Here is a quote from an article about it.
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Eyes have it
Deer see the world differently than hunters have assumed for years
November 22, 2009 10:00 AM
By Ben Moyer
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A whitetail buck grazed on a hillside in Washington County. Two does nipped grass just above him. The driver of a red pickup truck spotted the deer, 150 yards away, and braked. As the truck stopped, all three deer raised their heads and stared intently toward the intruding vehicle. The driver wondered: "Did those deer see my truck as an alien object? Or, had they simply heard the crunch of tires on gravel and sensed danger when the sound stopped?"
Such encounters happen all the time between humans and deer. Hunters, especially, ponder what deer can see and how to dress in the woods to avoid detection.
Ongoing research shows that hunters have over-simplified how deer see, especially in assuming that deer are "color blind."
In a series of studies at the University of Georgia, a research team anesthetized nine deer and recorded electrical responses in the whitetail's eyes to light shone on their retinas. While the retina of the human eye is equipped with a high density of "cone cells" that support color vision across the broad range of hues perceived as blue to red, deer have relatively few cones. Human eyes also have a "filter" which protects the eye from ultra-violet light and helps humans see objects in fine detail.
Deer eyes, though, are packed with far more "rod cells," enabling deer to see well in low light. From a human viewpoint, deer "sacrifice" broad color vision and detail for acute sight at night, dawn and dusk.
But it is wrong to say that deer are "color blind."
"What we discovered is that deer are not color blind, although they do see color differently than we do," said Brian Murphy, CEO of the Quality Deer Management Association and a wildlife biologist who participated in the University of Georgia research.
"Deer are essentially red-green color blind like some humans. Their color vision is limited to the short and middle wavelength colors. As a result, deer likely can distinguish blue from red, but not green from red, or orange from red."
Murphy explained that a deer probably perceives a hunter's blaze orange coat as neutral gray, which, if color were the only visual clue, might always blend in well with natural backgrounds. But the ultra-violet radiance of clothing can "give it away" in a deer's eye, even if color does not.
"It's too simplistic to say that wearing orange will not impact your hunting success," Murphy said. "There is color, then there is the UV radiance off that color, no matter what the color is."
