Budgerigars in their natural-habitats of Australia are noticeably smaller than those in captivity. This particular parrot species has been bred in many other colours and shades in captivity (i.e. blue, grey, greygreen, pieds, violet, white, yellow...) although they are mostly found in pet stores in blue, green and yellow. Budgerigar plumage is known to fluoresce under ultraviolet light (as most other parrot species do as well), a phenomenon possibly related to courtship and mate selection.
The colour of the cere (the area containing the nostrils) differs between the sexes; royal blue in males, pale-brown to white (non-breeding) or brown (breeding) in females and pink in immatures of both sexes (usually of a more even purplish-pink colour in young males). Some female budgerigars develop brown cere only during breeding time and later disappears. Young females can often be identified by a subtle chalky whiteness that starts around the cere nostril holes. Males that are either Albino, Dark-Eyed-Clear, Lutino and/or recessive pied (aka Danishpied aka Harlequin) always retain the immature purplish-pink cere colour their entire life.
It is usually easy to tell the sex of a Budgie over 6 months old, mainly by the cere colours but behaviours and head shape also help indicate Budgie's genders.
Mature males' ceres are usually light to dark blue but can be purplish to pink in some particular colour mutations (DarkEyedClears, Danishpieds aka Recessivepieds and Inos) and usually display much rounder heads. Males are typically cheerful, extroverted, highly flirtatious, most peacefully social and very vocal.
Females' ceres are pinkish as immatures and switch from being beigish or whitish outside breeding condition into brown (often with a 'crusty' texture) in breeding condition and usually display flattened back of heads (right above the nape region). Females are typically highly dominant and more socially intolerant.
Budgerigars are nomadic birds found in open habitats, primarily in Australian scrubland, open woodland and grassland. The birds are normally found in small flocks, but can form very large flocks under favourable conditions. The species is extremely nomadic and the 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 weeds, and sometimes ripening wheat.
Naturalised feral budgerigars have been recorded since the 1940s in the St. Petersburg, Florida area of the United States, but are much less common than they were in the early 1980s. Increased competition from European Starlings and House Sparrows is thought to be primary cause of the population decline (Pranty 2001).
Although budgerigars in their natural-habitats of Australia eat mainly grass seeds, captive budgerigars feed on either dry, sprouted and/or soaked seeds. A diet of only dry seeds is inadequate for budgerigars and/or any parrot species' optimum health. Avian veterinarians recommend pet birds' diets be supplemented with foods such as:
Adding these foods provides additional nutrients and can prevent obesity and lipomas, as can substituting millet, which is relatively low in fat, for higher-fat seed mixes. Adult budgerigars often do not always adapt readily to dietary additions, so care must be taken to introduce healthy diets as young as possible (ideally weaned onto fresh foods before introducing chicks onto seeds). Parrots and budgerigars learn mainly by mimicry and thus most adult budgerigars will be easily encouraged to try new foods by observing another bird eating the food, or by placing the new food on a mirror.
The wild budgerigar has evolved alongside the Eucalyptus tree and over a million years has developed an intimate bond with the tree and its leaves. Wet eucalyptus leaves excite and invigorate both the wild and aviary budgerigar. They love to bathe in the wet leaves and breeding hens destructively chew the bark. The eucalyptus oil from the leaves has medicinal properties that stimulate the immune system and promote a strong natural resistance to disease.
In the wild, virtually all parrot species require a hollow tree or a hollow log as a nest site. Because of this natural behavior, budgerigars most easily breed in captivity when provided with a nest box. The eggs are typically 1 to 2 centimetres long and are plain white without any coloration. Female budgerigars can lay eggs without a male partner but these eggs are unfertilized and will not hatch. This is just like the eggs that chickens lay, which are later sold at supermarkets. A female budgerigar will lay her eggs on alternate days. After the first one, there is usually a two-day gap until the next. She will usually lay between four to eight eggs, which she will incubate (usually starting after laying her 2nd or 3rd) for about 21 days each. Budgerigar hens only leave their nests for very quick defecations and stretches once they've begun incubating and are by then almost exclusively fed by their cocks (usually at the nest's entrance). 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.
It is very important to realize that most health issues and physical abnormalities in budgerigars are genetic. Care should be taken that birds used for breeding are active, healthy, and unrelated. Budgerigars that are related or who have fatty tumours or other potentially genetic health problems should not be allowed to breed. Parasites (lice, mites, worms...) and pathogens (bacteria, fungi and viruses), are contagious and thus transmitted between individuals through either direct or indirect contact. Nestboxes should be cleaned between uses. Splay legs, a relatively common problem in baby budgerigars, results from a young budgerigars slipping repeatedly on the floor of a nestbox. It is easily avoided by placing a small quantity of a safe bedding or wood shavings in the bottom of the nestbox. Alternatively, several pieces of paper may be placed in the box for the hen to shred into bedding. Budgerigars eggs are 1 to 2 centimetres long.
The eggs will take about 18-20 days before they start hatching. The hatchlings are blind, naked, totally helpless and their mother feeds them around the clock day and night. Around 10 days of age, the chicks' eyes will open, and they will start to develop feather down. The appearance of down occurs precisely at the ages (around 9 or 10 days of age) for closed banding of the chicks. Budgerigar's closed band rings must be neither larger or smaller than 4.0 to 4.2 mm.
They develop feathers around 3 weeks of age. (One can often easily note the colour mutation of the individual birds at this point.) At this stage of the chicks' development, the cock usually has begun to enter the nest to help his hen in caring and feeding the chicks. Some budgerigar hens, however, totally forbid their cocks from entering the nest and thus take the full responsibility of rearing the chicks until they fledge.
Depending on the size of the clutch and most particularly in the case of single mothers, it may then be wise to transfer a portion of the hatchlings (or best of the fertile eggs) to another pair. The foster pair must already be in breeding mode and thus either at the laying or incubating stages and/or rearing hatchlings.
As the chicks develop and grow feathers, they are able to be left on their own for longer and longer periods of time. By the fifth week, the chicks are strong enough that both parents will be comfortable in staying more and more out of the nest. The youngsters will stretch their wings to gain strength before they attempt to fly. They will also help defend the box from enemies mostly with their loud screeching. Young budgerigars typically fledge (leave the nest) around their fifth week of age and are usually completely weaned a week later. However, the age for fledging as well as weaning can vary slightly depending on whether it is the oldest, the youngest and/or the only surviving chick. Generally speaking, the oldest chick is the first to be weaned. But even though it is logically the last one to be weaned, the youngest chick is often weaned at a younger age than its older sibling(s). (This can be a result of mimicking the actions of older siblings.) Lone surviving chicks are often weaned at the youngest possible age as a result of having their parent's full attention and care.
Hand-reared Budgies may take slightly longer to wean than parent-raised chicks. Hand feeding is not routinely done with budgerigars, due to their small size, and the fact that young parent raised birds can be readily tamed.
The budgerigar is one of only two parrot species to be genuinely domesticated along with the rose-collared aka peach-faced lovebird (Agapornis roseicollis). It is widely acknowledged as the most common pet parrot in the world and possibly the most common cage bird. The budgerigar has been bred in captivity since the 1850s. Breeders have worked over the decades to produce a wide range of colour, pattern and feather mutations, such as albino, blue, cinnamon-ino (aka lacedwings), clearwinged, crested, dark, greywinged, opaline, pieds, spangled, suffused, and violet.
Standard-type (aka English or "show") budgerigars are about twice larger than their wild-type (natural form and sized) counterparts. Their overall larger sizes and puffy head feathers give them boldly exaggerated looks. The eyes and beak can be almost totally obscured by their fluffed head's and forehead's feathers. Most captive budgerigars in the pet trade are similar in size and body conformation to wild occurring budgerigars and thus aptly called wild-type budgerigars.
Budgerigars are intelligent and social animals and enjoy the stimulation of toys and interaction with humans as well as with other budgerigars. A common behavior is the chewing of material such as wood, especially for female budgerigars.
Tame budgerigars can be taught to speak, whistle tunes, and play with humans. Both males and females sing and can learn to mimic sounds and words and do simple tricks. Both singing and mimicry are more pronounced and much more perfected in males. As a whole, females rarely if ever learn to mimic more than a dozen words or so. Males can very easily acquire vocabularies ranging between a few dozen to a hundred words. Generally speaking, it are mostly pet budgerigars (and even more so lone pets) and thus, receiving the most attention which talk the best and the most.
In captivity, budgerigars live an average of five to eight years, but are reported to occasionally live to 15-20 if well cared for. The life span depends on each particular budgerigar's breed (show budgerigars typically do not live as long as wild-type budgerigars), lineage and overall health, which is highly influenced by exercise and diet.
Budgerigars (as do most other parrot species) and most particularly females love to chew on anything they can find in their cages and environments. This comes from the females' instinct in adapting by gnawing the all around interior of existing wild bird's nests. Mineral-blocks (ideally enriched with iodine) and cuttlebone and soft wooden pieces must be provided to help them satisfy their desire to chew and keep their beaks trimmed.
Bird lovers often comment on the differences in personality in each individual bird. Budgerigars each have their own unique ideas about how much they like to be handled, which toys are their favorites, and even what music they like or are indifferent to.
Budgerigars have been shown to cause "bird fancier's lung" in sensitive people, a type of hypersensitivity pneumonitis. This is primarily an issue with people keeping large numbers of budgerigars within a bird room.
Budgerigars are small but are very active, energetic, and lively birds. The absolute minimum size cage for one or two tame pet budgerigars who are allowed out for several hours a day is 18 inches long by 18 inches wide. However, larger cages and flights will be appreciated by these energetic little birds. An ideal cage is longer than higher (since birds fly horizontally like planes and not vertically like helicopters) and would be at least 30 inches long. The cage should not have bar spacing greater than 1/2 inch between bars. Budgerigars are not particularly destructive birds, and spacious cages, while not always easy to find, are usually not overly expensive.
Care should be taken when placing several female budgerigars together, as they can do serious harm to one another if they do not get along. It is easier and often more convenient to keep either an even number of both males and females or to only keep male birds altogether as these generally get along with each other without any problem. They are relatively easily tamed and bred.
Male specimens of budgerigars are considered one of the top five talking champions amongst parrot species, alongside Psittacus erithacus ssp. (Congo/Cameroon/Ghana/Princep's and/or Timneh African Grey Parrots), Amazona spp. (Amazon Parrot species), Eclectus ssp. (Eclectus sub-species) and Psittacula spp. (Afro-Asian Ringnecked Parakeet species).
A budgerigar named Puck holds the world record for the largest vocabulary of any bird, at 1,728 words. Puck, a male budgerigar owned by American Camille Jordan, died in 1994, with the record first appearing in the 1995 edition of Guinness World Records.