|This article does not cite any references or sources. (December 2009)|
- "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.
|Great blue heron (A. herodias)|
19, see text
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, flamingos and spoonbills, which extend their necks.
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 color, whereas it shows fewer similarities to the smaller white egrets.
- Great blue heron, Ardea herodias
- Grey heron, Ardea cinerea
- Goliath heron, Ardea goliath
- 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
- Great-billed heron, Ardea sumatrana
- Purple heron, Ardea purpurea
- Great egret or great white egret, Ardea alba (sometimes in Casmerodius or Egretta)
- Eastern great egret, Ardea (alba) modesta
- Pied heron, Ardea picata (sometimes in Egretta)
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, US) (fossil)
- Ardea sp. (Late Miocene of Love Bone Bed, US) (fossil)
- Ardea polkensis (Early Pliocene of Bone Valley, US) (fossil)
- Ardea sp. (Early Pleistocene of Macasphalt Shell Pit, US) (fossil)
- Ardea howardae (fossil)
The remains described as Ardea perplexa are nowadays usually believed to be from an ibis of the genus Geronticus or closely related thereto. "Ardea formosa" (a nomen nudum) is now Proardeola, "Ardea" brunhuberi and "A." similis refer to a misidentified cormorant (Phalacrocorax intermedius) and partridge (Miogallus altus), respectively. "Ardea" lignitum – a fossil of quite recent age as it seems – some large owl, perhaps even a Eurasian eagle-owl (Bubo bubo).
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