A hold out from the Pleistocene

Long-tailed vole photographed by Jake Kirkland during the Camera Trapping Workshop in July 

The long-tailed vole (Microtus longicaudus) is a nonconformist.

Unlike most other Microtus it is not a highway engineer -- it doesn't seek out lush pastures to make runways, zip back and forth gathering forage, and obsessively trim any intruding plant growth.

It's a vole of mountains, forests, and sometimes sagebrush.

Though it lives where there are plenty of wet grassy meadows, it prefers wooded habitats like this thicket of mountain alder between the Yuba River and red fir forest.

The modus vivendi of the long-tailed vole was shaped by the cool wet weather of the Pleistocene, which  is reflected in its distribution from southern Alaska to Arizona and New Mexico.

That may also explain why it thrives in disturbed areas -- fire, clear-cutting, and surface mining affects vegetation just like earth-moving glaciers.

In the arid lands of the southwest it is holding its own on "sky islands" -- mountaintop habitats that resemble areas farther north.

During the ice age the southwestern part of the US looked more like Canada today, but that started to  change when the glaciers melted.

So the cool breezy heights of the intermontane west are remnants of how it used to be, and refugia for hold-outs from the Pleistocene -- like the long-tailed vole.


References

Wilson, D.E. and S. Ruff (eds). 1999. The Smithsonian Book of North American Mammals. Smithsonian Institution Press, Washington, D.C.

Ingles, L.G. 1965. Mammals of the Pacific States. Stanford University Press, Palo Alto.

Verts, B.J. and L. Carraway. 1998. Land mammals of Oregon. University of California Press,  Berkeley.