NW150: Scent Theory and Dynamics

LECTURE ONE: Logistics and Data Collection Details

Equipment and Collecting Data

For the gold students, this course assumes that you are working a dog in tracking and/or detection. The dog does not have to be highly experienced, but keep in mind that for a very green dog some of these exercises might be a little bit too advanced. You can still do them but we might have to simplify the exercises just a bit to be fair to the dog. On the other hand, a highly experienced dog sometimes is so proficient at working scent that we have less of an opportunity to make observations. I find that intermediate dogs are often the most educational.

Measuring Air Flow/Wind Direction
The most important thing, in addition to the dog, is having something that will help you determine wind direction. There are a variety of items we can use to do this. I listed smoke matches and/or a "wizard stick" in the equipment needed for the course. In addition, especially if those items are unavailable, you will find a small bottle of baby powder useful as well. Some people like to use a puffer bottle of contractors chalk because it comes in a variety of colors. However indoors this will stain some surfaces (I once permanently stained the side of my house with it as well).

Here is an example of using a puff bottle to collect information on wind direction, with a GoPro, and then with a camera on a tripod.

And here I am using the wizard stick to look at airflow in a building:

Order of Working and Collecting Data
When collecting data work (and film) the dog first. THEN go back with your tools and take measurements. In this manner we will try to learn to predict the airflow based on the dog's behavior, letting the dog teach us. We can also be as messy as we want with the baby powder, smoke bombs, and other items that might affect the dog's work if we used them prior to the training exercise.

Captions and Markers in your Areas
People have different videoing equipment and skills. Don't sweat it if you are working "low-tech". I realize that there will be a learning curve as we all get up to speed on collecting data. However, if you can label or caption events occurring during your video that would be helpful.

When tracking I usually avoid using very many flags on my tracks, if needed, I just use the bare minimum to know where the track is. However, for these exercises, it will be useful to put more flags on the track in order to really know where the track is in regards to the airflow. 

Slow Motion in Video
Also, I find being able to show the dog working in slow motion is exceptionally useful when looking at scent detection. Things just happen too fast sometimes. When I watch videos if I don't want to add slo-mo I just freeze-frame the video forward in segments, I do this a lot when watching students tracking or nosework videos.

Here is a good example of the detail you catch in slow motion. This clip is a very fast, green dog just learning an odor. Watch her as she moves down the rack, goes past the correct target box, and then recognizes odor and goes back.

Data Collection
Almost everything that we discuss in this class will be a variable that influences airflow. Some variables will be less of an impact for indoor detection work; although airflow is still very much a concern. For the tracking people, environmental conditions have a much bigger impact on the dog's performance.

In addition to determining airflow and direction, we are going to try to routinely record the following data with our homework. Obviously, some of these will not apply to indoor exercises. As we progress through the class we will discuss the significance of some of these variables.

Temperature
humidity
dew point
weather conditions (sunny, ptly cloudy, cloudy etc)
age of the hide or track
wind speed

I usually use weather.com on my iPhone and pull up the current local weather conditions. However, for estimating wind speed you can also use this table:

Estimating Wind Speed
Less than 4 mph direction can only be determined by powder or smoke
4-7mph wind felt on face, leaves rustle
8-10mph leaves in motion, surveyors tape extends
11-14mph wind raises dust
15-25mph branches and small trees sway

Logistics - Areas and Repetitions Plus lots of Patience

As we experiment with scent dynamics we are going to attempt to set up scenarios. This can be tricky - we are attempting to control a variety of uncontrollable variables. You may need to scout out some areas that will meet the requirements for each exercise. Don't get frustrated if things don't go as planned, this is the nature of scent dynamics. We can still learn something every time we watch the dog work.

Here is an example of things not going as planned as I was getting ready for the class. My intention with this search was that Steel would work the area and help illustrate the "scent cone" that comes from the hide.

As you can see Steel pretty much ran straight to the hide like he was on a runway. No scent cone. Just a freight train to the hide. Not exactly what I had planned. However, take a look at what the airflow in that specific location looks like. The scent flow perfectly explains his behavior. With a strong wind pushing the scent to him, the "scent cone" was very narrow, practically a straight line.

As the tracking students in particular know, environmental variables are always changing. We can set up the same exercise every single day but the environmental variables will often change; resulting in drastic differences in performance. So repetition in this class is good. Repeating the homework exercises on different days will illustrate some of these differences.

I also want to remind you to keep things simple at first. The more variables we load into an exercise the more difficult it is to determine what is influencing the dog's performance. Most of the homework exercises will be relatively short. It is much better to repeat the short exercises than to try to work a longer elaborate scenario. As you do the exercises look for ways that you can make it more challenging as we progress. For example, with a high hide start out mid-height and then increase gradually. This will make the exercises more educational than if you just start out making things extremely challenging.

Also please remember - this class is about understanding what happens to influence the success of the search or track. Oftentimes we learn the most when things DON'T go well. So don't be afraid to post when things don't go according to plan. Hopefully, we can figure out together why that might have happened.

LECTURE FOUR: Water, Terrain, and High Hides

The Influence of Water on Scent

Water nearby can often have a dramatic influence on scent flow. In general, you should assume that scent will drift towards the water. In fact, thinking of scent acting like water is often a good analogy. if you are tracking uphill as well as parallel to a gully with water, it is likely that the wind flow will be towards the gully, and, as a result, the scent will drift down into the gully. This is particularly true if the body of water is moving, water movement is drawing air downstream and additional air is being pulled in from surrounding areas.

Here is an interesting smoke bomb clip from dusk. It's a bit hard to see the pond in the video but the smoke is all being pulled directly towards the pond. Remember from previous lectures that air also generally flows downhill at night. So in this example, you have both the air being drawn towards the water and also downhill. I think what is interesting to notice in this clip, even though it is dark, is how much more slowly the smoke is dissipating over the water compared to land.

Obviously, this phenomenon has more influence on tracking that it does on nosework and other detection activities. It is something to always keep in mind though. You don't need a raging river, sometimes a small gully is enough to draw scent. Think about the typical terrain upon which you might have a gully as well - probably a downhill slope towards the gully and quite often shrubs or brush along the edges. Air is being pulled toward the water, a downhill slope facilitates that movement, and the shrubs provide an area where the scent can be collected. This is why I quite often suggest to my tracking students that unless they will be trialing on their home fields, they should seek out terrain that will present challenges to the dog. An example of such terrain would be a spot where scent might be pushed away from the track, downhill towards the water.

Here is a diagram of what that complex track might look like. The track runs parallel to the slope and then makes turn uphill. The scent is likely to be drawn down the hill towards the water. 

In developing my dog's ability to learn to work himself through the above challenge I would simplify the tracks a bit. This would allow him to educate himself and to gradually become more and more scent gradient sensitive. I might offer him the following sequences of tracks before throwing in some water as well.

I would also want to track my dog past bodies of water in order to let him learn to work through any areas of potential drift. Here is an excellent example of a dog doing just that. She was running a parallel track along the edge of a pond and as she approached the water she drifted too far to the right, likely following scent that had been pulled towards the pond. She then self-corrects, reacquires the track, and continues along the track.

Like with everything we have studied so far, there are no hard and fast rules as to what scent will do in regards to water. However much of the time you can expect the scent to be pushed towards the water like in the smoke bomb video above.

High Hides

In placing a high hide we are disrupting the scent cone similar to what we did when we attempted to block the airflow during week two. However, in this case, we are modifying the scent cone vertically rather than horizontally. However, if the hide were placed high against a wall then you have both vertical and horizontal cones disrupted - which is why I suggest folks wait on doing that until the dog is more advanced. With the high hide, scent flow is once again dependent on the airflow.

If there is very little air movement then the scent is likely to drift down the side of the obstacles. Higher airflow will push the scent further before it drops down to the dog's level. Placing the hide up very high will also have a similar result - the scent has a greater distance to travel, giving it more time to be influenced by the air currents.

In this clip the dry ice fog allows you to observe the airflow from a high hide, followed by observing Steel working the hide. Note how Part One of his alert so closely matches the location where the fog is falling.

HOMEWORK

Tracking:

Pick an area where it would be likely to lay a track near some water. What does the airflow do as you walk about 20 feet away from the water? What other terrain features are there to influence wind direction?

If you have an experienced dog, try tracking the dog along the body of water. If you can start your track prior and then track past the water, observing how this influences the dog.

Detection:

Place a hide in the center of a room or open area moderately high. Remember you are setting up the hide to just observe how the scent drops down from above - so no corners or other obstacles nearby. Observe the dog work and then check the airflow. Where did you observe Part One of the alert? How does this match what you observed for airflow.

As with all of these homework exercises -make sure that you collect airflow information in the area where the dog works. Try these exercises in different areas. Each search will present a slightly different scenario.