The Humidity Factor

Posted on March 7, 2017

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Nobody is sneaking up on an unsuspecting buck without him knowing something is approaching.

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Slowly, ever so slowly, I crept along the trail of a huge buck. For the better part of the morning I’d been following his imprints left in the fresh blanket of snow. These seven inches under my boots permitted me to navigate the forest almost noiselessly. But now, at this point in the trail the buck had altered his course, which in turn grinded my progress down to a mere crawl.

As is often the case when a buck is about to bed, this deer’s trail made a sharp 90-degree turn up a slight grade on the opposite side of a brook. I painstakingly scrutinized every piece of the terrain before placing each successive step, being careful not to snap even the smallest twig. For a deer tracker, this was indeed high drama of the finest kind.

 

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My rifle filled both hands, finger on the safety and ready for immediate action. “He’s close” I thought to myself. I could almost feel his presence. No sooner had this bit of intuition surfaced, when 15-yards to my right from a fir thicket exploded a plume of falling snow. Instantly, my rifle was shouldered as the buck catapulted from his bed, streaking across the white parchment like a brown blur. Bang went the gun at the buck’s first leap, followed up quickly with a second round before he disappeared out of sight…

 

Beating a Whitetail’s Nose

At this point you may be asking, “How was I able to get that close to a bedded buck without alerting him?” Do I possess some uncanny stalking ability that defies even the keen detection of a wild whitetail? I only wish that were the case!

 

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I’ve often said, “Beat a deer’s nose and you can bag him almost every time.” The most acute of the whitetail’s five senses is their ability to smell. In fact, scent dictates most, if not all, of the animal’s choices. A whitetail’s sense of smell is at least 100,000 times greater than a human’s. We tend to rely heavily on our eyes and ears, often neglecting the sense of smell unless it serves a particular purpose. A whitetail’s very existence relies almost exclusively on its ability to detect, interpret, and react to every odor, even at long distances. For instance, a buck cannot visually single out the doe that is in estrus from a group, even if he has been directly behind her. It’s only through the odor that particular doe emits that keeps him with the right female deer. Unlike humans that go to a grocery store and make selections of what to buy for food based on sight, deer smell the food in order to both locate it and decide whether to eat it or not. Even though they can and do remember where a certain food source may be located, they still smell each mouthful prior to ingesting.

So how do we hunters gain an advantage over the deer’s seemingly unbeatable defense system of his nose?

 

Humidity

Experienced hunters know the value of hunting on days of a rapidly falling barometer (impending storm), and on a rising barometer (passage of storm front). At these times deer are up, moving and feeding. How heavily they feed depends on the severity and length of the storm. Most deer camps today have barometers as a key fixture and hunters check it daily. But, when have you ever heard someone from your hunting party inquire over breakfast what the humidity is? It rarely, if ever happens.

Understand there are three climactic variables that affect deer movement: barometric pressure, temperature (anything above 45-degrees shuts down northern deer movement) and humidity. If we are to beat a whitetail’s nose, then we must consider how humidity plays a key role in our ability to get close.

 

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Anyone that lives in the deep South, or near the coast during summer months, understands completely what high humidity means. The more the atmosphere becomes saturated the higher the humidity level becomes. It’s during times of increased humidity that odors become more prevalent, and with a lack of any noticeable wind, these smells tend to linger in the air.

 

How Humidity Affects Whitetails

A bedded buck is an appreciably tough animal to approach, much less bag, especially when you have no idea where he may be bedded. If we were to draw a circle around that animal, his awareness is only as big as what he can see, hear and smell. Anything approaching that buck’s position is going to make some kind of disturbance regardless of how stealthy they may be. However, the savvy hunter will use conditions to his utmost advantage. Soft fluffy snow deadens a hunter’s footfall rendering him noiseless in his approach. Using terrain and trees coupled with slow movement can disguise the approach, especially if snow is falling. But what about our scent?

 

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The cliché answer is to always ensure the wind is in your face, or at worst, hitting you across the cheek. With a steady, prevalent breeze this is sound advice. However, what happens when the only stirring in the atmosphere comes from an unpredictable thermal, especially when those thermals approach from behind? The key here is to pay close attention to any increase in temperature. Thermal expansion is the tendency of matter to change in volume in response to a change in temperature. When a substance is heated, and that means us, its particles begin moving and become active, thus maintaining a greater average separation. Based on this fact alone it is not surprising that bucks who have escaped the meat pole year after year have a knack for walking and bedding with the wind to their back.

Deer are constantly monitoring the air for particles of scent. Several factors affect scent and how far it may travel such as wind, temperatures and moisture. A moist, still atmosphere enhances a deer’s ability to pick up scent molecules, which in turn increases his circle of awareness. Humidity that ranges above 50 percent is ideal for scenting; it allows more scent to reach them from a further distance and will cause them to be much more nervous. On the flip side of the coin, low humidity hampers the animal’s ability to smell as their nasal passage dries out making it difficult to pick up scent molecules. Extremely low temperatures also further hinder a deer due to scent being pushed to the ground. This is the reason whitetails constantly moisten their nose with their tongue in dry conditions. It seems, at least from this writer’s perspective, that if a whitetail can’t smell danger he is less jumpy – ‘out of sight, out of mind.’

 

Snow and Humidity

As a deer tracker, snow is a very important ingredient for your hunts. If you are blessed to reside or hunt where snow blankets the ground during deer season, then you are fully aware that not all snow conditions are similar. Under falling snow, humidity plays virtually no role as scent is driven to the ground and is quickly diluted by the moisture. However, that is not the case when that blanket of white begins to melt. Under thawing conditions, the mercury rises, thus causing the melting snow to evaporate placing moisture in the air from the ground up. That increased water vapor (humidity) provides deer the ability to smell at far greater distances at nose level. Although tracking a deer in soft, wet snow is ideal for aging the imprint, getting close becomes much more of a challenge due to the increase in humidity. The absolute best snow conditions are a gently falling snow with three or more inches already underfoot and temperatures at or below 20 degrees. Couple this scenario with a slight constant breeze and the hunter will possess all the advantage in penetrating a buck’s circle.

 

Penetrating the Buck’s Bubble

… “He definitely seemed to lunge on my second volley,” I thought to myself. After cresting the small incline, I immediately noticed the long bounding imprints of a buck making his get away. A half-dozen more steps revealed what I hoped would accompany those tracks, droplets of red sprayed out on the clean white landscape. Seventy-five yards further, as I peeked over the next rise in the terrain lay a big ten-pointer, his head rocking back and forth much like a Canadian glider. His brown body looked huge lying there silhouetted in stark contrast to the white backdrop. I wasted little time admiring him before finishing the job with one final shot.

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Sitting next to the fallen beast, which would later dress out at 250 pounds, I pondered what gave me the ability to get so close to this mature buck without him knowing that danger lurked in the immediate shadows? I could have attributed my success to uncanny prowess, but that would only serve to bolster my pride, which as I’ve learned is a tough taskmaster when left unchecked. No, instead of self-adulation I wanted answers that would aid me on future hunts.

 

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Here is what I knew: the snowstorm had concluded by first light and temperatures remained in the teens with a slight breeze coming out of the Northwest. The snow was noiseless and the depth significant enough to absorb any noise of branches being cracked under foot. Moving slowly and utilizing the vegetation to my advantage gave me the opportunity to remain visibly undetected. What I didn’t understand at the time, but have later learned, was that whitetails tend to focus their attention at the periphery of their awareness. Once inside his bubble scent, the final obstacle was conquered. Because humidity levels were extremely low, the buck’s sense of smell had dwindled to a few scant yards, which is what ultimately permitted my access in the proverbial back door unaware.

 

Conclusion

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The unique aspect of hunting whitetails is that each day is different. Conditions vary (sometimes hourly), which will require adjusting our strategy to meet those ever-changing circumstances. The consummate hunter keeps track of not only the deer that is being hunted, but also of what’s going on in the atmosphere. Before stepping foot out of camp for your next hunt, besides checking the barometer, wind direction, temperature and precipitation, be certain to know what the humidity is for the day, as this will indicate just how close you can expect to creep up on a wily old whitetail. And as we have all learned – we need every advantage possible!

All images and text on this site are copyright protected and the property of R.G. Bernier
© 2017 R.G. Bernier Nature Photography – All rights reserved.

 

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Posted in: Whitetail Deer