|
The Indian rhinoceros (''Rhinoceros unicornis''), also called the greater one-horned rhinoceros and great Indian rhinoceros, is a rhinoceros native to the Indian subcontinent. It is listed as Vulnerable on the IUCN Red List, as populations are fragmented and restricted to less than . Moreover, the extent and quality of the rhino's most important habitat, alluvial grassland and riverine forest, is considered to decline due to human and livestock encroachment. The Indian rhinoceros once ranged throughout the entire stretch of the Indo-Gangetic Plain, but excessive hunting and agricultural development reduced their range drastically to 11 sites in northern India and southern Nepal. In the early 1990s, between 1,870 and 1,895 rhinos were estimated to have been alive. In 2015, a total of 3,555 Indian rhinoceros are estimated to live in the wild.〔(【引用サイトリンク】url=http://wwf.panda.org/what_we_do/endangered_species/rhinoceros/asian_rhinos/indian_rhinoceros )〕 == Characteristics == The Indian rhinoceros has a thick grey-brown skin with pinkish skin folds and a black horn. Its upper legs and shoulders are covered in wart-like bumps. It has very little body hair, aside from eyelashes, ear fringes and tail brush. Males have huge neck folds. Its skull is heavy with a basal length above and an occiput above . Its nasal horn is slightly back-curved with a base of about by that rapidly narrows until a smooth, even stem part begins about above base. In captive animals, the horn is frequently worn down to a thick knob. The rhino's single horn is present in both males and females, but not on newborn young. The black horn is pure keratin, like human fingernails, and starts to show after about six years. In most adults, the horn reaches a length of about , but has been recorded up to in length. Among terrestrial land mammals native to Asia, the Indian rhinoceros is second in size only to the Asian elephant. It is also the second-largest living rhinoceros, behind only the white rhinoceros. Males have a head and body length of with a shoulder height of , while females have a head and body length of and a shoulder height of . The male, averaging about is heavier than the female, at an average of about .〔 The rich presence of blood vessels underneath the tissues in folds gives it the pinkish colour. The folds in the skin increase the surface area and help in regulating the body temperature. The thick skin does not protect against bloodsucking ''Tabanus'' flies, leeches and ticks.〔 The largest sized specimens range up to .〔Boitani, L. (1984). ''Simon & Schuster's Guide to Mammals''. Simon & Schuster, Touchstone Books. ISBN 978-0-671-42805-1〕 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「Indian rhinoceros」の詳細全文を読む スポンサード リンク
|