| Ardea | ||||||||||||
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 Great Blue Heron
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Many: see text |
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
- 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
- Madagascar 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
- Pied Heron, Ardea picata or Egretta picata
- Intermediate Egret, Ardea intermedia or Egretta intermedia
- Swinhoe's Egret or Chinese Egret, Ardea eulophotes or Egretta eulophotes
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)
