Ardea


 * "Megalornis" redirects here. This name was also (invalidly) given to the pseudotooth bird genus Dasornis by Harry Govier Seeley and proposed (but not adopted) for the moa genus Dinornis by Richard Owen.

Ardea is a genus of herons. Linnaeus named this genus as the Great Herons, referring to the generally large size of these birds, typically 80–100 cm or more in length.

These large herons are associated with wetlands where they prey on fish, frogs, and other aquatic species.

Most members of this almost worldwide group breed colonially in trees, building large stick nests. Northern species such as Great Blue, Grey and Purple Herons may migrate south in winter, although the first two do so only from areas where the waters freeze.

These are powerful birds with large spear-like bills, long necks and long legs, which hunt by waiting motionless or stalking their prey in shallow water before seizing it with a sudden lunge. They have a slow steady flight, with the neck retracted as is characteristic of herons and bitterns; this distinguishes them from storks, cranes, and spoonbills, which extend their necks.

Taxonomy
Some members of Ardea are clearly very closely related, such as the Grey, Great Blue, and Cocoi Herons, which form a superspecies. However, the Great Egret, in particular, has been placed in other genera by various authors as Egretta alba and Casmerodius alba. Nevertheless, this species closely resembles the large Ardea herons in everything but colour, whereas it shows fewer similarities to the smaller white egrets.

Species

 * Grey Heron, Ardea cinerea
 * Great Blue Heron, Ardea herodias
 * Cocoi Heron, Ardea cocoi
 * White-necked Heron or Pacific Heron, Ardea pacifica
 * Black-headed Heron, Ardea melanocephala
 * Humblot's Heron, Ardea humbloti
 * White-bellied Heron, Ardea insignis
 * Goliath Heron, Ardea goliath
 * Great-billed Heron, Ardea sumatrana 
 * Purple Heron, Ardea purpurea 

A number of Ardea species are only known from subfossil or fossil bones. Their placement in Ardea versus Egretta may be provisional:
 * Bennu Heron, Ardea bennuides (prehistoric)
 * Ardea sp. (Middle Miocene of Observation Quarry, USA) (fossil)
 * Ardea sp. (Late Miocene of Love Bone Bed, USA) (fossil)
 * Ardea polkensis (Early Pliocene of Bone Valley, USA) (fossil)
 * Ardea sp. (Early Pleistocene of Macasphalt Shell Pit, USA) (fossil)
 * Ardea formosa (fossil)
 * Ardea howardae (fossil)
 * Ardea similis (fossil)

The remains described as Ardea perplexa are nowadays usually believed to be from an ibis of the genus Geronticus or closely related thereto.