Deer have very different vision compared to humans. Their eyes are located on the sides of their head, giving them a wide field of view to spot predators. Deer also see more shades of blue and ultraviolet light than humans do. Their vision is optimized for detecting movement and seeing in low light conditions. Understanding the differences between deer vision and human vision can help hunters be more successful and avoid detection.
Deer Have Wider Field of Vision
One of the biggest differences between deer vision and human vision is the wider field of view that deer have. Deer have their eyes positioned on the sides of their head. This gives them a field of view of about 310 degrees without having to move their head. They have a small binocular field of view of about 25-50 degrees where both eyes can focus on the same point.
In comparison, humans have their eyes facing forward, giving them a binocular field of view of around 120 degrees. The placement of deer eyes allows them to easily scan a wide area for threats without moving their head. It gives them early warning of predators approaching from the sides or behind. However, it also means they don’t have as much depth perception directly in front of them as humans do.
More Motion Detection Cells
Another difference between deer vision and human vision is the much higher concentration of motion detecting cells in deer eyes. Deer have a band of motion detecting cells called the visual streak that runs across the middle of their retina. This band contains around 5 times more motion detecting cells per degree than in the human eye.
This allows deer to easily spot moving objects in low light. Even the slightest bit of movement will be noticed by a deer, making it difficult for hunters to sneak through the woods undetected. The motion detecting cells allow deer to spot predators stalking them or react to other deer flashing their white tail as a warning sign.
More Rods Than Cones
Human eyes contain about 120 million rods cells and 6 million cone cells in the retina. Rod cells allow for night vision while cone cells detect color. Deer have a much higher proportion of rods to cones compared to humans. Their eyes contain around 250 million rods and just 2 million cones.
This rod-dominated retina allows deer to see well in dim light. Deer are crepuscular, meaning they are most active at dawn and dusk when light levels are low. The high number of rods helps deer forage and move safely during twilight hours. It also means their color vision abilities are more limited compared to humans.
See More Blue and Ultraviolet Light
While deer have less overall color vision abilities than humans, they can detect a wider range of blue and ultraviolet light. Their retinas contain two types of cone cells – ones that detect blue and ultraviolet light and others that detect green/yellow light.
Humans have three types of cone cells that can detect red, green and blue light. So deer have an advantage over humans in spotting blue/ultraviolet objects that absorb other wavelengths. This may help deer spot urine or other clues left by other deer in the area.
More Tapetum Lucidum
Anatomy inside the deer eye also helps explain their ability to see well in low light. Deer eyes contain a reflective membrane called the tapetum lucidum lining the back of their eye. This mirror-like layer reflects light back through the retina, effectively giving light a second chance to stimulate rod and cone cells.
Humans lack a tapetum lucidum, so we don’t get the same light amplification effects in our eyes. The tapetum is what causes deer eyes to glow bright green, yellow or blue when illuminated at night. It’s an adaptation to help deer see when other animals can’t.
Differences in Visual Acuity
Studies on deer vision have found they have lower visual acuity or resolution compared to human vision. Humans normally have a visual acuity of around 20/20 vision. For deer, their visual acuity ranges from 20/100 to 20/200.
This means deer lack the same level of fine detail and clarity at distance that humans enjoy. A deer looking at a human face 100 yards away would not be able to make out sharp facial features. But their motion detection abilities help compensate when viewing distant moving objects.
Slower to Detect Rapid Movement
While deer are super alert to small, slow movements, they actually have a slower response time to extremely fast motion compared to humans. When an object moves rapidly across the deer’s field of vision, it takes a fraction of a second longer to transmit and process that image.
This brief processing delay makes deer less able to react to the sudden movements of bullets, arrows and vehicles. By the time the image reaches the deer’s brain, the object has already moved to a new position, causing a confusing blur.
Minimal Color Discrimination
Due to the low number of cone cells, deer are essentially red-green colorblind like some humans. They have difficulty distinguishing reds, oranges and greens. Deer are best able to discriminate between shades of blue and yellow.
Human hunters look for camouflage clothing that blends into the environment. But for deer, camo patterns that incorporate red, green and orange will still stand out against blue, yellow and UV backgrounds. Understanding deer color vision can lead to more effective camouflage.
| Vision Aspect | Deer | Human |
|---|---|---|
| Field of View | 310 degrees | 120 degrees |
| Binocular Field of View | 25-50 degrees | 120 degrees |
| Motion Detecting Cells | 5x higher density | Lower density |
| Total Rod Cells | 250 million | 120 million |
| Total Cone Cells | 2 million | 6 million |
| Blue/UV Cone Cells | Present | Absent |
| Tapetum Lucidum | Present | Absent |
| Visual Acuity | 20/100 to 20/200 | 20/20 |
| Rapid Motion Tracking | Slower | Faster |
| Color Discrimination | Poor for red, green | Good for all colors |
Implications for Hunters
Understanding the differences between deer vision and human vision has important implications for hunters. Here are some tips to keep in mind:
- Minimize movement – Deer will detect even the smallest motions so move slowly and pause frequently.
- Approach from downwind – Let your scent blow away from deer so they cannot smell you.
- Use terrain masking – Use hills, trees and brush to break up your silhouette as you approach.
- Avoid stark colors – Camo patterns with blues, yellows and muted browns work best.
- Backlight yourself – With the sun at your back, you will appear as a dark silhouette.
- Be still when deer look away – Deer heads are constantly in motion, freezing when they look away can avoid detection.
- Take fast shots – Deer will startle but take a moment to visualize fast bullets and arrows.
As prey animals, deer have evolved sensory adaptations to avoid predators and stay alert. By understanding how deer eyes and brains process visual information compared to our own, hunters can beat deer at their own game and overcome their incredible eyesight.
Conclusion
Deer have a very different visual system compared to human vision. Their eyes are optimized for detecting motion, seeing in dim light, and scanning for predators across a wide field of view. Deer see better in blue and ultraviolet wavelengths but have limited color vision in red and green. Their vision gives them an advantage for survival in the forest and fields. But knowledgeable hunters can use an understanding of deer vision to their benefit and avoid detection.