The bittern is a thickset heron with all-over bright, pale, buffy-brown plumage covered with dark streaks and bars. It flies on broad, rounded, bowed wings. A secretive bird, very difficult to see, as it moves silently through reeds at water's edge, looking for fish. The males make a remarkable far-carrying, booming sound in spring.

It's very small, reedbed-dependent population make it an Amber List species.