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The European water vole or northern water vole, ''Arvicola amphibius'' (formerly ''A. terrestris''), is a semi-aquatic rodent. It is often informally called the water rat, although it only superficially resembles a true rat. Water voles have rounder noses than rats, deep brown fur, chubby faces and short fuzzy ears; unlike rats their tails, paws and ears are covered with hair. In the wild, on average, water voles only live about five months. Maximum longevity in captivity is 2 and a half years. ==Appearance== Water voles reach in length plus a tail of of this. Adults weights reported are variable. It is possible for large, optimal adults to weigh as much as However, these are peak weights. Elsewhere the mean body mass has been reported as , although this figure includes immature water voles.〔Saucy, F. (1994). ''Density dependence in time series of the fossorial form of the water vole, Arvicola terrestris''. Oikos, 381-392.〕 The minimum weight to successfully breed as well as to survive winter is reportedly in females and in males.〔Yavuz, Güliz, Ercüment Çolak, and Teoman Kankılıç. ''Investigations on the Ecology of Eurasian Water Vole, Arvicola amphibius (Rodentia: Mammalia) in Ankara Province.'' Pakistan Journal of Zoology 45.6 (2013): 1599-1605.〕 As a species the mean body mass is claimed as .〔Morand, S., & Poulin, R. (1998). Density, body mass and parasite species richness of terrestrial mammals. Evolutionary Ecology, 12(6), 717-727.〕 Overall, European water voles are a uniform dark brown colour, with slightly paler coloration on the underside. Their pelage is quite thick and they are furred over their entire body, including their tail, unlike rats. Their dark colour allows them to blend in well in the densely vegetated areas they inhabit.〔Niethammer, J. 1990. ''Water Voles (Genus *Arvicola *)''. Pp. 242-245 in S Parker, ed. Grzimek's Encyclopedia of Mammals, Volume III. NY: McGraw-Hill Publishing Company.〕 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「European water vole」の詳細全文を読む スポンサード リンク
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