Natural conundrum

The grass on the hills is run though with these winding trails, all no more than a couple of inches across where the grass has been squashed down. They run along, up and downslope and have occasional 'nodes'.

We could only suspect that they are the trails left by small rodents while the area was snow-covered as they scouted the ground under the snow and built themselves quite extensive runs. They are all recently exposed as the snow cover has melted.