Budgerigar

Budgerigar (Melopsittacus undulatus) is a small long-tailed Australian parrot naturally coloured green and yellow with black scalloped markings across the nape, back and wings. Body shape, bill structure, plumage pattern and voice provide the strongest field characters. Age, sex and season may alter its appearance, so identification should combine several features and careful direct field comparisons with similar species in the same habitat (Wikipedia, general species account).

It forms mobile flocks in open dry country, travelling in response to water and seeding grasses, feeding mainly on seeds and nesting in tree hollows; captive breeding has produced many colour forms. Its movements and social behaviour vary through the year, with breeding birds generally more dispersed and non-breeding birds gathering where food is concentrated. Japanese records place it within the country's documented avifauna as a resident, migrant or visitor (Wikipedia, general species account; Wildlife of Japan occurrence records).