MARTINO: Researchers offer insight on whitetail deer’s vision

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MARTINO: Researchers offer insight on whitetail deer’s vision

  • By JOHN MARTINO Outdoors columnist

SHADES: The eyes of whitetail deer contain only two types of photo pigments, giving them dichromatic color vision.

  • Submitted photo


MARTINO: Researchers offer insight on whitetail deer's vision


It’s a question asked since sportsmen have been mandated to wear “hunter orange” during specific deer hunting seasons. Are deer color blind or do you stick out like a blazing pumpkin? Everyone knows a deer’s best defense is its nose, but what about its eyes?

At a Quality Deer Management Association’s annual conference, researchers from the University of Georgia’s School of Forestry and Natural Resources presented findings of their in-depth study on whitetail vision.

First, let’s go back to our high school science class. Remember when we were taught our eyes contain specialized nerves called rod and cones? Photoreceptors in cones are what give us the ability to see colors. Rods contain special pigments that allow us to see in low light conditions.

The University of Georgia’s Dr. Karl Miller explained deer have far more rods in their eyes than humans do. They also have a reflective layer called the tapetum lucidum giving their eyes that familiar “shine.” That’s why when you spot a deer at night in the beams of your headlights they always appear to reflect back. That same layer reflects light back over the rods and cones again, giving deer far better ability to see in darkness than we can.

Humans possess what is called tri-chromatic color vision, meaning our eyes contain three types of photo pigments. This enables us to see short, moderate and long wavelengths of light, corresponding to blue, green and red colors.

The eyes of whitetail deer contain only two types of photo pigments, giving them dichromatic color vision. Scientists believe deer can primarily see short wavelength blue light and moderate wavelength light perceived as something between red and green. So the hunter orange they see may actually appear to be gray or brown.

According to Miller, the cones in a deer’s eyes are distributed across the back of the eye in a horizontal plane. The lens in a deer’s eye also cannot adjust to objects at varying distances. So what does this mean? These factors give deer less visual clarity than humans. An object a deer may be looking at straight on is equally in focus as something out to the side.

Humans on the other hand can see something straight on in focus but our peripheral vision lacks detail. So never assume just because a deer may not be looking your direction that it can’t see you. “A deer’s eyes are especially designed to detect movement,” said Miller.

In another study, biologist Dr. Brad Cohen trained deer to associate light wavelengths with food to test just how well they can see. Deer were given a choice of two empty feed troughs but would only receive food when they chose to eat where an LED light was illuminated. After they were trained the deer were tested on six different wavelengths of light to determine which colors they could see best.

Cohen found deer see blue colors best and red worst. Maybe that’s one reason why the Buffalo Plaid hunting clothing of past years was so popular. These early outdoorsmen knew this long before this scientific study was completed.

Cohen also learned deer can see green, yellow as well as UV light, but they can’t differentiate shades to the degree we can. This is why it’s not a good idea to wash hunting clothes in anything containing UV brighteners.

Technically, humans are a predator that’s why our eyes, like other predators, are situated on the front of our face. Our binocular overlap (the area that both eyes view at the same time) is about 140 degrees, allowing us to perceive depth very well. On the other hand, a deer’s eyes are located on the side of their head giving them about a 60 degree overlap with poor depth perception.

“Deer shift their head to gain a three dimensional perspective by looking at it at several angles. This is probably the main reason why they bob their head when encountering a possible threat,” explained Miller.

But having their eyes located on the sides of their head deer can see 300 degrees around them, leaving only a 60 degree blind spot directly behind them. Although detecting fine detail may not be a deer’s strong suit, detecting movement is.

So what can hunters take away from their findings? First is not to worry about hunter orange inhibiting your hunt. Avoid wearing or carrying anything blue. Most of all is to restrict movement when a deer is approaching your area to avoid being detected.

John Martino is the Tribune’s outdoors columnist. He may be reached by email at