Tracking Styles

I have always understood that there are several different ways that dogs can locate a person. Air scenting is popular with many forms of Search and Rescue, particularly urban search and rescue and consists of creating a grid of the search area and using the wind and other environmental conditions to work the dog in a manner that will allow him to hit any human scent cone and work it to its source. Tracking and trailing are very similar and in many areas are terms are often synonymous. Most however, break the two terms down to (1) tracking- the dog using a deep nose to follow the suspect's scent footprint for footprint and (2) the dog following the suspect's scent where ever it may be. To break these two terms down, let's consider the following. Tracking is designed to teach the dog to follow the scent at the exact location it was placed on the ground-in the footprint. Many argue that it isn't really the human scent that the dog is tracking, but perhaps the ground disturbance, or probably more accurately- a combination of both. At any rate, the dog is trained to follow the track with a deep nose, footprint for footprint. While that may work well in a nice vegetative environment, what happens when the target hits a suburban/urban area where there is hard surface such as parking lots, roads, city streets, etc.? With trailing, the dog is allowed more "freedom" to work the actual human scent, where ever it may end up. Anyone who has done extensive study of scent theory or behavior (ie. the effects of both environmental and manmade factors on scent) understand that scent molecules (skin rafts, etc.) behave in a drastically different manners. Factors such as terrain, topographical features (such as creek beds, ditches, etc.), structural features (such as walls, buildings, etc.), environmental factors (such as weather, wind conditions, temperature, humidity, etc.), and surface features (such as grassy fields, thick brush, woods, concrete sidewalks and curbs, roads, etc.) play an important role. Although the differences in tracking and trailing and their application during a deployment is a different discussion all together for another time, the focus of this discussion-provoking post is of a different nature, not the differences between tracking and trailing. It is to discuss the two different styles of tracking/trailing and whether or not there is a middle ground.
Whether or not you track or trail or both, there are two specific training styles of tracking/trailing- (1) Scent discrimination and (2) last trace disturbance (also called point of last seen). For the purpose of the rest of this post, we will use the term tracking to describe both tracking and trailing. With scent discriminate tracking, the dog is provided a scent "article" with the understanding that he is only to track that specific person. With last trace disturbance or point of last scene (POLS) tracking, the dog is placed into a productive area where the target was last seen and he picks up the track of the target and tracks the target. Let’s break down the pros and cons of each.
Scent Discriminate Tracking-
Pros- (1) Dog is able to be given a scent article, then search an area for a track for that specific individual, then strike the track, follow it through contamination and locate the individual. (2) Especially useful for missing children or those with mental disorders that leave an area (house, business, etc.) where the area is heavily contaminated by well meaning family members and friends, fire/rescue personnel, and fellow law enforcement attempting to locate the individual before calling for a K9 unit. (3) Useful when the exact “starting point” for the track is unknown.
Cons- (1) Scent articles are not always available, and often times when they are they become contaminated by often well meaning family members, fellow law enforcement officials, and fire/rescue officials. (2) Often in criminal cases, the collection of the scent article and chain of custody is a huge contention when a case goes to court, especially during the motion to suppress hearing phase of the court case. Often, the defense will try to argue that the article was contaminated in some way or fashion in a way to discredit the dog’s actual performance. (3) Takes more time to train initially.
Point of Last Seen-
Pros- (1) No pre-scented article is needed to start the dog. (2) No need to heavily document when, where, how, and by wh om the scent article was collected.
Cons- (1) Difficult to sometimes impossible to start in a heavily contaminated area where the target’s last known position is not known.
So which “style” is better for the police K9? My thoughts and opinion on this matter is the latter. Since most police K9 units (at least in my area) are deployed to track suspects involved in crimes than missing persons, I feel POS is more effective. In most circumstances where we utilize our K9’s to track suspects, we either have a good general area where the suspect was last scene, or physical evidence usually points us to the areas to start when no witness is available. Often times, we are able to narrow the productive area to start our dogs in down by utilizing sign-cutting (aka. hand tracking, Indian tracking, visual tracking, etc.). The question might be asked, well how does your dog know to track only that person when you encounter cross contamination if you did not provide him with an adequate scent article, such as used in starting and deploying a scent discriminate tracking dog? My contention is this- scent articles come in many forms. Some are clothing like seen in the movies, yet rarely encountered in reality. Some are large articles such as car seats, some small like firearms, and some can be “made” utilizing sterile gauze. But what about the actual starting point of the track? In my opinion, if the starting point is relatively free of contamination and the dog is trained and proofed on tracking through contamination later in the track, why can’t the starting point of the track be the “scent article” when utilizing the POS tracking dog? What I have found through research and my experiences in training and deploying our dogs is that if the dog has a clear starting point and is trained and proofed properly working through cross-contamination, the dog is able to locate the person he had started tracking in the beginning. While this is no means my “revelation” (I really cannot remember where I first picked up on this concept), I do remember the actual deployment where I realized it with my current partner.
K9 Bas and I were dispatched to a shoplifting in progress where the suspect pulled a knife and attempted to assault an employee. The suspect was last seen fleeing across a busy intersection to a nursing home. A patrol deputy located a shirt the suspect had shed (for some reason, a great deal of our criminals like to shed clothes). Though our dogs are not scent discriminate and the shirt would be little help to us, I knew the suspect had to be in close proximity to the shirt to shed it, so I put Bas down in the area of the shirt and he quickly located the track. We traveled through the woods, across a busy four lane road, and into a large parking lot of a shopping store. Bas lost the track in the large (several acre) parking lot that was full of shoppers (about 35 people). I worked the area in an attempt to pick the track back up when we approached an alleyway between two large stores and Bas aired up and drove us to a white fence about 75 yards away and attempted to jump the 6 foot fence. Directly behind the fence was the shirtless suspect. How was it Bas was able to sort through about 35 citizens in that parking lot, all in between us and the suspect’s location initially, yet show no indications they were the suspects? All genders and races were represented in the parking lot, including many that were the same as the suspect. My only conclusion was that Bas had enough uncontaminated track scent in the initial beginning of the track to know for who he was looking. How uncontaminated track is necessary for the dog to have that “locked” into his brain I feel depends on the dog, how fresh the scent is, and how free of contaminates exist.
The end result is a dog that is almost just as good as a scent discriminate trained dog, without the ritual of having a good scent article needed to start a dog. The dog team becomes more versatile and you get the best of both worlds and the handler doesn’t have as many headaches to deal with when it comes to court with regards to proving the article wasn’t contaminated and was collected properly. This skill comes with many, many hours of training the dog to work through contamination and having a clear understanding of his tracking picture in the beginning of the track (successive approximation). One might ask if this is just as reliable as a scent discriminate dog being able to track a suspect and pick him out of a crowd? I don’t know for sure, but I will say that if (here in the US) you are only relying on the dog to determine your suspect without any other evidence linking that suspect to your crime, you are asking for trouble when the case goes to court. Unfortunately, a small few handlers who claimed their dogs could achieve incredible feats that provided the only evidence of a suspect’s guilt. Many of these cases are being contested now due to these claims and no other corroborating evidence to their guilt.
To me, when the suspect is unknown, the dog is used as an investigative tool. You might find him, but he still needs to be connected to the scene. Just a late night rambling hoping to spur some thought. What are your opinions and thoughts?