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The northwestern salamander (''Ambystoma gracile'') inhabits the northwest Pacific Coast of North America. These fairly large salamanders grow to 8.7 in (220 mm) in length. It is found from southeastern Alaska on May Island, through Washington and Oregon south to the mouth of the Gulala River, Sonoma County, California. It occurs from sea level to the timberline, but not east of the Cascade Divide. Its range includes Vancouver Island in British Columbia and Cypress, Whidbey, Bainbridge, and Vashon Islands in Washington (Snyder 1963). ==Occurrence== The spotted forms occur in the northern portion of its range.〔Petranka 1998; Snyder 1963〕 A dividing line of 51°N latitude has been recognized between the two subspecies, with ''A. g. decorticatum'' occurring north of the line and ''A. g. gracile'' living to the south.〔Snyder 1963〕 Populations with neotenic adults are widespread; the frequency of gilled adults increases with altitude such that adults at low and intermediate altitudes are almost all terrestrial, while adults at very high elevations are mostly neotenic.〔Eagleson 1976〕 An example of a paedomorphic population of the northwestern salamander occurs at Crater Lake, Oregon; the population is syntopic with ''Taricha granulosa''.〔C.M. Hogan, 2008〕 Terrestrial adults live in mesic habitats ranging from grasslands to mesophytic forests. Terrestrial adults are mostly fossorial, and are usually active on the surface only during fall rains and spring migrations to their aquatic breeding sites. However, they can sometimes be found under logs and other surface debris outside of the breeding season.〔Petranka 1998〕〔Efford and Mathias 1969〕 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「Northwestern salamander」の詳細全文を読む スポンサード リンク
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