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MAMMAL TRACKS AND TRACK PATTERNS

Mark Elbroch

To better visualize and understand tracks on the ground, we must study whole animals, starting with their feet. Feet make footprints, and footprints are the building blocks of track patterns. Here we begin with the morphology of mammal feet, then move on to study the morphology of mammal tracks, then look at how mammals move, and finally delve into the science and interpretation of mammalian track patterns on the ground.

Foot Morphology

Bones

Thousands of years ago, the first mammals had five toes on each foot (Hildebrand and Goslow 2001). Over great lengths of time, through evolution and specialization, feet and legs evolved and became more varied. The foot structure of extant shrews is believed to reflect that of the first mammals.

The skeletal structure of the forefeet consists of the carpal bones, metacarpal bones, and phalanges, while that of the hind feet consists of the tarsal bones, metatarsal bones, and phalanges. The original mammals were plantigrade, meaning that they were supported by all the bones of their feet while they were moving, whereas today's mammals have diversified in structure and function. In general, modern plantigrade animals have relatively short limbs and prefer to walk, because the construction of their feet is not well adapted for jumping or running for long distances. In contrast, long-distance runners have long limbs, and the area of their feet that is in contact with the ground is as small as possible. To obtain a firm grip on the ground, the foot must exert the greatest possible pressure to dig into it. Because pressure is equal to force per unit area, the contact area must be as small as possible to ensure the greatest possible pressure. For example, in deer the second and fifth toes are reduced to form dewclaws, and their weight is supported on the third and fourth toes; thus, they have long legs and small feet relative to their size.

Bears and humans are examples of extant plantigrade species. Digitigrade species, such as felids (cat family) and canids (dog family), support themselves on the distal ends, or heads, of the metacarpal bones and the phalanges of the forefeet, and the distal ends of the metatarsal and phalanges of the hind feet. Even-toed unguligrade species such as deer and bison, and odd-toed unguligrade mammals such as horses, walk on the distal phalanges of the third and fourth toes, the equivalent of our toenails.

In animals with five well-developed toes (or digits), they are numbered from 1 to 5 beginning with the innermost toe, that which corresponds with the human thumb (see the accompanying illustrations of woodrat and river otter feet on pages 33 and 34). The third toe in most mammals is the longest and largest, followed in order of size by the fourth, second, fifth, and first. In some mammals the first toe is tiny and only makes a weak impression, or none at all. If all five toes are showing and the shortest toe is on the left side of the footprint, the track was made by a right foot. If only four toes are showing and the shortest toe is on the left side of the track, then it was made by a left foot.

Big-eared woodrat feet.

With evolution, however, some species developed structures and gaits that required different foot structures. Bang and Dahlstrom (1972) note that many species, such as deer, began to evolve longer bone structures to aid in running, while at the same time losing toe 1 altogether to become more streamlined.

Pads

Tough horny layers of skin cover elastic masses of connective tissue that protect bones and other foot structures from rough ground. In most mammals these pads are naked (rabbits are an exception), and the spaces between these pads are filled with fur (some species have completely naked feet, like Striped Skunks). The thick toe and metacarpal or metatarsal pads that compose the “palms” of each track are covered in sweat glands and deposit scent with each step (see the accompanying illustrations of river otter feet on page 34).

River otter feet.

The pads at the tips of the toes are called the digital pads. The pads that form the “palms” of footprints are called the metacarpal pads on the front feet and the metatarsal pads on the hind feet, and they correspond to the respective bones that they protect. In many animals, such as Bobcats and Coyotes, the metacarpal pads of the front feet and metatarsal pads on the hinds are fused to form one large pad. In addition to these, some animals have one or two additional pads to the posterior. The larger pad on the front feet is the carpal pad and covers the carpal bone. When there is a second, it is another metacarpal pad linked with a reduced and sometimes redundant inner digit (see the figure of the woodrat on page 33). In mammals, carpal pads are found only on the forefeet.

Feet

If the front end of an animal is larger and heavier than its hind end, the forefeet will be larger and broader than the hind feet. The forefeet support the head, chest cavity, and forequarters of the body, which are often heavier than the hindquarters. Some mammals, such as bears, rodents, and otters, have larger hind feet and more massive hindquarters than forequarters.

The forefeet are generally rounder in shape than the narrower hind feet, because the forelegs are almost perpendicular to the ground while the hind legs are positioned such that the heel is held at an angle to the ground. A cylinder that is perpendicular to a plane has a circular cross section, while a cylinder that meets a plane at an angle has a larger, elliptical cross section.

Evolutionary adaptations of feet reflect specific types of locomotion, as well as their use in some animals as tools or weapons. Predators have soft pads for stealth, and some have sharp claws to hold down their prey, or short, blunt claws that aid in traction. Some animals have claws that are tools for digging, and others that are adapted for grooming. Feet adapted for soft, muddy ground require a large contact area for support. Sharp, pointed hooves can dig into soft, sandy terrain to obtain a firm grip, while hooves must be rounder to better grip firm ground. Aquatic mammals often have webbed toes or a stiff fringe of hair to increase the surface area of their feet and therefore the resistance with which they pull themselves through the water. Animals adapted to arboreal environments have sharp claws to dig into the bark of trees, or opposable joints or toes to grasp branches.

Male Bighorn Sheep, approximately seven years of age. Note the huge disparity in size between the front and hind feet.

The more massive ungulates, such as American Bison, have broad, round hooves, while lighter deer have slender, narrow hooves. Very sharp, pointed hooves are an adaptation for speed, especially in soft, sandy substrate, and act like spikes to prevent slipping. Pronghorns, which prefer open terrain, have to rely on speed to escape being captured, and have sharp, pointed hooves. While habitat specialization results in foot structures with certain advantages, it also places the same animal at a disadvantage in alternative habitats. For example, the large, webbed feet of beavers are ideal tools for aquatic living but cumbersome obstacles while negotiating land at speed.

Track Morphology

Most mammal tracks are composed of claws, digital pads, metacarpal or metatarsal pads (the palms), carpal pads and other heel structures, and the negative space in between these structures (see the figure on page 36). To start, study beautiful footprints in damp, slightly muddy earth, wet sand, a thin layer of loose dust on firm substrate, or a thin layer of fresh snow. In these conditions you will be able to see clear, complete tracks and better understand them. An individual animal's footprint will vary according to its age, mass, sex, condition, and the substrate in which it steps, and these nuances can only be recognized once you have enough experience with a species to know what a “normal” track might look like.

North American River Otter tracks.

The specific details of track morphology for different species are covered in depth in the species accounts at the end of the book. However, as an introduction to the topic, consider these eight key questions to species identification and some examples of why they might be useful:

1. How asymmetrical is the track? Track symmetry is the comparison between the right and left sides of the track. In a perfectly symmetrical track, the left and right sides align and match perfectly. However, nearly every mammal track is asymmetrical to some degree, and it is the degree of asymmetry that will be useful.

For example, the front tracks of Bobcats are often much more asymmetrical than the hind tracks. The opposite is true for river otters, where the front track often appears more symmetrical than the hind track.

2. How many toes can you see in the track, and are they all on the same plane? Shrew tracks have five toes on both front and rear feet, and they all tend to register in footprints. Hares have five toes on their front feet (although the innermost toe is tiny and easily overlooked in the track or does not register at all) and four toes on their hind feet. Canid and felid tracks tend to register four distinct toes, even though they have five toes on their front feet; digit 1 on each front foot sits on a higher plane on the inside on the leg and registers when they run.

The loping tracks of a river otter. From right to left, right front, left front (below)–right hind combo, left hind. Compare the relative sizes and symmetries between front tracks and hind tracks. Study the shapes of the digital pads and claw marks.

3. What is the shape of the digital pads? Teardrop-shaped toes are characteristic of felids, especially females, as well as the digits in mink and smaller weasel tracks. In Fisher tracks the bulbous toe pads are separate from the metacarpal or metatarsal pads, while in raccoon tracks the cigar-shaped toes tend to be connected to the metacarpal or metatarsal pads.

4. Can you see nails? Look closely, because sometimes nails register as tiny pricks in the ground, as in Gray Foxes; in other instances they are massive and difficult to miss, as in American Beavers. Are they sharp or blunt? Are they coming straight out from the toes, or do they curve down from a location on top of the toe? In deep snow, Bobcat tracks often show claws, which register in the wall of snow in front of the track, on a plane higher than the digits. Domestic Dog tracks tend to have large, blunt nails in comparison with the sharp, thin nails of Coyotes. The outer nails of Coyotes also often register so close to the inner toes that they are overlooked.

5. What is the overall shape of the metacarpal or metatarsal pads (palms)? In some animals, including canids and felids, the metacarpal pads have fused together to form one palm pad. Characteristics of felid tracks include an anterior (leading) edge with two lobes, termed bilobate, and a posterior edge with three. The palm pads of felid tracks also tend to fill the overall track. This means that, in terms of area, they compose a larger proportion of the track than do the palm pads in tracks of canids. In both canids and felids, the palm pads are much larger on the front feet than the hind.

A comparison of the negative space in the front feet of three carnivores.

6. Can you make out a heel in the track? All mammals in the order Rodentia, from mice to beavers, excepting the porcupine, register two round pads behind their metacarpal pads in their front tracks. One is a carpal pad on the heel and the other a modified metacarpal pad. In the front tracks of weasels, Ringtails, and bears, a carpal pad can be found, and in some mammals the heels of the hind feet register only as impressions.

7. Can you see hair in the track, and if so, where? Rabbits lack naked pads and have completely furred feet. Red Foxes have very small toe pads surrounded by lots of hair, and Striped Skunks have no hair between their toes at all.

8. What is the shape in between the toes and palm pads, here called the negative space? Look for an “X,” “H,” or “C” shape in felid and canid tracks. The front tracks of Gray Foxes and Domestic Dogs tend to show an “H,” while those of Red Fox and Coyote show an “X.” Look for a “C” in the front tracks of cats.

The Effects of Substrate

Substrate is a catchall word for what an animal has stepped in, whether it be sand, mud, snow, or grass. The depth of substrate, which is reflected in the depth of the print, has an enormous influence on the appearance, size, and shape of the track, as well as on how the animal moves. In shallow substrates, like moist, hard sand, animals move easily and therefore tend toward their normal gaits. In deep or slippery substrates, animals tend to slow down. The conditions of different substrates in which an animal may step are infinite and thus create great challenges for the tracker.

The toes on soft feet are rounded in soft ground but will spread out on firm ground and appear larger and different in shape. On very hard ground only the tips or edges of hooves may show, or only the claws of padded feet. Movement and activities also change the shape of a track. For example, sliding feet may give the impression of elongated toes, and twisting and dragging feet may partially obliterate track features. The forefeet and hind feet may also be superimposed, so that the toes of one foot may be confused with those of another. Running animals may also splay their feet. Certain species have tremendous control in how much they spread their feet. For instance, cats walking in soft mud or wet snow splay their feet and leave tracks nearly twice as large as those left when on firm ground.

To illustrate the effects of substrate and behavior on tracks, compare the following three photos. In this picture, a Bobcat has stepped in firm mud and its resulting tracks are clean, tight, and easily recognizable.

Here a Bobcat is walking normally in soft, deep dust that obscures the edges of the tracks, making them more difficult to identify.

These are the tracks of a Bobcat stepping in soft, moist mud, and the cat responded by spreading its toes (resulting in splayed tracks) and in some instances, extending its claws to improve traction. Three radically different sets of tracks, all made by the same species.

When loose windblown sand has accumulated in a footprint that was made in damp or wet sand, it is sometimes possible to carefully blow away the loose sand to reveal the features of the footprint underneath. Footprints in mud may in fact be preserved for quite a long time underneath a layer of loose sand or leaf litter. When leaves are covering the track, or even when the animal has stepped on top of leaves, they can be carefully removed to reveal the track. When studying tracks in loose sand or other difficult substrates, you should try to visualize the shape of the footprint before the sand grains, snow, etc., slid together to obliterate the welldefined features.

What Else Can Tracks Tell Us?

While species can be identified by characteristic features, there also exist individual variations within a species. These variations make it possible for an expert tracker to determine the sex as well as estimate an animal's approximate age, size, and mass. A tracker may also be able to identify a specific individual by its footprint. For example, Stander et al. (1997) tested these abilities in four Ju/'huan trackers in Namibia, and they correctly answered 557 of 569 questions. The Ju/'huan team correctly identified the species that made the track in 100 percent of tests. They correctly identified the relative ages of Cheetahs and Leopards (that is, cub, juvenile, young adult, adult) 100 percent of the time in 30 tests, but the relative age of African Lions only 34 out of 39 times (87 percent). Their mistakes were all in calling a subadult animal a full adult. They correctly identified the sex of Lions in 100 percent of 39 tests, Cheetahs in 12 of 13 tests, and Leopards in 16 of 17 tests. It is also in principle possible to identify an individual animal from its track. It may have a unique way of walking or a particular habit that distinguishes it from other individuals. The Ju/'huan trackers correctly identified the individual Lion, Leopard, or Cheetah by its tracks in 30 of 32 tests (96.4 percent).

Determining the Gender of an Animal

Many mammal species show characteristic sexual dimorphism, meaning that one sex is significantly larger and heavier than the other. In the case of California's mammals, it is likely to be the male that is larger. Sexual dimorphism is especially prevalent and blatant in California's carnivore species, including canids, felids, pinnipeds, mustelids, and bears, where adult males are always the larger sex. In species where dimorphism is especially pronounced, such as Cougars and Fishers, the tracks and trails of adult males and females can quite easily be differentiated. In other species, such as river otters and skunks, sexual dimorphism is minimal, and therefore track size alone is not as useful a character in differentiating males from females.

On the left are the tracks of a mature male Fisher, and on the right the much smaller tracks of an adult female.

What follows are some useful track characters to consider in determining the sex of select carnivore species. With considerable aid from numerous African trackers who have determined how to sex Leopard and Lion tracks, one of us (Mark Elbroch, unpublished data) has developed this list to aid researchers in identifying the sex of Cougars from their tracks. He has identified the sex and relative age correctly in 100 percent of trials with wild Cougars (n = 28), where the animal was subsequently caught as part of larger research efforts to verify the interpretation. The ability to reliably determine the sex of Cougars from their tracks is widespread in Cougar houndsmen that hunt them for sport, with depredation permits, or for a living, and this skill would be a valuable one to document further and quantify.

When studying the following track characters, you should build a case for a particular gender; that is, determine how many characters indicate female and how many male. Sometimes a track yields conflicting evidence, and the gender cannot be determined with certainty.

The left front and hind (lower right) tracks of a young adult male Cougar, approximately three years of age, which means he still had a bit more growing to do.

Track features: (1) Tracks of adult male Cougars are larger than those of adult females, and the areas of the metacarpal and metatarsal pads are also larger. Measure the width of the metatarsal pads (palm) in the hind track, and use a cutoff of 50 mm to determine sex. This is a very reliable tool in determining the sex of Cougars, especially when the other characters described here provide conflicting evidence. This method has also been used by other researchers (Shaw 1979; García et al. 2010). Only the odd female will approach this cutoff, but adult male palm pads typically start at 53 mm wide and can be much larger. García et al. (2010) also report that in captive Cougars they used to study tracks, the “shape of the heel pad in males can be described as relatively narrow in the middle, while that of females is more extended in this zone.” (2) The toes of males in both front and hind tracks are blockier than females; the toes of females are more slender and more teardrop-shaped. (3) The front tracks of males are almost always wider than long and are at least as wide as long; the front tracks of females are often narrower than long or as wide as long. (4) There is a smaller area of negative space between the metacarpal pads and the toes in the front tracks of males than those of females. It is as if the palm fills the track more in male tracks than in female ones. (5) The negative space between the metatarsal pads and the toes in the hind tracks of males is much smaller than that found in hind tracks of females; typically male palm pads nearly touch the toes, and in females there is a significant rectangular gap. (6) There is less space between the toes of the hind tracks in males than in females. (7) The hind track of males is generally narrower than long, but not to the degree that the hind tracks of females are.

Front and hind (above) tracks of an adult female Cougar, with penny for scale.

Trail characteristics: (1) The strides of females (measured from left hind track to left hind track, or right to right) average about 36 in. and the strides of males about 40 in. (Boone Smith, personal communication). (2) The width of walking trails is much wider in males than in females.

Elbroch has applied these same characters to other species, including Gray Foxes, Ringtails, Bobcats, American Minks, and Fishers. Preliminary results are very positive yet not so much so that we can say with certainty that they work all of the time. We encourage you to start gathering the data needed to develop these skills further, and the track and trail measurements from known-sex animals, so that we can begin to compile useful parameters for species in North America.

In hooved species, the relative weight difference between an individual animal's front and hind ends is proportional to the discrepancy in size between its front and hind tracks. In Bighorn Sheep and Mule Deer, where males are adorned with large horns or antlers, their front ends are much larger than their hind ends to support this additional weight; their feet and footprints reflect this discrepancy, and their front tracks are much larger than their hind ones. Female Bighorn Sheep and Mule Deer also have larger front tracks than hind tracks, but only slightly larger, and their front and hind tracks are much more similar in size. Females of both species carry their weight more evenly distributed between their front and hind ends than do their male counterparts. It is the larger difference between the length—and more often the width—of front and hind tracks of males that helps trackers determine an animal's sex. That difference in size between front and hind tracks of females is much smaller.

Carefully note the large disparity between the length and width of the front track above and hind track below in a mature Mule Deer buck.

The sexes may also be distinguished by association. The track of an adult in close association with a juvenile is probably that of a female with her young. Nursery herds may be identified by the presence of several young, or the absence of young may indicate a bachelor herd. When a species is gregarious, a solitary individual will probably be an adult male.

Determining the Relative Age of a Mammal

The relative age of an animal may be indicated by the size of the feet. The hooves of young deer will have sharper edges, while older individuals may have blunted hooves with chipped edges. Younger individuals with padded feet may have more rounded pads. Some animals have specific breeding periods. If it is known at what time of the year an animal is born and you know the relative growth rates for the species, a reasonably accurate estimate of a young animal's age can be made from the size of the track.

Here the larger track of the adult female Cougar on the left is easily differentiated from her five- or six-month-old kitten on the right. Through association, determining the sex of the adult is made easy, and with practice (and ample opportunity to see the animals responsible for making the tracks), determining the relative age of the younger animal from the size of its footprint is possible.

Track Patterns

Competent trackers complete two tasks in interpreting a series of animal tracks. First, they analyze the pattern of tracks on the ground so as to visualize how the animal was moving. Second, they interpret the behavior—the meaning in what they are seeing. The first task is more systematic and scientific, while the second is more speculative, relying more upon imagination. Let's take each in turn.

Gaits and Track Patterns

A gait describes the way in which an animal is moving; it is not a description of a specific track pattern. There will be numerous track patterns for each gait, depending upon the speed and behavior of the animal, as well as the anatomy and morphology of the species.

We must also be aware of the complications introduced by language differences. Trackers around the globe use different words to describe the same thing. Some people prefer words that describe track patterns on the ground, while others prefer terminology that describes the way an animal was moving (the gait). This book presents the vocabulary most widely accepted by trackers across the globe, and that which was used by Eadweard Muybridge (1957) in his pictorial presentation of Animals in Motion. This vocabulary provides you with visual information about how an animal is moving—which is crucial in envisioning and becoming that animal in advanced levels of tracking (Liebenberg 1990). But understand that no terminology is better than another. What's important when communicating with others about gaits and trails is that you are all envisioning the same motions.

Here we separate gaits into three categories:

1. Walks and trots in which the front feet fall at consistent, rhythmic distances from each other (created by keeping the spine straight and allowing the momentum to be driven by motion in the legs);

2. Lopes, gallops, hops, and bounds in which the front feet land in alternating short and long distances from each other (created by stretching and contracting the spine, in addition to moving the legs); and

3. Bipedal gaits in which animals move on only their hind legs.

Walks and Trots

Walking

Walking is a slow gait in which each foot moves independently, and at no point during a cycle of footfalls does the animal lose contact with the ground. We will arbitrarily begin with the right hind foot in our example. The right hind leg moves forward, and just before touching down, the right front lifts up and moves forward. For a moment, two feet are off the ground, and then the right hind touches down. The right front continues forward and then touches down. The left hind moves forward, and just before it touches down, the left front picks up and moves forward. For a second time in the cycle of footfalls there are only two feet in contact with the ground, and then the left hind touches down. The left front continues forward and then touches down. Immediately the cycle begins again, and the right hind picks up and moves forward. Rhythmically, this would sound like “1, 2, 3, 4, 1, 2, 3, 4, 1, 2….,” where each number is an independent footfall. Note that the rhythm is continuous—that is, without breaks or pauses.

A walking Polar Bear.

When an animal is walking, its hind foot may land in any relation to the front track made by the front foot on the same side of the body. Remember, the right front foot picks up and moves forward before the right hind foot touches down. For this reason, the hind foot may land exactly where the front foot had been placed—that is, atop the track made by the front foot, called a direct register—or even touch down beyond the front track, called an overstep.

A good portion of time during each cycle of footfalls, only one leg is lifted from the ground, which allows for three feet to support the animal while in motion. These three legs act similarly to the legs of a tripod, which is a sturdy arrangement that efficiently balances heavy objects, including wide animals with short legs.

Walking is common among almost all the animals. For many widebodied animals, such as beavers, porcupines, and bears, it is their most common method of moving. It is also the common gait for deer, elk, antelope, and all members of the cat family. Other species walk when exploring or while traveling in deep substrates, like snow, to save energy.

A variation of the walk is the stalk. In the stalk, only one limb moves at a time, but the order in which the feet move is the same as for the walk. The right hind foot moves forward and touches down. The right front foot moves forward and touches down. Then the same sequence occurs for the left hind foot, followed by the left front. The resulting trail is an understep walk, which means the hind tracks in each pair register behind the front tracks.

There are numerous variables to consider when interpreting speed from a series of tracks in a trail, but a general rule holds true for walking gaits. As an animal walks faster, its hind track will move over and beyond the front track in each pair. Therefore, an understep (where the hind track lies behind the front track) is probably a slower gait than a direct-registering walk where the hind lies on top of the front, and both are probably slower than an overstep walk, where the hind track registers beyond the front track. A fast walk is also called an amble. Remember, there are other variables to consider as well, such as depth of substrate, and the anatomy and morphology of the specific animal you are tracking. However, the speed can generally be inferred, up to a point, by considering the placement of the hind track in relation to the front, for an animal can only walk so fast before it must change gaits to increase speed further.

The direct-register walk of a female Cougar moving along a hiking trail in shallow snow.

The overstep walk of the same female Cougar, in which the hind tracks pass over and register beyond each front track.

The peculiar walking gait of the raccoon.

RACCOONS AND 2 × 2 WALKS. Raccoons walk in distinctive fashion. The front and hind legs on each side of the body move nearly simultaneously (called a pace), and they really stretch forward with their front limbs. In the resulting track pattern the tracks are paired, and each pair consists of a front or hind foot from one side of the body and the opposing front front foot from the other side of the body. This means that if in one pair you see a left front and a right hind track, the very next pair of tracks will be of the right front and the right hind foot. Refer to the illustrations.

This variation of the walk can also be altered by adding or subtracting speed. Look at each pair of tracks, and note where in relation to the front track the hind track registers. When raccoons walk slowly the hind track falls behind the front track, and when they walk quickly the hind track falls beyond the front track in each pair. The distinctive fast walk of the raccoon is trotlike in speed and unique to this species.

Trotting

Faster trots are easily differentiated from slower walks, in that a front and hind leg on opposing sides move together, as if joined by a cable. Rather than each foot moving independently, two legs move simultaneously, and there is a moment during each cycle of footfalls when the animal becomes airborne, completely losing contact with the ground. This vertical component is easily seen in any canid, from foxes to Domestic Dogs; there is a little bounce in their common gait. This means that as the right hind foot shifts forward in the air, so does the left front foot. Just before the right hind and left front are placed down, the right front and left hind feet push off, maintaining forward momentum. Then, just before the right front and left hind touch down, the animal pushes off with the right hind and left front feet. The cycle begins all over again. Rhythmically, the beat is a continuous, unbroken 1, 2, 1, 2, 1…, where each number is two diagonally placed feet landing simultaneously.

The common gait of canids (members of the dog family) and many voles is the trot. Many other species also use trots as a travel gait, including badgers, Mule Deer, American Black Bears, and members of the cat family. Bighorn Sheep tend to trot on flat ground, where they are at greater risk of predation.

The classic 2 × 2 pattern created by a walking raccoon is a distinctive character that aids in their identification.

A trotting wolf.

A Domestic Dog illustrates the side trot.

Direct-register trots, in which hind tracks are superimposed on front tracks of the same side of the animal, are common in many species. Hind feet land exactly upon the recently made front tracks, as the front foot and opposite hind pick up just before the alternate pair touches down. The forward momentum of the animal carries the hind foot directly over the track just made by the exiting front foot on the same side of the body.

The perfect straight line created by a trotting Coyote—moving away from the photographer.

As with walking, speed estimates can be inferred by the position of the hind foot in relation to the front track. Direct-register trots are theoretically slower than overstep trots, in which hind tracks in a given pair register beyond the fronts. Overstep trots are achieved by species in different ways. The hind foot can only move forward so far before it collides with the front foot of the same side. Animals typically overcome this obstacle in two ways. Canids tend to use the side trot, or crab, and trot with their entire body at an angle; they kick out their rear end to one side. In this way the hind feet pass to one side of the front feet so as to move at a faster pace. When an animal is using a side trot, all the front tracks appear on one side of the trail, and all the hind tracks on the other side; the hind tracks are also slightly forward of each front track in each pairing. This unique gait and track pattern is easy to find along Coyote, Wolf, and Red Fox trails; Gray Foxes very rarely side trot.

The side trot of a Red Fox in light snow. On the left side of the trail are all of the hind tracks, and on the right are all of the front tracks.

A Caribou illustrates the straddle trot.

Another option is to kick each hind leg out to either side of the front legs, and this is called a straddle trot. All the canines use this gait, but it tends to be for short sections of trail and most often is a transition from a direct-registering trot to a side trot. However, Gray Foxes use this gait very often, as do Mule Deer and several shrew species. The final option to successfully overstep trot involves a longer airborne time, allowing the hind feet to glide over the front tracks with forward momentum, as seen in lizards and occasionally other animals. This last option is rare in mammals but is sometimes incorporated into dominance displays and aggressive interactions.

Some lizards can trot in the technical sense, and achieve high speeds, while other reptiles and amphibians use a gait that simultaneously exhibits characteristics of both trotting and walking. Most turtles and tortoises are so wide and heavy that they move each foot independently, as described under walking above, so as to benefit from tripod support from their remaining three legs. Others, including salamanders, walk with their opposing (diagonal) front and hind limbs in synch—as described under trotting above. However, unlike trotting animals, they never leave the ground when moving in this manner, and their movements often appear exaggerated as they curve their spines side to side to increase speed. Note, this is why it is impossible for a salamander to completely direct-register walk; the right front foot is still on the ground when the right hind comes in behind, and therefore blocks it from moving any farther forward. For this slower gait, we suggest the term diagonal walk to differentiate it from trotting. In a diagonal walk the animal remains in contact with the ground yet is propelled forward by diagonal limbs moving simultaneously.

Lopes, Gallops, Hops, and Bounds

Lopes and Gallops

Lopes and gallops are very similar gaits, and the fastest gaits for mammals. During lopes and gallops, each foot lands independently of the others but in rapid succession. During both gaits the animal becomes momentarily airborne, just after pushing off with the front legs, but during gallops there is a second point at which the animal is in the air, just after pushing off with the hind legs. Not only is it difficult to catch this second, short flight when watching an animal move, but it is also challenging to distinguish between lopes and gallops when interpreting track patterns on the ground.

A Caribou in a slow lope.

A loping Wolverine–also called a 3 × 4 lope.

A galloping Bobcat.

There are two possible sequences in which the feet touch the ground during lopes and gallops. If they land in a circular fashion—left front, right front, right hind, left hind—it is called a rotary lope or gallop. If the order does not circle the body but instead cuts across the body—left front, right front, left hind, right hind—then it is called a transverse lope or gallop. Rhythmically there is a three- or four-beat sequence for lopes, followed by a pause: 1, 2, 3, pause, 1, 2, 3, in which the number 2 is the overlapping strike of the second front and the first hind foot to touch down, or 1, 2, 3, 4, pause, 1, 2, 3, 4, pause, 1, 2…. Gallops produce a four-beat sequence, followed by a pause: 1, 2, 3, 4, pause, 1, 2, 3, 4, pause, 1, 2…Neither lopes nor gallops produce continuous rhythms, as are found in walks and trots.

When looking at track patterns on the ground, a lope typically becomes a gallop when both hind feet land beyond both front feet, but this is not always the case. If the order of tracks on the ground in a single set of four prints is front, hind, front, hind, then it is a lope. If the order is front, front, hind, hind, then it is more likely a gallop.

Similar to walks and trots, the placement of the hind tracks in relation to the front tracks betrays speed. As the pair of hind tracks moves beyond the pair of front tracks, this indicates a faster lope or gallop. Also note the distance between the groups of four tracks. In general, the longer the distance spanned by four tracks in a series and the shorter the length in between groups of four tracks (called the stride), the faster the animal is moving. At all-out speeds, some mammals will leave track patterns that look to the casual observer like trots, in that tracks are placed regularly and in a straight line. But each mark is a single track, rather than two.

Three particular lopes are characteristic of the mustelids, or weasel family. They are the 3×, 3 × 4, and 2 × 2 lopes. The 3× and 3 × 4 lopes are rotary lopes, in which a front and hind on the same side of the body may land in the same space, giving the impression of only three tracks in a set (the 3×), or land so that all four tracks are clearly evident (the 3 × 4). Hildebrand and Goslow (2001) show that weasels still have a front foot on the ground when the first hind foot touches down, and therefore this gait is a true lope.

A Fisher in a 2 × 2 lope.

The 2 × 2 lope is a transverse lope, although other than the order of footfalls it is very similar in body mechanics to the 3 × 4 lope. The same fluid arcing motion is used for both gaits. What is unique about the 2 × 2 lope is that the front feet pick up and the hind feet land directly upon the front tracks—creating a trail of paired tracks, where each set of two prints is actually a set of four, the fronts registering first and the hind feet registering directly on top of them. Meadow voles and smaller shrews also use this gait in deep snow. Based upon Hildebrand and Goslow's research on the 3 × 4 lope, we assume that a front foot is still in contact with the ground when the first hind touches down. Should we be wrong, then this gait would technically be a gallop.

Hopping and Bounding

The hopping and bounding gaits of rabbits and many rodents are different from lopes and gallops, in that the hind feet land and push off simultaneously, or nearly so. This is evident in the trail, because the hind tracks appear parallel to each other. Any local park should present ample opportunities to study squirrels using these gaits. Hops are similar to lopes, in that there is one moment when the animal is airborne during each cycle of footfalls, just after the hind feet push off. Bounds parallel gallops, in that there are two times when the animal is airborne during each cycle of footfalls—first after the front feet push off, and again after the hind feet push off.

The 3 × 4 lope of a Fisher in a dusting of snow.

The 2 × 2 lope of an American Marten.?

A hopping Snowshoe Hare.

A stotting Mule Deer.

The difference between the track patterns of hops and bounds is found in the relationship between hind and front tracks. When hopping, an animal's front feet land in front of the hind feet. Hopping is less common than bounding but can be observed in large voles, Muskrats, flying squirrels, and toads and frogs.

Hopping and bounding begin in the same way: the front feet either land as a pair (next to each other), or one after the other (one in front of the other), but in bounds the hind feet move forward beyond and to either side of the front feet. The front feet pick up as the hind feet pass to the outside, and there is a moment where the animal loses contact with the ground before the hind feet come down and push off again. This pushoff is followed by a second moment in the air, before the front feet touch down and the cycle begins again. Numerous species bound, including squirrels, chipmunks, and rabbits.

Stott or Pronk

An unusual gait used by Mule Deer, Pronghorn, Elk, and occasionally other mammals is the stott. In this bouncing gait, an animal pushes off with all four feet at the same time, and then lands upon all four feet simultaneously, or nearly so. Mammals moving in this way appear to be using pogo sticks. Although not as fast as the gallop, the stott is better suited to traveling quickly over broken terrain, as well as allowing an animal to respond to external stimuli more quickly and to change direction when its feet hit the ground.

The trail of a stotting Mule Deer.

The bipedal hop of a kangaroo rat.

Bipedal Motion: Gaits on Two Legs

Bipedal Hopping

Both hopping and skipping are saltorial motions in which the front limbs remain elevated off the ground, and the resulting track patterns include paired hind footprints. Few mammals use bipedal motion, and in California the most likely culprit will be a kangaroo rat or kangaroo mouse. Birds, too, hop and skip. In hopping trails, paired hind tracks appear right next to each other, or nearly so, and the gait is the typical kangaroo-style hop. This pattern is possible because both hind feet hit the ground simultaneously. Technically, feet would only truly hit simultaneously if the feet were placed exactly next to each other, or the animal were coming straight down. However, for our purposes we'll use the word “simultaneously” to mean at the same time, or nearly so.

Bipedal Skipping

In skipping trails, tracks are also paired, but each hind foot lands completely independently of the other. Looking at the trail pattern, a hop becomes a skip when one hind foot registers completely in front of the other hind track. When kangaroo rats skip, they stay very close to the ground and take very long strides. Their hind feet rotate forward, one striking down before the other, and as the body moves forward over this foot, the second foot touches down. Their momentum continues, propelling the body forward over the second foot. As the body continues forward, the first foot to have touched down lifts up behind the animal. Continuing forward, the second foot joins the first behind the animal, then the animal lifts off, and together the hind feet rotate forward to begin another cycle. Momentum is more horizontal than vertical, and very little energy is wasted in rise.

Interpretation of Track Patterns

Until now we have discussed how an animal is moving in the technical sense of which limbs are moving when and in what order limbs make contact with the ground. Next, we leap into speculative interpretation based upon our initial understanding of how an animal is moving, and ask ourselves why an animal is moving in a particular way. Because we can never know what an animal was thinking or exactly what an animal was doing at a particular moment (unless we actually witnessed the event), we speculate on its behavior and make our best guess. As in all aspects of tracking, we build a working hypothesis and test it as we continue to follow the animal. As we gather more information as we follow the animal, we either toss out our original hypothesis and create a new one, or continue to refine and support it.

Natural Rhythms and Energy Efficiency

Gaits and their associated track patterns are reflective of energy conservation, substrate, and behavior. Energy efficiency is a tremendously important variable in interpreting trails, as well as in predicting how a given animal will move in a given depth of substrate. It is certainly true that the slower an animal moves, the less energy it expends; however, it's more complicated than this. Every species possesses an anatomy, locomotion, and set of behaviors that improve its fitness. Fitness is quite simply the quality of success experienced by an animal, and in ecology, fitness is measured by how well an animal reproduces and perpetuates its genetic lineage. An animal has high fitness when it produces numerous offspring that themselves produce many offspring. Think of the measure of success as the number of grandchildren an animal has, because having grandchildren indicates successful production of offspring that were, in turn, able to survive and reproduce.

To simplify things further, let us focus upon only energy input and output. Each species balances its energy intake, meaning food collection, and energy output, which includes the ground covered to locate and/or pursue said food. Weasels have high metabolisms, insatiable appetites to meet their energy requirements, and gait preferences that propel them quickly over long distances. A weasel that walks too often may save energy in the short term but is denying that which makes it a weasel, and will die of starvation in the long term because it does not gather enough food to meet its energetic requirements. The balance point between energy intake and output influences the ways animals move, and the common gait that an animal has adapted to use for traveling is called its natural rhythm (Elbroch 2003). Let's compare Bobcats with Coyotes.

Each species has a body structure and biology that balances its individual energy intake and energy expenditure. Bobcats walk. Cats move through the forest slowly and stealthily, sitting and pausing frequently to study their environment, hoping to see or sense potential prey before they themselves are noticed. They may even lie in wait for prey and do not generally cover long distances while hunting. When a potential prey is selected, they stalk in and, when close enough, explode with enough speed to catch their intended victim before it is aware of them, or before it can escape. They grip their prey with their curved claws and deliver a killing bite to the head or neck.

On the left is the trail of a trotting Coyote and the animal's resulting drag lines, and on the right, the clean walking trail of a Bobcat. Study the distance between footprints and the width of the trails in both animals.

Coyotes trot through the bush, hoping to catch smell, sound, or sight of potential prey, or to startle something to flee before them. Of course Coyotes do occasionally stalk, but in general, Coyotes cruise longer distances than medium-sized cats, allowing scents and sounds to betray the presence of prey species. When opportunities present themselves, they run down their intended prey, gripping and subduing it with their teeth. Their claws, which are never sheathed, project straight out from their toes and aid in traction while running.

Can Coyotes walk? Of course. Can Bobcats trot? Yes. Every animal is capable of a variety of gaits and speeds; however, each animal will have one or two gaits that are the most energy efficient for them, and they use these most of the time. Their common gaits are their natural rhythm.

Understanding the natural rhythms of animals is important, because it gives us a place to start. Think of an animal's natural rhythm as its normal speed, or middle ground. Each time an animal shifts from its normal speed, there is a reason and thus an opportunity for us to speculate why. Consider yourself as a starting point to better grasp how one might approach trail interpretation. You have your typical walking gait, speed, and subsequent track pattern. Should you be late for work or very focused upon a specific destination, your pace and track pattern will change. If you are hungry and stand within sight of five great restaurants, you will probably wander a bit and then move with determination once you have decided where to dine. You jump if you are scared and run when your life is threatened. The list of possibilities goes on and on. Why wouldn't all these sorts of changes be apparent in wild animal trails? The answer is that they are.

Certain gaits are associated with specific environmental conditions (substrates), while others betray behaviors or intentions. From a series of footprints you can determine whether an animal feels exposed and potentially uncomfortable, or whether it is hunting. And if you really become familiar with an area and its inhabitants, the way an animal behaves and moves may betray that it is out of its usual territory, or allow you to identify a transient or trespasser.

Interpretation of track patterns is advanced tracking and only comes with experience and lots of mistakes. The more natural history information you have about a species and the more time you spend trailing a particular animal, the better armed you are for this process. Regardless of experience, there will always be trails that will perplex you. Be reconciled with the fact that tracking is not a perfect science but a lifetime of learning.

Beginning Interpretation

With experience, interpretation can be highly detailed, and we discuss advanced aspects of interpretation later in the book. Here we encourage you to begin by interpreting the way an animal is moving as one of three categories: slow, normal (natural rhythm), or fast.

1. Slow—a speed slower than its normal gait (natural rhythm), that might indicate foraging, stalking away from danger, hunting, scent marking, exploring another animal's scent post, or numerous other potential behaviors.

2. Normal—its natural rhythm, the common gait in which an animal moves. The animal is exhibiting little or no undue stress, and is not blatantly reacting to any stimuli in the environment. You might say that the animal is acting “casually.”

3. Fast—a speed faster than normal that might indicate that the animal is chasing prey, being chased by a predator, or startled by something in its environment. The animal may also be exposed and/or uncomfortable in their surroundings.

A portrait of a Desert Kangaroo Rat hiding in cover in the Mojave National Preserve in southern California.

Each of the three speed categories is associated with some general interpretations. The key to applying this to some animal you are tracking is in knowing what is their normal gait and associated natural rhythm. You can acquire this knowledge through experience in the field, watching animals in videos, or reading guides to tracking and animal behavior. As described above, the normal gait for Bobcats and Cougars is a walk, but the normal gait for Coyotes and foxes is a trot. The normal gait for squirrels is a bound, and for kangaroo rats, a bipedal hop.

Consider the Desert Kangaroo Rat (Dipodymys deserti), an animal the authors have never seen use any but three gaits and speeds: slow, normal, and fast. When moving slowly, Desert Kangaroo Rats bound on all four feet, like a squirrel, and they drag their tail on the ground behind them. They move in this way when they are foraging and scent marking, or when they are exploring the scents of other kangaroo rats. The normal gait of Desert Kangaroo Rats is a bipedal hop, which they use to travel between their burrows, foraging areas, and areas where they leave territorial scent marks. The bipedal hop is generally a sign of comfort and that everything is normal. Desert Kangaroo Rats skip to evade predators (it is a sign of fear) and in territorial chases with other kangaroo rats, including the courtship rituals that precede mating. Thus, we have three clear categories of movement, three speed categories, and three distinct categories of behavior associated with these gaits and track patterns. This of course can be done for any and every animal you follow.

In mammals that use more than three gaits, consider dividing each of the three categories into three; thus, you have nine potential speeds and interpretations. For example, Mountain Lions (or Cougars) use an overstep walk, or amble, as their normal gait. They speed up into a trot when exposed and crossing open ground, traveling to a known destination with some agenda in mind, and when confronting conspecifics in territorial encounters (stiff-legged trots communicate dominance in many mammals). They gallop when pursuing prey or startled, and lope when slowing down when they recognize that an initial threat is not as dangerous as they first thought, or is remaining stationary—three versions of “fast,” each with different potential interpretations. But start with just three categories, and then add more as you feel more comfortable with the basics.

Bounding trails with tail drag of slowly moving Desert Kangaroo rats.

Rapid skips of an evading Desert Kangaroo Rat.

The beautiful trail of a large black bear sloshing in an overstep walk up a muddy riverbed in the Los Padres National Forest in southern California. Killdeer trails cross in the forefront of the photo.

The Effects of Substrate on Gaits

Let us use ourselves as models. Compare the trails you leave while walking in an inch of snow and two feet of snow, or on firm ground and in deep, dry sand if you live in arid regions. It is likely that the length between your tracks decreases in deeper snow (softer, deeper sand) and that the width of the entire trail pattern increases. This is a wonderful lesson in the effects of the depth of substrate upon trail characteristics. Now, let's add another variable: speed.

In deep snow a black bear is forced to use a direct-register walk, as seen here in this bear switching dens in the middle of winter near Tahoe. Compare this trail to that on page 67, where a bear moves in shallow mud.

When looking at trail characteristics in relation to depth of substrate, it may be more accurate to discuss energy output rather than speed. Let us return to our two trails in snow. If you were to use the same amount of energy in each trail, you would move more slowly in the deeper conditions. Moving at the same speed in both trails would require a higher degree of energy output to maintain that speed in two feet of snow. Consider running in the two snow conditions. Could you run at the same speed in two feet of snow as in an inch of snow? Would the energy output be equivalent while maintaining a run in these two very different conditions?

Just as we adapt to changing conditions, so do other animals. In fact, as you track across varied substrates, you will begin to note that animals change the way they are moving in ways that reflect an awareness of energy efficiency. Trotting in deep snow is intensively difficult, if not impossible at times, and so Coyotes are often found walking or bounding for short distances in these conditions. Fishers, which tend toward a 3 × 4, or rotary lope, change tendencies to a 2 × 2 or transverse lope in deep, soft conditions, and often walk longer distances as well.

Tracking in Snow

Snow tracking varies from a simple exercise in perfect track identification to incredibly difficult interpretations of deep, windblown trails. Below are some techniques and approaches useful when interpreting tracks and trails in snow:

TRACK PATTERNS. Learn to rely more on track pattern identification than print identification, and in this way be able to identify species from greater distances and through binoculars. In open areas of the North, biologists complete track transects of far-ranging mammal species, such as Wolverines, by small plane.

GAIT CHANGES. Be aware of the gait changes animals make when moving in snow. Animals that do not typically direct-register walk suddenly begin to do so. As an example, consider the raccoon, which uses a distinctive 2 × 2 walking gait in shallow substrates. But in snow, raccoons use a direct-register walk. Also mammals that tend to trot or lope in shallow substrates, walk more frequently in deep snow. Remember that the depth of substrate is one of the key variables in determining how an animal moves.

DETERMINING DIRECTION. The direction of travel in a given trail can be determined by identifying the deepest part of an individual track (the deep end points forward), but check several tracks to be sure. Place your hand into trails filled with snow to feel the direction of travel. This is best done without gloves, so be prepared and be conscious of conditions.

TOUCHING TRACKS. Feeling snowed-in tracks offers more than the direction of travel. The mound in the center of canine tracks can often be clearly felt, or the ridge between palm and toe pads in a cat track, or hooves. You'll also be able to tell the approximate size of the track, and how flat the floor of the track is. For example, the floor of canid tracks in deep snow is significantly steeper than the floor of tracks made by felids.

Feel snowed-in tracks very gently without gloves. The area compressed by the animal will always be firmer than the snow that has blown or fallen in. Use the body heat of your hands to melt out tracks; in this way you can sometimes not only feel the track but recreate it visually. However, do not force fingers into spots too quickly so as to create the track you want; carefully and slowly melt out the existing track floor.

BLOWING OUT SNOW. When light snow has filled in a set of tracks, you can often blow them out and keep the track intact. This is an especially useful technique when temperatures are cold and a fresh, light layer of snow has covered tracks.

CLAWS. Look for the placement of claws in snow tracks. In deep snow, all that may be clear in Coyote tracks are the pinprick claw marks of toes 3 and 4 at the very end of the track; you may have to squat to see them. Tracks of Bobcats and other cats may be differentiated from canine tracks by looking for claws that register in the snow on a higher plane than the floor of the track. The claws will appear to be above the toes, because this is where they sit when “sheathed.”

In deep snow, when track details are obscured, the shape of the front wall created by the foot as it enters the snow is especially useful in species identification. Compare the shapes of the walls for the species presented here.

TRACK WALLS. The walls of tracks created as a foot enters and exits snow are filled with clues for species identification. The back wall found behind the track may hold a metacarpal pad or dew claws on a higher plane than the track. The shape of the front wall is especially important for interpretation. Is the track pointed or rounded? Refer to the illustrations for examples.

DRAG MARKS. The drag marks found between the tracks are also useful. One method in which gray squirrel and cottontail trails can be differentiated is by studying the drag marks made between sets of four tracks; squirrels tend to drag on the outside edges of the track pattern, while cottontails tend to drag along the median line.

The shapes of the drag marks and the entrance/exit holes along the surface of the snow are also worthy of study. As an example, consider the shapes left by Bobcats and Domestic Cats when walking in snow. They move in such a way as to create perfect triangles. Or look for the paired lines created by dragging hooves in deer trails.

Recognizing Track Patterns for Interpretation

There are also specific track patterns with which you will want to become familiar, so that you can quickly interpret them in the field. With practice you will be quickly able to surmise what an animal was doing from a peculiar series of tracks—sniffing something, pausing, urinating, feeding, etc. Deer “point” to food with a single hoof, many mammals “T-up” when they pause (see later), and Bobcats kick out a hind leg when passing an object they intend to spray with urine. Study the accompanying illustrations to help get you started.

A feral hog demonstrates pointing; look for the track angling off to the left, and just beyond, the mark of the animal's snout where it rooted and devoured some vegetation in passing.

Pointing

Follow a deer trail in good substrate for a short distance, and you will probably find a spot where a front track registers off to the side, an anomaly in an otherwise redundant zigzagging pattern of tracks. This is a front track that was positioned to hold the weight of the head as it reached out and browsed passing vegetation. The leading edge of deer tracks is pointed, and the “arrow” created by this track often points directly to the vegetation browsed by the deer. Pointing can be found on all the ungulate trails, as well as where carnivores step out to investigate a passing scent.

Sit Downs

Learn the shape of patterns created by sitting mammals. “Sit downs” are a feature of hunting Bobcat and Cougar trails, which often pause where views of prey are good or in prey-abundant areas. If they wait for a longer period, they are more likely to lie sphinxlike rather than on their sides, as when resting. Canids sometimes sit in areas with wonderful views or when soliciting a reaction from a conspecific. Sitting in both felids and canids is also a sign of curiosity and investigation, because they often sit to watch something with which they are unfamiliar. Sitting is also common at den and rendezvous sites, and near kill sites of larger prey.

The sit of a Cougar kitten demonstrates the complete hind feet, including the heels, so rarely seen in many moving digitigrade mammals.

A Bobcat in Santa Barbara County illustrates the “T stop,” as it pauses on a hunting round. The “T” was created when the Bobcat broke its walking pattern and placed its left front foot on the ground adjacent to its right front.

“T-Trails” and “Box Stops”

When walking and trotting animals pause momentarily or stop for longer periods, there is often a “T” in the trail. The vertical line of the “T” shape is the typical trail pattern, and the horizontal slash (the “cross” on the T) is created by two front tracks sitting next to each other that break the typical rhythm of footfalls. T-trails are common where animals have heard something in the distance, are pausing to investigate a road before crossing, and have paused at trail junctions. On rare occasions the horizontal slash in the T can be made by two hind feet instead of two front feet; in these cases the animal holds a front foot up and stabilizes itself with the remaining three legs.

A variation of the T-trail is the box stop, where an animal stops and places all four feet on the ground at the same time. Typically the two corners of the “box” that are part of the normal trail pattern are deeper and easier to see; the two additional “corners” are the extra front and hind tracks that fall outside the normal rhythm of footfalls, and these tracks are often lighter and harder to see.

A Ringtail in the Sacramento Valley demonstrates the “box stop.” Look carefully to see the lighter prints of the left front and right hind feet.

The double fronts of a Snowshoe Hare where it paused—one set behind the larger hind tracks, and the second set in front of them.

Double Fronts

A pause or stop in a bounding animal such as a cottontail or squirrel is obvious in a trail section where one pair of rear tracks is accompanied by two sets of front tracks. When the animal is bounding normally the front tracks touch down and are followed by the rear tracks beyond them. When it is time to stop, the rear tracks stay put, but the front feet, which have just picked up to allow the rear feet to register beyond them, touch down a second time in front of the rear feet to stop forward momentum. When it is time to move on, the front feet are lifted up and the rear feet push off.

Determining the Position of the Head

The position of an animal's head can often be determined by looking for the deepest part of an individual front track; however, large head movements are often more easily determined by studying the overall track pattern. What we describe here is a method to determine the position of the head, and potentially where it was looking or smelling, that works for the slower gaits of walking and trotting. When walking, an animal that shifts to look over its right shoulder will typically influence three pairs of tracks and cause an understep on the side of the body to which it turned. In contrast, when an animal is trotting, the same maneuver often causes a slight overstep, because the momentum of the hind feet continues even though the front foot lands short on account of the shift in the weight of the head. Simple role playing in sand or other suitable substrate will prove out these concepts.

In both trails the animal is looking to the right. In trail A the animal is walking and turns more to the right, and the turn occurs over a longer duration of time. In trail B the animal is trotting; the look to the right is much shorter and the head is not turned as far.

As a footnote, there has been discussion in the field about the usefulness of interpreting where a canid is looking by which side of the animal is kicked out during a side trot. However, canids can look wherever they want, regardless of which side the rear end is angled.

Measuring Mammal Tracks and Trails

A ruler is a wonderful tool to help you build confidence in your perceptive and intuitive skills. Track and trail measurements aid in identification and are critical for scientific documentation of species in your area; when you are documenting a rare or potentially controversial species, always take measurements and include a ruler or other scale in photographs. Measurements can also be shared in research and used as a means with which to compare species characteristics. Tape measures, however, if relied upon for too long to aid you in species identification, will likely become a hindrance to further developing your perceptive and intuitive skills. For instance, the registration of toe 1 in the front tracks of the Douglas's Squirrel is a less ambiguous, and therefore more useful, means with which to differentiate their tracks from those of other tree squirrels. Learn to look for and appreciate the details.

Measuring Tracks

Here track parameters include nails and posterior pads. Some trackers do not include the nails; however, certain mammal species, including porcupines and pocket mice, rarely register digital pads, and thus measurements would be impossible without them. Also, be cautious to avoid measuring drag marks or the impressions made by feet as they enter and leave a particular substrate; measure the floor of the actual track and not the walls.