Chapter 4 - Deer Behavior: Deer Senses

Hayden KrimmerSep 16, '21

CHAPTER 4: PAGE 2 - DEER SENSES

INTRODUCTION

Deer have one primary goal - to survive. To do so they use their senses to detect danger and avoid predators. Of those senses, arguably the most important is their sense of smell. A big part of woodsmanship is knowing how and when to move, minimizing noise you make, and using the wind and thermals to your advantage to avoid being smelled. These skills take time to develop and the best way to learn is through trial and error. Deer are pretty unforgiving, you make a mistake and they will let you know!

HEARING

Deer have excellent hearing, right? The answer is yes, but interestingly, studies have shown that the frequency range of deer and human hearing is actually similar. Dr. Karl Miller suggests that deer likely hear higher-frequency sounds better than humans, but we hear lower frequencies better than they can. However, deer have an advantage with large radar-like ears that have ability to rotate direction independently of each other allowing it to pin point the source of the sound. Also, deer are masters of their environment, they know what they’re supposed to hear and learn to filter and interpret noises. Any sound that is unnatural or out of place will put them on alert. If you’ve ever had the opportunity to watch a bedded deer for any amount of time you’ll see how they constantly “scan” their surroundings by rotating their ears.

How much noise you can get away with while hunting or moving through the woods will depend on a lot of factors. While it’s almost impossible not to make any noise, the goal of a hunter should be to eliminate ALL unnatural sounds. If a deer hears rustling in the leaves or a twig snap it may put it on semi-alert, however, if it hears the metal clang of your tree stand it will put it on full alert and will probably spook out of the area. Wearing quiet clothing and silencing your gear will go a long ways towards avoiding spooking deer. Any points of metal contact on climbing sticks or tree stands should be silenced using materials like stealth strips or paracord.

Your bow’s rest should have silencing material to ensure a quiet draw. The list goes on and on, so pay attention for any unnatural noise that you or your equipment makes and be diligent to silence it. It makes a difference! Dead calm days are particularly difficult to get away with making any noise because deer can easily pick up on then compared to a breezy day. This short video clip here shows how tough it can be to get to full draw on a deer on a cold, calm morning.

Knowing how to move through the woods is a very important skill. There are several measures you can take to sound more “natural” and spook less deer. First and foremost, go slow! A lot of hunters move at a “normal walking pace” to their hunting location and the sound of the uninterrupted cadence of a human walking is a dead give away to deer. Instead of walking at a steady pace, break up your cadence and stop for short periods of time. This will also give you a chance to survey your surroundings to look for sign or deer. Watch your footsteps being sure that are no twigs or branches that will pop underfoot. If you do make a loud noise stop for 15-30 seconds or more, it will give potentially nearby deer time to settle down after hearing abrupt sound. Also, look for bare patches of dirt, sand, or logs that you can step on that won’t make noise. Another trick is to wait for cover noises such as planes, trains, or the wind to mask your sound as you move. Attention to the little details can make a huge difference, especially if you’re hunting close to bedded deer.

VISION

A deer’s eyes are designed to help them detect danger and are quite different from ours. Extensive research done by Dr. Karl Miller and his team at the University of Georgia as well as helps explain how a whitetail’s vision works. A deer’s eyes are positioned on the sides of its head, giving them a wide field of view (approximately 300 degrees) and they can detect the slightest movements, meaning a hunter has to carefully choose when it’s safe to move without getting picked off.

Deer also have the ability to see well at night because of shape of their pupils, the proportion of rods vs cones, and a mirror-like layer in the back of the eye called the “tapetum lucidum.” That is why when you shine a light on a deer’s eyes you see the reflection back. These adaptations allow a deer’s vision to work best in low-light periods, which is why they move primarily in the early morning and late evening hours.

Contrary to popular belief, deer are not color blind, nor do they see color the way we do. A study by Dr. Brad Cohen found that deer see blue colors the best and red colors the worst. Deer can see green, yellow as well as UV light, but they can’t differentiate shades to the degree we can. Compared to us, a deer’s visual acuity is not great. Dr. Miller’s research estimated deer vision is approximately 20/60, which is three times worse than humans (20/20) and that they don’t see fine detail to the extent we do. So even though deer’s vision isn’t great at seeing fine detail, they are excellent at detecting movement.

So what does this all mean for a hunter and how do you beat a deer’s eyes? First, it would be wise to avoid wearing blue and not to wash your clothing with UV brighteners. Second, is to eliminate unnecessary movement. While looking for game it’s best to make slow movements, whether it’s a head turn or raising your binoculars. Fidgeting and moving around unnecessarily is a great way to tip off nearby deer that you may not know are there. While it may be difficult for some people to sit still for long periods of time, these little details can make a huge difference in the outcome of your hunt.

SMELL

Of all the deer’s senses, smell is the most important. They use their noses to detect predators, food, and to learn about the status of other deer though scent communication. You’ll probably hear it more than once in this course - that deer, especially mature bucks, live and die by their noses. Often times if a deer hears or sees something it can’t identify it will use its nose to confirm and if they smell danger (in this case you as the hunter) it’s game over. Researchers at Mississippi State University found that a deer's sense of smell, like a dog’s, can be anywhere from 500 to 1,000 times more acute than a human’s.

Deer constantly use their noses to survey their surroundings. Within their environment they use wind currents, including swirling winds caused by terrain features, and thermals to smell danger. Thermals are rising and falling air currents that occur due to changing air temperatures and are most pronounced in hilly and mountainous terrain In the mornings, as the air is warmed by the sun, it begins to rise and any odor in the air rises with it. In the evenings it's the opposite - as the air begins to cool it falls and pulls your scent with it. It’s an important concept to understand and we’ll cover it more in Chapter 5, especially how it relates to your setup.

Deer can detect human scent from several hundred yards away and even farther under perfect conditions. They also detect odor molecules left on the ground from boot prints and on vegetation that you brush against. How long those odors persist depends on environmental conditions, but deer know that you’ve been there for hours or possibly a day after you’re gone. How they react to that scent depends on various factors but it’s important not to underestimate the effect of the scent you leave behind while in the woods. If you use trail cameras take note of how the first pictures you get the deer are usually nervous and reacting to the scent you left while hanging the camera.

As we said, deer live by their noses and use the wind to their advantage as much as possible. When it comes to bedding behavior, bucks often bed with the wind blowing over their backs. This allows them to watch for danger approaching from the front while using their noses to detect danger approaching from behind them. Also, they will often times bed or move through areas where they can take advantage of both prevailing winds, swirling winds, or thermals. As we’ve said before, mature bucks are masters of survival and their nose is the number one defense! They not only use their sense of smell to survive but also the check out areas or sounds without having to go directly to them. They especially do this during the rut to “scent check” doe bedding areas or cross trails attempting to pick the scent of a doe.

Another way bucks use their nose it to “circle downwind” of a sound they want to investigate, often times a hunter using a grunt call, snort wheeze, or rattling antlers. By doing so they can smell what they are hearing before they see it, especially in thick cover. It’s a survival strategy that has saved countless bucks’ lives. We’ll discuss how to overcome this tendency in more detail in Chapter 7. Here’s an example of how a buck circled downwind of Greg’s setup after he grunted at him.

So how do you beat a deer’s nose? The first and most basic strategy is to “play the wind”. Simply put, deer can’t smell you unless the wind carries your scent to them. Your route to your hunting location and the setup itself needs to be planned out so that the wind isn’t carrying your scent into the area where you’re expecting deer to come from. Another way to beat a deer’s nose is to understand how thermals work and setup in a way that uses the rising or falling currents to your advantage. We’ll elaborate on these tactics in the next chapter.

Another way hunters attempt to beat a whitetail’s nose is with the use of scent containment and scent control products. While it has long been debated how effective these products actually are, one thing is for sure, there is no shortage of scent control products for hunters to choose from. Some clothing companies use anti-microbial treatments to kill odor-causing bacteria on the skin. Others use “activated carbon” in the garment to capture human odors. Probably the most popular products are “scent elimination” sprays that are supposed to prevent odors from forming in the first place. Other products use ingredients that act as olfactory inhibitors that are supposed to prevent deer from being able to smell you. In recent years, ozone generators have become increasingly popular and are used to shower ozone down through your scent stream and bond with your scent so it makes it undetectable to deer. For better or worse, there’s no shortage of scent control products available to hunters! We’ll discuss these more in Chapter 6.

When it comes to these products, our general consensus is that if you consistently practice a strict scent control regimen there may be situations where you get an opportunity you otherwise wouldn’t. So why wouldn’t a person want to do that? Well, for us the added expense, time, and inconvenience isn’t something we want to mess with. We’ve done it to varying degrees in the past and it just wasn’t fun for us. We prefer to spend more time scouting or learning how wind and thermals work in the spots we hunt. But for some hunters, they find the scent control process enjoyable and that it gives them an extra edge, which is great. Whatever works best for you!

Figuring out how wind currents and thermals work where you hunt can take a lot of time, but once you get a basic understanding you will be a more effective hunter. One of our favorite ways to do this is to regularly release milkweed into the air and see where the air currents take it. You can learn a lot by watching the fluffy white seed float through your hunting location!