Squirrels are rodents, and like all rodents they have four toes on their hand-like front feet and five toes on their hind feet. The hind feet have a distinct heel and offer an important clue for track identification for rodents - the three middle toes of the hind feet are parallel to each other, and noticeably longer than the two side toes. Alaska his home to two tree squirrels, the red squirrel and the northern flying squirrel, and Arctic ground squirrels are the single ground squirrel species.
Squirrels move mostly by bounding - and the hind feet land in front of the front feet. Flying squirrels actually hop; in a hop, the front feet stay in front of the hind feet. Flying squirrels are nocturnal and they're rarely seen, but you may find sign. In winter, you might spot the sitzmark in snow, the impression made by the squirrel's feet and body where it landed. A sitzmark in an open area with tracks leading off is a good indication of a flying squirrel.
A gliding animal like the flying squirrel can be expected to leave intermittent trails, but so does the red squirrel, because its trails are mostly tree to tree. Red squirrels store food in underground caches, and their tracks reveal their routes between holes at the base of trees. They're territorial, so their tracks form a small group of trails as they run repeatedly back and forth between the holes and trees in their home range.