultaneously unless under sunlight or a UV lamp.Timothy H. Goldsmith and Byron K. Butler in Journal of Comparative Physiology A, Vol. 191, No. 10, pages 933–951; October 2005. 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 over-stimulation.
HabitatBudgerigars are nomadic and flocks move on from sites as environmental conditions change. Budgerigars are found in open habitats, primarily in scrublands, open woodlands, and grasslands of Australia. The birds are normally found in small flocks, but can form very large flocks under favourable conditions. The nomadic movement of the flocks is tied to the availability of food and water. Drought can drive flocks into more wooded habitat or coastal areas. They feed on the seeds of spinifex, grass seeds, and sometimes ripening wheat.
ReproductionBreeding in the wild generally takes place between June and September in northern Australia and between August and January in the south, although budgerigars are opportunistic breeders and respond to rains when grass seeds become most abundant. They show signs of affection to their flockmates by preening or feeding one another. Budgerigars feed one another by eating the seeds themselves, and then regurgitating it into their flockmate's mouth. Populations in some areas have increased as a result of increased water availability at farms. Nests are made in holes in trees, fence posts or logs lying on the ground; the four to six eggs are incubated for 18–21 days, with the young fledging about 30 days after hatching.
In the wild, virtually all parrot species require a hollow tree or a hollow log as a nest site. Because of this natural behaviour, budgerigars most easily breed in captivity when provided with a reasonable-sized nest box.
The eggs are typically one to two centimetres long and are pearl white without any colouration if fertile. Female budgerigars can lay eggs without a male partner, but these unfertilised eggs will not hatch. Females normally have a whitish tan cere; however, when the female is laying eggs, her cere turns a crusty brown colour. Certain female budgies may always keep a whitish tan cere or always keep a crusty brown cere regardless of breeding condition. A female budgerigar will lay her eggs on alternating days. After the first one, there is usually a two-day gap until the next. She will usually lay between four and eight eggs, which she will incubate for about 21 days each. Females only leave their nests for very quick defecations, stretches and quick meals once they have begun incubating and are by then almost exclusively fed by their mate . Females will not allow a male to enter the nest, unless he forces his way inside. Depending on the clutch size and the beginning of incubation, the age difference between the first and last hatchling can be anywhere from 9 to 16 days. At times, the parents may begin eating their own eggs due to feeling insecure in the nest box.
Sometimes, budgerigars are not interested in the opposite sex, and will not reproduce with them; a flock setting—several pairs housed where they can see and hear each other—is necessary to stimulate breeding.
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