It's The Nose That Knows

A hunting dog's most prized trait is its great olfactory ability, and the good sense to use it wise

"It takes little talent to see clearly what lies under one's nose, a good deal of it to know in which direction to point that organ." Poet W.H. Auden wasn't talking about the canine nose when he penned this statement, yet few writers have better summed up—albeit inadvertently—the nature of hunting dogs. Then there's the well-worn cliché that says, "Reduced to basics, a bird dog is a nose on four legs." Although dogs are a lot more than mobile sniffers, there's a bit of truth in that old saw. But what is this organ, the nose, that we prize so highly?

However much a dog's nose looks like a simple wet knob on the end of a muzzle, what takes place inside that nose is anything but simple. Behind the nostrils is the nasal cavity, an intricate passageway that runs the length of the dog's muzzle. This cavity is lined with a mucus membrane rich in nerves that connect with the brain's well-developed olfactory center—the nerves and the olfactory area are the core of a dog's scenting mechanism.

A dog's nasal membrane is honeycombed and folded to increase its surface area, and contains roughly 220 million scent receptors. (The human nose has a paltry 5 million receptors.) Another telling comparison is that if a hunting dog's nasal membrane could be unfolded, it would be at least the size of a handkerchief, while that of the dog's owner would be little larger than a postage stamp.

When a dog inhales bird scent—whether foot or airborne body scent—the chemical-based vapors, and possibly particles, contact the nasal membrane's scent receptors where chemical interactions convert to electrical signals, which are transmitted via nerves to the brain for processing in the olfactory center. Even though dogs' brains are substantially smaller than ours, their olfactory centers are disproportionately larger. And it's the brain that interprets the information carried by nerves and tells a dog what to do with the scent its nose has collected.

Most of us aren't concerned with the details of how dogs smell—the process is a complex blend of biology, neurology and behavior not fully understood even by experts—though a bit of knowledge helps us appreciate the results. What really matters is that our dogs' noses work, sometimes at astonishing levels.

Amazing Olfactory
The wind on the rolling prairie was light by Kansas standards. It flowed over the land's undulations in waves that swirled grass still stiff with melting frost. Two head-high pointers were working at an angle to the wind when one of them stopped abruptly, thrust its head higher and aimed it at a broken-down farm several hundred yards away. My partner yelled, "Hie on," and both dogs worked steadily and without pause toward the overgrown homestead.

The upshot was that after hunting the perimeter of the weed- and bramble-choked barnyard, the pointers locked up near a cluster of bent-over sunflowers. At least 15 quail flushed in a tightly packed covey. And a few minutes later there was a bonus of two ringnecks the dogs caught skulking in thick cover.

The issue here isn't the work of veteran pointers, but the fact they apparently winded the birds from more than 200 yards away. By any standard, under any conditions, that's an impressive distance for dogs to pick up even a whiff of game. My partner and I tried to come up with another explanation, but there wasn't one—the dogs knew birds were ahead of them in the direction of the old farm.

For years, I was reluctant to accept the notion that hunting dogs of any breed could smell birds over substantial distances, even under ideal scenting conditions. But that reluctance flew in the face of what I, along with many others, had seen on numerous hunts. The question isn't can a dog nose detect game both near and far, but what enables it to do so?

No one has ever attempted to put all of the information (fact along with fancy) about gun dogs and scent between the covers of a book; it would take a treatise the size of "Gone with the Wind" to tackle the subject. What we do know—though much of that knowledge is prone to misinterpretation—is a dog's ability to pick up scent is influenced by a number of environmental factors.

Moisture, Wind And Temperature
Across the board, moisture seems to impact scenting conditions more profoundly than other factors. Free-floating scent attaches to, and is held by, airborne water molecules as well as by moisture on the ground and vegetation. That's one of the reasons why scenting is often best in early morning, when dew or a melting frost is on the earth. Along with transient moisture, like dew, I've also seen a first-class dog work on cool days in a mist or light drizzle, even a gentle snowfall. On the other hand, if the sky opens up with a hard rain, you might as well pack it in. Heavy precipitation washes away scent—exactly where along the moisture continuum that breaking point lies is anyone's guess.

Wind is right up there with moisture in importance—indeed, the use of wind is a primary hunting dog issue—and similar to moisture in that there can be too much of a good thing. Other factors being equal, a light to moderate headwind can maximize a dog's ability to make game. Conversely, strong winds gusting or constantly shifting direction can be as bad, or worse, than no wind.

Moisture allows a "scent cone" to form around birds, and a hard wind scatters that scent cluster, making it difficult for even the best of dogs to pin game. On top of that, birds behave differently in windy conditions; they're spookier and seek protective cover or terrain that lessens the wind's impact on their bodies and keen senses, mainly that of sound. Indeed, many of the problems dogs have locating game on windy days might be the result of changes in bird behavior, rather than an inability to scent them.

It's tough to get a grip on the effect of temperature as a single factor in scent detection because of the other conditions it creates: Heat impacts dogs physically and exceptional cold usually means very dry air that impedes scenting. What we can say about temperature is that cool air is denser than warm air; therefore, it holds scent better. But even with acceptably cool midrange temperatures, moisture and wind remain the major players in the scent game.

Other factors, like dusty terrain or undulating land that channels wind or causes it to swirl, can impact scenting conditions. As can thick-green early season cover or the reverse of dried out, brittle-to-the-touch cover. On the plus side, some cover types create microclimates that hold moisture, can be either warmer or cooler than the ambient air and in an instant can improve scenting conditions. How about birds with their variable, sometimes erratic, behavior? Many exhibit penchant for moving, thus encouraging false points. And what about their aggravating habit of "air washing," which seems to cleanse them of scent after a strong flush or when they hit the ground stone dead? We've all seen dogs stand within feet of a dead bird, especially on bare or nearly bare ground, and not have a clue it's in front of them.

Then there are dogs themselves. Conventional wisdom holds that certain breeds have better noses than others, though a number of technical experts and professional trainers believe there's more significant variation from dog to dog than among breeds. That said, in real terms, what's the difference between a dog with a so-called "great" nose, one with a "very good" nose or one with simply a "good" nose? Those are judgment calls that lack meaning, human opinions of a process beyond our grasp. Gun dogs are born with individual scenting abilities of such subtlety that it's pointless to compare them.

Moreover, those comparisons assume the quality of a nose is the determining factor underlying the caliber of a bird finder. It isn't. The key is what a dog does with the scent its nose passes to its brain; how it deciphers "bird data" is what matters. And that skill, though in part innate, can be enhanced by training, experience and plenty of bird contacts. You can't change the nose nature gave your dog, but you can develop a working partner by helping it learn to use what that nose tells it.

It's a rare day when we can work our dogs into a light headwind in ideal cover on perfect days that are neither too hot nor too cold, too wet nor too dry. We hunt when and where we can under the conditions that exist, and we trust our dogs to get us into birds. From any angle, bird scent is tricky; it's shifty and inconsistent, often here and gone, as ephemeral and nebulous as a fleeting thought. Yet gun dogs, with their marvelous native endowments and perhaps a hint of magic we'll never understand, seem to know in which direction to point their noses.

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