Voles are a rodent. They eat vegetation including grass. You may be noticing tracks in your lawn and large patches of brown. Typically, these areas are fluffed up with loose grass on top. See above image. These areas are not dead but will need some extra attention. You can lightly rake these areas, but do not dig down into the ground to rip out the brown grass. Seeding can help quicken the recovery. It will take until mid-May or later for these areas to recover.
Snow mold is a disease that forms in cool, wet conditions that are often found under snow. Snow mold causes patches of matted over turf in the spring. Often it will look like spider webs on the surface. These areas are also not dead. You should lightly rake these areas and seed to speed up recovery. The recovery will also take until mid-May.
Salt damage occurs from ice melt applied during the winter. Salt damage looks like normal grass but brown. It will not be torn up and typically not matted down. Salt damage is often located next to driveways and sidewalks. Salt damage kills the grass, so seeding or sodding will be needed to repair the area. It is natural to want to repair the area immediately, but soils need to warm substantially to get good establishment of new grass. We recommend watering the area if we do not get adequate rainfall to wash the salt through the soil.