The fickle nature of scent
When talking about scent, we must consider how different conditions impact upon it, as Graham Cox explains.
cent is truly an act of God. We have no direct access to it, still less any ability to influence it: and yet nothing is more critical to the way our dogs work and the way we choose to handle them. For we see, time and again, how challenges that are almost effortlessly overcome can, in other circumstances, present seemingly insurmountable obstacles.
Close observation and careful reflection are important, of course. But they can only take us so far and often our hopes and our best expectations are thwarted. We find ourselves struggling when conditions seem favourable or, perhaps, breezing it when we envisaged having to work really hard. So what do we know for sure? Well, we know what we don’t know – references in the literature of hunting to it being a ‘mystery’ are legion – and we should acknowledge that it is infinitely variable: and that, generally, makes over-generalised descriptions of days as being ‘good’ or ‘bad’ scenting days quite inappropriate. That’s hardly surprising though, because the list of relevant factors that have some causal impact is a mighty long one. It’s particular to time, place and atmospheric conditions and… who knows what else?
Scent consists of molecules of a volatile substance and the more volatile the substance the more molecules are given off. The particles are of varying weights so some float in the air while the heavier ones fall to the ground. Some are absorbed by surface tension on to droplets of moisture. The resultant phenomena are air scent, ground scent and the scent that adheres to vegetation against which the quarry has brushed. To try to understand air movement and scent we grope for analogies and the best is probably the one that sees it as a plume of smoke which may swirl and eddy as it disperses. Indeed, the fate of the scent molecules is entirely dependent on a whole range of conditions: most obviously radiation, convection, wind and the nature of the ground cover. Certainly, the analogy enables us to understand why a strong wind so often presents a problem as the scent molecules are scattered hither and thither such that dogs will perhaps get a ‘touch’ far from the location of their quarry, which they struggle to ‘work out’.
Of course their ability to do that at all depends on a range of learned competences, and that’s why the beginning of wisdom on the subject is to recognise that we should always talk of nose and scent rather than just scent. But for our dogs and our best guesses, what handle would we have on the subject at all? That’s why Vincent Routledge, in his 1929 essay The Ideal Retriever and How to Handle Him, begins his ranking of the qualities of a retriever with the unequivocal assertion that: “Nose comes first with a big F”. But, that said, he follows it with the observation that brains are every bit as important, if not more so, since without brains a dog will not adapt itself to prevailing conditions.
Later, in emphasising that a handler should never presume to know better than a dog when it comes to making a first cast, Routledge draws on an insight from a celebrated 18th century text on hunting. Peter Beckford published his Thoughts on Hunting in 1781 and no book better exemplifies the value of close observation and reflection on the experience. He says for instance that: “Storms in the air are great enemies to scent and seldom fail to take it entirely away.” He continues: “In some fogs I have known the scent lie high, in others not at all, depending on the quarter the wind is in. I have known it lie very high in a mist, when not too wet; but if the wet should hang on the boughs and bushes, it will fall upon the scent and deaden it…” and “when cobwebs hang on the bushes there is seldom much scent”, and so on. His gaze is precise and the conclusions he draws are tempered by his recognition that “it is very difficult to ascertain exactly what scent is”. The general thrust of his insights, however, is that the temperature of the ground just below its surface, relative to that of the air, is critical in determining scenting conditions.
“When cobwebs hang on the bushes there is seldom much scent for dogs to detect.”