Gray-tailed vole

First collected in 1895, it is endemic to the Willamette Valley, Oregon, and Clark County, Washington, in the Pacific Northwest region of North America.The generic name Microtus derives from the Ancient Greek words μικρός (small) and οὖς (ear).[3] The remaining specimens, collected in McCoy, were part of the US National Museum Biological Survey under C. Hart Merriam.[6] It was classified as a geographic race or subspecies of the montane vole by Hall and Kelson in 1951,[4][6] but laboratory analyses, including electrophoresis and karyotype evaluations, subsequently confirmed that they are two separate species.[4] They can be distinguished by appearance, because Townsend's vole has darker colorings, a longer tail, and differences in the structure of the hard palate.[4] Gray-tailed and montane voles also differ in some aspects of hard palate structure, especially the incisive foramina.[4] Gray-tailed voles are prevalent in agricultural areas: they are found in and around pastures, hayfields, grain fields, and disturbed habitats.[5] Vernon Orlando Bailey describes the Willamette Valley as part of the humid division of the Transition Zone.[14] The account of his journey is relayed by Daniel Giraud Elliot, referring specifically to the terrain inhabited by the gray-tailed vole.The timbered land is covered with forests of yellow pine (Pinus jeffreyi), Douglas fir (Pseudotsuga taxifolia), white oak (Quercus zarryana), etc.The region evidently is Transition in character of its vegetation as shown by the presence of the yellow pine and white oak."[14] Mammals sharing the Transition Zone with the gray-tailed vole include: Roosevelt elk, Columbian black-tailed deer, Columbian white-tailed deer, Washington rabbit, brush rabbit, silver gray squirrel, Douglas's squirrel, Townsend's chipmunk, Douglas's ground squirrel, Oregon flying squirrel, dusky wood rat, ruddy deer mouse, California red-backed mouse, red tree vole, white-footed phenacomys, Townsend's vole, Oregon creeping mouse, mountain beaver (Aplodontia rufa), jumping mice including Zapus princeps and Zapus trinotatus, Camas pocket gopher, Mazama pocket gopher, and northwest coast bobcat (Lynx rufus fasciatus).[13] Birds in the range include: sooty grouse, Oregon ruffed grouse, band-tailed pigeon, California pygmy owl, Harris's woodpecker, northern pileated woodpecker, Lewis's woodpecker, Vaux's swift, Steller's jay, Townsend's warbler, western winter wren, California creeper, Oregon chickadee, chestnut-backed chickadee, wrentit, western golden-crowned kinglet, and black-headed grosbeak.[16] Gray-tailed voles are difficult to capture live in the wild, as they are unlikely to enter enclosure type traps.[18][4] There is not much data available to calculate population density in the field, but studies in more controlled settings yield estimates of around 600 animals per 1 hectare (2.5 acres).