Eurasian Bittern

Eurasian Bittern (Botaurus stellaris) is a heavy, buff-brown heron densely patterned with dark streaks, giving strong camouflage among upright reeds. 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 remains hidden in extensive reedbeds and marsh vegetation, where it feeds on fish and small vertebrates; males advertise in spring with a far-carrying booming call. 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).