After a long absence fishers have returned to our northeastern forests and made themselves completely at home. These medium-sized members of the mustelid family can travel miles in a single day at their habitual loping gait, shown in the photo below (direction of travel toward the upper right). At the lower left you see four separate prints; the sequence, starting at the left, is left front, left rear, right front, right rear. The next set is also made up of four prints, but it looks like just three because the left rear fell mostly on top of the right front. By the way, the arrangement you see on the ground is not the same as the order of footfalls, which is left front, right front, left rear, right rear for both groupings.
The addition of fishers is a benefit for our ecosystems, but aside from that, having fishers in the woods makes for some interesting tracking. If you follow fisher trails you may come upon spots, such as the piece of wood in the next photo, where the snow has been strangely disturbed and smoothed. A fisher came in from the left and rubbed its belly over the wood, depositing chemical signals from the scent glands in its skin. Fishers usually choose protruding objects for marking, and the process can involve some amazing bodily gyrations. Rubs are sometimes topped off with a little urine or scat, and the finished creations serve to communicate territorial claims or availability to potential mates.
Fishers are drawn to trees, and when travelling they often move from one tree to the next to investigate for the presence of squirrels, one of their principal prey items. So it’s no accident that the fisher that made the trail below headed directly to a tree. The animal was travelling at a double-register bound, leaving a string of paired impressions separated by relatively long spaces. A bounding fisher covers the spaces between tracks in graceful arcs and lands on its front feet almost, but not quite, simultaneously. As it lands it draws its body into a tighter curve, and the front feet lift off just as the hind feet come in to land where the front feet were. The animal then takes off from its hind feet in another arcing leap. By bringing the hind feet into the same holes made by the front feet the fisher conserves its energy when travelling in deep snow. Note that one of the impressions leads the other, and that the two hollows are close together and relatively large. Squirrels, and most other animals, also alter their gaits in deep snow for more efficient movement. If a squirrel had bounded toward the same tree its trail would also be a sequence of double impressions, but each hollow would be smaller and the two would be mostly even with each other and more widely separated.
Fishers are expert hunters. It’s rare to find a kill site, but it’s not uncommon to find a trail that reveals a successful hunt. In the photo below the prints of a bounding fisher go from left to right across the middle of the frame. Above each group of tracks you can see a slightly curved line carved into the snow. The fisher was carrying a prey animal in its mouth, probably gripping the back of its victim. Something dangling to the side, a foot or an ear, brushed the snow each time the fisher landed. Such marks can fall outside the trail or within it, but they always occur at regular intervals in synchrony with the predator’s gait. Random gouges made by wind-blown leaves or other objects may fall in or near a trail, but they don’t repeat in synchrony with the track groups the way the marks of a prey item being transported do.
Winter is mating season for fishers, and when a male and female come together the story is recorded in the snow. If you come across a wild-looking collection of tracks like those in the photo below check for size differences. Male fishers are generally almost twice as large as females, and their tracks reflect their greater size. In the photo, male and female tracks are mixed together near the tree, but the smaller tracks of the female can be seen by themselves at the lower left. This female was probably receptive (not always the case) because their prints were mixed together over a wide area.
Looking carefully I found some nice prints, shown in the next photo, which showed the size difference. A small female track lies to the left of a much larger male track, both heading from left to right.
I’ve already mentioned the fisher’s affinity for trees. The animals are excellent climbers, able to scale vertical tree trunks to get into hollows sheltering squirrel nests or attack porcupines clinging to upper branches. A fisher’s rear feet can rotate 180 degrees, allowing it to grip with its rear claws when descending head-first. You may find fisher trails that lead to and end at trees the way squirrel trails often do. And sometimes, if the snow is deep and soft, you might find a place where a fisher skipped the downward climb and leapt from the tree trunk. In the photo below a fisher jumped from a tree outside the frame at the upper right and landed in the upper right quadrant. There’s a rectangular hole made by the fisher’s body with four pits at the corners made by its four legs. To the right of the hole its tail made a curved gouge. Its first bound can be seen in the lower left quadrant.
When trailing fishers you might have to keep at it for a while–it’s amazing how much distance the animals can cover in a single hunting or mate seeking episode. But if you’re persistent you’ll be rewarded with fascinating evidence of of their daily activities.
beautifully detailed prints. In the photo on the right (direction of travel to the right), the right rear track is at the bottom of the frame, and the right front is just above it. The other two prints are at the top, the left rear just behind the left front. The toes and middle pads show up nicely in both front and rear tracks. The heels of the rear prints made impressions, and the paired heel pads of the right front track can also be seen.
arranged almost identically except that the left front track is just below the left rear. There’s a similar amount of detail, with toes and middle pads clearly visible in both front and rear feet and the paired heel pads showing in both front feet. I had hoped that if I found really detailed tracks I would see features that would separate chipmunks and southern flying squirrels, but to my eyes there are no appreciable differences between the tracks in the two photos. The dimensions are similar as well: both sets of prints have a trail width (the distance from the right edge of the right rear print to the left edge of the left rear print) of 2 inches, and the length of the front track is 9/16 inch for the flying squirrel and 5/8 inch for the chipmunk, not significantly different. So how did I know that the tracks in the first photo were made by a southern flying squirrel, while those in the second belonged to a chipmunk?
Southern flying squirrels have flaps of skin (patagia) that connect the front and rear legs all the way out to the ankles, so they move differently from chipmunks (and also from tree squirrels, for that matter). The front tracks of a bounding southern flying squirrel are set almost as wide as the rear, and they are usually in front of, or occasionally between, the rear tracks. Because of the skin flaps, flying squirrels are not as fleet-footed on the ground as other small rodents, so their leaps are shorter. Compare the southern flying squirrel bounding trail in the photo above (traveling from bottom to top) with the next photo of a trail made by a chipmunk (traveling from top to bottom). 
In its normal traveling bound the chipmunk consistently places its rear feet ahead of its front, and its leaps can be much longer than those of the flying squirrel. Of course chipmunks do sometimes make short leaps, and they do sometimes place their front feet between (as in the second photo of the blog) or ahead of the rear. That kind of pattern in a chipmunk trail is an indication of a break in the rhythm, while it falls withing the normal bounding pattern for a southern flying squirrel. (By the way, neither of the bounding photos came from the day I took the close-up shots, but they illustrate the trail patterns I saw that day.)
For an animal the size of a flying squirrel even a few inches of soft snow can be enough to change its gait pattern from its normal bound to a double-register bound like the one in the photo at the right (direction of travel from lower right to upper left). The relative positions of front and hind prints no longer apply, but trail width can still be measured, and this trail had a trail width of 2 1/8 inches, squarely in the range for the southern flying squirrel. A chipmunk trail would have had a similar trail width, but the trail pictured above was made during a long stretch of cold weather. Chipmunks wait out winter’s coldest periods in a state of torpor in their underground refuges, while flying squirrels come out regularly even in frigid temperatures.
he one that first caught my eye was the right rear print that lies off by itself in the lower right part of the photo. The much larger rear print of a gray squirrel lies above it, and at least two other chipmunk tracks are visible among the unrelated disturbances in the upper part of the photo. The chipmunk’s right front print sits in the left part of the frame midway between top and bottom, and its left rear print can be seen above the squirrel track. The left front print isn’t obvious but a few small depressions suggest that it lies above the right front in the upper left quadrant of the photo. The chipmunk was moving toward the right.
so I’ve focused in on them in the photo to the left. The toes and claw marks are visible, four of each in the front track (at the upper left) and five in the rear track (at the lower right). Behind the toes you can see the grouped depressions that make up the middle pads of both the front and rear tracks. For such a small creature those tracks are exquisite.
central three toes lie close together and point forward, while the inner and outer ones sit farther back and are angled to the sides. The four toes of the front prints are spread more or less evenly. The middle pads of both front and rear feet are made up of four depressions, arranged in a crescent in the rear and a more triangular shape in the front. In the front print the heel pads, located just behind the middle pads, show as small paired depressions.
It took perfect mud to register the details in these white-footed mouse tracks (heading toward the top of the photo), but the family resemblance comes through clearly. The numbers and arrangements of the toes are the same, and the middle pads of both front and rear prints are similar to those of the chipmunk and the squirrel. You can even see the heel pads, albeit slightly smeared, in the front tracks!