Encore.204, Lockport area.
Good post Byron!
The following information, is common knowlege to handlers with mantrailing K9s. Most K9s can be used to mantrail and most can be used as for scent descrimination, some better than others. Scent descrimination just means that the K9 is not only trailing human scent but, specific human scent. Human scent is much like DNA and probably contains some of the various DNA acids. Even identical twins have been proven to have their own "scent." Your scent is specific to you and I have run hounds on adults using hair from their first baby haircut. Not much different to a trained K9 than fingerprints to a trained CSI officer. Can a coyote scent descriminate? I would bet he could. I'm betting he can smell me and my buddy when we are hunting together.
Trailing K9s are different than tracking K9s. Tracking K9s are trained to follow footsteps on grass. They are actually smelling and keying on the crushed vegetation from walking. Just like you smell your lawn after mowing. Trailing K9s are following the scent trail left be a person they are trailing. Depending on weather conditions, age of the trail, ect. they may be well off the actual trail that that person walked. Human scent and it's migration has been demonstrated using smoke bombs. It's easy to see the drift of the smoke in the wind and it's collection on vegetation. I prefer to think of human scent like leaves in the fall of the year, drifting in the wind and collecting on vegetation, curbing, buildings, ect. Also swirling and gathering in a breeze around buildings, rocks, trees.
Man vs Dog
It's been estimated that a human has approx. 5 million olfactory sensory cells compaired to a German Shephard which has 220 million. I don't know what a coyote (or fox) has but I would guess that it would be close.
Human scent
Human scent can be found in anything that you come in contact with, any body fluids, secretions and gases. The following has been a long held theory as to what a K9 is scenting when they recognize human scent, the FBI is currently doing more scientific studies and the results may differ when they are completed. It's known that a human sheds "skin rafts" at a rate of 40,000/minute. These skin rafts are microscopic, are dead or dying cells and usually are 1 to 4 cells in size. In addition to these cells or rafts, they are inhabited by bacteria. It's believed that when these bacteria break down the cells, the gas that is released, is what K9s key on. Other fluids (sweat) or gases (breath) also provide human scent detection. Recently, it was discovered that the human body has a natural airflow caused by heat rising, much like a chimney. Starting at the feet and ending at the head, natural airflow causes thse rafts to be spewed out of the collar area in clothing. Rafts can also escape through clothing but this air flow is the main transmission of skin rafts. These rafts will rise to a height of approx. 1.5 above your head and flow down, like a fountain. They are then acted upon by the prevailing wind and carried. Keep in mind that the airflow around your body may at times be enough to carry rafts upwind in a slight breeze. When a human stays in an area, he creates a scent pool. A large, intense area of scent and this pool will grow in size dependng on how long a person stays in one place. Because a K9 is using the gases produced by the bacteria breaking down skin cells, temperature and humidity plays a large part in human scent detection by K9s. Hot (above 90), dry weather inhibits this bacterial breakdown. Cool, damp weather is actually the best for bacteria. A dog having probelms in the heat of the afternoon will many times work better the next morning when it's cool and damp. Rain doesn't "wash away" your scent, just the opposite. If anyone is interested in further reading, check out "Scent and the Scenting Dog" by Syrotuck.
How long does human scent last? It depends on the weather and how long it takes for that organic matter to break down. I have had bloodhounds run trails over one week old. There are documented cases of hounds running trails much older than that. We have also used collected scent materal from an individual that was frozen for 11 years.
So what can we do to eliminate human scent? The only way to eliminate would be to completely cover with a non-permiable suit. We would also need to filter breathing air, remember breath? Other than that, the common rules of hunters apply. Use the wind, don't let them get downwind. I like to hunt areas saturated by human scent if possible, I would rather hunt near highways or working farms then deep woods.
Keep in mind that none of this is cast in stone. I have had animals respond to calls directly downwind with reckless abandon. Go figure. That to me, keeps it interesting.
Sparky