Understanding the science of a whitetail's scenting ability might not guarantee you a filled tag, but it definitely can't hurt.
On a brisk November morning in 2008, as I was running the video camera for my friend Chris Ellington in Clark Co., Illinois, we spotted a fat-bodied buck cruising up the ridge about 100 yards to our east. The chilly west wind was dragging our scent perpendicular to the buck’s line of travel, and we could tell the two were about to intersect.”This ain’t gonna be good,” Chris hissed.
The big buck’s body language screamed “lovestruck zombie.” His mouth was open, his nose was almost on the ground, and he was doing the classic doe-seeking speed walk. In short, he was all but oblivious to his surroundings.
But when the buck hit our wind cone, his reaction was instantaneous. As if human scent had hit him in the face like an invisible baseball bat, the buck’s careless, rut-induced autopilot mode disappeared. He stopped in his tracks so quickly that his skin and fat shuddered.
The buck whipped his head, swinging his chocolate rack around in a whirl, and looked across the ravine directly at us. His black eyes were wide with alarm. It took all of about five seconds for him to take that first half-step backwards and then bail off the ravine away from us, blowing and flagging.
This episode was an example of how quickly a buck’s demeanor can change when human scent is intercepted. We all know whitetails possess excellent olfactory ability, and this buck offered but one example of it in action. Let’s examine the whitetail’s superpower sense of smell a little more deeply.
Defining Scent
So, what is scent? The answer gets a bit technical, but understanding scent and its origin is critical. After all, how can we as hunters attempt to control or eliminate scent if we don’t understand it on a biochemical level?Biologist Dr. Bronson Strickland of Mississippi State University’s Deer Lab describes “scent” as a generic term for what’s known to chemists and wildlife researchers as volatile organic compounds (VOCs). He explains these substances originate as organic compounds given off by a subject. Due to their high vapor pressure, these lead to large numbers of molecules evaporating into the surrounding air.
VOCs entering the air can come from numerous sources. Manmade products such as gasoline, diesel fuel, paints, oil, tar and perfumes all give off unique VOC signatures. Plants give off their own VOCs when leafing, pollinating, flowering and growing. These signatures change throughout their annual growth cycle.
Our bodies give off literally thousands of VOCs. The human liver, kidneys, lungs and skin are all tasked with taking toxins from normal metabolism and rendering them chemically removable from our system through excretory pathways found in feces, urine, breath, sweat and saliva.
In one study, more than 1,800 distinct VOCs were determined to come from our body! Breath (872), skin and hair (532), feces (381), saliva (359), milk (256) and blood (154) made up the list, with some overlap among the compounds. Bacteria also give off their own unique VOC signatures on our body and clothes.
The take-home message is simple here: Normal body processes make us like a lightning rod projecting scent into the air in the form of VOCs. To put it frankly, we stink!
The Olfactory Pathway
Now that we’ve defined scent in its true chemical form, let’s climb into a VOC molecule and take a ride through a whitetail’s nose. Hold on tight.A scent molecule is inhaled through the broad nasal openings and captured by little hair-like cellular projections called cilia in the mucous membrane. Once captured by the cilia, VOC molecules dissolve into and through the mucous and are transferred to the olfactory epithelium. Note: The whitetail epithelium is reported to have 297 million olfactory receptors. (The human epithelium has only 5 million.) These receptors translate the scent signal as electrical impulses up through nerves that extend through the roof of the mouth and into the part of the brain known as the olfactory bulb.
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