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western reef heron
The western reef heron (''Egretta gularis'') also called the western reef egret, is a medium-sized heron found in southern Europe, Africa and parts of Asia. It has a mainly coastal distribution and occurs in two plumage forms, a slaty-grey plumage in which it can only be confused with the rather uncommon dark morph of the little egret (''Egretta garzetta'') and a white form which can look very similar to the little egret although the bill tends to be paler and larger. There are also differences in size, structure and foraging behaviour. There have been suggestions that the species hybridizes with the little egret, and based on this, some authors treat ''schistacea'' and ''gularis'' as subspecies of ''Egretta garzetta''. Works that consider the western reef heron as a valid species include the nominate ''gularis'' and ''schistacea'' as subspecies.
==Description==
This bird has two plumage colour forms. There is an all-white morph and a dark grey morph; morphs can also occur with intermediate shades of grey which may be related to age or particoloured in grey and white. The white morph is similar in general appearance to the little egret, but has a larger yellower bill, extended yellow on thicker legs, and when foraging tends to be very active, sometimes also moving its wing or using it to shade the water surface. The grey morph has a whitish throat and is unlikely to be confused with any other species within the range of this egret with beak and legs similar to that of the white morph. During the breeding season the legs and facial skin are reddish. Breeding birds have two long feathers on the sides of the nape. The nominate subspecies ''gularis'' has a range from West Africa to Gabon, with some birds breeding in southern Europe. Subspecies ''schistacea'' (Hemprich & Ehrenberg, 1828) breeds from the Persian Gulf along the coast of India to the east of the India Peninsula. The form on the eastern coast of South Africa is usually separated as the dimorphic egret ''Egretta dimorpha''.〔 The dark and white morph is thought to be controlled by a single allele with the dark character being incompletely dominant over the gene for white.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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