During winters like we have just experienced, voles spend much of their time traveling along under the snow. Unfortunately, as they travel back and forth deep in the grass, they leave trails that are clearly evident in spring.
Voles are primarily vegetarians, living on seeds, bark and the occasional insect.
That is what they are looking for in your lawn. You may notice lots of trails around bird feeders or brush piles. Voles stay active year-round, but they are shy creatures and are seldom noticed. The good news is that the damage voles do to lawns typically goes away as the grasses become more active. You may need to rake out excess dead material, but if your lawn is healthy, the grass will fill back in without any further work on your part.