The Eurasian Bittern or Great Bittern (Botaurus stellaris) is a wading bird of the heron family Ardeidae.
In the UK, the main areas are Lancashire and East Anglia with an estimated 44 breeding pairs. Europe as a whole is estimated at 20-44,000 males.
Its folk names include "barrel-maker", "bog-bull", "bog hen", "bog-trotter", and "butterbump, mire drum, mostly refer to the mating call of the male, which is a deep fog-horn or bull-like boom, easily audible from a distance of 2 miles on a calm night. The Latin for bittern, Botaurus, also refers to the bull. The other part of its scientific name, stellata is the Latin for starry, in reference to its plumage.
Surveys of Eurasian Bitterns are carried out by noting the number of distinct male booms in a given area.
The Eurasian Bittern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.