Deer have a very different visual system compared to humans. Their eyes are located on the sides of their head, giving them a wide field of view. However, this comes at the expense of having poor depth perception directly in front of them. Deer also see color differently than humans and are essentially red-green colorblind. Understanding how deer see allows hunters and wildlife managers to work with a deer’s natural instincts instead of against them.
Field of View
A deer’s eyes are positioned on the sides of its head. This gives them a field of view of about 310 degrees. They have a blind spot of around 20-50 degrees directly behind them. Having eyes on the sides of their head gives deer a huge advantage when watching for predators trying to sneak up from many directions. However, it comes at the cost of reduced depth perception and ability to detect objects directly in front of them.
Humans have a concentrated field of view of around 180 degrees directly in front. This narrower focus gives us excellent depth perception and ability to detect objects right in front of our eyes. However, it leaves large blind spots on the sides that make us vulnerable to sneak attacks from predators.
Because a deer’s eyes are located on opposite sides of their head, they do not have overlapping fields of vision. Each eye functions independently in what is called monocular vision. Images from each eye are processed separately in the brain.
In contrast, human eyes are located front and center on our face. This means our left and right eyes see overlapping visual fields, giving us binocular vision. Our brain combines the images from each eye to produce a single unified picture and provide depth perception.
The monocular vision of deer means they lack depth perception and 3D vision directly in front of them. However, their excellent peripheral vision from 310 degrees of monocular fields compensates and helps spot lurking predators.
While deer lack fine detail and depth perception directly ahead, their monocular vision excels at detecting motion. Each independent eye is like a motion detector, scanning a huge 310 degree arc around the deer. Even though the images are monocular, any detected movement triggers a signal to the brain.
This motion sensing ability makes deer extremely difficult to sneak up on from the sides or behind. A deer can pick up the slightest motion and be alerted to potential danger. Their eyes are optimized for sensitivity to motion instead of visual acuity.
Deer are essentially red-green colorblind like some humans. They have dichromatic vision containing two color pigments (cone photoreceptors) instead of three like in human trichromatic vision. Deer see short (blue) and middle (green) wavelength colors but lack long (red) wavelength cones. This makes it difficult for deer to distinguish red from green.
Deer likely can see colors in the blue to yellow range but miss the red end of the spectrum. Their color vision is shifted towards the blues compared with humans. This has implications for everything from choosing food plants to detecting hunters in camouflage.
Deer Have More Rods Than Cones
|Around 92 million rods
|Around 4.5 million cones
|Around 150 million rods
|Around 2 million cones
Deer retinas contain a very high proportion of rod photoreceptors compared to cones. Rods function at night and detect shades of gray. Cones are active in daylight and detect color. The high percentage of rods helps deer see at night but reduces their daytime color vision.
In comparison, human eyes have more cones than rods. We have excellent color vision in daylight but very poor night vision. Our eyes did not evolve for nocturnal activity like deer.
Seeing at Night
Deer are crepuscular, meaning most active at dawn and dusk. However, their eyes contain a reflective tissue called the tapetum lucidum that allows for better night vision. This tissue sits behind the retina and reflects light back onto rods, giving light a second chance to stimulate the rods. Humans lack a tapetum lucidum.
The reinforced rod vision gives deer decent nighttime eyesight. Combined with their motion detecting monocular vision, deer remain vigilant for predators 24 hours a day. Dusk and dawn are times of peak activity for deer.
While excellent for detecting motion, a deer’s vision lacks fine detail and visual clarity. Maximum visual acuity is around 20/100 based on tests of deer autopsy eye specimens. This means a deer standing 20 feet away would see an object the same as a human 100 feet away.
In comparison, average human visual acuity is around 20/20. We have higher resolution due to a concentrated field of view and more cones on the retina. A deer’s 320 degree field of view sacrifices visual detail for an expanded view.
Implications for Hunting
- Approach deer from downwind to avoid scent detection
- Minimize movement when deer are looking in your direction
- Wait for deer to look away before drawing bow or raising firearm
- Avoid red clothing since deer can’t distinguish red from green
- Camouflage should mimic blue, yellow, or gray colors
Understanding that deer lack red color vision allows hunters to choose better camouflage lacking red hues. Knowledge of the deer’s 310 degree field of view means sneaking up from behind works better than a straight on approach.
Since deer senses are adapted for predator detection instead of fine detail, hunters can beat them at their own game through stealth, cunning, and understanding how deer perception works. Paying attention to the wind and moving only when the deer looks away from you will dramatically improve your odds of getting a deer within range.
Implications for Drivers
- Deer can appear suddenly from brush at side of road
- Scan for eye shine reflecting headlights at night
- Slow down when passing wooded areas at dawn or dusk
- Use high beams when no oncoming traffic
- Watch for multiple deer crossing together
Understanding that deer vision is optimized for detecting motion rather than detail helps defensive drivers take proper precautions. Deer can bolt out from woods unexpectedly due to their poor depth perception. Slowing down and scanning helps spot them. High beams at night illuminate eyeshine so deer are visible. Multiple deer together means more will likely follow. Staying vigilant and shedding speed in deer zones makes collision less likely.
Implications for Wildlife Managers
- Motion-activated deterrents work better than passive deer fencing
- Laser lights can scare deer at night when vision enhances
- Placement of deer crossing signs considers best approach angles
- Salt licks and feed areas located accounting for prevailing winds
- Hunting zones consider landscape features that impede vision
Knowing deer rely on motion detection helps wildlife managers install crossing signs and deterrents in optimal locations. Feeding areas downwind of bedding areas allows deer to use scent when vision limited. Hunting areas take advantage of terrain like ravines and hills that can conceal hunter approach due to deer’s poor depth perception. Understanding deer vision allows managers to work with their natural instincts for positive outcomes.
Deer have evolved a visual system optimized for predator detection at the expense of visual detail and color perception. Their eyes are located on the sides of their head, giving them a wide 310 degree field of view but creating a blind spot behind them. Each eye provides an independent monocular image to detect motion but lacks depth perception directly ahead. The placement and structure of deer eyes sacrifice central vision to excel at spotting danger. This guides deer behavior and instincts for survival. Hunters, drivers, and wildlife managers benefit from understanding deer vision capabilities and limitations when interacting with these animals. Knowing how deer see allows people to work with deer senses instead of against them.