Scent success: help your dog make the best use of his nose.
According to Scent, Training to Track, Search and Rescue, by Milo Pearsall and Hugo Verbruggen (Alpine, 1982), "The dog can smell some odors at as much as one part per trillion." The authors go on to say that while a man's nose has 5 million receptor cells with six to eight cilia per cell, a dog's nose has 125 to 200 million reception cells with 100 to 150 cilia per cell.
Studies also suggest considerable variation in scenting ability among breeds, family groups and individual dogs. This accepted variation is a prime reason "use of nose/bird finding ability" are matters of record at hunt tests and field trials and are a point of interest to discriminating breeders. The assumptions are that some lines do better than others and they should become the producers.
We probably would agree that when certain dogs are on the ground, scenting conditions seem to improve. In fact, some individuals are real "bird finders," consistently out-producing other dogs. The question is, what part does a given olfactory percentage play as compared to attitude, drive, experience, the dog's physical condition, etc ...?
Couple the inherited characteristics and learned variables of each individual dog with other factors like humidity, temperature, altitude, vegetation, terrain, game movement, wind direction/speed and we begin to understand just how complex finding a "quail in a hayfield" might be. This brings up another point, namely your responsibility in knowing your birds and hunting likely cover--for example, quail aren't usually found on hay ground.
Given the opportunity, I'll someday ask the good Lord how this all works as I'm certain he's the only one who really knows. Until then, we'll have to get by with scientific facts and years of experience with repeated observation and luck for a productive day's hunt.
* OPTIMUM SENSE "Spoor," the total track, combines disturbed ground cover and vegetation, actual molt clinging to vegetation, along with lighter smells of broken vegetation, the bird's body and breath scents carried by air movement. I also have a very strong feeling dogs can sense warmth or variation in air temperature from the bird's body and breath when they're close, especially in colder weather.
Lighter spoor/molecules/smells will mix and travel a good distance on currents of air. These "gaseous" collections of spoor dilute as they expand and, travel, but in optimum conditions can provide pretty good opportunity and reward to a diligent search.
With this in mind, we should visualize clouds of scent as our target rather than the actual bird. This also helps us see why modern pointing breeds have evolved to depend on sensible ground coverage, coursing the cover with the head up, consciously searching air currents and hoping to catch a whiff of body scent and in turn, pin the birds.
A good, productive bird dog only uses its eyes to identify good cover/objectives, then awareness and reasoning guides him to the downwind side. You might imagine the dog's entire being and mentality designed to carry or position his nose to an advantage as a means of finding game. A good hunting dog eagerly courses likely cover and edges, focused on detecting the slightest wisp of bird scent.
Yes, after the shot a good gun dog will rely on a combination of ground tracking and body scent to retrieve cripples, but ground tracking before the shot is generally slow and not too productive.
Scent disperses well under optimum conditions and provides a good target, but what's optimum? This is where some speculation comes in, but most will agree on a cool moist morning, maybe overcast and with a light breeze.
We choose morning because birds will be moving to feed, spreading scent over a bigger area. Moist, denser air seems to carry spoor better and at the same time allows the dog's mucus site to remain moist and clean, aiding olfactory function. Overcast and cool, so our dogs can perform at a higher efficiency for longer periods, with a light breeze to disperse and carry scent, thus providing a bigger target.
Some may disagree, but give me this day and I'll enjoy myself whether we come home with birds or not. But seriously, let's use a couple of examples at opposite extremes for further illustration.
* SPOOR CONDITIONS How about a hot, dry, dusty day with bright sun and calm air? With no wind there's no cooling effect on the dog or carrier for spoor; the dog's nose dries and congests, blocking the receptors to the point the dog couldn't smell a pork chop in a phone booth. At this point, he may well start thinking about the heat, his sore feet and which bush to pee on rather than the hunt.
We can't change conditions, but we can plan ahead and choose our dog from good stock known for persistence, desire, an attitude to apply themselves, and of course, good nose. We can provide preseason exercise to toughen and condition our dogs for better endurance and efficiency. We should carry water to keep our dog hydrated and to flush the nose and mouth. Maybe we could work the cover differently too.
Too little wind provides no carrier, but too much wind presents another set of problems. High winds dilute and scatter scent, make birds spooky and hard to work. Too much wind tends to push dogs off as they cast into it and it pulls them out on the downwind move, often right over the top of birds.
Knowing this, we might try to work valleys, thick edges, or other sheltered areas out of the heavy wind when we can. Birds sometimes feed early and take to heavy cover on those days, and the wind is slowed for better scenting in sheltered areas.
Now that we're thinking of ever-changing abstract shapes or "clouds of scent" as our target rather than actual birds, how about working the wind to its best advantage? Understanding your dog's objectives can make you a better handler and does away with a good deal of the frustration of "over-handling" or handling contrary to your dog's natural tendencies.
Working directly into the wind tends to stall the dog's forward travel because his tendency is to cast or sweep perpendicularly along the wind's face while taking advantage of likely objectives. So we have to slow down and give our dogs time. to work.
When walking perpendicular to the wind across uniform grassland, most dogs tend to "yo-yo" out and back along the wind, so again, give them time to be sure the likely spots are checked.
When traveling with the wind, a good many hunters allow their dog to cast downwind then turn them to sweep back and forth, covering all the good spots as they work back upwind.
Of course, when working a creek or brush edge we like the wind drift coming out of the cover, carrying our target--the "scent cloud"--with it. But that can't always be, so we make do, and help/allow our dog to position himself to the best advantage, using whatever wind and cover are available.
Think all this through, taking into consideration wind intensity, wind direction, the lay of the land and your dog's innate tendencies, and plan your hunt accordingly. If you do, you'll soon need a skillet or a baking pan!
RELATED ARTICLE: How are they different?
The canine nose is divided into two parts, one being an olfactory recess with its ethmo turbinates (greenish yellow), and the other being specific to respiratory function with the maxilloturbinate (pink). The differences between the human and canine nasal passages that make dogs more macrosmatic (keen-scented) lie not only in the amount of nerve receptors and cilia in its tissue (or epithelium) used to pick up scents, but also in the way the two sections are separated in dogs and other keen-scented animals.
A bony horizontal plate called the lamina transversa sections off, and aids in airflow to the olfactory region from the respiratory region. The receptors for scent detection are present only in the olfactory area. The specially designed surfaces (ethmo turbinates) maximize the air's exposure to the scent detecting nerves.
As you can see, humans have only three turbinate ridges, no specific olfactory recess, and only one rather small concentration of scent detecting tissues. And that's also why some folks recommend you should breathe through your mouth when cleaning up a particularly ripe pile of dog manure.
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|Date:||Jul 20, 2012|
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