Deer have dichromatic vision, meaning they see color differently than humans. While humans are trichromats and can perceive red, green, and blue light, deer only have two types of color photoreceptors. This means they can only distinguish between two primary colors, which for deer are blue and yellow. As a result, deer see the world in shades of blue and yellow rather than the full color spectrum visible to humans. Understanding what colors deer can and cannot see has important implications for deer hunting, wildlife management, and deer safety.
Deer Color Vision
Deer have dichromatic vision because they only have two types of cone photoreceptors in their eyes that are sensitive to short (blue) and medium (green) wavelength light. They lack cone cells that can detect long wavelength red light. In contrast, most humans have three types of cones that are sensitive to short (blue), medium (green), and long (red) wavelengths, giving humans trichromatic color vision.
Having only blue and green cone cells limits the range of colors deer can perceive. However, deer still have Rod photoreceptors that allow them to see shades of gray in dim lighting conditions. While these rods do not provide color vision, they aid deer in seeing movement and contrast during dawn and dusk when color vision is reduced.
Blue and Yellow Vision
With dichromatic vision, deer effectively see the world in shades of blue and yellow. The blue cones allow deer to detect short wavelength blue light, while the green cones enable them to see medium wavelengths in the green and yellow range. However, without red cones, deer cannot distinguish red from green and instead see both as shades of yellow.
This blue-yellow vision is similar to human color blindness conditions like deuteranopia where people cannot perceive red light. So while humans see the visible spectrum as a continuum of violet, blue, green, yellow, orange, and red, deer see only blue on one end and yellow on the other. Mixed wavelengths in the center are not perceived as distinct colors but shades of yellow.
Implications for Deer Hunting
The limitations of deer color vision have important implications for deer hunting. Since deer cannot distinguish red from green or orange, wearing these colors does not make a hunter more visible. In fact, red and orange will both appear as shades of yellowish-green to a deer. This explains why some hunters continue to see deer while wearing orange safety gear.
However, deer can still see the blue spectrum. So blue hues stand out and are very visible to deer. Deer also see UV light that humans cannot perceive. Bright optical UV brighteners found in laundry detergents can make clothing stand out. Eliminating these brighteners and wearing colors like blue, gray, or brown will help hunters blend into a deer’s surroundings.
Benefits of Dichromatic Vision
While dichromatic vision limits the colors a deer can distinguish, it also provides benefits:
- Enhanced night vision – Rod cells improve night vision while fewer cone cells reduce daylight noise.
- Better motion detection – With fewer color photoreceptors, more retina space is available for motion-detecting rods and peripheral vision.
- Increased contrast – Red-green color blindness can improve contrast between shifting shades of yellow and blue.
These benefits served an evolutionary purpose for prey animals like deer to better notice predators, forage, and survive in the wild. So while deer do not see the full color spectrum, their vision is adapted to their niche as a prey species.
Implications for Drivers and Road Safety
Deer color vision also has important implications for driving safety. Since deer cannot distinguish red from green, brake lights and traffic signals appear yellowish to them. This makes it difficult for deer to determine if cars are stopped or moving.
As a result, stationary red or green vehicles may appear to deer as open passageways to move through. In low light, deer also cannot discern brake lights from headlights, increasing the risk they will freeze in headlights rather than avoiding oncoming vehicles.
Understanding these limitations can make human drivers more alert to the potential of deer misunderstanding traffic signals and car lights. Driving cautiously in deer crossing zones, particularly at dusk and dawn, can help reduce collisions.
Conclusion
Deer possess dichromatic color vision, allowing them to see the world in hues of blue and yellow. Their eyes lack red receptors, causing red colors to appear yellowish-green. This has significant impacts on deer hunting, making red and orange less visible camouflage colors. It also affects road safety, as deer may have difficulty distinguishing stopped vs. moving red vehicles and brake lights. While dichromatic vision limits the color spectrum deer perceive, it provides benefits for prey animals including enhanced night vision, motion detection, and contrast. Understanding the unique capabilities and limitations of deer vision can allow both deer and humans to better share forest and roadway environments safely.
| Color Wavelength | Human Perception | Deer Perception |
|---|---|---|
| 400-450nm (violet-blue) | Violet to blue | Blue |
| 450-495nm (blue-green) | Blue to green | Blue to yellow |
| 495-570nm (green-yellow) | Green to yellow | Yellow |
| 570-590nm (yellow-orange) | Yellow to orange | Yellow |
| 590-620nm (orange-red) | Orange to red | Yellow |
