Article Date: Friday, October 21, 2011
By Bob Humphrey
White-tailed deer are truly magnificent animals, and the most sought-after big game species on earth. Among the traits that make them so fascinating and challenging is their eyesight.
Deer are prey animals. As such, their eyes are located on the sides of their head rather than in the front; so they have a much broader field of view - roughly 310 degrees. They also have two blind spots. One is just in front of their nose, the other is a 50-degree arc, directly behind them.
Their three-dimensional binocular vision is more limited than our own; so they have poorer depth perception, except directly in front of them. However, they focus on a banded area rather than a specific point, which gives them a much wider field of view - better peripheral vision - but with less detailed focus.
Their eyeballs differ from ours in other ways too. A deer's pupil opening is three times the size of a human's. According to Dr. Karl Miller of the University of Georgia, that means nine times the light gathering ability. Furthermore, the back of their eye has a light reflecting organ called the tapetum, which effectively doubles light gathering ability; so now we're up to 18 times that of a human.
Eyes of all animals have rods and cones; rods detect light, cones color. Deer have far more rods than we do, further enhancing their ability to see in darker conditions.
However, they have fewer cones, which reduces their color perception. According to Miller, deer perceive color much as a human with color blindness would. They see blues, greens and yellows very well, but orange and red appear only as different shades of gray. That means they do not see blaze orange the way we do. Instead, it appears as gray.
Some laundry detergents contain fabric brighteners. Essentially, they change the wave length of colors, brining them out of the ultraviolet range, into the blue range we humans can see. This is also the range where deer have the highest color detection ability. Products like ATSKO's UV-Killer counteract the effect of fabric brighteners by reducing the reflectivity of colors in the blue and purple range.
Parts of this article were excerpted from Bob Humphrey's new book: Pro Tactics: Whitetail Hunting, available at better book stores and sporting goods retailers, or online at www.bobhumphrey.com