Budgerigar (Melopsittacus undulatus)

BirdParrotAustralia

Two wild-type green and yellow budgerigars (Melopsittacus undulatus) perched on a branch, showing black barring on the wings. — Wild-type budgerigars in Australia. Wild birds are green and yellow with black barring; other colours are captive-bred varieties.
Image: Jim Bendon from Karratha, Australia, CC BY-SA 2.0, via Wikimedia Commons.

Overview

The budgerigar (Melopsittacus undulatus) is a small, long-tailed parrot native to the arid and semi-arid interior of Australia. Wild budgerigars are green and yellow with fine black barring across the head, nape and wings — the barring is the origin of the species name undulatus.

It is the only species in its genus and belongs to the group known as grass parakeets. In the wild it is a bird of open country, feeding on the ground on grass seed and travelling in flocks that can be enormous.

The budgerigar is also the wild ancestor of the domesticated 'budgie'. Captive-bred colour varieties — blue, white, yellow, grey and many others — are the product of selective breeding and do not occur as the normal wild type. This profile covers the wild species; it is not a pet-care guide and offers no husbandry, feeding or veterinary advice.

Habitat & Range

Budgerigars live across the dry interior of Australia — open grassland, scrub, mallee, savanna woodland and dry farmland — and are largely absent from the wetter coastal fringes and dense forest. They depend on access to water and on grass seed, and their distribution shifts with rainfall rather than staying fixed.

Diet

Budgerigars are seed eaters, taking the seeds of grasses and low plants almost entirely from the ground. Feeding is concentrated in the cooler parts of the day, and flocks visit water regularly — a dependence that shapes where they can be at any given time.

Behavior

Wild budgerigars are highly gregarious and nomadic rather than migratory: they move in response to rainfall and seeding, so flocks appear where conditions are good and vanish when they are not. After good rains, flocks can reach spectacular sizes. They nest in tree hollows, especially in eucalypts, and breeding is triggered by rainfall rather than by a fixed season. Budgerigars are vocal, with constant chattering contact calls, and are capable of mimicry.

Human Interaction & Conservation

The budgerigar is one of the most widely kept pet birds in the world, and captive populations vastly outnumber attention paid to the wild species. In the wild it remains common and widespread within Australia, where it is protected and export is prohibited. Feral populations have established in a few places outside Australia. This profile covers the wild bird only and gives no advice on keeping, feeding, breeding or the health of pet birds — those questions belong with an avian veterinarian. Verify current status at the IUCN Red List.

Sourced facts

Each value below is traced to the specific reference that states it. Open a row's evidence to see the source, where to look in it, and how firmly it supports the value. Sources checked 2026-10-09.

Sourced facts about the Budgerigar, with the reference supporting each
Fact	What the source states	Evidence
Geographic range	Native throughout Australia except far-eastern and far-south-western coastal areas; introduced in many countries but established only in southwest Florida.The introduced-range statement cites Juniper (1998) and may be out of date.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Geographic Range Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Habitat	Semi-arid and sub-humid habitats, mainly in Australia's interior; sometimes in dry grasslands of the southeast.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Habitat Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Diet	Ground-feeding seed eater: seeds of grasses and crop plants, especially spinifex and tall tussock grasses; drinks about 5.5% of its body weight daily.ADW classes the primary diet as herbivore/granivore.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Food Habits Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Body size	18-20 cm in length.ADW does not say whether this is total length, nor whether the figure is from wild or captive birds.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Physical Description Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Body mass	An average of 30 g.ADW cites AnAge, and does not say whether this is a wild or captive figure, or which sex it describes.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Physical Description Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Activity pattern	Active by day, beginning just before sunrise.ADW's behaviour tags list it as both 'diurnal' and 'nomadic', and its habitat text says it migrates north in winter; the profile describes nomadic movement following rainfall.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Behavior; Habitat Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Social structure	Strongly social, gathering in large flocks; monogamous, breeding in large colonies.ADW records some extra-pair copulations and no apparent hierarchy within groups; females are generally more aggressive than males.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Behavior; Reproduction Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Distinguishing traits	Small size, pointed wings and tail, and distinct plumage; most wild birds have a yellow forehead, a yellow-and-black striped head and purple-and-black cheek marks.Wild plumage only; ADW notes that caged birds differ greatly in colour. Juveniles have a barred forehead. Breeding females have a light brown or beige cere; otherwise the cere is blue.	Matches source · Animal Diversity Web — how we know Animal Diversity Web — University of Michigan Museum of Zoology Where Physical Description Checked by FaunaHub 2026-10-09 Limits A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
Conservation status	Least Concern (LC), global assessment, 2018	Matches source · IUCN Red List of Threatened Species — how we know IUCN Red List of Threatened Species Checked by FaunaHub 2026-10-09 Limits Read from the Red List export IUCN publishes to GBIF; iucnredlist.org itself does not answer automated reads. Categories are reassessed over time.

Not stated here, and why

Lifespan— no source accepted yet: The ADW account states no wild lifespan. Its only figure is 21 years in captivity (AnAge), which was left out because this profile covers the wild species only.

References for the facts above

UniversityAnimal Diversity Web — University of Michigan Museum of ZoologySupports: Range, habitat, diet, body size and mass, lifespan, activity and social structure, as the account states them. Retrieved 2026-10-09.Limitations: A peer-edited account written largely by students under faculty review. Figures are compiled from the literature rather than from a single study, and some are regional.
ReferenceIUCN Red List of Threatened SpeciesSupports: The global Red List category and the year of the assessment. Retrieved 2026-10-09.Limitations: Read from the Red List export IUCN publishes to GBIF; iucnredlist.org itself does not answer automated reads. Categories are reassessed over time.

Frequently Asked Questions — Budgerigar

What colour are wild budgerigars?

Green and yellow, with fine black barring across the head, nape and wings. The blue, white, grey, yellow and other colour varieties seen in pet birds are the result of selective breeding in captivity and are not the normal wild appearance.

Are budgerigars nomadic or migratory?

Nomadic. Rather than following a fixed seasonal route like a migratory bird, budgerigars move in response to rainfall and the seeding of grasses. Flocks appear in an area when conditions are good and leave when they deteriorate, so their distribution shifts year to year.

What do wild budgerigars eat?

Grass seed, taken almost entirely from the ground, along with seeds of other low plants. They feed mainly in the cooler parts of the day and must drink regularly, which strongly influences where flocks can be found in arid country.

Where do budgerigars nest?

In tree hollows, particularly in eucalypts along watercourses. Breeding is triggered by rainfall rather than by a fixed calendar, so after good rains large numbers may nest at once, taking advantage of the flush of grass seed that follows.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.

UniversityAnimal Diversity Web — Melopsittacus undulatus (budgerigar) — University of Michigan species account
Wildlife referenceSmithsonian's National Zoo & Conservation Biology Institute — Animals — Educational species pages from the Smithsonian Institution
Wildlife referenceIUCN Red List of Threatened Species — Authoritative source for current conservation status