|
The cattle egret (''Bubulcus ibis'') is a cosmopolitan species of heron (family Ardeidae) found in the tropics, subtropics and warm temperate zones. It is the only member of the monotypic genus ''Bubulcus'', although some authorities regard its two subspecies as full species, the western cattle egret and the eastern cattle egret. Despite the similarities in plumage to the egrets of the genus ''Egretta'', it is more closely related to the herons of ''Ardea''. Originally native to parts of Asia, Africa and Europe, it has undergone a rapid expansion in its distribution and successfully colonised much of the rest of the world in the last century. It is a white bird adorned with buff plumes in the breeding season. It nests in colonies, usually near bodies of water and often with other wading birds. The nest is a platform of sticks in trees or shrubs. Cattle egrets exploit drier and open habitats more than other heron species. Their feeding habitats include seasonally inundated grasslands, pastures, farmlands, wetlands and rice paddies. They often accompany cattle or other large mammals, catching insect and small vertebrate prey disturbed by these animals. Some populations of the cattle egret are migratory and others show post-breeding dispersal. The adult cattle egret has few predators, but birds or mammals may raid its nests, and chicks may be lost to starvation, calcium deficiency or disturbance from other large birds. This species maintains a special relationship with cattle, which extends to other large grazing mammals; wider human farming is believed to be a major cause of their suddenly expanded range. The cattle egret removes ticks and flies from cattle and consumes them. This benefits both species, but it has been implicated in the spread of tick-borne animal diseases. ==Taxonomy== The cattle egret was first described in 1758 by Linnaeus in his ''Systema naturae'' as ''Ardea ibis'',〔 but was moved to its current genus by Charles Lucien Bonaparte in 1855.〔 Its genus name ''Bubulcus'' is Latin for herdsman, referring, like the English name, to this species' association with cattle.〔 ''Ibis'' is a Latin and Greek word which originally referred to another white wading bird, the sacred ibis.〔 The cattle egret has two geographical races which are sometimes classified as full species, the western cattle egret, ''B. ibis'', and eastern cattle egret, ''B. coromandus''. The two forms were split by McAllan and Bruce,〔 but were regarded as conspecific by almost all other recent authors until the publication of the influential ''Birds of South Asia''.〔 The eastern subspecies ''B. (i.) coromandus'', described by Pieter Boddaert in 1783, breeds in Asia and Australasia, and the western nominate form occupies the rest of the species range, including the Americas.〔 Some authorities recognise a third Seychelles subspecies, ''B. i. seychellarum'', which was first described by Finn Salomonsen in 1934.〔 Despite superficial similarities in appearance, the cattle egret is more closely related to the genus ''Ardea'', which comprises the great or typical herons and the great egret (''A. alba''), than to the majority of species termed egrets in the genus ''Egretta''.〔 Rare cases of hybridization with little blue herons ''Egretta caerulea'', little egrets ''Egretta garzetta'' and snowy egrets ''Egretta thula'' have been recorded.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Cattle egret」の詳細全文を読む スポンサード リンク
|