bittern

Any of several species of small herons, in particular the common bittern Botaurus stellaris of Europe and Asia. It is shy, stoutly built, buff-coloured, speckled with black and tawny brown, with a long bill and a loud, booming call. Its habit of holding its neck and bill in a vertical position conceals it among the reeds, where it rests by day, hunting for frogs, reptiles, and fish towards nightfall. An inhabitant of marshy country, it is now extremely rare in Britain. In 2000 there were only an estimated 20 pairs of bitterns breeding in the British Isles.