They were left by a pair of Red Squirrels mating. The first image shows where they mated and the second image shows where they moved away together and then split off in separate directions.
Squirrels leave a set of four prints in each group on a trail, that fill a square no more than 150 mm. For anyone not familiar with their appearance the third image shows such a group. The footprints widest apart are the hind feet and the two closer together are the fore feet. The Squirrel is moving in the direction of the hind feet because when the Squirrel hits the ground it lands on its fore feet and brings its hind feet in front for the next jump.
