Sports

Knowing what deer can sense is beneficial

Outdoors
Dave Sartwell
Published: November 18, 2008

Recent scientific studies on Whitetail deer have defined in detail what deer can hear and see.

Although stories in deer camp abound about their remarkable abilities, knowing just exactly what they can and cannot hear and see can be very helpful in pursuing them in the woods.¬ 

Let's start with their hearing. A deer's ear is, on average,¬  about seven inches long and three inches wide when cupped for a total of about 24 sq. inches when flattened out. A human ear is about 3 1/2 sq. inches. When we hear a sound we tend to turn our heads toward the sound. A deer can rotate the ears independently of each other so they can move their ear toward the sound without moving their head at all.¬ 

While this gives them great directional ability, studies at the University of Georgia by David Osborn and Larry Marchinton based on some initial research by Arthur Stattleman, show that their hearing is about the same as ours.¬ 

"The deer was conditioned to seek and accept food whenever it heard a sound," says Osborn. "A machine called an audiometer was used to create a wide range of sounds varying intensity (loudness as measured in Decibels) and frequency (tone as measured in Hertz). The intensity at each frequency was increased until it produced a positive response from the deer.

"When repeated over time this procedure provided some understanding of what sound the deer was able to hear. The results of the experiment are compared to some common sounds and the minimum hearing capability of humans. Deer and humans apparently can detect sounds of low-to-moderate frequency at approximately the same intensity.¬  Deer probably detect high frequency sounds slightly better than humans."

These findings are probably at odds with what most hunters believe, but the simple fact is that deer do not hear normal sounds any better than we do. However, because their life depends on their paying attention to sound, they tend to concentrate on noise and are more in tune with the sounds around them we are.¬ 

When it comes to sight, deer do not see that much better than humans. However, there is considerable difference between humans and deer about the amount they see. It starts with location.

Deer eyes are located on the sides of their skull as opposed to ours which are in front. Their eyes bulge a bit out from the side of their face and are curved a bit more while ours are sunken into our skull and protected by the socket.¬  As a result of their location, deer are able to see more than 270-degrees around them.¬ So if a sound occurs to their side, they can move their ears to locate it and actually see it without moving their head.

Dr. Jay Neitz, an animal-vision expert at the Medical College of Wisconsin, has studied vision in deer.¬  He has concluded that while humans have three classes of cone photoreceptors which allow us excellent color vision, deer only have two cone photoreceptors which means they can have no better than two-color vision.

They can see blue and violet but cannot see green, yellow, orange and red. As a result we can see a whole range of colors that are combinations that deer simply see as gray. Blue, violet an UV components would make a garment stand out as both bright and colored against a natural background while hunter orange would not.

Another big difference is their ability to see at night. They can see much better than us at night and, in fact, spend much of their waking hours in low-light and after dark.

As a result of this research, Dr. O'Neill, formerly of the United States Military¬  Academy, worked out colors, textures and shapes that would be most effective for camouflage.

"The first and most obvious trick," according to Dr. O'Neill, "is to fade into the background, as a leopard's spots enable it to do while it's patiently waiting to ambush a prey. The spots aren't shaped like leaves or branches, but they form an overall "micropattern" matching the colors and overall texture of the woodland background. That trick, though, won't work for a predator on the move, which is why a tiger doesn't have spots. It has a "macropattern" of stripes that break up the shape of its body as it's stalking or running."

"The prey can detect the tiger's movement," Dr. Neitz says, "but if the shape isn't recognized as the outline of a tiger, nothing registers in the higher center of the prey's brain."

So then the trick is how do you develop patterns that will effectively fool deer? What should a hunter buy to be relatively invisible in the woods?

"The essence of digital camouflage goes back to the old question: Is the purpose of camouflage to match the background or to break up the shape of the target?" Dr. O'Neill says. "The answer is yes — you do both. You create a micropattern that matches the 'busyness' of the background and makes it harder to detect the target, and you overlay it with a macropattern that makes it harder to recognize the shape of the target once you've detected it.

"But no matter how carefully the patterns have been computed, no matter how precisely the new hunter's digital camouflage is calibrated to deer's vision, there remains one large uncertainty: Will hunters wear overalls covered with pixelated squares that look like computer-generated abstract art? Or will they stick with their traditional preference for representational art?"