The puzzling grass mystery

The snow melted at last and this serpentine appeared. About 4 feet long, a couple of inches deep and winding its way down the hill and under the fence, I thought it was erosion from the melt. Another clue came to light when I was digging in my flower beds. At the fence line was a hole in the dirt about an inch in diameter. While consulting Larry Sager's web site for an unrelated bug issue I came across an article about pesky little critters that are not dormant in the winter. They burrow along the ground under the snow and can wreck havoc in your yard by eating the bark around trees, etc. Hum, perhaps my interesting erosion could use further inspection. Facinating...yep, each little branch-off is matted down and kind of bowl shaped. Puts me in the mind of Marshmellow our hamster and his nesting habits. Hum, droppings in each nest area? Yes! The mystery is solved. Our backyard was covertly being used as a Mouse Marriot.