Bitterns are birds belonging to the subfamily Botaurinae of the heron family Ardeidae. Bitterns tend to be shorter-necked and more secretive than other members of the family. They were called hæferblæte and various iterations of raredumla in Old English; the word "bittern" came to English from Old French butor, itself from Gallo-Roman butitaurus, a compound of Latin būtiō (buzzard) and taurus (bull).

Bitterns usually frequent reed beds and similar marshy areas and feed on amphibians, reptiles, insects, and fish.

Bitterns, like herons, egrets, and pelicans, fly with their necks retracted, unlike the cranes, storks, ibises and spoonbills, and geese which fly with necks extended and outstretched. The genus Ixobrychus was recently found to be paraphyletic with the Botaurus genus, and Ixobrychus was then merged into Botaurus.

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