Human Eye vs. Deer Eye

By: Wade Nolan Bowhunting Biologist

We all know that different animals have special adaptations that allow them to more efficiently plug successfully into their niche. Earthworms have small spikes on each ring that allows them to pull forward when digging, willow ptarmigan exchange brown feathers in the fall for all white ones which allow them to wear snow camo all winter and deer have specialized eyes that allow them to avoid predators. Flash – You are a predator.

We know a lot about deer vision due to research done by animal vision scientists who were able to modify human eye research equipment to investigate deer eyes. Because deer operate primarily during low or no light, they have ten times more rods (low-light sensitive receptors) as cones (Daytime color vision receptors). We upright walkers have thirty times more cones than rods because we are daytime creatures.

This means that deer can see about 300 times better than we can in low light. In deer, the rods and cones are found in a band across the back of the eye’s retina. In Joe bowhunter’s eye, the cones are all packed into a central depression called the Fovea. It is packed with cones with no rods. It is a vision hot spot. This means Joe’s eye can see great detail and perfect color in one spot…great for a daytime hunter.

This buck was paying attention when God was handing out eye adaptations. He can see better than you in low-light and can pick you out if you wiggle.

The deer’s eye has a band of receptors that is mixed with both rods and cones. He can see the entire low-light 320-degree horizon with detail as he eats and watches for bowhunters and other predators.

Here is another amazing benefit that a deer has when it comes to detecting a stalking predator. Our receptors are connected to one single nerve for sharpness. These nerves are bundled into the optic nerve that connects our eyes to our brain. A deer’s receptors are wired to multiple nerves. It gives him a fuzzier picture but it greatly increases its sensitivity to movement. They can pick you out if you move. Move like the second-hand if you don’t want to be caught.

We’ve all looked into someone’s eyes and seen the pupil dilate or close. The pupil does this in relation to light. More light smaller the pupil. Our eyes were the model for camera lens. If too much light comes in the picture, it is washed out so you close the aperture or iris. Smaller iris sharper focus. The small opening also concentrates our visual acuity so we can see detail. As you read these words, the word you are focusing on is totally clear (unless your over 50) but the words out at the edge of the page are blurry. For deer, there is a big difference.

First, a deer pupil can open up nearly 10 times wider than your pupil can. This is very important at night when light is at a minimum. However, there is more, the band across the deer’s retina or what researchers call the Visual Streak is packed with both rods and cones. Because they can close their pupil into a slit rather than a round opening, they can focus their attention on, not one small spot, but across 320-degrees. They don’t have to be looking straight on at you to see you perfectly.

This Ohio buck didn't watch well enough to miss being featured in this hero shot with my friend James Coffelt. Next time, we'll look into the UV-spectrum.

If you didn’t already know this, the company who is most familiar with deer vision are the scientists and staff at Atsko . They are the developers of Sport-Wash, a host of scent suppression products and UV-KILLER, a solution that covers up and eliminates the ultra-violet glow that camo can emit if it carries brighteners in the fabric. Deer see UV.