The nose knows ... but we don't, entirely.
As Mr. Jorrocks said in Handley Cross. Jorrocks ended this pronouncement by adding,” ‘cept a woman.” But I think I’d end it differently: “There’s nowt so queer as scent, ‘cept what we’ll do to try to understand it.” More of that in a moment.
“Oh, that weary scent!” exclaimed Mr. Jorrocks, “that weary, incomprehensible, incontrollable phenomenon! ‘Constant only in its inconstancy!’ as the hable hauthor of the noble science well said.”
Indeed. Everyone knows what scent is, by definition: it’s an odor, or “an odor left in passing, by means of which an animal or person may be traced,” according to www.dictionary.com. But it’s almost impossible to get a precise understanding of how scent behaves, though many have tried. How, exactly, does something generate a smell, what carries the scent, and how does a hound’s nose capture the odor? The jury is out on that, apparently. There are two basic theories of how smells work that are competing for subscribers. One says that molecules’ shapes and how those shapes fit with sensors are what give something a distinctive scent; the other says that the particular vibrations of molecules are what does it. We do know that hounds, like dogs generally, have large olfactory lobes in their brains, meaning that scent and the ability to detect it is important to them and they are highly attuned to it. No one understands that better than the people who handle working hound packs, whether beagle, basset, or foxhound, as well as the people who work with bloodhounds.
And yet we still know so little about the thing that is at the very center of our sport: scent and the ability to track it. There have been many attempts to understand and measure scent, to unravel the effects of temperature, geography, moisture, and wind on its behavior, and these efforts have driven scientists, huntsmen, and curious amateurs to some peculiar (and highly entertaining) experiments. One book by Milo Pearsall and Hugo Verbruggen noted that “experiments have shown that a person traveling above the ground when suspended from a cable trolley could not be tracked by dogs.” (More importantly, what did the neighbors think?)
If that were not alarming enough, consider the next phase, in which Pearsall and Verbruggen tested the importance of human skin flakes to a hound’s ability to track a person: “A person dressed in full surgical gear, wearing total body isolation garments, laid track for a dog who had successfully tracked that person several times. The result: the dog showed no interest at the starting flag, nor anywhere else even when led on lead. When the person removed hood and mask, the dogs easily could follow a fresh track … When the person’s boots were cut off but while he wore the hood and mask, the dog easily followed both a fresh and aged track.”
On the other hand, responding to that experiment’s conclusion, one Lieutenant Weldon Wood wrote an essay for the National Police Bloodhound Association Book and asked, “If this is true, then how is it explained that a dog has followed the trail of a person on a bicycle or in an open car?”
Good question, Lt. Wood, and we still have no idea, despite decades upon decades of study.
Happily for trackers of hare, cottontail, fox, coyote, and the like, game doesn’t wear “total body isolation garments,” although there are times when scenting conditions are so poor it seems as if the quarry is. Scent and its operation on the canine nose are mysteries, but the more pressing mystery, from a huntsman’s point of view, is why scent is so changeable and how conditions of land and weather can change its behavior. Here again, ceaseless study has not led us very far. It is generally understood that hot weather and sunlight are bad for scenting, but there are myriad theories as to why this might be true.
The English Master of Fox Hounds H. M. Budgett wrote a classic text, Hunting by Scent, in 1933 that amply illustrates the lengths hunters were driven to in their fervor to get a grip on scent. Budgett employed a pair of magnificent bloodhounds, Ledburn Baal and Hopeful of Hambrook, to help him test his theory that what hounds actually track are particles and oils left behind by the quarry (human or animal) touching the ground ahead of the hound and laying a scent trail directly on the grass or soil, not by the mere whiff of air over the body as it moved past. He was ferociously thorough. He used runners on glass-capped stilts, runners in tall wooden sandals, runners clad in riding boots and rain gear secured with rubber bands to prevent any particle from flying loose to make even the fragment of a trail, convinced that if the man did not contact the ground, the hound would not track him (more or less what Pearsall and Verbruggen had found). But it didn’t always work out that way.
“Even when these precautions were taken the bloodhound picked out the trail with perfect ease, and appeared to have learnt by experience how to follow the scent left by the stilts and foot-boards,” Budgett reported in some frustration. “I must confess that at this point my faith was badly shaken. I had hitherto felt convinced that the ‘body scent’ theory would prove to be fallacious, and that scent tracks would be found solely to consist of particles of matter left by the contact of the quarry. It now appeared, however, that I had been mistaken, as it seemed impossible for any odorous particles to be deposited on the ground from the carefully washed glass bottles on which the stilts were mounted. My family marvelled at the obstinacy with which I stuck to my convictions; they suggested that I should give up the unequal struggle and accept the opinion of others having a wider experience of bloodhound tracking than myself.”
I don’t think I blame them.
Budgett, however, didn’t stop his inquiries, and the subheadings of a couple of chapters in Hunting by Scent will sound very familiar to hunters who have asked the same questions, and devloped their own theories based on their own experiences, about what variables affect scenting on a hunt day–and why. The subheads outline every hunter’s quest for understanding: “Conditions under which scent is good or bad. Direction of air currents on which scent is carried. Relative temperatures of air and ground. Examples. Effect of sun. High wind. Woodlands. Ploughland. Snow and frost. Hound’s knowledge of scent conditions. Meterological considerations. Forecasts of scenting conditions. Effects of moisture in the ground and in the air. The use of smoke to determine movements of air currents. Experiments with anemometer fan and spider’s web. Valuable results obtained with this delicate apparatus. Reasons for its abandonment. Electrical scent instruments. Walking-stick scent indicators.”
If that reads like a cross between Merlin’s lab book and the diary of a man slowly going insane, well, probably there are many huntsmen who feel a little like both as they try to parse the scenting and the weather and then determine where to cast their hounds.