mud tracking – Page 2 – Linda J. Spielman

Dog Tracks: Common But Not Always Commonplace

Our familiar companion animals leave their tracks everywhere, and we see them so often we may find ourselves giving them only superficial attention. But if we look more carefully we may be surprised at how much they have to teach us. Dog tracks can show us the traits that are shared among dogs and their wild relatives, and they can also reveal the remarkable range of variation that could only belong to a long-domesticated animal.

The photo below (direction of travel toward the top) illustrates a number of core features that are shared by dogs, foxes, coyotes and wolves. The front track (lower left) is larger than the rear track (upper right). Both front and rear tracks have four toe impressions, and a single smooth middle pad. The tracks are symmetrical, meaning that if an individual track were divided down the middle and the right half were folded over onto the left half the two halves would superimpose almost perfectly.

There are a few additional traits in these prints that are shared among some–but not all–dogs and their wild relatives: The overall outlines of both front and rear prints are oval, the toes are held tightly together, and the claw marks point straight ahead. The larger ridges between the toes and the middle pad form the celebrated canine X, and the center of each track is occupied by a rounded dome or plateau. But although the tracks are roughly coyote sized, we see several additional traits that indicate dog rather than coyote. The claw marks are wide and deep, the middle pad of the front print is large compared to overall size of the track, and its trailing edge is rounded.

A comparison between the dog tracks above and the coyote tracks in the next photo will highlight the differences. (The coyote front print is below and a little ahead of the rear, and the direction of travel is to the right.) Like the dog tracks, the coyote prints are compact, with oval or egg-shaped outlines and tightly held toes. But some of the claw marks are missing, and those that are visible are delicate rather than robust. The middle pad of the front track is relatively small, and its trailing edge is concave.

The dog front track shown in the next photo is even more of a departure from the two preceding illustrations. Instead of being oval the print is round in outline, and the toes, especially the inner and outer ones, are widely spread and angled to the sides. The upper arms of the canine X seem to have been pressed apart, and there’s a curved ridge instead of a dome at the center of the track. Like the previous dog tracks, the print in the photo below has wide claw marks and a large middle pad. A track like this is easily recognizable as dog.

The photo below shows another dog track variant. The overall outline is rounded–in fact the print is a little wider than it is long. In contrast to the triangular middle pads of the previous dog tracks, this print has a trapezoidal middle pad with a broad leading edge. Instead of an X the internal ridges form a distorted H shape, and there’s a horizontal ridge rather than a dome in the center of the track. The absence of claw marks is unusual for a dog print. This is the kind of track that might be mistaken for a feline–a house cat, bobcat, or even a cougar depending on the size of the print. But there are clues that indicate dog, and they become obvious if we look at a true feline print.

The photo below shows the right front track of a bobcat. If we test for symmetry using the folding test described in the second paragraph, we can see that the dog track above is symmetrical and the bobcat track below is asymmetrical. There’s a leading toe (second from left) and a trailing toe (rightmost) in the bobcat print, and the middle pad is canted to the right. Instead of the canine X we see an angular C-shaped ridge that is also canted to the right. Another important feline trait is the contrast in size between the large middle pad and the small toes.

Wild canines have a way of placing their feet quietly, without tension or unnecessary movement. Dogs, on the other had, often express slight jiggles or shifts in the movements of their legs, and the difference can sometimes be seen in their tracks. In the photo below you see two dog tracks (in the upper left, the front a little below and behind the rear) and two coyote tracks (the front in the upper right corner and the rear just below the two dog tracks). Displaced bits of snow lie inside and around the edges of the dog tracks, while the coyote tracks have mostly smooth floors and margins. The best way to see the action that produces this kind of difference is to watch a dog walking or trotting directly away from you. You may see subtle shifts in the body or slight wobbles as the legs contact the ground.

Dogs lead easy lives compared to wild animals, and this often shows in the trails they make. The tracks of three creatures can be seen in the photo below. A dog meandered from top left to bottom right, leaving two partly superimposed tracks in the upper left corner, two tracks close together midway down the left side, and two more widely separated tracks at the lower right. A coyote trotted from top to bottom leaving smaller direct register prints, one between the dog tracks in the upper left and another at the lower left. And my boot tracks can be seen to the right of the dog tracks.

Wild creatures cannot afford to waste energy. There are exceptions: young animals play, and during mating season mature animals can make some wacky moves. But the business of survival demands efficiency of movement. Dogs, on the other hand, can expend energy without the pressure of finding their next meal. The coyote in the photo above had a destination in mind and moved with purpose. The dog was well fed and carefree, and counted on finding food and shelter when it got home. And I was focused on the story those tracks told about the lives of dogs and and their wild relatives.

Beavers at Work

Some animals live among us almost undetected, and others leave evidence that is obvious and long-lasting. Beavers are a good example of the latter, leaving signs of feeding on woody plants and creating dams and lodges that may last for years. The featured photo shows a lodge made of mud and sticks and surrounded by protective moat of water. What we can’t see is the underwater entrance which leads upward to a dry, multi-level living area. In the upper left quadrant of the photo there’s a dam, seen from the upstream side. The freshly peeled sticks that decorate the lodge and the dam, and the water lapping right up to the top of the dam, indicate that there were beavers in residence when the photo was taken.

Beaver dams can be impressive structures. The next photo is a view of a dam from the downstream side. The heaped up sticks conceal inner layers of mud interlaced with more sticks. Beavers react to the sound of flowing water, and any leaks are plugged with mud and more sticks. As long as the dam is maintained, the water level stays high enough to keep the lodge (not seen in this photo) secure in its watery surroundings.

A little exploration around the edges of an active beaver colony will turn up additional signs. When whole trees are removed the only thing left may be a chewed stump like the one below. Wood chips scattered nearby show where branches were removed and the trunk was sectioned and dragged off.

Some logs may remain where they fell, but they seldom go unused. One such log is shown in the next photo, and it’s a nice demonstration of the beaver’s chewing technique. The horizontal row of small cuts along the edge of the bark shows where the upper incisors were anchored. The vertical grooves in the lower peeled part of the log were made as the lower incisors were drawn up toward the anchored upper incisors. And why all this chewing? To get at the living cambium cells, located between the wood and the outer bark. Although there are exceptional cases where other food is available (such as the rhizomes of water lilies), most beavers depend on the cambium of woody plants for survival when leafy vegetation isn’t available.

Many dams and lodges are used for several years in succession, and newly added sticks and branches stand out against the mud and older sticks. The residents of a beaver colony also create deliberate messages indicating their claim to the location. In the photo below you see mud that was dredged up from the bottom and deposited on top of a grass hummock to create a scent mound. Whatever is handy at the edge of the pond, whether it be mud, muck, or rotting vegetation, can be dredged up and carried to the shore to make a pile. The final touch comes when the beaver drags its anus over the mound and deposits urine and secretions from its anal glands and castor sacs. The smell is not unpleasant, but it’s hard to describe. It reminds me of a horse barn, but it has also been compared to musk, human sweat, cheese, fruit, leather, birch beer, or some combination thereof. Scent mounds are most often created in spring, and the distinctive odor can persist for weeks.

If ponds and small streams aren’t available, beavers take up residence in creeks and rivers. But these habitats are subject to regular flooding, and the volume of flow during high water would destroy dams and lodges, so river beavers make their homes in the stream banks, digging underwater entrances and excavating living spaces above water level. If beavers are living in a river you may find peeled sticks, cut stumps, and scent mounds along the riparian margin. Another good clue is tracks in silty or muddy stream margins.

The tracks in the photo below were made by a beaver walking from lower right to upper left. The large hind prints make a wide zig-zag, starting with the left rear in the lower right corner. As in other four-footed walking trails, there are two footfalls–a front and a rear from the same side–at each zig or zag, but the front prints are mostly covered by the larger rear prints. All, that is, except for the two tracks at the upper left. The larger print above is the right rear, and next to it, just below, is the much smaller right front. Some of the rear prints may remind you of the tracks of a large bird. That’s because beavers often touch down lightly or not at all with their two inside toes, so the outer three toes make the most prominent impressions. But the heel marks behind the toes (as well as the wide palm areas at the bases of the toes) tell us it was a beaver, not a bird.

Whether they’re pond beavers or river beavers, at some point the animals will have exhausted the local food supply and will be forced to relocate to a better situation. If dams and lodges are not maintained water levels will fall. Chewed stumps and peeled sticks will weather to dull gray. Even though they aren’t fresh, these signs will persist and provide clues to the past presence of beavers.

But an abandoned beaver pond can offer its own discoveries. The amount of material amassed to form a dam or a lodge can only be appreciated after the water is drained. The exposed mud can be a great place to find the tracks of other creatures. And old beaver ponds provide great opportunities to find beaver scat. The animals normally defecate in the water, so seeing fresh scat is rare. But once the water has drained out, scats may be left on the sloping inner sides of the dam and the perimeter of the pond. Beaver scat is oblong and can be anywhere from 1/2 to 1 1/4 inches in length. The fibrous content is easy to see in the photo below–a beaver needs to chew through lots of bark and wood to get enough nutrition.

I never get tired of visiting beaver sites, because there’s always something new to discover. Whether it’s the prodigious size of a felled tree, the clever way the animals engineer channels to make transporting logs easier, or a muddy stream margin decorated with the tracks of beavers commuting to and from work, it’s always fascinating. Beavers lead complex lives and show great ingenuity in dealing with their surroundings, and the signs they leave can give us a window into their cleverness and adaptability.

Bears on the Move

[A note about last month’s post: you may have gotten a belated notification of the June blog; if so, my apologies. I had some trouble with my website, and the messages didn’t go out until the problem was fixed.]

Imagine you’re hiking on a sandy forest road, checking all the good spots for tracks. Suddenly you’re surprised to see what appear to be the barefoot tracks of a person. Could someone have been walking around way out here without shoes on? But as you look again, you realize that there’s something odd about the prints. Instead of the big toe being on the inside of the foot, it’s the outside toes which are larger and positioned farther forward. In fact, the big toe isn’t really very big. And ahead of each toe there’s the unmistakable mark of a claw. These tracks belong to a different creature altogether–a bear.

The black bear (the only bear we have in the east) that made the tracks above was moving at an indirect register walk, placing each rear foot on the spot just vacated by the front foot from the same side. The zig-zag pattern matches the pattern made by a walking person, but it’s a messy zig-zag because the coverage of the front prints by the hind ones isn’t precise. That’s a sure clue that the trail was made by a four-footed creature.

Another kind of movement often used by bears is the overstep walk, a gait in which the rear foot comes down just ahead of the front foot on the same side. In the next photo a bear moved from bottom to top at an overstep walk, leaving a sequence of tracks made up of sets of two. Each set is composed of a hind track trailed by a front track, and the pairs of tracks are arranged in the familiar zig-zag of a walking gait. Starting from the bottom, the sequence of tracks is: left front, left rear, right front, right rear, left front, left rear.

In the next image you see a left front and a left rear print taken from an overstep walk sequence. The direction of travel is toward the right, and the rear print with its fully impressed heel looks larger–and more human–than the heel-less front track behind it. In both front and rear tracks the outer toe (the upper one) is slightly larger than the others, but compared to human tracks the difference in size is less pronounced. The inner toes shows nicely in both tracks, and they’re distinctly smaller than the rest. There are a few claw marks, but they’re not easy to find because they’re not exactly in front of the corresponding toes.

Bears are classified as plantigrade creatures, meaning that their heels often touch the ground when they are moving at a normal walk. I’m hedging a bit here because heel registration in bears is variable. Rear tracks may show complete and well connected heels, as in the photo above, or partial heel impressions as in the upper sets of tracks in the preceding photo. And if you look at the first photo you’ll see heel marks that are separated from the middle pads by ridges.

Front prints commonly lack heel impressions, but there are times when the full length of the front foot, from heel to toes, does register in the track. The right front track in the next photo (direction of travel toward the left) is a good illustration. The middle pad forms a broad, slightly curved depression in the center of the photo. To the left the four largest toes and their claws show as clear imprints, but the smaller fifth toe (which would have been toward the bottom of the photo) didn’t touch firmly enough to register. To the right of the middle pad there’s a separated circular impression made by the heel pad.

Female bears which bore young over the winter are now travelling with their offspring and leaving tracks like the ones in the next photo. At the lower left you can see the mother’s print. The more delicate prints of the cub, with their prominent claws, are above and to the right. Young bears are active and playful, but they are also vulnerable to predation by coyotes, bobcats, and even adult male bears. Those sharp claws allow cubs to climb to safe refuges high in trees.

Bears are constantly on the move to access a variety of seasonally abundant food sources, often travelling miles as wild fruits and nuts ripen, colonial insects become available, or crop plants mature. Wherever they cross silt beds, sandbars, muddy forest roads, or other trackable surfaces they may leave prints for us to find. So when you find tracks that bear an uncanny resemblance to human tracks, look again. You may be on the trail of a roaming bruin.

Animal Artists

Nature is the original artist. Whether it’s the pattern of ice crystals in a frozen stream or a flock of birds wheeling together in the sky, we’re surrounded by striking compositions. And animal tracks are no exception. I’ve been photographing these works of art over the years, and I’d like to share some of my finds with you. For each one I’ll also include my deductions and speculations on how it came to be.

Those are mouse trails (deer mouse or white-footed mouse) that seem to pour out of the upper right corner of the photo below. In each trail the deeper landing spots are connected by lighter tail marks. The indistinct trail farthest to the right is older than most of the others. To the left of that one is a trail (superimposed on another older one) that looks like it is heading uphill, based on the shorter jumps and the angles of the tracks. The next one to the left (mostly centered in the photo) seems to be a single passage, and a few tail marks that go to the side (check out the small mark above the lowermost landing spot) tell me that the mouse was going downhill. The trails farther to the left are combinations of at least two passages, and it’s hard to say which way the animals were going. All of the trails radiate from a depression in the snow next to a tree trunk at the upper right of the photo. Openings like this allow access to spaces under the snow pack which are crucial for the winter survival of small animals.

The tracks pictured below were made in a warmer season. A toad walked through the mud and left some natural calligraphy. The direction of travel is from right to left, and the front tracks, with their four toes oriented inward, lie inside the rear ones. The curved lines were made as the trailing toes of the front feet occasionally dragged through the mud as they touched down. Toads often seem to walk on the tips of their rear toes, which is why the hind tracks look like curved rows of dots. The difference between the front and hind prints is best seen in the tracks from the left side (the lower ones) where there’s more separation between the two. At the extreme left there are two left rear tracks near one left front. It looks like the toad put its rear foot down lightly, picked it up and put it down more firmly nearer to the front print.

If you’re having trouble picturing how the feet of a toad could be positioned to make tracks like these, this photo of an American toad might help.

Snakes can also produce artistic creations. A garter snake made the designs in the sand shown below. The sinuous trail near the stones was made by simple forward movement toward the upper left. You can see several places where the tail must have lifted and the back end moved slightly sideways, leaving a ridge outside of the main groove. It’s harder to figure out what happened in the lower half of the photo. The wider flattened areas suggest sideways movement, almost as if the snake was having a good stretch. Do snakes do that?

Meadow voles bulldozing their way through shallow snow made the next work of art. You can see tiny tracks in the grooves, too many to have been made by just one passage. Tail marks show in a few places. The haphazard nature of the voles’ travel suggests they were searching for something edible, seeds perhaps.

A crow is the featured artist in the next photo. The bird landed at the lower center and walked toward the deep hole just above center. It must have dug around there, maybe in search of some edible item. (Or did it already have something that it put down and manipulated there?) It then turned to the right and took off, leaving a tail mark to the left of the hole and a pair of nearly symmetrical wing marks to the right. (If it had been landing instead, the wing marks would be next to or to the left of the hole.) There are some additional feather marks in the photo that are harder to figure out. The ones in the lower right corner that seem to drag down to the left may have been made when the crow landed. Just above those there’s another set of wing marks, and there are two more on the left side of the frame, one above and another below the tail mark. These are more of a puzzle, since they don’t seem to be connected with the landing or the take-off. Maybe the crow swooped around before it actually landed, or maybe another crow was harassing it.

I’ve saved my favorite one, a red fox track decorated with ice crystals, for the very last. This is an interesting phenomenon that occurs during very cold weather. When the track was made it would have looked normal, with a thin floor of compressed snow bordered by low walls of snow. After the fox stepped there the temperature stayed cold so the soil beneath the track, although frozen, was warmer than the air above. The warmth at ground level caused ice in the ground and the snow in the floor of the track to undergo sublimation and recrystallization. Water molecules became detached and formed water vapor, which moved upward and formed new ice crystals in the colder air just above. Since this was a slow process the new crystals had time to get much larger than the crystals in the original snow.

This same process gradually transforms solid snow at the bottom of a deep snow pack into a warren of tunnels and chambers. Remember the mouse trails in the first photo? The trails connected to an opening which gave the mice access to spaces under the snow pack created in the same way as the crystals in the fox track, by sublimation and recrystallization. You can read more about this process, called constructive metamorphosis, here.

Natural art is all around us, and expressed within this beauty are the lives and relationships of living things and the physical world they live in. It’s certainly possible to appreciate the art of nature on its own, without any deeper analysis. And if that is your inclination I encourage you to simply be open and drink in natural beauty whenever you can. But for me, understanding how nature works adds much more to my experiences of natural art. For instance, when I look at a track filled with ice crystals I both marvel at the delicate design and imagine how that design was created by water molecules drifting up from below and attaching to crystals at higher levels. I revel in both the beauty and the finely tuned interactions that produce it.

What’s Underfoot Makes All the Difference

I’ve been finding lots of coyote tracks lately, and as I go back over my photos I’m amazed at how different they can look from one another. It’s not that the substrates are radically different–just sand, silt, or mud. And to make my point I’ve narrowed down the gaits to just walks and trots. But still, no two tracks are alike. How can what seem like small differences in conditions give tracks such strikingly different appearances?

Moist, dense sand captured the tracks of a trotting coyote shown below, a front at the lower left and a rear at the upper right. The animal’s feet sank in just enough to show lots of details: the difference in size between the front and rear prints, the compact positioning of the toes, the greater depth toward the tips, and the alignment of the claws straight ahead. Both middle pads show only lightly, and the smaller pad of the rear print can barely be seen. In the front track there are small clumps of sand in the two leading toe impressions that were tossed there by the claws when the foot was lifted.

But all sand is not the same. In the photo below of a front print (for the sake of comparison I’ll stick with front prints for the remainder of this article), partial drying resulted in dark toe and middle pad impressions surrounded by lighter dry sand. I suspect that the sand was uniformly wet when the track was made. If the sand around the perimeter of the track had been dry when the coyote’s foot impacted, it would have lost its coherence and crumbled or flowed outwards. Instead pressure from the toes formed plates and fissures (known to trackers as pressure releases). Since nothing disturbed the track before I found it later that morning, these formations dried without disintegrating (although part of the ridge between the two leading toes did fall to the side).

In addition to the larger areas of dry sand there are tiny, light colored squiggles in the floors of the toe and middle pad impressions. These also indicate that the sand was wetter when the track was made; small bits of wet sand adhered to the coyote’s toes and middle pads (dry sand doesn’t do this), and came up as the foot was lifted. Being slightly elevated and also less dense, these particles dried faster than the packed floor of the track. You can see the same thing at an earlier stage of drying in the first image.

This kind of partial drying can often tell us how long ago a track was made. Dew creates wet soil surfaces, so tracks made early in the morning in substrates subjected to dew-fall look uniformly moist immediately after they are made. But on dry summer days the elevated parts begin to lose moisture quickly, and lighter colored halos form around the darker depressed parts of a track. As the substrate continues to dry the entire surface becomes lighter in color and the structure in the cracks and plates disintegrates, resulting in a track with softer edges and uniformly lighter color. Another round of dew-fall and daytime drying may reproduce the halo effect, but the softer edges usually give away the greater age.

The track shown below was made in dry sand, and any structure that existed within the sand disappeared with the impact of the coyote’s foot. Instead of forming plates and cracks in response to the pressure of the foot, the sand moved more like a liquid, producing soft outlines and rounded pressure releases. Although some detail was lost, the compact form of the foot and the triangular shape of the middle pad are still evident. If this track was moistened by dew-fall the night after it was made, it would look wet early the next morning and would develop a lighter colored halo as drying progressed. But the rounded edges would show that it was made at least a day earlier, when the sand was dry.

The photo below shows what fine, moist mud can do to reveal track features. The toes and middle pad are crisply outlined and show very little disturbance, suggesting that it was made at a walk. In front of and behind the middle pad (and a bit at the sides of the toes) there are impressions of the hair which fills the spaces between and around the toes and middle pad–in November, when I found the print, the coat was already thickening ahead of the cold weather to come. We even see the slightly pebbled texture of the skin, especially in the middle pad. This beautifully detailed print illustrates several important diagnostic features of coyote tracks: the trim outline with tightly held, forward pointing toes; the lack of claw imprints telling of shaping through natural abrasion; and the outline of the middle pad with its triangular forward edge and lobed trailing edge.

You may wonder why particles of mud weren’t lifted from the floor of the track the way clumps of sand were in the first two examples. After all, mud is sticky, isn’t it? It certainly is, and the stickiness shows in the narrow ridges pulled in by the toes and the middle pad. This is especially obvious in the lower edge of the left leading toe, the back edge of the right outside toe, and the back edge of the middle pad. But mud is also very fine-grained and has greater internal coherence than sand, so it doesn’t pull apart as easily, especially after it is compressed by the weight of an animal’s foot.

In the next photo the silty mud was not as wet and was much firmer, so the track is shallower and the toes and middle pad look smaller. It’s not that this coyote actually had smaller toes. It’s rather that less of the toe and pad surfaces touched the mud. Think of holding a beach ball and pressing it into soft beach sand to make a large circular impression, then compare that with pressing the ball onto a sidewalk where the contact area is much smaller. The outer toes look especially small, and the lobed trailing part of the middle pad is narrower compared with the same area in the previous photo. Another striking feature is the disturbances in the toe impressions. Cracks and displaced sections in the forward parts of the toes show that the foot pressed backwards against the substrate. These and the tiny punctures made by the leading claws suggest that the animal was moving with more energy (perhaps at an overstep walk or trot) than the coyote that made the track in the previous photo.

Finally, here’s a slightly quirky example of the way tracks can come to have different appearances. I found the print shown below on a truck trail that had been surfaced with pulverized rock quarry tailings. The coyote had walked through a stretch covered with fine white rock dust before it crossed the dried mud in the photo. The dust adhered to its feet and was deposited on the mud to make light tracks on the darker background. As in the previous photo, the toes and middle pad are relatively small and separated by wide negative spaces, but the diagnostic features of a coyote print can still be seen.

There’s so much to learn from tracks: how the track was made, what the conditions were like at the time, how old the track is, and what happened after the animal passed by. We can even get glimpses of some of the challenges in the daily lives of animals. Understanding the subtle (or not so subtle) differences in the appearance of tracks can help us to delve deeper into the myriad messages tracks carry.

Walking the Rails

When I was a kid I used to enjoy exploring the woods and fields near my home, and one of my routes involved travelling along a seldom used railroad line. The rocky bed that supported the ties and rails was hard to walk on, and the spacing of the ties was just a little different from my natural step, so I often walked on one of the steel rails. Recently I found myself doing the same thing–walking along a seldom used railroad line and attempting to keep my balance as I walked on a rail. As I stepped carefully along I saw some peculiar muddy smudges on the rail ahead of me.

I thought at first that someone with muddy sneakers had been there ahead of me. But the marks didn’t look like the tread pattern of a shoe, and some of the groups of muddy spots seemed to form zig-zags rather than the centered prints that a person would make. My puzzlement turned to delighted comprehension as I noticed more details. The zig-zag sections were separated by areas that were smeared or had a jumble of muddy marks, such as the the area at the top right in the photo above. It was as if a walking animal had occasionally lost its balance and shifted its steps to keep from falling off the rail.

In the clearest impressions, arrays of small mud spots seemed to form half-circles around central clusters of smudges, as in the two photos below. The more I looked at them, the more the outer marks looked like toes and the inner clusters like middle pads. And those half-circles of widely separated toes, spreading across most of the top of the rail, could only have been made by an opossum.

Compare the images above with the photo of opossum tracks in mud (from a different opossum encounter) below–the left front track at the upper right and the left rear track below. Notice how the widely spread front toes encircle the middle pads; the upper two middle pads show as triangular impressions and the lower two as faint roughenings of the shiny mud surface. Four toes of the hind print point toward the upper left and the innermost hind toe–probably superimposed on the innermost front toe–points toward the right. The front print is a pretty good match for the mud-on-steel prints in the photos above.

Here’s another shot (from last winter) of opossum tracks, the left front on the right and the left hind on the left. The perfect tracking snow recorded the triangular to oblong middle pads of both front and rear feet beautifully. In the front print the position of the middle pads inside the circle of toes reproduces the positioning of the inner clusters and outer circles of mud marks in the tracks on the rail.

The positioning of the rear feet of a walking opossum is often erratic, and the animal that walked on the rail left many rear tracks that were smeared, distorted, or partly missing. In the photo below the middle pad area of the left rear foot (on the left side) made the large smudge behind the left front print (on the right), and the four outer toes of the rear track left spots and smears on the sloped upper edge of the rail. The lack of precision in the placement of its rear feet may have caused some missteps as the opossum attempted to balance on that three-inch rail.

Putting it all together, the whole scene made sense. I found the muddy slough the possum had crossed, coating its feet in ooze, before it climbed up onto the railroad bed. There were sloppy smears and spatters on the rocky shoulder of the railroad bed, and on the ties where it had first stepped onto the rail. The zig-zag pattern of the walking gait was occasionally punctuated by sections with extra steps and smeared mud where the opossum had struggled with its balance. (What would it look like if a more precise walker–like a cat–had left muddy prints on a rail?) At each step mud was transferred from the opossum’s feet to the rail, and the tracks grew fainter and finally disappeared. I continued in the same direction toward a road bridge which crossed the railroad line. Under the bridge there was a wide, dusty area, and when I stepped away from the tracks to investigate I saw a recently made opossum trail. Could it have been the same animal? I can’t be sure, but I feel a kinship with the opossum that made the muddy tracks. In spite of our balance problems we both found walking the rail to be a good way to get where we wanted to go.

Raccoon Spring Fever

Winter is still with us, but the season is advancing and mild days are beginning to outnumber the cold ones. Raccoons have spent the frigid periods in a state of torpor, denned up in hollow trees, rock crevices, second-hand burrows, or perhaps under your porch. On warm days the animals emerge from their winter dens and roam about in search of food and mates. Their habitual use of a gait called the pace-walk gives their trails a unique and easily recognizable appearance.

In the pace-walk the tracks lie in sets of two, each set made up of front and rear prints from opposite sides. One of these prints generally falls ahead of the other (although they can be perfectly even). In each successive pair the sides of the front and rear tracks switch and, if they are uneven, the leading side also switches. In the photo above the larger hind prints lie ahead of the smaller front ones. The succession of tracks, starting at the lower right corner, is: left front with right rear, right front with left rear, left front with right rear, and right front with left rear.

Raccoons are not good at digging, and as long there’s a substantial snowpack they have difficulty getting at edibles in the leaf litter. But seeps and unfrozen streams are not only free of snow and ice–they also harbor tasty morsels like aquatic insect larvae, worms, snails, and other invertebrates. Seeps are likely to form during mild weather, and they’re usually found in the same places each year. Muddy tracks like the ones below tell us when raccoons have been visiting them.

There are two separate passages in the photo above, the upper one heading from left to right and the lower one going in the opposite direction. If you focus on the darker tracks in the middle of the photo, you can see the similarity between the patterns in the two photos. But in addition to being more irregular, the mud-on-snow tracks have a slightly different arrangement. In each set of two the larger hind foot touched down a little behind the smaller front foot. This, and the fact that the steps are shorter, tells us that the animal was going slower. The icy crust was probably slippery and the raccoon needed to be more careful with its footing.

As spring–and mud season–draws closer, raccoon tracks can be found in all sorts of wet places. When the photo below was taken a thin blanket of snow covered most of the landscape, but the silty stream margins were clear and unfrozen. The small tracks heading in both directions were made by minks, and the larger ones belong to a raccoon. There’s a pretty clear hind print near the right edge of the frame, but the other raccoon prints (one to its left and another toward the bottom of the frame) are distorted because the animal slipped in the mud. In fact the very weird track at the lower edge of the photo is actually two prints, one on top of the other. Apparently the heavier raccoon had more difficulty with its footing than the smaller minks did.

Here’s another trail made by a pace-walking raccoon on a nicely moistened sand road. The pairs of prints are a little closer together than the ones in the first photo, and the rear tracks fall slightly behind the front–both signs of lower speed. Maybe with its feet sinking slightly in the soft sand the animal chose to move more carefully, or maybe it just wasn’t in a hurry. On a mild spring day even a raccoon might feel like taking it easy.

A Red Wolf Tracking Adventure

A few weeks ago I spent some time at the Alligator River National Wildlife Refuge (ARNWR) on the coast of North Carolina. The refuge covers 238 square miles and includes upland forests, swamp forests, marshes, ponds, creeks, brackish waterways, shrubland, and current and former cropland. The diverse habitats are home to an amazing array of mammals, birds, reptiles and amphibians. I had my first wildlife encounter in a port-a john before I even set foot on a trail. A green tree frog jumped out of the toilet paper dispenser, ricocheted off my arm, and leaped onto the wall. It posed while I got a photo and then scooted straight up the vertical surface.

With that welcome I knew I was in the right place. But I was really there because of one specific animal–the red wolf. Alligator River is home to the only wild population of red wolves in the world. Historically the range of the red wolf stretched from Texas to the Atlantic seaboard, and from the Gulf Coast to the Ohio River valley. But persecution and habitat loss decimated populations throughout the range, and by the mid-1960s just a few small remnants remained in the coastal prairies and marshes of western Louisiana and eastern Texas. Red wolves were on the verge of extinction, and the U. S. Fish and Wildlife Service determined that the best strategy was to capture the last wild wolves and move them to captive breeding facilities. The red wolf pictured below was photographed at a facility in Texas. After several decades of captive breeding, 4 male-female pairs were released at ARNWR. The animals have thrived there, and the red wolf recovery program is seen as a model for reintroductions of other species. You can learn more about the program here.

Photo by the U. S. Fish and Wildlife Service

The more I thought about this amazing story, the more I wanted to go there and see red wolf tracks. So about a month ago I set off for North Carolina. I had high hopes, but I didn’t know how hard it would be to find the wolves or what kind of tracking conditions I would encounter.

I learned more about the current status of red wolves and strategies for their future when I visited the Red Wolf Education and Health Care Facility in Columbia, NC. There’s lots of information on Center’s website, which you can find here. If you ever visit ARNWR you should definitely stop at the Red Wolf Education Center.

One helpful bit of information was that the red wolves spend most of their time in the northern parts of the refuge around the agricultural areas. And once I did some exploration and located the sandy roads and trails, I found wolf tracks aplenty. Red wolf tracks are similar to other wild canines–they have the typical central dome and canine X, and the claws usually show as small indentations ahead of the toes. The species most likely to be confused with the red wolf is the coyote, but there are several features that set the two animals apart. Compared to coyote tracks, red wolf tracks are wider in proportion to their length, and have larger middle pads.

There’s also a distinct difference in size. Red wolf front tracks range from 2 1/8 to 3 inches wide and 3 to 4 1/4 inches long. Even our northeastern coyotes–larger than western coyotes–fall in the lower end of this range. The coyotes at ARNWR are more like western coyotes in size, so their track dimensions don’t overlap those of red wolves. I didn’t find any coyote prints in the areas where the wolf tracks were–apparently the wolves don’t tolerate the presence of coyotes. The coyote front print below, which I found in the southern part of ARNWR, measured 2 5/8 inches in length and 1 3/4 inches in width.

Here’s another photo of red wolf tracks, and these are also distinctly different from coyote tracks. The overall shapes of both the front track (upper left) and the hind track (lower right) are more rounded, and the middle pads are larger and more triangular. As in other wild canines, the front tracks of red wolves are larger than the rear tracks, and the claws don’t always show on all the toes.

ARNWR is a haven for all sorts of wildlife, and one group that was clearly thriving was snakes. Several times I saw snakes basking on roads, and every time the snake was very reactive to my presence, either fleeing or adopting a defensive posture. On my way out one afternoon I came upon this very large–at least four feet long–rattlesnake. (I wasn’t as close as it looks–I used the telephoto setting to get this photo). But there was something wrong with this snake. It wasn’t moving away or coiling up, and it seemed unable to raise its head or straighten out its neck. There was no obvious wound, but it must have been hit by something.

The next morning I drove in on the same road, and where I had seen the snake the day before I saw this:

Remains of rattlesnake eaten by red wolf, ARNWR

Along the sandy edge of the road I found wolf tracks leading up to the snake carcass and then continuing in the same direction away from it. To make a meal of the disabled snake, the wolf must have known not only that the snake was vulnerable, but also how to go at it without getting bitten. For me this was an incredible look at a slice of the life of a red wolf, and at the way the animals make use of every opportunity. Their intelligence and adaptability has served them well for thousands of years. If we just give them a chance they can thrive for thousands of years into the future.

A Gallery of Red Fox Tracks

I’m fascinated by track variation. No two tracks are ever exactly alike, even if they were made by the same animal doing the same gait on the same substrate. Sometimes variations within the prints of one species are so extreme that it’s hard to believe that they were made by the same kind of animal. This applies to all creatures, but I think the red fox is a particularly good illustration.

In the photo below you see a front print made by a red fox traveling from left to right. This is a typical track: oval in shape with finely pointed claw marks, and a curved impression–called a bar or chevron–running vertically through the middle pad. A striated texture in the toes and middle pad shows how the fur which covers the underside of the foot pressed into the mud.

The track pictured above also has some features that are found in all of our wild canines. There’s a dome in the center, and the major ridges meet at the dome to form an X shape. The toes are held tightly together and the claw marks point straight ahead.

Here’s another front print made by a red fox, again traveling from left to right but at greater speed. This time the mud was firmer, so the track is shallower and the marks of the hair are lighter. Instead of lying tightly together, the toes are spread and the claws, especially the inner and outer ones, angle outward. The bar in the middle pad is the deepest part of the track, suggesting that the horny protrusion might have served to increase traction.

A fox moving on even firmer mud and at even greater speed made the next example, again traveling from left to right. We see only the claw marks, the tips of the toes, and the middle pad bar. As in the previous photo the toes are spread and the claws angle outward.

Sometimes the fur on the underside of the foot is the most obvious feature of the track. In the next photo, made in wet mud, the direction of travel is from right to left, and the texture of the hair seems to cover the entire track except for the middle pad bar. But take a close look at the areas toward the tips of the toes, especially the two leading toes. There’s a spot in each toe impression that’s deeper and doesn’t have the striated texture. These marks aren’t just accidental artifacts–they’re real (although seldom seen) features of red fox tracks. Each toe has a small, hairless bump near its tip which can protrude through the hair to leave a mark.

There are other anatomical parts which can show up in tracks. The print in the photo below was made in soft sand by a red fox moving from left to right at high speed. The spread toes and deep toe and middle pad bar impressions should be familiar by now, but just behind and above the middle pad there’s an additional mark. This was made by the dew claw, the reduced fifth toe present on the insides of the front feet of most canines. And to the left of that and straight back from the middle pad there’s a shallow indentation made by the carpal pad, a knobby protrusion found higher up on the back of the front leg. This is another feature found on foxes, coyotes, and domestic dogs.

Dewclaws and carpal pads only show in tracks if the lower leg joint (it’s actually the carpal joint) is well flexed or the foot sinks down into the substrate. The print pictured above had some of both–the foot sank into the sand and the galloping gait caused significant flexion in the carpal joint.

I’ve been focusing on tracks in mud and sand because they show track details so beautifully, but snow can be just as revealing. The red fox that made the prints below was traveling from left to right. There’s a nice bar in the middle pad of the front track (at the lower left), and as we expect in the red fox, the rear track (at the upper right) has a smaller middle pad with no bar. The dome and canine X show clearly in both tracks. Small depressions at the tips of the toes of the rear track show where the hairless protrusions (the same ones seen above in the wet mud) pushed deeper into the snow. In dry, fluffy snow like the substrate in the photo below, the fur on the undersides of the feet doesn’t leave distinct marks. Instead it has the effect of blurring the outlines of the toes.

Track variants can be puzzling, but they can also lead to better understanding of foot anatomy and animal movement. So when you’re perplexed by an unusual print take a breath, focus on something different for a moment, and let the pieces of the puzzle fall into place at their own speed. It will be well worth your time.

A Perfect Storm of Jumping Mice

I guess I was just in the right place at the right time. I was in a part of the western Adirondacks where the soils are sandy–they’re called glacial outwash soils, and they’re a gift from our glacial past. After a day with several heavy downpours the weather cleared, and the next morning I went out to look for tracks. I headed to one of my favorite spots, a sandy truck trail that meanders through a mosaic of wet meadows, marshes, and shrubby uplands. The low spots in the road had filled with water during the rain, but the sandy soil had allowed the pooled water to drain away, leaving perfect tracking mud.

And there were tracks aplenty, mostly small rodents. But not just the usual small rodents–many tracks had the distinctive features of a very special animal. In the photo below (direction of travel toward the top) the five-toed hind tracks are in the upper section, nearly even with each other and set widely apart. Below them are the four-toed front tracks, one leading the other and set more narrowly.

These are the tracks of a small rodent called the meadow jumping mouse. (It’s cousin, the woodland jumping mouse, is restricted to boreal forests and would not have been found where I was tracking that day.) The meadow jumping mouse is pictured in the photo below by Martha Beck (from her blog, Martha’s Blog). This beautiful little creature has a very long tail, large ears and eyes, long back legs, and really interesting rear feet.

Here’s another example of the tracks I found that day. The direction of travel is toward the right, and the front prints (on the left side) are distorted by the impact of landing from a long jump. Nevertheless you can see that the rear tracks (on the right side) are much larger than the front,

especially in this example in which the entire lengths of the rear heels touched down. These long heels are unique to the jumping mouse, as are the long, slender toes. The three central toes are often slightly curved, and they spread more than the corresponding toes of most other small rodents. Another special feature lies in the elongated middle pad area of the rear prints. The inner and outer toes attach considerably behind the area where the three central toes come together.

In the photo below, another one from that amazing day, the elongated middle pad area shows nicely in the left rear print (farthest to the left). The right rear track is on the extreme right, the two front tracks lie between the two hind tracks, and the direction of travel is toward the top. Some interesting details of the front prints can be seen in the right front print (the lowest of the group): it’s canted toward the outside, with the innermost toe pointing up and a little to the left, the toe next to it pointing almost directly upward, the third toe pointing toward the right, and the outermost toe pointing downward. The middle pad area of this track is in the center, and the paired heel pads show at the lower left edge of the print.

Once you’re aware of the critical details, jumping mouse tracks look very different from the tracks of other small rodents. The meadow vole tracks in the photo below, also from that wonderful day on the sand road, are in the same relative positions as the jumping mouse tracks in the previous photo. But the front and rear prints of the meadow vole are similar in size and there is no elongation of toes, heel, or middle pad. The inner and outer toes of the hind tracks show as small ovals on either side of the middle pad area, and the front tracks are only slightly angled.

Although their feet are larger, jumping mice are actually much smaller than meadow voles, but they’re similar in size to another common small rodent, the white-footed mouse. But white-footed mouse tracks are also very different from jumping mouse tracks. The white-footed mouse tracks in the photo below (direction of travel toward the top with hind tracks above and front tracks below) are tiny compared to jumping mouse tracks, and the toes in both front and rear prints are small ovals with no connections to the middle pad. The three central toes of the rear print are close together and parallel with each other, and the middle pads are a distinct series of bumps.

My walk along the sand road that day was a real revelation. Although the drying mud puddles may have been more attractive to jumping mice than to other small rodents, I still have to believe that the abundance of jumping mouse tracks indicated high population numbers. Those scattered, moist habitats were just the kinds of places favored by meadow jumping mice, and the muddy low spots were perfectly situated to capture the animals’ movements. Since jumping mice spend the winter in extended hibernation we don’t have the luxury of seeing their tracks in snow. But a perfect storm of favorable influences created conditions rivaling the best snow tracking, revealing jumping mouse tracks like I’ve never seen them before.

9/26 – I just got a comment from Janet Pesaturo about the range of woodland jumping mice, which is broader than I realized. They’re found in mixed softwood/hardwood forests in temperate zones as well as in boreal forests. Thanks, Janet.