by Ben Koerth, Institute for White-tailed Deer Management and Research
Like all warm-blooded animals, deer have five senses: smell, taste, touch, hearing and sight. Each of these senses is developed to various degrees in different animals depending on their lifestyle. Eyesight, for example, is poorly developed in gophers. What good would eagle eyes be for an animal that spends the majority of its time below ground? On the other hand, eyesight is well developed in deer who depend upon eternal vigilance for survival.
After centuries of evolution, the eyes of deer have developed some important aspects that make them uniquely adapted for survival. Location of the eyes on a deer's head is typical of prey animals. Eyes located on the sides of the head and bulging somewhat beyond the skull give deer the ability to see a much greater area at one time than humans. While deer cannot see directly behind, they can see within about a 310 degree arc. Most humans, for comparison, can see a little less than 180 degrees.
However, most of the large radius of vision of deer is monocular. Therefore, most of their vision is two dimensional, similar to us looking at a photograph. Relative distance of an object in the front to another object in the back is indistinct. However, monocular vision is well suited to detect movement, which usually is by another creature. If potential danger is recognized, deer will turn to face the threat. This brings their binocular vision into play.
Deer can see in three dimension, or binocular vision, in about a 50 degree arc in front of their face. Alarmed deer commonly will move their head as far as they can from one side to the other while facing the object of interest. This behavior is believed to enhance the dimensional aspect making the object seem to stand out from its surroundings.
Aside from identifying potential threats, three dimensional vision is important in many day to day activities. For example, being able to judge distances is necessary for activities like feeding and avoiding objects while walking, running or jumping.
Until just a few years ago, it was widely believed deer were colorblind. The world, from a deer's eyes, was simply seen as shades of gray; similar to us watching a black and white TV or an old movie. However, researchers have discovered deer do see color. They probably don't see color exactly the same as humans, but color nevertheless.
While their color vision is limited compared to humans, deer can see farther into the ultraviolet spectrum than we do. Primarily this is because deer are better adapted to low light conditions. Deer prefer to move at dawn and dusk and on through the night. If active during the day, deer try to limit their activities to shady areas away from intense sunlight. Under low light conditions, true color rendition means little. Try it for yourself. Under dark, shaded conditions or as dusk turns to night, dark colors seem to turn toward black. Light colors tend to change toward gray.
Being able to better use low light intensities and seeing farther into the ultraviolet spectrum allows deer to discriminate objects better in the dark than we do. Deer do this by having much larger eyes than humans. The pupils are larger and capable of opening much wider. Therefore, more light is received by the eye. Also, deer have a much higher proportion of rods than cones in their retina. Rods are the cells responsible for receiving light and dark signals and are capable of only black and white vision. Cones are the cells responsible for perceiving color.
Another adaptation of nocturnal animals is the presence of a structure in the back of the eye called the tapetum lucidum. The tapetum lucidum acts much like a mirror that reflects light back through the retina after its initial pass. This reflective process allows the incoming light to be reprocessed and essentially doubles the stimulation of the rods and cones. The tapetum lucidum is the reason deer's eyes have their distinctive shine in a bright light at night.
Another structural difference between the eyes of deer and humans is the lack of an ultraviolet filter. Because humans are primarily active during daylight hours when harmful UV rays are present, our eyes have a filter to block these rays. Without this filter, serious damage to the eye would result. In fact, UV light is considered one of the major causes of cataracts in humans. Being relatively short-lived, deer have no worries about cataracts. This UV filter allows humans to see in much sharper detail in daylight.
As far as their vision, the number one thing that alerts deer to your presence is movement. Keep in mind deer are monitoring a much larger area with their eyes than we are. Also, they are not thinking about the Cowboy's game or what may be happening at home or the office. They are attuned with what is happening in the present.
All of this information plays a direct role in the kind of camouflage you should consider using while hunting deer. Dressing in a complete suit of a new camo pattern is fine for the hunting lodge or taking grip and grin photos. However, tailored clothes mean little once you hit the brush — just look at what professional guides wear. They depend on the most durable and effective protection they can get.
When deciding on a camo pattern, think a little about where you will be doing the majority of your hunting. Because we think deer do not see color exactly as we do, matching exactly the colors of your camo to the background is very appealing to humans, but probably means little in hiding you from the prying eyes of a deer. The key is to blend into the form of the background.
Think about the difference in coat patterns you see in the wild. Tigers have stripes because they want to blend into light and dark patterns of tall grasses. Deer fawns have spots because they want to blend into the dappled sunlight patterns found under tree canopies. Also, when these animals want to hide, they remain very, very still. Fish are lighter on bottom and darker on top because their predators usually lurk in deeper waters and look upward toward the light trying to spot their prey.
No single camo style is best for all situations. Really it may not be necessary at all. Our grandfathers killed a whole bunch of deer long before modern camo patterns were developed. One of the best patterns I have ever tried is the old plaid wool coats in dark colors. I don't particularly like camo with small, intricate patterns. For hunting on the ground, large patterns of leaves and tree trunks is probably a good idea as long as there is good contrast between the pattern. For tree stands, larger dark and light areas will help you blend into the tree limb, open sky view you see when looking upward. For snow conditions, white or grey, broken by a few dark areas works wonderfully.
I have yet to comprehend the necessity of dressing from head to toe in camo gear to hunt from a box blind or riding in the cab of a pickup! However, I'm for using anything that will help you go undetected. If it does nothing else but give you more confidence, then it is of benefit.