I live in Pittsburgh, PA. I used to have chipmunks problem of my yard. I saw chipmunks occasionally on my yard and found holes close to trees and storage. After the snow was completely melting in mid March, I found at least 10 strange open tunnels on my yard. Each one is about 2'-6' long, 1"-2" wide and about 2"-3" deep, and they in curve like guts. See the attached picture. The soil under the grass expose to the air in those grooves. There were very heavy snow falls in Feb. Were those grooves digged by a hungry animals or pests under the snow? In warm days I can see squirrels or chipmunks on yard. I didn't see any foot print on the snow and all those grooves are only in one area about 150 sft. Is it possible cut by the ice? With the deep snow on top for a long time the ice may generate on bottom. I hope besides chipmunks problem, I don't have to face the new problem anymore!