Monday, March 30, 2009

Subnivean Voles

Yesterday we saw the biggest meadow vole ever in our yard. It scurried from the region of our bird feeder, along our house foundation, then behind boards under the deck. Voles are busy throughout the year, and unlike moles and shrews are commonly seen above ground. During winter they are active in the subnivean zone -- the space in and under the snow. After snow melt in spring (right about now) their network of tunnels are clearly visible.

The meadow vole (Microtus pennsylvanicus) is mainly vegetation, favoring grasses, bulbs, tubers, and other plants. Like miniature lawnmowers they clip the vegetation to maintain their tunnels. In winter, moving about in their subnivean tunnels, they sometimes chew the the bark of trees; voles especially like fruit trees. Shrews and moles are insectivores, feeding on grubs and other insects, helping gardeners along the way. Voles are often looked upon more unfavorable since they are rodents and like to eat plants. Yet voles are the primary food for hawks, owls, foxes, and coyotes. When you see a fox pounce in a field or a red-tailed hawk swoop down from a tree, they are most likely catching an unwary vole.

Female voles are territorial and fierce in the defense of their nest. Voles will breed year-round, even in winter if the snow pack is deep. A few winters ago we were playing in the nearby Mitchell field up on Bald Hill Road with our dogs Fargo and Aria. Fargo was fond of pouncing on the ground -whether he actually heard or saw something we were never sure. One morning a small, brown, furry animal popped out of the snow, stood on its hind legs, bared its teeth, and disappeared just as suddenly (think Ewoks in the Return of the Jedi). We were all a bit stunned at this tiny vole defending its spot in the field from a 90-pound yellow lab.

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