Rounding a corner on the back road home, your headlights catch the reflection from several sets of eyes. Instinctively you slam on the brakes and the deer seem frozen at first, yellow eyes staring unblinkingly in your direction. Then they turn and in a flash of brown and white, they’re gone. Their eyes saved their lives, which they do in several more ways. 

Deer and many other animals have a layer on their retina called the tapetum lucidum. When light strikes the retina, some of it hits light receptive organs called rods and cones. The rest strikes the tapetum and is reflected back so that more is absorbed, then ultimately transmitted to the brain for interpretation. That’s one reason deer see better in low light, but it’s not the only reason.

They have larger eyes than we do, which allow more light to reach the retina. There, cones process color while rods are sensitive to light in general, and further help with visual perception in low light. A deer’s rods are much bigger than ours, and bundled three to each nerve ending, offering still greater advantage.

They lose a little when it comes to color, though. Deer are dichromats, meaning they have two types of cones. In their case, one for blue and the other for about halfway between what we perceive as red and green. They don’t see red or orange, which is advantageous to the hunter. However, they see color in the blue-violet end of the spectrum very well. As it happens, this offers further advantage for low-light visual acuity. And their eyes lack the yellow filter ours have that diffuses blue light.

They also have a few advantages for daylight vision. Eyes positioned on either side of their head rather than facing forward gives them a 300-degree field of view compared to our 180 degrees. Further, the whitetail’s flicker-fusion rate (the speed at which visual images are processed) is about four times faster than ours. In effect, they see things in slow motion, which gives them more time to react. 

Instead of being round like ours, their pupils are ovoid, almost rectangular, giving them keen vision on a horizontal plane along that 300-degree field. But their peripheral vision above and below is less acute. That gives elevated hunters a slight advantage if they remain still.

Having eyes on the side of their head rather than forward-facing also reduces their depth perception. That might make it harder to pick out stationary objects, especially if they’re concealed in camo, but one false move and you’re busted. 

Add keen hearing enhanced by large ears that capture and funnel sound to the inner ear, and a legendary sense of smell, and a daunting set of senses is presented for the hunter to overcome. Still, we sometimes find a way. There are all manner of gadgets and solutions like scent suppressing soaps, and sprays and designer camo patterns we use. More often it’s the basics like being still, quiet and unobtrusive where we gain the greatest advantage.

The deer still win far more often, but we only have to win once.

Bob Humphrey is a freelance writer and Registered Maine Guide who lives in Pownal. He can be reached at: bob@bobhumphrey.com