animal tracking – Linda J. Spielman

Bark Eaters

For the indigenous peoples of our region bark was a starvation food, but for many animals, bark is a regular, or at least occasional, component of the winter diet. Most of the thickness of a woody plant stem or branch consists of dead wood and bark cells, but the innermost layer of the bark, located between the wood and the outer bark, is made up of living cells. This stratum, known as the cambium, is responsible for the production of new tissues when growth resumes in the spring. It’s no more than a few cells thick, but for both human and animal consumers these living cells are the only part that provides useful nutrition in the winter.

Bark feeders leave conspicuous evidence of their activity, and this evidence is especially obvious in early spring before it gets obscured by plant growth. With careful observation it is usually possible to pinpoint which species the bark eater belonged to. In the photo below you see the results of cottontail rabbits feeding on downed branches of black cherry. The branches were relatively low to the ground, within reach of a rabbit either standing on the ground or supported by the winter snowpack. The rough appearance of the chews is characteristic of rabbit feeding–the bites penetrate to varying depths, often beyond the cambium into the sapwood. Gouges made by the incisors can be seen in several places.

Rabbit chews on staghorn sumac, shown in the next photo, show similar irregularity in the depth of the debarking. Rabbits seem to take in more woody material than they really need to, perhaps because they can make use of it through coprophagy. Rabbits have an intestinal pouch called a caecum in which partially digested material is fermented by beneficial bacteria. The soft stools produced by this process are passed out of the anus and eaten, allowing the animal to absorb more nutrients before expelling the twice-digested material as fecal pellets.

Chews made by squirrels are usually higher above ground level than rabbit chews and don’t show as much irregularity in depth. The staghorn sumac stems in the next photo were fed on by gray squirrels. Young, vigorously growing stems like these have thin bark and are an attractive meal for a hungry squirrel.

A close-up of one of the stems in the preceding photo is shown below.

The debarked patch on the staghorn sumac branch shown in the next photo was about four feet off the ground. This was an older stem with thicker bark, but gray squirrels had no trouble removing it to get at the cambium.

Deer occasionally feed on bark and leave tooth gouges similar to, but larger than those of squirrels. Their debarking is generally found between two and five feet off the ground. Since deer lack upper incisors, they can only access bark by drawing their lower incisors upward. This leaves thin hanging flaps of tissue like those seen on the staghorn sumac stem in the photo below.

Porcupine chews, like the one on beech in the next photo, have a more organized appearance. They can be anywhere from ground level up, but are often seen high on the trunk or upper branches.

Beaver chews, like rabbit chews, are limited to the reach of an animal standing on the ground or on the snowpack. The tooth marks are organized in regular patterns, sometimes in neat rows like those on red maple in the photo below. The upper incisors made the small digs in the bark and the lower incisors created the long grooves below them.

Our smallest bark feeder is the meadow vole. The buckthorn shown in the photo below was fed on by meadow voles working below the level of the snowpack. Tiny tooth marks can be seen at the edges of some of the dark areas. Meadow voles prefer to stay hidden under the snowpack, so their chews are generally located close to the ground.

In the next photo you see debarking by a pileated woodpecker on a big tooth aspen. Woodpecker feeding is often mistaken for mammal chews, but woodpeckers mine dead trees to get at insects, while rabbits, rodents, and deer chew on living trees to access the cambium. Woodpecker feeding can occur at any height, from downed logs on the ground to trunks and branches high in the canopy. The debarked area is textured by the digs and gouges made by a bird beak rather than mammal teeth.

Deer, meadow voles, and squirrels resort to feeding on bark only when other foods aren’t abundant, but for beavers, porcupines, and rabbits bark is a mainstay of the winter diet. Once the growing season begins the choice of foods becomes more diversified, but in winter and early spring the living cells hidden within the branches and twigs of woody plants can make the difference between life and death.

Good Luck for a Fisher

I was out with a group of fellow trackers last weekend, and we came upon an unusual trail. There was a groove several inches wide running through the snow, and what seemed at first to be disorganized tracks next to the groove. We saw spots of blood in the groove. It looked like the trail of a predator carrying a prey item, and we spread out to investigate. I backtracked, wondering if I’d be able to find how it originated, and it didn’t take long before I came to the scene shown in the photo below.

A wider view, shown in the next photo, shows the rabbit tracks coming in from the upper right at an easy pace, making a turn to the right, and ending near the base of the shrub. The predator’s tracks (hidden behind the branches in the upper part of the photo) showed leaps of varying length moving in a linear path toward the shrub. Just before it passed beneath the leaning branches the animal made a few short leaps, then turned right to make the kill. The rabbit tracks didn’t show any evasion behavior, and the predator didn’t seem to be in a hurry as it approached the shrub. These details suggest that it was a chance encounter rather than a pursuit or ambush. The rabbit either didn’t realize the predator was near until it was too late, or froze when it detected danger.

The trail leading away from the kill site was easy to follow: a deep groove with tracks along one side.

Most of the tracks were indistinct, but there were a few that were clear enough to reveal that the predator was a fisher. There’s a fairly good one in the center of the next photo. I suspect that this was a female fisher, for two reasons. The tracks shown in the preceding photo are in a loping pattern, but their arrangement suggests a labored gait rather than the effortless lope we usually see in fishers. And the groove is quite deep, indicating that the body of the rabbit was not held very high off the snow. A male fisher is large enough to carry a rabbit easily, but a smaller female would have more trouble.

The trail proceeded through the woods in a generally straight direction. Spots of blood appeared every once in a while.

There were several places where the fisher put the rabbit down and either rested or repositioned it.

Finally I saw the feeding site at the base of a pole-sized sapling, shown in the next photo.

A closer shot shows plenty of fur, some entrails, and lots of blood. One hind foot lay at a distance from the main deposit of remains, but other than that I saw no bones or body parts.

I wondered why there were there no bones or body parts left at the feeding site. The condition of the tracks at the kill site and along the trail suggested that the fisher killed the rabbit early in the morning, so there would have been time for scavengers to work over the remains before we arrived in the afternoon. There were lots of coyote and raven tracks around the remains, so they were probably responsible for removing much of what the fisher didn’t consume. I also wondered why the predator carried its prize for so long before stopping to eat it. Something made the fisher feel unsafe, and it may have been the presence of coyotes in the area. We’ll never know for sure. But what’s a tracking outing without an unanswered question?

We don’t often find stories of predator-prey encounters recorded so completely. The fisher was in the right place at the right time, and so were we.

Furry Feet

It’s been awhile since I’ve put out a new post, due to some medical issues I’ve been having. But things have improved, so I’m happy to be back in action.

Going barefoot, or more accurately, bare-toed, is quite popular among wild mammals. The tops and sides of the feet are typically furred, but most mammals in our region touch the ground with bare skin. This applies to both toe pads and middle pads, and sometimes the heel area as well. In the photo of red squirrel bounding tracks below (direction of travel toward the top) the hind tracks are set more widely above the front tracks. The clean borders and smoothly compacted interiors of the toe and middle pads–and the heel pads in the front prints–are unmistakable evidence of bare skin.

But there are a few inhabitants of our region that buck the trend. The feet of rabbits and hares, for example, are thickly furred, and this fur has a blurring effect on the impressions of the toes and pads. In the photo below you see the tracks of a cottontail rabbit bounding toward the left. The toes are visible, but they lack the clear outlines and smoothly compacted interiors seen in the squirrel tracks shown above.

The fisher is another animal with thickly furred feet. The tracks in the photo below were made by a fisher loping from lower left to upper right, and the toes and middle pads are almost completely muffled by the fur.

In the preceding photo the snow was cold and dry, but if the snow is wetter the toes may be more recognizable. The next photo shows tracks made by a loping fisher traveling from lower right to upper left. In the warmer and more easily compacted snow the toes made visible impressions, but the blurring effect of the fur can still be seen in the middle pad and heel areas.

River otters share many features with fishers but differ in having unfurred toes, middle pads, and heel areas. In the next photo there’s a collection of otter tracks (as well as a few dog tracks). The otter loping pattern in the middle and lower part of the photo (direction of travel from lower right to upper left) is the important part, but it’s a little confusing so bear with me and I’ll try to sort things out. Starting at the lower right the sequence of the otter loping tracks is right front, left front, right rear, left rear. There are a few more otter tracks in the upper area of the photo, and in between the two otter front prints there are two dog tracks, a front with a rear just to its left, oriented to the right. The otter prints in the loping array, especially the left hind print at the far left, show the clearly outlined toe and middle pads and the smooth heel areas characteristic of bare skin. And incidentally, the rear dog print also has cleanly outlined toe impressions made by toes of bare skin.

We have two species of foxes, one with furred feet and the other without. The unfurred feet belong to the gray fox. In the cluster of gray fox prints in the next photo the rightmost and leftmost tracks were made by front feet, and the clearer of the two tracks in the middle was made by a rear foot. The distinct margins bordering the toes of both front and hind prints, and the middle pad of the front track on the right, are evidence of skin covered pads.

Red foxes have thick fur covering almost all of the undersides of the feet, and the blurring effect can be seen in the next photo (rear print on the left, front print on the right, and direction of travel toward the left). But here things get a little complicated. I said the feet were “almost” completely covered because there are two places that don’t grow fur. In the middle pad of the red fox’s front foot there’s a curved ridge, sometimes called the bar, which is unfurred–it can be seen in the front track at the lower right in the photo. There is also a small, hairless oval near the tip of each toe on both the front and the hind feet. In the photo these bare regions show as dark spots in the tips of the toe impressions.

Although tracks in snow usually reveal the presence of fur, mud is better for rendering the fine details. In the next photo you see the front print of a red fox oriented to the right. The fur pressed into the mud shows as thin striations in the toe and middle pads. The unfurred parts of the foot, the bar in the middle pad and the small hairless ovals in the toes, interrupt the striated texture left by the hair.

Felines are characterized by bare toes and middle pads, so their tracks have the cleanly outlined pads of other animals with unfurred feet. But bobcats have separate, interesting feature connected with fur. The fur covering the tops and sides of the feet is very thick, especially in winter. When snow conditions are right this fur pushes into the snow around the outside of the track, creating what’s called a hair halo. In the photo below of a bobcat’s right front print (oriented toward the right) the hair halo shows as a sloping bevel outside the toes.

Hair halos aren’t generally seen in house cats–or canines for that matter. In the next photo you see a coyote front print bordered by abrupt walls rather than a sloping bevel. The inclines at the front and back of the track are entry and exit disturbances, and the grains of snow scattered over the track are due to a light snowfall which must have ended just after the track was made. And as a side note, only bare toes could have made the very distinct and cleanly outlined toe impressions you see in the photo.

Do furred feet help in survival? Probably, since thicker fur over the whole body develops as winter approaches. Are furred feet essential to survival? Probably not, since only some mammals have this trait. For the tracker, it’s enough to recognize furred feet as an interesting characteristic and to appreciate the effect fur has on tracks of some animals.

Getting a Good Night’s (or Day’s) Sleep

All animals need to sleep, but the evidence of sleeping creatures can be hard to find. There is, however, one animal whose beds are often more visible–deer. And there are details in deer beds that can make for some interesting insights.

Deer beds are oblong or oval and measure between 25 and 45 inches in length. Mature bucks make beds covering the upper part of the range, while does and yearlings generally fall toward the lower end. But beware: there may be outliers in both sexes. The oval shaped form shown in the photo below was made when the body of a sleeping deer melted the light dusting of snow and compressed the leaves.

But the shape in the photo above isn’t a perfect oval. About half of the outline is evenly curved (the part in the upper left quadrant of the photo), and the remaining part (in the lower and right-hand area of the photo) is more irregular. This is because deer curl up when they sleep–the back is curved, the legs are drawn together, and the head is tucked back along the body. This creates two kinds of outlines: a smooth curve where the back is and a more broken outline where the legs and head lie. The sleeping fawn shown in the photo below (positioned similarly to the way the deer would have been in the photo above) is a perfect example.

Even without snow to emphasize the outline, the position of the animal can often be determined. In the photo below the dried and compressed leaves that were underneath the deer’s body reveal the oval shape. The orientation is similar to the bed and the fawn in the photos above, and the back of the deer formed the smooth curve in the upper left quadrant. In the upper right part of the photo the leaves are drier but not pressed down–perhaps the deer shifted its head occasionally as it slept. The uneven boundary at the lower right was made by the tucked legs.

Both of the beds in the preceding photos were on forested slopes with little understory growth. This, combined with their location near feeding areas, suggests that they were night beds, convenient for episodes of feeding but with good escape routes should danger threaten. Day beds are more likely to be in areas with thick cover. and may or may not be near feeding areas. The animals usually bed down for most of the daylight hours, and day beds may or may not be near feeding areas.

If an animal shifts its position while it rests or a bed is used more than once, the bed may not be oval. Two beds can be seen in the tall grass shown in the next photo. The compressed area in the foreground was used repeatedly and possibly even by more than one deer. It’s about twice the size of a normal bed, and its shape is anything but oval. The same is true for the bed in the background (in the upper right of the photo). These were probably day beds, because they weren’t close to areas normally used by people and the tall, weedy growth provided excellent cover.

Of course, the best recording medium for deer beds is snow. In the photo below the deer’s orientation was the same as in the bed shown above, and the curve of the back is evident in the upper left quadrant. The outline isn’t complete because it was disturbed by deer and dog tracks where the upper back and neck would have been. The interior of the bed is mostly a concave hollow–this is where the animal’s back and side rested on the snow. The deer’s hocks and lower legs formed a trough in the lower center of the photo, and its knees dug into the snow toward the upper right. If you were at the scene and were able to feel the concave area, you would find that the surface was hard and icy. This is because the snow is first melted and compressed by the warmth and weight of the deer’s body, and then refrozen after the animal stands up and cold air hits the bed. As the animal rises it often steps in the still soft interior of the bed, leaving what’s called a stand-up track. There’s a nice one just to the left of the hock impression.

I’ll end this post with an interesting story. I live near the edge of a small village, and deer often walk through my side yard, heading toward the village center in the evening to feed and back out toward the surrounding fields and woodlots in the morning to bed down for the day. One morning a few months ago, I watched a deer walk through my side yard in the opposite direction from normal, toward the interior of the village. I was intrigued, so later that day I followed the deer’s route toward a hedgerow that separates my back yard from my neighbor’s. I was startled when a deer jumped up out of the weedy growth and galloped away. You can see the hedgerow in the next photo.

The growth was quite dense, and it took some effort to push through it toward the place where the deer seemed to have come from. As I got closer I could see the bed through the vegetation (shown in the next photo).

I struggled closer yet and there it was–a definite deer bed.

I took the next photo standing right next to it.

The compressed area was a little bigger than a normal bed and more oblong than oval, which told me that the deer had used the bed several times. Until I discovered it, the spot was a perfect day bed, well shielded and undetected by the humans in the back yards which surrounded it.

Although I’m keeping my distance, I don’t think that particular deer has been back to my hedgerow. But maybe a different animal has discovered the spot. The deer still walk through my side yard in their dusk and dawn travels, and as my scent fades from the area it may again attract a deer seeking a good day’s sleep.

A Backyard Mystery

There’s been a bare spot in my backyard since early summer when the mower hit the dirt and scraped off the vegetation. It looked unremarkable until early July, when I noticed that the soil had been disturbed. I wondered what kind of creature would have been doing something–and what it would have been doing–in some dusty soil in my backyard.

One morning–quite early–I was looking out my window, and I saw a cottontail rabbit lying stretched out on the denuded spot. It wasn’t stirring up a cloud of dust the way birds do in dust baths, but occasionally it wiggled and pushed its body from side to side with its back feet. Between movements it just lay on its belly. Eventually it jumped up and hopped away.

When the light was better I went out with my camera and photographed the fresh signs, shown in the photo below. There were gouge marks (there’s one at the lower left of the close-up photo below), and I could see soil that had been scattered on top of vegetation (check out the plants at the upper right). Fine dust penetrates into fur or feathers and helps control parasites, so the dry soil made an ideal dust bath. So mystery solved, right? Not quite.

In the area just beyond where the rabbit had been I saw more disturbances, but these didn’t look the same. You can see them in the upper part of the next photo. They looked more weathered than the fresh signs of dust bathing I found after I saw the rabbit. But without more to go on I was at a dead end.

A few rainy days changed the soil texture, and the dust bath changed into a patch of wet dirt. But I kept watching, hoping to see what else happened in that bare area. Once a squirrel came by but didn’t do any digging and didn’t stay long. Finally, I saw the culprit–a flicker digging for ants. It poked and shoveled and as it attacked the dirt it scattered clumps of soil in all directions. In the next photo you see the craters and beak gouges just after the flicker made them. This was done when the soil was moist, so the texture is coarse rather than fine and dusty. Bits of dirt lie on top of the vegetation around the digs.

I thought at first that the flicker preferred mining for ants in bare dirt, but then I noticed small holes in areas with plant cover, especially moss. In the next photo you can see the openings in the moss made by the bird’s beak. Even if I hadn’t seen a few ants, I would have guessed that the flicker had detected a subterranean ant colony, because the flicker digs were spread out over several square feet.

Since my observations of the rabbit and the flicker it’s been quite rainy, and the surrounding plants have grown in over the bare patch. The chance conditions that brought each creature to the spot were different, and they may not be repeated. But my next interesting sighting could happen any time, so I’ll keep looking out my window at every opportunity. And when the next interesting thing happens I’ll hurry out to see what kinds of signs were left.

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.

The Secret Lives of Voles

Unless you own a cat with an inclination toward hunting, you’ve probably never seen a vole. These little rodents prefer to lead their lives out of sight, spending their time hidden in thick grass, tunneling in forest leaf litter and humus, or sheltering beneath the snowpack. They are sought out by many predators, but their secretive habits and prolific rates of reproduction allow them to thrive.

There are a number of vole species, and they all have chunky bodies, short legs, and stubby ears, like the meadow vole pictured in the photo above. As the name suggests, grassy fields and meadows are the domain of meadow voles. They’re also known as meadow mice or field mice, although wild mice (white-footed and deer mice) differ from voles in their lifestyles and dietary habits. Another common vole species is the woodland vole (also called the pine vole), which prefers forests but also frequents orchards. Voles are not to be confused with moles, which are insectivores, not rodents.

When conditions are right, voles do reveal their presence to us. In winter this can happen when the snow forms into icy crusts which the small creatures can’t penetrate. In the next photo the hard crust was covered by a shallow layer of new snow, and voles (probably woodland), could only bulldoze their way through the softer top layer. Why the meandering pattern of grooves? The animals may have been searching for food, or for cavities leading to underground spaces. Woodland voles are more fossorial than meadow voles and often dig tunnels in the upper layers of forest soils.

When winter snows accumulate, voles find safety and plenty to eat under the snowpack. Meadow voles range throughout snow covered fields, creating runs that they use repeatedly as they search for food. The evidence of their travels shows up after the snow melts as grooves in the flattened grass thatch like those in the next photo.

The diet of meadow voles is diverse but usually includes grasses. Cut sections of grass like the ones in the next photo are often found after the snow disappears.

Another kind of evidence to be found in newly exposed vole tunnels and feeding areas is vole scat, which consists of tubular pellets like those in the central part of the next photo.

The construction of subnivean runs involves the removal of dirt and plant material from active runways, and once winter is past these appear as windrows of debris. The ones in the photo below were made by a meadow vole. Woodland voles leave similar piles of dirt and humus on the forest floor.

When the snow is deep voles are able to access an additional food source, the inner bark of woody plants. Large chews made by voles can be seen on the white pine in the next photo–this would have happened when the animals were safely hidden by deep snow. The thin layer of living cambium cells is the only nutritious part, and fragments of the inedible outer bark sometimes accumulate below the chews.

Tiny tooth marks, like the ones on the buckthorn stem in the next photo, can sometimes be seen.

In the warmer months vole sign is harder to find, but if you wander slowly through grassy fields and meadows you may make some interesting discoveries, especially when vole populations are high. Small openings like the one in the photo below are the first clue to the presence of the shy creatures.

Vole runs are usually completely hidden by the covering of grass and thatch, but if you spread the grasses backward from an opening, you’ll expose the corridors used by the voles.

If you’re very alert as you walk through a field, you may find a meadow vole nest. I found the one shown below in mid-May, so it was only partially hidden by new grass growth. Later in the season they’re much harder to find.

In the next photo you see another unoccupied nest that I opened to show the finely divided fibrous lining. Winter nests like this one are well insulated against the cold. Exits to the tunnel network can be seen at the upper left and the lower right.

Vole populations go through cycles of abundance and scarcity, and when numbers are high, changes in behavior may bring the animals into the open. During a population boom you may–if you stand very quietly–catch a glimpse of a vole as it pops out of a tunnel. But whether or not you ever have that experience, there’s always evidence of the presence of these animals to be found if you know what to look for.

Lean Times for Squirrels

With the coming of spring nature is breaking its winter dormancy, but we’re still a long way from the bounty of summer. In some years the food stores that carried squirrels through the winter are depleted by the time spring comes around, and when this happens the new season may bring food stress instead of abundance. This is especially true if there’s a new litter of young to raise. But over the last month or so I’ve been finding evidence that squirrels are still making use of winter’s leftovers. Digs like the one in the photo below show where an edible item was extracted. I’m confident that this was a recent dig, because the leaves around the dig were still pushed up and the soil was freshly disturbed. If this were an old dig the heavy rains we had earlier in the month would have flattened the leaves and washed the soil back into the hole.

Without further investigation it’s hard to see what the squirrel was after. When I carefully removed the leaves (as shown in the next photo), I saw not only evidence that this was a fresh disturbance but also evidence of what was removed: a firm-walled cavity that was the perfect shape of an acorn.

More proof that buried acorns are still being utilized by gray squirrels is shown in the next photo. The brightness of the acorn remnants indicates that they were not more than a few weeks old when the photo was taken in mid-April.

Instead of acorns, red squirrels rely on conifer seeds for survival over the winter, and in many locations they are still making use of the stores of cones that were gathered last summer. A few weeks ago I found a spot (shown in the next photo) where a red squirrel had extracted the seeds from a red pine cone. The bright colors of the cone core and cone scales show that the feeding activity occurred recently. Additional corroboration of recent feeding comes from weather observations. In early April we had several intense downpours, and if the cone remnants had resulted from winter feeding the heavy rain would have washed them off the log.

I’ve noticed lots of recent feeding on white pine cones this spring. In the next photo you see a midden at the base of a large white pine. The feeding perch was on the branch at the top center, and entrances to the underground storage areas can be see a little below on both sides of the feeding perch. Again, the brightness of the discarded cone scales suggests recent feeding.

A close-up of one of the tunnel entrances shows dry material that was brought out of the storage space as the resident red squirrel retrieved stored cones–more evidence of recent activity.

Even if winter leftovers are still available they may have suffered some deterioration, forcing squirrels to seek supplemental foods. A squirrel harvested the boxelder twigs shown in the next photo and fed on the buds. The end buds are missing from the twig on the left, and several lateral buds were taken off of both twigs. Why weren’t all of the buds eaten? Perhaps because there were so many buds and twigs available that the squirrel could be haphazard in its feeding.

Grubs are common in grassy areas, especially in suburban lawns, and they can be important in squirrels’ spring diet. I found the dig shown below in my back yard.

Squirrels are also known to eat conifer needles. In the next photo you see white pine needles that were fed on by a red squirrel. Compared to acorns and grubs, conifer needles don’t seem very nutritious, but they may fill a need for nutrients that are otherwise lacking.

The rising sap of deciduous trees is another source of calories, and it usually becomes available just when squirrels need an energy boost. A red squirrel tapped the black birch sapling shown in the photo below. There’s a fresh bite (with a slight greenish hue) about midway up the stem, and old bites from previous years can be seen above and below. There’s another fresh bite along the side of the stem near the top. Squirrels are expert sap harvesters and use an efficient method to extract the maximum benefit. Rather than lap up the dilute sap, the clever animals let the water evaporate and return the next day to eat the concentrated solids.

Some foods may become less available in spring, but other dietary options are simultaneously becoming more available. Squirrels are flexible in their eating habits, and this is the perfect time to observe their ability to make use of a wide range of foods.

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.