The bitterns are members of the heron family Ardeidae. The wading birds in this group which are named as bitterns tend to be the shorter necked, often more secretive members of this family.

The heron family is one of the families in the order Ciconiiformes, which also includes other wading bird families:

Ciconiiformes

• Ardeidae herons and bitterns
• Cochlearidae: Boatbill
• Balaenicipitidae Shoebill
• Scopidae Hammerkop
• Ciconiidae: storks
• Threskiornithidae ibises and spoonbills
• Phoenicopteridae flamingos

Bitterns often frequent reedbeds and similar marshy areas, and feed on amphibians, reptiles, insects and fish.

Unlike the similar storks, ibises and spoonbills, herons and bitterns fly with their necks retracted, not outstretched.

The genus Ixobrychus contains mainly small species:

• Little Bittern Ixobrychus minutus
• Cinnamon Bittern Ixobrychus cinnamomeus
• Stripe-backed Bittern Ixobrychus involucris
• Least Bittern Ixobrychus exilis
• Yellow Bittern Ixobrychus sinensis
• Schrenck's Bittern Ixobrychus eurhythmus
• Dwarf Bittern Ixobrychus sturmii
• Black Bittern Ixobrychus flavicollis

The genus Botaurus is the larger bitterns:

• American Bittern, Botaurus lentiginosa.
• Great Bittern or European Bittern, Botaurus stellata
• South American Bittern Botaurus pinnatus
• Australasian Bittern Botaurus poiciloptilus

The following genera of the Ardeidae are considered under the Heron article:

Ardea
Zebrilus
Philherodias
Tigrisoma
Ardeola
Bubulcus
Egretta
Agamia
Butorides
Tigriornis
Tigrisoma
Gorsachius
Syrigma
Zonerodius
Nycticorax