fisher – Linda J. Spielman

What Do Claw Marks Tell Us?

Claws, like hair and feathers, are made up of proteins called keratins and are characteristic of mammals, reptiles, and birds. In mammals claws evolved into a variety of forms, including fingernails and hooves, but it’s the hard, tapered appendages we consider true claws that are the focus of this post. The marks they make in tracks can tell us a lot about the lifestyles and behaviors of their owners.

The gray squirrel right and left front tracks in the photo below (direction of travel toward the left) show conspicuous claw marks. The tiny pricks made by the claws tell us they’re quite sharp, as we would expect in an acrobatic climber like a squirrel. Behind each claw mark is a toe impression, and behind the toes there is a tight group of middle pads. Two heel pads lie at the back end of the track. The combination of sharp claws and protruding toe, middle, and heel pads is what gives the gray squirrel its excellent climbing ability.

There’s another interesting feature in these prints: on the inner side of each set of heel pads there’s an impression of the vestigial fifth toe, something not often seen.

Porcupines, although not as graceful as squirrels, are also good climbers, and their feet are equipped with impressive claws. The photo below shows three sets of front and rear porcupine tracks, all heading toward the upper left. At the lower right you see a left rear track with a left front track above and to the left of it. Almost directly above those there’s a right rear print with a right front print above it. At the upper left there’s another pair of left front and rear prints. In each set the hind track is the larger of the two. The spaces between the claw marks and the oblong sole areas appear at first glance to be unoccupied– porcupine toes frequently don’t register in tracks. But if you look closely you can see faint toe impressions in the front tracks. You’ll notice that the claws of the front feet make marks a little farther forward compared to those of the rear tracks.

Fishers are also good climbers, so it’s not surprising that their tracks show the marks of sharp claws. The next photo shows the left front print of a fisher, oriented toward the left, with narrow claw gouges at the tips of the toes. But fishers don’t just use their claws for climbing–these animals are predators, and their sharp claws are essential for catching and subduing prey. The five toes, each tipped with a claw, make a lopsided crescent, and the middle pad and heel area make up the rest of the print.

Claws also come in handy for digging. Striped skunk tracks, like the left front print shown below, have prominent claw marks which extend well ahead of the toes. The claw impressions are more robust the ones in the first photo–not very good for climbing but hefty enough to make good digging tools.

The presence or absence of claw marks is sometimes considered diagnostic for track identification, but, like many aspects of tracking it’s not an absolute. The next photo shows front (lower left) and rear (upper right) prints of a gray fox, direction of travel from right to left. Gray foxes have semi-retractable claws, and prints without any claw marks, like the ones below, are common. The same goes for bobcats and house cats, which have retractable claws.

But if a gray fox needs extra grip it can extend its claws, making tracks that look like the ones in the next photo. The larger front track is on the right and the smaller hind track is on the left, and the direction of travel is toward the top. By extending its claws the animal was able to gain more purchase in the soft mud. The marks vary in thickness because of the varying depth of the tracks and movement of the toes, but the rear track shows slender grooves which are consistent with claws that are very sharp. Although not as arboreal as squirrels and fishers, gray foxes are good climbers. Their sharp claws assist not only in climbing but also in capturing prey. Claw marks are sometimes seen in feline tracks under similar conditions.

Animals with retractable and semi-retractable claws are able to draw their claws completely or partially inside their toes. But all animals, even those with robust claws, can control their position by flexing or extending the toes. The front track in the next photo (made by a coyote walking toward the left) shows beautiful impressions of the toes and the middle pad, but no claw marks.

A coyote moving at a side trot toward the right made the front (upper left) and hind (lower right) tracks in the photo below. Claw marks lie ahead of all four toes of the front track, and ahead of the leading toes of the hind track. The depths of the tracks made at the walk and at the trot are similar, but the toes were flexed enough at the faster gait to make most of the claws dig into the sand.

Partial sets of claw marks often occur in wild canines. The coyote front (left) and hind (right) prints (direction of travel toward the left) in the next photo show tiny pricks ahead of the leading toes, indicating that just the tips of the two leading claws in each print touched down.

Dog tracks, like the front print (direction of travel toward the right) shown below, are more likely to have blunt, robust claw marks that routinely show in tracks, even when walking or at rest. In the photo the claw marks have rounded leading edges due to their wider tips. In addition to the blunt claw marks, the more rounded overall shape and the outward angles of the inner and outer toes are indicators of domestic dog rather than coyote or fox.

To further drive home this point, contrast the dog print above with the red fox front track (heading toward the right) in the next photo. The red fox claw marks are slender and pointed, and they’re oriented straight ahead–or even slightly inward on the leading toes. The claw marks of the inner and outer toes are tucked tightly against the sides of the leading toes. It would be rare for a dog track to show this kind of compactness in soft mud.

There’s a explanation for the differences between the claws of dogs and wild canines. Coyotes and foxes spend their lives on the move, so their claws are constantly shortened and shaped natural abrasion. Dogs spend more time resting and less time travelling over the landscape, so their claws are not naturally worn down and must be trimmed manually. Consequently, the claws of dogs are usually longer and blunter than the claws of coyotes and foxes. Similarly, the feet of wild canines have excellent muscle tone, and this creates tracks that are tight and compact. The less fit feet of dogs spread out more and leave tracks in which the toes and claws often angle outward.

Cottontail rabbits and snowshoe hares have thick fur on the bottoms of their feet, so claw marks don’t usually show in tracks. In the photo of snowshoe hare tracks below, right and left hind tracks (oriented to the right) take up the center, a smaller left front track heading toward the left lies on the left, and part of a left hind track, also heading toward the left, can be seen at the upper right. The fur thins out somewhat in the summer, but even in July when these tracks were photographed, it was thick enough to muffle the claw marks in the rear tracks. They do show just a little at the tips of the toes in the front track.

But rabbit and hare claws are surprisingly sharp. Rabbits defend themselves with strong kicks, and the claws can inflict real damage. Claws also help the animals to grip the ground in the weaving and dodging escape maneuvers that help them evade predators. In the next photo you see two rear prints made by a leaping cottontail rabbit. The claws dug in deeply to give the rabbit a powerful take-off.

Why claw marks appear the way they do, why they’re present or missing, how they’re used by different animals–these are all questions that deserve our attention. Every track we find presents opportunities to explore this topic further.

Leafy Disturbances

Leaves: at this time of year the woody plants are bare of leaves, and last summer’s weather-beaten foliage covers the forest floor in all directions. Is there anything we can learn about the lives of animals from this seemingly mute carpet? The answer is a resounding yes! In the photo below we see a well-used deer trail. The dry, undisturbed leaves on either side contrast with the darker, disturbed texture in the trail. Even when it’s compressed, deciduous leaf litter is harder to walk on than pre-existing trails, so deer often create runs between bedding and feeding areas.

It’s not as easy to detect deer tracks if they’re not on well used trails. The next photo shows an individual deer track, orientated toward the right. The hoof pressed down into the leaf litter and the outer rims left curved depressions on the top layer of leaves. But if you just were hiking along, would this print attract your attention? Probably not. To find individual deer prints it helps to study areas where the animals have spread out from obvious trails into feeding or bedding areas.

Fall is mating season for whitetail deer, and back then the males were spending most of their time trying to attract females. Bucks made scrapes on the ground and left their scent at the site by depositing urine in the scrape. They also left their olfactory signature by rubbing their foreheads and faces on overhanging branches. The signs of these mating rituals often last into spring. In the photo below (taken a few weeks ago) you can see a scrape just below an overhanging branch still bearing a few leaves.

A close-up of the scrape has a weathered look but still shows signs of deliberate disturbance.

Deer aren’t the only animals that clear leaves. Turkeys sweep leaves aside as they search for insects and other edible tidbits beneath the leaf litter. In the photo below debris lies on top of the leaves at the bottom and lower right, showing that the turkey stood facing the upper left as it tossed the leaves backward. By using both of its feet the bird created a roughly triangular cleared patch.

But turkey feeding scrapes aren’t always triangular. In the next photo you see one that’s more irregularly shaped. There can be a lot of variation in the shape of the cleared area and the amount of displaced debris.

Buck scrapes and turkey scrapes can be quite similar, but there are ways to tell them apart. First, deer mate exclusively in the fall, so buck scrapes discovered in the spring will show signs of several months of weathering. Turkeys make feeding scrapes in all seasons, so at this time of year they range from fresh to weathered in appearance. Both of the turkey scrapes shown above are relatively recent, while the buck scrape in the preceding photos had been created about five months earlier.

Another difference between deer and turkey scrapes is their distribution. An individual buck usually makes a limited number of scrapes, almost always associated with overhanging branches, in an area he is patrolling. Turkeys usually feed in groups, and they go wherever the eating is good, so turkey scrapes are likely to be more numerous and scattered more irregularly.

Squirrels also disturb leaves. The next image shows a cleared area at the base of a tree. When I found this I wondered if it was the result of frequent use as a take-off spot by squirrels.

To check, I looked at the bark above the cleared spot (shown in the next photo) and saw that the moss and outer bark had indeed been abraded. I’m attributing this to squirrels, the most common tree climbers, but I can’t entirely eliminate the possibility that it was a raccoon. Other climbing animals are unlikely because they are less likely to climb one tree repeatedly.

Like turkeys, squirrels search for buried nuts and insects, especially in the spring when stored food supplies may have run out. Both red and gray squirrels obtain these items by digging small holes. In the next photo you see a dig made by a squirrel. Debris from the hole can be seen below and to the right, so the squirrel must have been facing the upper left as it dug.

Here’s another image of a squirrel dig, this time in a layer of pine needles. If the buried object was a nut or acorn the hole usually retains a firm impression of the object. In the digs shown in both photos the bottoms of the holes were loose and irregularly shaped, so the food items were probably insects.

Deer also dig at leaf litter in search of nuts and acorns. White oak acorns are consumed by many animals and birds, so they disappear soon after they drop. The higher levels of tannins in red oak acorns make them less palatable, so they mostly lie uneaten on the ground until soaking rains leach the tannins out. But once they’re more digestible red oak acorns are sought out by many animals, including deer. Where red oaks are the predominant oak species, areas of churned up leaves like those in the next photo (taken last December) can be found in late fall and winter. You can see fragments of acorn shells and meats the deer dropped as they chewed.

If there’s a heavy, wet snowpack in late winter that compresses the leaves, deer feeding areas may be hard to recognize by the time spring arrives. But after winters with little snow like the one we just had, the signs are evident. A few weeks ago I went back to the area where the photo above was taken to see what it looked like. In the photograph below you can see that the leaves still lie loosely in piles and windrows. There aren’t any acorn fragments to be seen–if the deer weren’t interested enough to gather them up they would have been eaten by other animals like squirrels, mice, raccoons, crows, foxes, or even fishers. You’re not likely to find fresh evidence of deer foraging for acorns because the fall crop has been mostly consumed.

Areas where the leaves were not churned up by deer (or turkeys) look very different. Fall rains and the little snow we did have were enough to flatten autumn’s leaf fall into a smooth-looking mat like the one pictured below.

Some places cleared of leaves are more mysterious . Is this the work of a deer? Or a turkey? Actually, neither.

When you see the same spot in the more distant shot shown below, you’ll see what moved the leaves: water. The close-up above comes from the area in the lower left quadrant of the distance shot below. During a heavy rain, water flowed down the trail on the right and spilled over the edge into the leaves. As the water rushed downhill it made channels in the leaves and moved them into heaps along the edges.

Leaves have stories to tell, and to understand them we need to get familiar with undisturbed leaf litter. Once we begin to pay attention to leaves, and to places that depart from the unaltered baseline, we’ll have a whole new window into the lives of animals.

When Animals Break the Rules

Bobcats walk in direct register. Deer walk in indirect register. Red foxes have a bar in the middle pad of the front foot but not in the rear foot. Fishers move at a lope or bound. Cats have four toes. These and other statements are the received wisdom of the tracking literature. But are they always true? As we’ll see in the following paragraphs, there are exceptions to even these seeming inviolable maxims.

Let’s start with walking deer. They do indeed place their feet in indirect register most of the time. The photo below shows tracks made by a deer walking in indirect register toward the upper right. At the lower left you see a left rear print partly superimposed on the left front print. Roughly in the center of the photo there’s a right front track with a right rear track partly on top but a little behind. At the upper right the left rear track sits a little behind and slightly to the inside of the left front track. The zig-zag pattern is the signature of the walk, and each set of impressions is made up of the front and rear prints from the same side. It’s the partial superimposition of the two prints that makes it an indirect register walk.

Direct registration occurs when the rear print is perfectly superimposed on the front print. As the next photo (the trail of a white-tail deer walking from right to left) shows, this does occur, especially in younger deer.

As this close-up (from a different trail from the one shown above) shows, direct registration makes it hard to tell if the track was made by two feet or just one. Among all the deer trails you see, there are bound to be a few that show direct registration.

Bobcats are said to walk in direct register, but again this is not an absolute. The bobcat trail in the photo below (direction of travel from left to right) is in very obvious indirect register. The zig-zag pattern indicates the walk (and as a side note, you can see how much narrower it is than the zig-zag of the walking deer). In each set of two prints the hind print falls partially but not perfectly on the front print.

In case you have some doubts, a close-up from a different part of the same trail will convince you that this is indeed a bobcat trail.

Was the bobcat distracted? Or tired? We’ll never know. Later in the same trail the animal switched to an overstep walk, a gait that’s often seen in bobcats, so its overall behavior didn’t throw up any red flags.

The next photo shows a direct register trail made by a bobcat walking toward the upper left. In each impression you see what appears to be a single track, but is actually two tracks, the rear print superimposed on the front print. And here’s another interesting aside: The concave hollows around the tracks are not connected to registration, but were instead made by the thick fur covering and surrounding the bobcat’s feet. They’re known as hair halos.

Staying with felines for the moment let’s look at toes, which are supposed to be four in number (counting those which normally touch down) in both wild felines and domestic cats. In the next photo you see some tracks which are clearly feline, but don’t fit the four-toed paradigm. My friend Ben Altman has two house cats, both of which have feet with more than the standard four toes. This is called polydactyly and it’s caused by genetic mutations. It’s not uncommon in domestic cats but is rare in wild felines.

We’re told that fishers prefer to move at a lope or a bound but this, too, is not always the case. In the next photo you see a fisher trail going from lower left to upper right and a red fox trail moving from bottom to top. The fox is travelling at a lope, a gait similar to the habitual gait of a fisher. But what’s the fisher doing? Definitely not the typical lope or bound. Because the front tracks of the fisher are larger than the hind tracks we can work out what the gait is. At the very lower left in the fisher trail there’s a right rear print, and the sequence of the next eight tracks (up until the pattern changes at the upper right), is: right front, left front, right rear, left rear, right front, left front, right rear, left rear. This extended pattern shows that the fisher was speeding along at a flat-out gallop. Fishers don’t often do this, but they obviously can. Something alarming must have pushed the animal into unusual speed.

One of the absolute statements we often hear has to do with red fox tracks. The going wisdom is that there’s a bar or crescent shaped depression in the middle pad of the front track, but not in the rear track. A ridge of horny skin that protrudes through the hairy covering of the pad is the source of the bar, and it’s supposed to be absent from the middle pad of the hind foot. Here’s what we’re accustomed to observing–notice the bar in the front middle pad (on the left) and the absence of the bar in the rear middle pad (on the right).

But on rare occasions we see red fox tracks with a bar in the middle pad of both the front and rear prints. Here’s one example. The front track is at the lower right and the rear track is at the upper left.

Just so you don’t think this is a one-off, here’s another example. The front print is in the upper right and the rear print, with a reduced but visible bar, is at the lower left. (The carboard square in the upper left is one inch on a side.)

Raccoon trails are a common find, and the next photo shows the way a raccoon pace-walking trail is supposed to look. What we expect to see is sets of two prints, each set a front from one side and a rear from the other side. In the photo the direction of travel is from lower left to upper right, and the hind prints are larger than the front prints. Starting at the lower left, the first set is left front with right rear, the second is right front with left rear, the third is left front with right rear, and the last is right front with left rear.

The raccoon which made the trail in the next photo (direction of travel lower left to upper right) appears to be in serious violation of the rules of tracking. Instead of alternating front and rear tracks there are two sets with left rear and right front, then two sets with left front and right rear, and again two sets with left rear and right front. Can a raccoon even do that?

The answer is, no, a raccoon can’t do that. But two raccoons, one following close behind the other, can do that. It you focus on every other set of two you’ll see a normal raccoon pace-walk trail. So what appeared to be an impossible situation turns out to be a perfectly normal, albeit unusual, event.

We need to learn what’s most common in animal tracks and trails, but we also need to think out of the box when faced with uncommon track and trail patterns. Whether it’s two animals conspiring to create a confusing trail, or one animal with an unusual track or behavior, nature can always throw up something we’ve never seen before. It may take days, weeks, or even months to understand what we saw, but that’s part of the excitement of tracking. It’s why we keep coming back for more.

Bringing Home Dinner

When we come upon a site where a predator killed a prey animal, we’re able to see in detail the interaction between hunter and hunted. But finding such a site is a rare. It’s more common to find the trail of a successful hunter carrying its prey, and this also makes for fascinating study. To understand such a trail we must pick out the crucial evidence from the other disturbances that occur in animal trails. Let’s start with a fairly straightforward example.

In the photo below you see a trail made by a fisher loping from left to right. There are three typical fisher track groups, each group a place where the fisher landed and then took off. Above each track group you can see a curving gouge in the snow made by something the fisher was carrying. But what exactly was being carried? Could it have been a stick? Not likely, based on the length of the trail involved (it went on for quite a distance) and the consistency of the patterns. There’s also the fact that the marks are curved, suggesting that the item being carried was swinging slightly. (If you visit a place where dogs have been playing with sticks you’ll see how different it looks when a stick is being carried.) The predator would have been gripping the body of its prize, and something that extended to the side would have touched the snow at each landing. The curving marks are actually made up of two parallel lines, and these lines seem too widely separated to be claw marks from a dangling foot. Their size and positioning do seem about right for the tips of wing feathers, suggesting it was a bird. If it was a bird it couldn’t have been large, since it only touched the snow at the low points in the fisher’s bounding gait. A turkey would be much too big, and even a grouse would probably have left more traces in the snow. Perhaps it was something the size of a blue jay or a junco.

A short-tailed weasel bounding from upper left to lower right made the trail in the next photo. The trail consists of paired track impressions, a common pattern for small mustelids. To the left of each set of weasel prints there’s a thin, slightly curved line in the snow. There’s also a shorter and wider mark just ahead of the weasel tracks. The thin lines are the right size for a tail, and the wider depressions could have been a foot. Given the small size of a short-tailed weasel, it’s likely that the predator was carrying something equally small. A white-footed mouse seems unlikely, because its long tail would have made a longer stroke in the snow. My guess is either a meadow vole or a woodland vole.

The next photo shows the tracks of a fisher loping from right to left, and just below the tracks you see a wide groove. Below that groove you can see several lighter lines. These finer marks aren’t completely parallel with the deeper groove, so the deep groove and the fine lines must have come from separate body parts. The wider groove seems too deep and even to be something as light as a feather–was it a tail or perhaps a thickly furred foot? The finer lines could be the marks of dragging claws. This example is less clear than the two preceding ones, but I’m inclined to think the prey item was a mammal, perhaps a rabbit.

Now to some examples of marks that we often find in animal trails that don’t indicate dragging parts of a prey animal. In the next photo you see the trail of a long-tailed weasel bounding from bottom to top. There are grooves behind each landing spot, but they weren’t made by something being carried; the marks were made by the animal’s tail. Each time the weasel took off for the next bound its body sank into the snow, and the tail left a tapered groove. Tail marks are always connected to body impressions rather than being off to the side of the tracks as they are in the three preceding photos.

Here’s another example of potentially confusing disturbances that are not indicative of something being carried. The next photo shows the trail of a fisher walking from the lower right to the upper left. The fisher dragged the tips of its feet through the snow with each step. Notice that the drag marks are within the trail rather than to the side, and each drag mark extends completely or partially between two tracks.

Drag marks aren’t always as obvious as the ones shown above. In the next photo you see the trail of a coyote walking from top to bottom. In the lowest part of the photo there’s a thin line that was made by a single claw. There are wider gouges above that made by the rounded tips of the feet. But again the grooves lie within the trail width and always connect to tracks.

In the next photo we see what at first glance looks like the trail of some kind of otherworldly creature. It’s actually several coyote trails moving from left to right on a frozen waterway. To sort this out we need to focus in on the trail of each individual animal. The central part of the sequence draws our eye first: There’s an wavy drag mark that seems connected with the series of tracks in the center. If we look at just those tracks we see that they were made by a walking coyote. The drag mark seems to touch the prints, but toward the right it swings to the side and misses the tracks. This tells us that it’s not a foot drag but something that’s being carried. Above the central area there’s a similar string of tracks, and if we concentrate on those we see that they were made by another walking coyote. A third track sequence which lies below was made by yet another walking coyote. The outer trails are close to, but not on top of, the central trail, so there must have been two animals following close behind the one with the food item.

This scenario is supported by the next photo, which was taken in a place where the coyotes slowed down to go through a culvert. The tracks are closer together and the drag mark is more irregular. The drag mark touches one coyote print but misses the others, so it wasn’t made by the coyote’s feet. It’s definitely evidence of something being carried.

As to what was being carried, we can say it was a medium-sized object with a blunt projecting part and enough weight to make a deep groove in the snow. Claws would be thinner, an animal’s nose would be wider, an ear would be softer, and a tail would be fluffier and lighter. That would seem to eliminate all the medium-sized, winter-active animals in our region. But there’s another possibility: the detached body part of a deer with a protruding bone. The area where I found these tracks is a popular spot for hunters, and in mid-December, when I took the photos, coyotes would still have been scavenging on deer carcasses.

I’ll never know for sure, but a deer part is a reasonable conjecture, and conjecture is often what we’re left with when we attempt to understand the trail of a predators carrying dinner. Even without definite conclusions, the process of sorting out the details can be satisfying in itself.

Zig-Zags

In past posts I’ve used the term zig-zag to describe certain track patterns. In this article I’d like to delve more deeply into how zig-zags arise and what they can tell us about the animals that make them. When we humans walk in a relaxed, natural manner we place our feet in a zig-zag pattern because each foot falls to its own side of the line made by our moving center of gravity, the center line of the trail. It’s easy to verify this: Just walk naturally in snow or mud or on a dry surface with wet feet and then look at your tracks. The same logic applies to birds, so we often see patterns like the one in the next photo, made by a turkey walking from left to right. Each print angles inward, which helps to distinguish right from left. The sequence, starting at the left, is right, left, right, left, right.

Two legged zig-zags are pretty straightforward, but four-footed animals also create zig-zags, and it’s not as easy to understand how a four-footed animal can do that. Watching animals helps, but it’s hard to follow foot placement when animals are moving in real time. Fortunately for us twenty-first century trackers, there’s a tool that can bridge the gap–the internet. So let’s take a look at a video of a horse. If you click on this link: Bing Videos, then click on horses walking youtube and start the video, you’ll see a horse walking in slow motion. Notice that as each front foot leaves the ground the rear foot on the same side comes down in the spot just vacated by the front foot. The video doesn’t show the pattern on the ground, but it’s easy to see how the horse leaves a series of double impressions, each one a front track overlaid by a rear track. And since the feet on each side fall to their own side of the center line, the overall pattern is a zig-zag. The trail in the next photo, made by a deer walking from bottom to top, is a good example of a zig-zag made by a four-footed animal.

But all zig-zags aren’t the same. The physical characteristics of animals vary, and this affects the kinds of patterns they leave when they walk. There are also different types of walks, with differing relative placement of the front and rear tracks. In the photo above the walk is an almost perfect direct register gait, meaning that the rear feet fell almost exactly on top of the corresponding front tracks. The next photo shows tracks made by a woodchuck walking from lower left to upper right (and just below the second impression, tracks of a squirrel bounding toward the bottom). The trail is more variable but the tracks are mostly in indirect register, meaning that the rear tracks fell partly but not completely on top of the corresponding front tracks. Starting at the lower left the track sequence for the woodchuck is: right rear on right front, left rear on left front, right rear, right front, left rear on left front. Even in this more irregular trail the zig-zag is apparent.

The width of the zig-zag, known among trackers as trail width, varies from one species of animal to another. To measure trail width, find a relatively straight part of the trail and imagine or draw out two parallel straight lines that just touch the outsides of the alternate sets of tracks. Then measure the perpendicular distance between the lines. This is diagrammed in the next photo of the indirect register track pattern made by a walking opossum heading toward the upper right.

In the next photo you see a trail made by a gray fox walking from right to left. The trail has a different look from the opossum and woodchuck trails, both because of its narrower width and also because the fox’s step lengths are longer. But the zig-zag is still apparent. Trail widths, combined with step length, can be helpful in identification, since chunky animals like woodchucks and possums make wider trails and take shorter steps than slimmer, longer-legged animals do. And trail widths are especially important when you’re considering animals with similar step lengths. For example, trail widths for a walking coyote are generally between 4 and 5 inches while trail widths for deer moving at a walk range from 5 to 10 inches. Even when the tracks are degraded or obscured by collapsing snow it’s usually possible to differentiate between a coyote trail and a deer trail.

Animals find it harder to move in deep snow, but when they’re walking their trails still show the zig-zag pattern. In the photo below a red fox walked from bottom to top leaving a zig-zag arrangement of deep holes in the snow.

All of the gaits discussed above (and the one the horse was doing in the video) fit into what I call the regular walk–also called the diagonal walk in the tracking literature. But that’s not the only kind of walk animals can do. A common variant is the overstep walk. To see a dog doing the overstep walk click on this link: Bing Videos and then click on dog gaits youtube and start the video. The recording shows a dog walking at actual speed followed by the same sequence in slow motion. If you keep your eye on the spot just vacated by a front foot you’ll see the corresponding rear foot come down a little past it. (This video also does a nice job with the amble, equivalent to the pace-walk of the raccoon, and the trot.)

The interesting thing about the overstep walk is that the pattern of tracks on the ground also makes a zig-zag, but the points of the zig-zag consist of sets of two prints, front and rear from the same side, rather than the impressions of two superimposed tracks. In the next photo you see an overstep pattern made by a house cat moving from lower right to upper left. Because a cat’s front tracks are wider and shorter than the rear ones we can see that in each set the front track is behind the rear. The sequence, starting at the lower right, is: right front, right rear, left front, left rear, right front, right rear. Among animals that are habitual walkers, overstep walks are common.

Another variation you’ll come across is the understep walk. The next photo shows the trail of an opossum doing an understep walk, heading from the lower left to the upper right. Again, the prints are arranged in sets of two, each set the front and rear from the same side. In each pair the hand-like hind track, with its thumb pointing inward, lies behind the front track with its more evenly spread toes.

We sometimes find zig-zag walking patterns in the trails of animals that aren’t habitual walkers. Fishers move mostly in bounds or lopes, but they walk when extra caution is needed or when the footing isn’t secure. The trail in the photo below was made by a fisher walking, mostly in direct register, from lower right to upper left.

Walking trails are less common for minks than for fishers, and for minks it seems to be mostly about the animal’s dislike of unstable surfaces. In the next photo a mink walked from right to left through mud (looking pretty dry in the photo but probably much wetter and slipperier when the tracks were made), leaving sets of paired tracks. But which walk is this, overstep or understep? We can tell because the middle toe in the mink’s hind print usually angles a little to the outside. So the sequence, starting at the right, is: left rear, left front, right rear, right front, left rear, left front, right rear, right front, and this is an understep walk.

White-footed mice are even less likely to walk than minks, but the next image attests to the fact that they do it on rare occasions. A white-footed mouse walked from bottom to top, leaving sets of paired tracks. The four-toed front prints lie behind the five-toed rear prints in each set, so the mouse was doing an overstep walk. The trail both before and after the walking part was on drier footing with normal mouse bounding patterns, so it was the wet mud that made the mouse shift to a walk.

Many animals get around mostly at a walk, and zig-zags abound in the tracking world. The details of the patterns can tell us a lot about the nature of the track maker. But the sight of a zig-zag for an animal whose default gait is not the walk is an even more compelling call to investigate. In addition to their help in species identification, zig-zags can tell us how animals interact with each other and with their surroundings. In this post we’ve only made a start. There are other kinds of zig-zags, and even patterns that look like zig-zags but aren’t. I’ll keep these topics for a future article. In the meantime, follow the zig-zags wherever they lead.

Gray Fox Affairs

It’s been a strange winter. In my neck of the woods we had some significant snow early in the season, but no big storms since then. Temperatures have been up and down (more up than down), and with all the melting, the snow we do have has consolidated into a dense, icy layer. Much of the time the conditions have been terrible for tracking, but every once in a while something wonderful has happened: warmth and liquid precipitation have been followed by dropping temperatures and a change from rain to snow. When this happens, snow that falls while the air is still relatively warm becomes bonded to the crust. As the temperature drops and additional snow falls, it forms a soft layer on top. The result is a non-slip and easily navigable surface that is a perfect medium for recording tracks.

A few days ago I encountered just such conditions: an icy base covered by a thin layer of soft snow. I was in an extensive natural area, and both the forest road I was following and the surrounding landscape offered beautiful tracking conditions. Animals of all sorts had been moving easily over the snow, and there were tracks everywhere. I found myself following the trail of a gray fox. The animal went for quite a distance at an easy trot, but then it did something that was quite puzzling.

The photo below shows the fox trail as it goes from upper left to lower right. (You can also see a coyote trail to the right of the fox trail, and a mountain bike trail to the right of that.) As it entered the frame the fox was walking (the first three tracks at the upper left). In the next section (between the last walking step and the edge of the tree shadow) the pattern was very different, and following that the trail looks unlike either of the previous sections. I wanted to know what was going on and why the middle section looked so different.

In a situation like this the first thing to do is identify each track. The zig-zag of the walking section helps us to tell right and left, and the fact that the front foot is larger than the hind foot distinguishes front from rear. The next photo shows a gray fox front print on the left and a gray fox rear print on the right. You can see the difference in overall size and also the difference in the sizes of the middle pads.

The photo below shows just the puzzling middle section, and if you compare photos you’ll see that the front and rear in the photo above are actually the first two tracks in the middle section. It’s pretty clear that the first four prints in the photo below are left front, left rear, right front, right rear. After that it gets harder. The track just above the right rear is smaller than the one to its right, so those two prints must be left hind, left front. Three tracks from the right side come next, and it looks to me like the sequence is right rear, right front, right rear. The final two before the tree shadow are the left front and the left rear, and at the edge of the tree shadow there’s a right front with a right rear partially superimposed on it.

In the next photo I’ve added labels showing my take on right/left and front/rear. If we start at the beginning of the whole sequence, the animal was trotting (those tracks aren’t seen in the photos) and then slowed down to a walk (the first three tracks in the distance shot). The next section shows that the fox slowed even more to an overstep walk (the first four prints in the photo below), then slowed even more to an understep walk. There’s an extra right hind that’s puzzling, but I’m guessing the fox just repositioned its right hind foot. Then the overstep walk reappears after which the fox picked up the trot (the two impressions at the lower right in the first photo). Notice that the step lengths in the overstep part are shorter than the regular walk steps that preceeded them, and the step lengths in the understep part are shorter yet.

That analysis was rather involved, but it leads to a picture of what the fox actually did. As it trotted along something it detected made it slow down, first to a walk and then almost but not quite to a standstill. It was probably sniffing and listening intently as it moved very slowly. Once the animal concluded that it was okay to move on, it resumed its journey at a trot. It’s impossible, without more evidence, to know what caused the fox to react the way it did. It may have been a threat, but it could also have been something that interested it for a different reason. It is, after all, mating season for wild canines.

And the fox I was following was definitely tuned in to mating season. Farther on I found a spot (shown in the next photo) where the animal had detoured to urinate on a small spruce branch. If you look in the center of the frame you’ll see a squiggle of urine that runs horizontally from the upper edge of the spruce branch. Because the urine wasn’t squirted out the side of the tracks we know this was a female. She would have lifter one hind leg forward and supported herself on the other hind leg (plus two front legs) as she urinated. The relative depths of the tracks tell us that the supporting rear foot was the left. Its track is in the prominent double impression above and to the left of the urine.

I’ll never know what made the gray fox slow down and leave the pattern discussed in the beginning of this article. It could have been a threat–there was certainly a coyote in the neighborhood, or it could have been the mountain biker. A fisher (whose tracks I also found on that day) would have made the gray fox nervous. And there were red fox trails as well. But the trail shown in the photos above doesn’t suggest alarm so much as cautious interest. The fox didn’t change direction but just continued on. Was it another gray fox, one she was familiar with, or one she had mated with in a previous year? We have a small part of the whole story, and we can only speculate about the rest, but it’s fascinating just as it is.

When Trails Cross

Was the fox afraid of the fisher? Did the coyote chase the rabbit? Questions like these often come up when we find animal trails that intersect. And as always, the tracks tell the story. In the photo below a coyote trotted along a forest road, the direction of travel from upper left to lower right. A rabbit bounded across the road, leaving a trail heading from right to left. Both trails had been made early on a cold morning, and I came upon them not long afterwards. Neither trail showed any changes in pattern or speed in the vicinity of the intersection (although the rabbit took a few slow hops as it entered the road). The tracks in the photo tell us that whichever animal came second, it wasn’t alarmed or excited by the trail it was crossing.

Here’s another example: A coyote had trotted from upper right to lower left, and at least a day later a fisher loped from lower right to upper left across the coyote’s trail. The unchanging pattern of the fisher trail tells us that it had no apparent reaction to the older coyote trail.

In the next photo you see another instance of a fisher crossing a coyote trail. The coyote was trotting towards the upper right, and the fisher loped from right to left. But this time the tracks near the intersection reveal a definite reaction on the part of the fisher. The change in rhythm and the extra tracks tell us that the fisher was very interested in the coyote trail.

Parsing out all those extra tracks is tricky, but you can see my interpretation of the encounter in the next photo, a close-up in which I’ve labelled the tracks. The coyote trail is a nearly straight sequence of tracks on a rough diagonal from lower left to upper right, and its tracks are marked as CL F+H, CR F+H, etc. The fisher tracks are labelled RH, LH etc. Starting at the lower right there’s a right rear track from the fisher’s loping approach, and to the left of that track there’s a group of five prints. Four of those tracks make up a shortened lope pattern and the fifth sits above them and points toward the eventual continuation of the fisher’s journey. The tracks closest to the coyote trail show how the fisher paused and did a thorough examination. Apparently satisfied with its inspection, the fisher continued loping in the original direction.

Why was the fisher so interested in the coyote trail? A coyote would represent a danger to a fisher. A fight between the two could cause the fisher’s death and also pose needless risk for the coyote. But encounters between predators rarely happen because they keep tabs on each other’s movements. The tracks would have revealed the identity and nearness of the coyote, and the fisher apparently decided that it wasn’t in any danger.

I found the coyote tracks in the next photo on a sunny morning following an overnight snowfall. I must have been there not long after the coyote came through, since its tracks didn’t show any signs of melting. The coyote walked from right to left, changing its direction as it crossed an otter trail (which also showed no signs of melting) but otherwise taking little notice of the mustelid’s slide.

I continued to follow the coyote trail and soon came upon a spot (shown in the next photo) where the animal had encountered several pheasant trails. The pheasants had been there earlier in the morning before the sun had risen above the distant trees. The snow would have been several inches deeper, and the pheasants would have dragged their feet through it. Once the sun rose higher it began to melt the snow. By the time I came along the depth of the snow had been reduced and the pheasant tracks had been transformed into a series of pits connected by a raised, wavy ridge. How did this happen? Disturbances created by footfalls create slightly denser snow around–and between, if the feet drag–tracks, and denser snow melts more slowly than undisturbed snow. The compacted snow around and between the pheasant prints sank down more slowly and was transformed into the raised ridge. The coyote came along shortly before my passage, so its tracks hadn’t been exposed to the sun for very long and were unaltered. As the coyote investigated the pheasant tracks it left a jumble of prints, but it probably decided the birds were already far away and not worth pursuing.

So why did the coyote react differently to the two trails it crossed? The otter trail was more recent, judging by the lack of alteration, but a powerful animal like an otter would not have been seen as potential prey by a coyote. A pheasant, on the other hand, would provide a welcome meal for a hungry predator.

Signs of interaction when creatures cross paths may not be as obvious as the examples I’ve described above. You might just see a lighter track a little to the side, made as an animal paused before continuing on. Or differences in speed or gait may reveal an awareness of the recent presence of another creature. Whatever the reaction, it will always be transmitted through the animal’s feet and written in its tracks. Reading those tracks opens a window into the life of that animal.

Fisher Frolics

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.

Getting to Know Porcupines

I’ve been thinking about porcupines. There are porcupines in central New York where I live, but they’re not common, so in that region (unlike in the Adirondacks) I don’t often encounter their tracks. But this spring we had some late April snowfalls, and on two different occasions I was surprised and excited to find porcupine trails. In the photo below (direction of travel from right to left) you can see the left front and left rear tracks. The hind track (on the left) shows the flattened sole area of the foot nicely, with the marks of the claws to its left. The smaller front print lies to the right but isn’t as clear because the thin snow fractured in the sole area and three of the four claw marks were covered by the hind print.

Those meager April snowfalls weren’t ideal for recording clear tracks, so I’m including a more revealing photo of porcupine tracks that I took a few years ago in the Adirondacks. There was a light skiff of snow on a dark, icy base, and the soles and claws can be seen clearly. Again, the tracks are left front and hind, and the direction of travel is toward the upper left. In the rear print (on the right) the sole is larger but the claws are shorter than in the front print (on the left). If you look carefully at the front track you can see the faint imprints of the front toes (which usually don’t show up at all) just behind the dark holes made by the claws. And those streaks that run toward the upper left from the front claw impressions are drag marks made by the claws as they came forward when the foot was lifted.

So what if there’s no snow? Following trails may not be an option, but porcupines leave plenty of other evidence of their presence. Their winter diet includes the inner bark of trees, both conifers and hardwoods, and the buds and leaves of conifers. Scenes like the one pictured below (on yellow birch) show how efficient a porcupine can be at removing the cambium tissues of living trees. And this kind of evidence lasts long after the actual feeding was done. Small debarked patches high in hardwoods (but not conifers) could also be due to squirrels, which may turn to bark feeding when other food is scarce. However, the amount of exposed wood in the photo below is more than a squirrel would be able to achieve.

To get at tree buds or leaves a porcupine climbs high into a tree (where the most vigorous branches are), bites off twigs, eats the buds or leaves, and then drops the twigs. The photo below shows a scattering of nip twigs which accumulated on the ground as a porky fed in the hemlock tree above. When porcupines feed on the swelling buds of sugar maples in early spring, or on acorns in late summer, they harvest and discard the twigs in a similar manner.

But twigs and branches can fall with no help from porcupines, so how do we know whether a porky was the culprit? The first clue is the relatively even sizes of nip twigs (mostly 1 1/2 to 2 1/2 feet), compared with the wide range of sizes when wind or ice damage is the cause. Another clue is the appearance of the separation site. Randomly broken branches and twigs have ragged, irregular ends. The photo below shows the clean, angled cut found on a red oak twig that was nipped by a porcupine.

To get to feeding spots high in the canopy a porcupine must climb trees, and on trees with light bark, like the aspen in the photo below, climbing marks are very visible. Aspens are sought out by porcupines in spring when the leaves are young and easily digested, and preferred trees are often visited several years in succession. Bears also climb trees to feast on young leaves, nuts, and fruits, but the spacing between porcupine claw marks, between 1/4 and 3/4 of an inch, is much closer than the spacing in climbing marks left by bears.

Porcupine dens are another unmistakable sign. Unlike many other animals, porcupines defecate in their sleeping areas, and when scat piles up they simply plow through it or push it out of the way. The trunk of the sugar maple in the photo below had a hollow space which served as a porcupine den, and the waterfall of scat which fell down from it is evidence of an extended period of occupancy. Porcupine scats are cylindrical to kidney-shaped, and they can also be found among the nip twigs dropped from favored feeding trees.

In spite of their prickly defense, porcupines are preyed upon by most medium-sized carnivores. I found the coyote scat in the next photo last winter, earlier but in the same general area where I found the nip twigs and the tracks in the April snow. The coyote could have been responsible for the porky’s death, but it’s also possible that the initial killer was a fisher, and that the coyote scavenged the carcass later. The quantity of quill fragments is surprising and makes me wonder whether any quills entered the coyote’s body.

By now porcupines have left the mature forests and moved to more mixed habitats where they can find the growing herbaceous shoots and leaves, cattails and other wetland plants, roots, tubers, and fruits that make up their spring and summer diet. There are lots of other animals which consume the same plants, so unless you actually see a porcupine having a meal it’s hard to recognize the signs of summer feeding. But if you’re alert you may find long-lasting evidence of their cold weather activities.

An Encounter with a Fisher

Sightings of wild mammals are generally rare, and when they do occur it’s usually just a quick glimpse of the tail end of the animal as it flees at top speed. So my recent encounter with a fisher was doubly unusual. I was walking downhill on a sloping section of forest road (Hammond Hill Road in Hammond Hill State Forest for those who know the area). That part of the road is straight so I could see pretty far down the hill, and I suddenly realized there was a dark animal moving around on the road far below. I froze, not sure at first what kind of animal it was and hoping it wouldn’t realize I was there. It didn’t–in fact it actually began coming up the hill toward me. As I got a better view of its elongated body, short legs, and long fluffy tail I realized it was a fisher. I watched as it moved in a completely relaxed manner–apparently unaware of my presence–and marveled at its beauty. I was afraid if I made a move to get out my camera the fisher would take off, so I didn’t dare try for a photo. But here’s a good photograph of a fisher obtained from the Vermont Center for Ecostudies (https://vtecostudies.org/blog/walk-with-the-fisher-on-outdoor-radio/).

Photo courtesy of the Vermont Center forEcostudies

The fisher continued to move uphill in my direction at a steady bounding gait, with an occasional pause to look around. When less than 50 feet separated us, it suddenly realized I was there. It stood up on its hind legs, stared at me for a few seconds, and then bounded off into the trees.

Of course I immediately went to look at the tracks. Because the snow was dry and fluffy most of the prints weren’t clearly defined, and the cloudy conditions made things even harder to see–and nearly impossible to photograph. But there was a spot farther down the hill where the snow was firmer and the track details showed up better. A set of four prints from that part of the trail is shown in the photo below (direction of travel from right to left). The pattern

Track sequence, starting from the right: right front, left front, right rear, left rear.

resembles the bound of a cottontail rabbit: the two front tracks are narrowly set behind the rear tracks, and one (the left front) leads the other. The rear tracks are more widely separated and almost even with each other. Typical mustelid structure shows in the prints: the five toes are arranged in a lopsided crescent and the middle pads form a smaller crescent behind the toes.

That was only one of several different gait patterns I saw as I backtracked along the fisher’s trail. In true mustelid fashion the animal had been very flexible in the way it placed its feet. Rather than showing the rather poor photos from that day I’ll illustrate two of the variations I saw with shots that I took on other days (the direction of travel again is from right to left). As in the opening shot the four tracks in the photo below are well separated, but the rear prints are staggered rather than even with each other, and one is positioned slightly behind the leading front print.

Track sequence, starting from the right: right front, right rear, left front, left rear.

In the next shot the left rear foot came down on top of the left front, leaving a pattern that looks at first like there are only three tracks. But in the heel area of the middle impression there’s an inner ridge and a wider area of disturbance to its left, showing that two feet did actually land there.

Track sequence, starting from the right: right front, left rear on top of left front, right rear.

In addition to those two there were other variations–changes in the leading front or rear foot and slightly different placements of the second and third feet to hit the ground–but to my eyes the fisher’s bounding movement appeared to be uniform and unvarying. Except for momentary pauses it moved steadily uphill with the gently arching leaps that are so typically mustelid. One difference did stand out, and that was a variation in the leap lengths: the four-print patterns that matched the one shown in the first photo were separated by slightly longer distances than the patterns shown in the second and third photos. The fisher apparently wanted to move faster, and I suspect that the more even placement of the rear feet in the first photo delivered more power and enabled longer leaps. But there were many variations in the patterns that didn’t involve any changes in leap length, so there must be other factors that cause a fisher to vary the way it places its feet. I can only imagine the subtle interactions that go on between the animal and its surroundings. I hope that with further study of fisher trails, and maybe even some additional encounters with fishers, I’ll be able to understand more of the puzzle.