Trailing versus tracking: The keys to success
Author Jeff Schettler discusses the finer points and techniques of scent trailing
By Jeff Schettler
Trailing frequently is confused with tracking, and the two terms are often used interchangeably. Tracking is based on the human visual perception of an event through visible tracks or spoor. I believe that the term is used mistakenly to describe our human interpretation of events that only the dog can perceive. K-9 tracking most often involves having the dog follow a specific set of footprints without deviation. Often, the dog's nose is forced to the ground with a lead running under his leg to the neck. When the handler exerts tension, the lead pulls the dog's head downward, presumably to keep the dog's nose in the scent zone of the footprint. My argument has always been: How do you know that there is scent left in the footprint? This article discusses some of the finer points and techniques of scent trailing. Hopefully it will provide a greater understanding of how K-9s interact with human scent to locate a specific individual.
The theory behind tracking is twofold: (1) the footstep that caused the ground disturbance is the odor that the dogs follow, and (2) the footsteps are the location where human odor is most concentrated. It is easy to see why many early trainers felt that way. They trained on nothing but soft surfaces in relatively fresh conditions; thus, perception was reality — the dog's nose hovered close to the actual track of the human.
Consequently, training regimens were created that subscribed to the training philosophy. If the dog's nose strayed from the prescribed height above the track, his nose was promptly forced back into it without anyone ever examining the reasons for the behavioral change. It was automatically presumed that the dog was outside of odor. Many people believe that the dog must be within inches of the track to actually smell the odor. I believe that perception comes from our own scent-limited world and false rationalization. Nothing could be further from the truth, and simple tests have proven time and again that most dogs can detect odor from a fixed location and at a variety of distances — from inches to yards and more. Consider this question: if it is proven that a dog can detect odor from either ground disturbance or from the human that created it, and from more than mere inches of the physical track, why must a dog's nose be forced into said track?
Now let's examine what happens to human scent when the paradigm shifts. Step from the corn farmer's freshly plowed field onto an adjacent gravel road. If you are lucky enough to see the track from the onset and, furthermore, can detect the faint changes of rock discoloration from top to bottom, perhaps you might be able to determine the human track and direction of travel. Then change the farmer's gravel road to the highway beside it. The track disappears, and it is now impossible to place the dog's nose into it. With that being said, the hard surface trail rarely pans out for the average police K-9, and that is a shame.
Unlike a tracking dog, a trailing dog is allowed more freedom of movement and, more importantly, a certain amount of independence. Independence in a police dog is normally considered an oxymoron; however, it is crucial to understand that scent is the dog's world, and there is an excellent possibility that the dog might have a better grasp on locating it than humans do. Our job as handlers is to simply interpret the dog's actions and hang on accordingly. That does not mean that the dog is allowed to go about his business in any manner he sees fit; rather, it is a partnership based on mutual understanding of limitations and individual ability.
In my opinion, trailing epitomizes the dog's natural instincts to scent patterns and replicates or approximates what a wild canine such as a coyote or wolf might do when following prey based on scent. Take that one step further by adding scent discrimination to the equation. Each and every animal, human or otherwise, produces a distinctive odor based on species and other sub-determining factors such as infirmity, relative age, sex, and certain individual identifying traits. The amount of odor produced depends on several primary factors: mental conditions, such as fear or anger; exertion; and relative health issues. Frankly, some people simply smell more than others to our dogs. The more they smell, the better. The human handler addition to the equation ensures that the trailing dog stays on one particular scent as long as it might last.
The Nature of Human Scent on the Trail
Trailing takes into consideration the fact that scent does not stay put in the "track" of the subject of being hunted, especially on hard surfaces. Depending on the conditions, human scent from a walking subject could easily travel hundreds of yards or more. It is illogical to force a dog to follow a scent path that simply might not exist anymore in the place where it originally fell.
Take, for example, an extremely hot, dry, windy day in the downtown area of any city in America. There is little or no vegetation, and the heat can be seen radiating off the surface of the blacktop much like from a fast-order chef's grill. The blacktop heat reflects and destroys scent, and the scent will not stay where it falls, if it falls at all. Instead, the scent particles are dispersed by wind, heat waves, and physical manipulation to any barrier that might catch them. Barriers such as moisture-bearing objects — for example, vegetation — attract scent particles more. My theory is that scent particles — rafts, or whatever you want to call them — have a tendency to be hydrophilic. That is, they are attracted to moist, cool places that are high in oxygen content. The reason for that is because any biological matter is subject to forces of biological breakdown. Carbon-based matter, or human particles that produce scent, are subject to the same aerobic type of bacterial action as the similar matter. As the matter degrades, its odor also degrades. I believe that odor also changes, or ages, as it degrades. Certain gasses, such as carbon monoxide, appear to have a negative effect on scent as well.
In locations that have little to no vegetation, however, scent will still collect in areas that might keep it from moving or being destroyed. Cool, shady areas — such as the north side of buildings — hold scent far better than flat, open tracks of hard surfaces that are subject to the sun's radiation or human manipulation.
A scent trail is not something that can be determined by sight; rather, it is invisible and interpreted by reading a dog's physical reaction to its presence or lack thereof. Being able to read a dog when he is working is one thing, but handlers often become tangled when they are reading a dog that is not on scent or, more importantly, when he is not on the scent he started with. The ease with which a police K-9 can switch animal or human scent trails — unbeknownst to the handler — is absolutely uncanny unless the handler has a unique understanding of his or her dog's subtle behavioral changes when he jumps trail.
Humans are visually oriented, and our natural habit is to rationalize things from a visual standpoint. Thus, when I discuss the nature of human odor, I like to find a way to make it visible, even if for only a moment and within our imagination. Picture, if you will, a person standing alone in the middle of a grassy park holding a red smoke grenade — red being the color that identifies this person above all others. If there is any wind, the red smoke will drift with the wind and collect against any object that might hold it, such as in a small valley, against a tree, or even around blades of grass. As this person walks or moves about, so does the smoke trail. Changes in conditions — such as more or less wind, rain, high heat, or humidity — all have an effect on the scent trail to a greater or lesser extent.
Now let's add another human who has a different color of smoke grenade, and who walks and mingles with the first person's scent trail. Both scents may stay visibly separate, yet a clear division will be difficult to determine. Complicate that further with yet another person and then another. A point may come at which it is almost impossible to separate one color from another. Dogs, I believe, face the same dilemma but in a different context. Rather than visualizing a scent trail, the smell it. Who has the easier job?
I like to keep the above scenarios in mind when I am training a new dog for training. During early training sessions, most dogs can easily differentiate the scent of one person, and perhaps even two people. However, adding a city street into the mix with thousands or millions of unknown scents can be a nightmare for any dog regardless of how good the scent might be. Trailing training is best accomplished in small, easy steps with a clear goal in mind.
I take green trailing dogs and expose them to each step of scent discrimination from minimally to massively contaminated. The training can take up to a year to complete and special techniques are required to ensure reliability.
Trailing is often considered synonymous with scent discrimination, or the ability for a dog to detect an individual human odor amongst many. Numerous schools of thought exist concerning this issue. Some people believe that dogs do not have scent discrimination ability and instead work on the basis of the freshest track out of an area. In order to properly debate that subject I'd need to write a book. Suffice it to say, I believe that all canids have the ability to discriminate human or animal scent, and that is what sets them apart in our natural world as superb hunters. However, I do not believe that this ability is always 100 percent accurate. Certain forces on the trail of prey can confuse and distract a dog. That is especially true when a dog is required to wade through the melting pot of human aroma in the middle of suburbia or a downtown city street. The degree to which the dog works is commensurate with his training and native traits or prey drive.
The Scent Article
More often than not, everything at a scene might be contaminated. In that case, it is important to remember who was present at the scene and who had contact with the intended scent article. There is a method for using a contaminated article called missing member. The dog is allowed to pre-scent on the people who have been at the scene and differentiate between their scent and that of the missing person(s). My experience with the missing member approach is extensive yet inconclusive .I have found it to be a necessary tool with a contaminated scene, yet it is not wholly reliable. Regardless, I have found success with this method, and I believe that is should be practiced when scent articles are seriously contaminated.
The scent article is not always necessary for a trail to be successful, but it is a useful tool that a handler should always be able to identify and employ. Small-to medium-size scent articles need to be protected at all costs if they are to be used to start a trailing dog. I keep an inventory of various sizes of heavy-duty zip-top bags in my patrol car. Paper bags don't work because they are far too permeable, and any object inside quickly becomes contaminated. If, due to evidentiary value, an object is too sensitive to be moved and handled by a K-9 handler, the next best bet is to extract scent from the object. I also keep a supply of sterol, 4x4-inch gauze pads in my vehicle's trunk. Scent is easily transferred from most objects to the pad by simply placing the pad on the object and letting it sit for a few moments.
A scent article does not have to be a moveable or baggable object; it can be fixed in place, like a windowsill, a car seat, or a doorknob. It might even be a victim. A person who has been touched by another person can be a scent article, too. That is not an easy way to scent the dog, but it can work.
Once a trailing dog is trained to discriminate scent and follow individual trails among many, it becomes increasingly important for the handler to stay cognizant of the variability of a particular scent article and how easily it can be contaminated. The scent article must have an overwhelming odor of the subject, and the subject's scent trail must be within the area in which the dog started, if the dog is going to be successful. An extremely large part of our trailing training regimen focuses strictly on the nature of human scent, collection, preservation and presentation.
It takes very little contamination from other humans to corrupt the quality of a scent article. Couple the contamination problem with that of the contaminator being the freshest trail out and you have a basis for a scent article failure; in other words, the dog may simply follow the freshest trail. The problem with the most scent-article training is that many handlers and trainers do not take into consideration how easily the scent article can be contaminated. Furthermore, they rarely take counter measure to bypass the problem or prevent it in the first place.
Scent-article and scent-discrimination training are the most important parts of the trailing continuum, yet most often they receive the least attention. The reason for that is the mistaken belief that if you simply show a dog a scent article with someone's odor on it, he will know what to do with it. In most cases, the article is meaningless when there is a fresh trail out for someone else.
The natural canid response appears to be to always follow the freshest trail out or that which is strongest. Good scent-article training requires the trainer to override the natural canid response to fresh scent stimuli and do something counter-instinctual. Good scent discrimination training takes special steps to ensure that the dog can follow one door among many, based on scent presentation from the handler. That does not happen easily or quickly. Also, some dogs cannot be trained to "out" off the fresh or hot trail syndrome; they are so oriented toward instant gratification that specific scent selection and following are literally impossible for them.
The second part of proper scent discrimination training is scent, sight and sound distinction training. The trailing dog must be able to work through all three distracting factors with relative ease and the handler must be able to read the subtle, or not so subtle, body language changes with the dog encounters them. The trailing k-9 needs to be exposed to every facet of human and animal distraction possible in structured scenarios where the handler has the opportunity to read the behavioral response and incorporate the appropriate counter measure to ensure that the K-9 stays on the trail he originally started on. The problem is that most dogs can switch to another human or animal trail and the average handler has difficulty detecting the switch, so he blissfully follows the dog until the new trail peters out or the distraction is encounter.
The two most crucial pieces of K-9 equipment for a trailing dog are the long lead and the harness. A trailing dog must have a harness and never be run strictly on a collar. The intensity and duration of the work will place too far much strain on a dog's neck and create health problems.
I prefer leads of 20-to-30 feet, which many handlers consider far too long for control. My reasoning is that any high-drive patrol dog has a tendency to work at a fast pace when he is allowed to trail rather than track. If the dog is not offered enough freedom to operate, the weight of the handler becomes a distraction and an anchor, increasing the probability of losing the trail, especially in an urban environment. A 30-foot lead allows the dog more freedom in large-open areas but can be shortened to a few feet if safety becomes a concern. It is a simple matter of reeling in and reeling out. Most handlers don't practice enough with the long lead to become comfortable with it: the keys to success are lead control and lots of practice.
After much experimentation on tracks with my heavy Bloodhounds, I settled on a fairly large, draft-horse-style leather harness that appeared bulky but turned out to be incredibly comfortable for my dog and easy to put on. The breast pad was made out of double-thick 12-ounce leather that was very wide yet smooth, spreading the force of resistance over a large surface area of my dog's chest, thereby reducing fatigue and skin abrasion. Attached to that was a 30-foot leather lead made from rolled 14- to 16- ounce bull hide. That type of leather is rare and highly-sought after. It is powerfully strong and resilient, yet gives the handler a good connection to the dog. It does not knot easily and, more important, it does not burn the hand when leather is rifled through a loose grip if the dog decides to open up full bore.
Many people might question the need for such strength and expense when it comes to trailing equipment for a dog, but I have discovered that you get what you pay for. A training deployment can last from a few yard to many miles, so good equipment designed for the trailing dog is a must. When it comes to the life-and-death work of a trailing police dog, no expense is too great.
For my personal equipment, I soon learned that lighter was better. If I anticipated that the trail was going to be long and difficult, I carried very little. In the trunk of my patrol car I always kept a stripped-down pistol belt that contained my sidearm, an extra magazine, and canteen. I would swap that gear for my Sam Brown leather that I always wore on patrol. Later, I switched to a Camelbak-type backpack for water. Boots were always important, and I had to be able to run in them for long distances and not get foot-sore. I quickly learned that appearance meant nothing and that only my own physical comfort should be considered. If I became tired or sore a short way into any trail, my ability to read my dog was compromised. Needless to say, traditional wool uniforms are horrible to wear for running. Polyester and cotton blends are far more comfortable. Of course, what an officer carries in the field is based on personal preference coupled with his or her agency's general orders.
First on the Scene
If officers are already canvassing the neighborhood, see if you can slow things down a bit or even momentarily suspend them while you get your dog started and out onto the trail. If the K-9 gets scent and finds a trail out, the investigation will get fired right back up again. There is nothing better than a good, scent-discriminating, trailing dog to help find evidence anyway, and the change of disturbing evidence already present is minimal with a savvy handler. Sometimes a well-meaning investigating officer will inadvertently touch or contaminate your intended scent article and lead his or her scent trail out of the area. If the officer was the freshest scent on the article and has the freshest trail out of the area, your dog will follow the officer. That has happened to me several times.
If you do not have the luxury of being on the scene immediately, ask someone in charge about those who have come and gone, where have they been and, if possible, what they were doing. Better yet, if everyone is still present, give your dog a change to smell each person before you start your trail. It is not difficult and can be done in a matter of seconds.
When I arrive on the scene, I quickly obtain the overall story about how the crime evolved without getting into too many details .I do like to know directions of travel and certain witness statements as long as they are correct.
Contrary to popular belief, witnesses do lie, often to suit their own ego or just to make an impression with police. I take all statements from witnesses with a grain of salt and read my dog's behavior for signs of the true exit trail. Once I know the general situation, I look for my best scent article, collect it if possible, bag it, tag it, and keep it protected. If anyone touched my article, I try to make sure that they are present when I start my dog. That way I stand a far better chance of finding my suspect's trail.
The last thing I do is to give my dog a break and let him canvass the area himself. This is a good time for him to void his bladder and it allows him a chance to scent-inventory the area outside the scene. I try to make one full circuit around the scene with my dog on a short lead and by the collar, and then walk him by each and every person still there. This can occur relatively quickly and at a trot. Watch the dog carefully during his circuit because, depending on the nature of the crime and how emotionally charged it was, the suspect may have left a trail that stands out above all others. We may be walking along and suddenly my dog gives a quick little head pop in one particular direction. I catalogue this reaction but do not encourage it just yet. We are not working yet and the trail has not begun. The head pop could indeed indicate a suspect's direction of travel, or it could indicate that my dog sees his best cop buddy. Catalogue but do not encourage.
The starting point to scent your dog can be tricky. Many people believe that the best place is directly where the suspect was last known to have been. That may not always be easy for the dog from a physical or scent perspective. The scent situation often is the worst situation. If the place last seen (PLS) is the suspect's home or a location that he or she frequents, large amounts of the suspect's scent may saturate the area, creating a huge scent pool with many exit points that have varying degrees of age. That can be confusing for even the best trailing dog.
The common denominator for a dog that can't find his way out of a large or distracting scent pool is his previous training regimen. Handlers often work their dogs in relatively "clean" areas, or in the same areas over and over again. Rarely are scent scenarios set up to mimic actual crime scenes. Once my trailing dog is proficient in the basic skills of his craft, all of our future training is done with scent contamination and distractions in mind.
When I encounter a scene that my dog has trouble finding his way out of and the scent article is not to blame, I have to consider two major possibilities. First, the person I am looking for may not have been there to begin with; or second, the scent trail is too disguised or contaminated and it is time to work the perimeter. I use an old visual tracking technique to help locate a new track when the old tracks peter out. I work my dog in prescribed concentric circles from the starting point. The distance for each circle will vary with terrain and conditions; however, I like to keep it within 20- to 30-foot intervals. I repeat the circles until my dog either picks up the trail or clearly finds nothing and it is time to stop. If you push a dog long enough, chances are he will pick a trail just to satisfy you. That type of work cannot be expected of a dog that has never been exposed to it. As with every task, the dog must be trained for it. I start with a trail being available for the dog on the first circuit and, once he is proficient, I increase the size of the circuit or add another.
Reading a Trailing Dog
Every trailing dog exhibits specific behaviors when he is on a scent trail. However, each dog is different. It is a mistake to think that a particular tail position or head set is the same for each and every K-9. When a trailing dog is actively scenting his quarry, his body reacts based on instinct and on the physical traits of his particular breed.
Depending on the animal's ability to detect scent, the head might be high or low to the ground. Environmental conditions play a part, too; however, a cold-nosed ( weak scent) dog will often maintain a head level higher from the ground than his peers. When I'm looking at the head of a trailing dog, I find it prudent to look also at how the ears are placed. Are they pricked forward, laid back along the sides of the skull, or splayed wide? Even floppy-eared K-9-s such as Bloodhounds, Labs, and other hunting breeds will exhibit distinct differences in ear set, although it is not as evident in these breeds as it is in the pointy-eared breeds.
When monitoring head position, handlers often fail to interpret the set of the dog's mouth. How open is it and what is the tongue doing? Normally, the dog's mouth will be partially open to fully closed in order to allow him to best use his nose and take up scent.
There is absolutely no set tail position for trailing that I have noticed. Most commonly, the tail is held out and up, but many dogs' tails droop, swing to the side, or wag incessantly. The most important thing to remember is your dog's tail set when he is actively trailing his quarry. That position will stay relatively constant unless there is an injury or some other issue.
The last body movement to consider is how the dog moves along the scent trail. Some K-9s tend to move in and out of the scent trail. I have noticed that Malinois have the tendency far more than any other breed. It appears to be relative to speed and a general impatience to find the quarry.
A savvy handler will catalogue all those subtle body-language cues in his or her memory for future use. If the dog's head, tail and body language remain constant, it is safe to assume that the dog is actively trailing. A change in one or all traits indicates an interruption in the scent trail.
Few dogs will stop immediately when there is a scent change; instead, they generally keep moving in the original direction. As the scent cone dissipates to nothing, a dog often stops or begins to quarter into the wind in an attempt to relocate odor. The problem with that is the length and breadth of the scent cone. In some cases, human odor may have spread out over hundreds of yards past the quarry's original trail or perhaps over a turn that was made. That is especially true on vast, hard surfaces such as parking lots and wide city streets. If the handler fails to register a subtle change in the dog's body language as the trail is being overshot or the turn is passes, the dog could get so far off the actual trail that he might not find it again. However, if the handler registers the body language cues as they are manifested, he or she will be far better prepared to relocate the trail and cast the dog.
The biggest problem I have noticed with most trailing dog teams is the inability of the handler to read distraction behavior. Distraction behavior is any K-9 behavior that differs from trailing behavior or body language. This behavior is prompted by scent and sound. Scent, by far, is the most difficult to deal with because most handlers confuse the distracting scent behavior with trailing behavior. In other words, most handlers can't tell when their dogs are following a human or another dog. The trail may start out following the person, but often even the best trailing dog jumps trail to something more interesting — such as another dog or a hotter human trail.
Most handlers are oblivious to subtle distracting odors that take their K-9s off their subject trails, and even when they do recognize distraction behavior, they are often afraid to correct the problem because they are unsure about the distraction and the quality of the original trail. It is important that every service-trailing dog have distraction training in which the distractions are diverse and known. I have established a distraction training regimen with all of my dogs that easily identifies the distraction so that the handler can easily correct it.
The second biggest problem with reading a trailing dog is the K-9s propensity to follow the freshest or closest trail regardless of a scent article. Most handlers, myself included, will follow a dog that is locked on odor when we read it. What happens when you have multiple trails leaving a single source point, and they all vary in age? If the dog has not been trained for that eventuality, he will invariably follow the freshest trail every time. That has given many in law enforcement the false belief that dogs do not discriminate human scent and has led to reinforcing simple, soft-surface, fresh-scent tracking training methods.
A training regimen that works fairly well to counter that problem is called split-trail training. That is where two trails are laid side by side and the subjects split at the end. The second phase of this training is splitting the trail at the start. The dog is forced to find the correct person at the end based on the original odor on which he was scented at the beginning of the trail. This training is usually pretty successful and easy to do.
Trailing is almost as old as man's constructive use of canine nose. Dogs do scent-discriminate, they can follow scent trails that are many hours old, and they can negotiate most urban jungles as long as they have the correct training to do so. Occasionally, a dog comes along that defies all training and simply is a master at trailing right out of the box. However, such dogs are few and far between. K-9s, like their handles, work best through muscle memory. We work as we train; if our training is lacking, our work will be lacking also.
Jeff Schettler is a retired police K-9 handler and current K-9 trainer. He has worked with the FBI's Hostage Rescue Teams' K-9 Assistance Program in locating and apprehending high-risk fugitives. He also has specialized in tactical trailing and has been an expert witness in the areas of scent evidence and trailing with Bloodhounds. This article was excerpted from Jeff's Book, Red Dog Rising, copyright 2009, and used with the permission of the publisher, Alpine Publications. To learn more about Jeff and his training methods, please visit his website: www.GAK9.com.
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