Voles

These fellows look like a fat mouse with half a tail. They're the ones that leave the U shaped trails in the lawn and mulch, after the snow melts. They eat seeds, roots bark etc., in fact many times when people see the bark eaten away from they shrubs and small trees, they blame rabbits when the real culprit is the voles. 

To stop them from destroying your shrubs and saplings spray them with cheap cooking oil and then dust them with hydrated lime. Be generous and re-apply more as needed. If you would like to eliminate as many of these critters as possible, use my "Chipmunk Method", listed on my website. If you use this method and have squirrels in the area, you should add the small adjustment to my method, as follows: Get two 4 inch caps and drill a 1 inch hole near one edge. After baiting the pipe, install both caps with the holes in the same location. Set the pipe down with the holes at ground level and secure it in that position so they have easy access.