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Published: Wednesday, Oct. 24, 2012 / Updated: Wednesday, Oct. 24, 2012 10:49 AM

Deer vision: A clearer perspective

Ask any experienced outdoorsman just what makes deer so tough to hunt and, odds are, the first thing he or she will mention is their keen sense of smell. Because we understand just how powerful a deer’s nose is, successful hunters pay a great deal of attention to their efforts to be as scent free as possible.

We wash our hunting clothes in unscented detergents, purchase expensive, “scent killing” hunting garments that contain carbon or silver, spray everything down with scent eliminating sprays and give careful consideration to our tree stand placement in relation to the wind direction.

For as much as all of this definitely helps to raise our odds in the field, it’s often another less understood deer sense that ultimately costs us a chance at that big old bruiser buck.

Wildlife biologists have spent decades trying to figure out exactly what cervids (deer and elk) see and how their vision works. Only recently have great strides been made in resolving this since it took a ton of technological advancements over the course of time to make some real determinations possible.

Let’s take a look at what’s now known to be true about a deer’s vision. The reality of it just might surprise you and a good grasp of it may make you a better hunter.

The eyes of all living things are of a truly remarkable design. They feature a retina that’s located in the back of the eye to receive the image and specialized cells called rods and cones.

The rods are responsible for providing the amount of vision that we mammals have at night and we’ll get to more on them in a minute. It’s the cones that help us to differentiate colors and provide our daytime vision.

I can’t remember the first time that I was told that these animals are color blind but it’s been considered common knowledge in the hunting community for as long as I’ve been climbing into trees to pursue them.

The problem is the term “color blind” is a tad bit misleading. Deer do, in fact, see color. They just happen to see it somewhat differently than we do.

This is because the eyes of a deer only feature two cones as opposed to the three that we have. The cone that’s missing is the one that would allow them to see long wavelength colors well, such as those in the red/orange family.

Despite most states having some sort of law requiring the use of blaze orange for safety purposes, many hunters have resisted using it out of fear that they’ll stand out to deer just as well as they do to humans.

There’s no denying that these animals do see it but, because their perception of it is entirely different than our own, it doesn’t appear unnatural and out of place to them. This is why it’s ridiculous for anyone to take chances by not at least wearing it as they travel to and from the stand.

Colors that deer see very well are both greens and blues. Anything green will obviously appear somewhat natural to their surroundings but heading out to hunt in a blue jacket or pair of jeans wouldn’t exactly be a smart move.

Have you ever thought that the reason for entering the woods before sunrise was so that you could slip in under the cover of darkness? If so, you’re badly mistaken.

When God was designing these critters, he went to extremes in giving them every advantage over us. Their keen nighttime vision is in some ways even better than what they’re capable of during the day.

This is possible because of several physical differences between their eyes and ours. First is the extremely large pupil that they possess. By being able to open so widely, far more light is gathered which works in much the same way as a good rifle scope or pair of binoculars.

Haven’t you ever noticed how much brighter things appear in your scope at dusk than to your naked eye?

And, remember those rods that I mentioned earlier? Deer have a much higher concentration of them. As if that weren’t enough, they were also blessed with something called a tapetum. It’s a mirror of sorts that reflects light entering the eye and allows it to bounce around in there, passing over the rods more than once. In effect, it’s a light multiplier.

If you’ve ever gotten nighttime photos of deer with a trail camera or had one standing in front of your car’s headlights after dark, you’ve seen how their eyes can glow. What you’re seeing is the light from either the camera’s flash or your headlights being reflected off of the tapetum. Although the effect is somewhat similar as “red eye” that happens in photos of people taken with a flash, the deer’s glowing eyes are far more intense.

“Red eye” is caused by direct light bouncing off of connective tissue in our eyes called the choroid. We weren’t lucky enough to be given a tapetum.

What all of this means is that there’s no such thing as a “cover of darkness” when it comes to being invisible to deer. Their vision in the dark is more than 50 times greater than what we’re capable of.

Oh, and the real reason for hitting the woods before daybreak? It’s so that you’re there well in advance of that first hour of light, when the deer movement is at its peak.

There’s no sense in walking through at the very same time that the deer are mostly likely to be doing the same thing. You’ll blow any chance that you might have had if you’d gotten in early.

Besides these differences in day and night vision, cervids have a short, wide field of view with fairly poor depth perception and an inability for fine details. This is why camouflage patterns do a great job of hiding us so well. But, make no mistake about it; movement will catch their attention in a heartbeat.

Finally, the eyes of a deer are unable to filter ultraviolet light as ours do and many experts believe that clothing washed in regular household laundry detergents will appear to deer as if it’s glowing.

The truth is, nobody really knows the reality of this yet but it makes enough sense to me that I don’t wash my hunting clothes in anything but hunting specific, scent free laundry detergents without UV brighteners. You can bet that anything that you pick up at the grocery store is full of them and my time in the woods is far too valuable to me to take the chance.

So there you have it. Just what you needed, huh? More things to have to consider when planning out your hunt!