Animal color vision
Short answer
Squirrels are dichromats with two cone types near 444 nm and 543 nm. They see blues and yellows but confuse red with green, and unlike most mammals they have a cone-rich retina built for daylight.
In detail
Squirrels are red-green color blind by human standards but have unusually good daytime vision for a mammal. Behavioral and electrophysiological tests on the gray squirrel found two cone classes, peaking at about 444 nm and 543 nm, and a spectral neutral point near 500 nm — the signature of dichromatic color vision.
What sets squirrels apart is the retina itself: a cone-rich, daylight-adapted retina, far denser in cones than a dog's, a cat's or a deer's. A squirrel sees a two-color world, but it sees it sharply and in full daylight.
Squirrels carry 2 cone classes to our three. The missing long-wavelength class is what turns red, orange and green into one axis for the animal.
| Cone class | Squirrel | Human |
|---|---|---|
| S (blue cone) | ~444 nm | Nearest: S cone ~420 nm |
| M/L (single long cone) | ~543 nm | Nearest: M cone ~530 nm |
Squirrels see blues and yellows and confuse reds with greens. In the gray squirrel, behavioral color tests revealed a spectral neutral point at about 500 nm — a wavelength the animal cannot tell from white or gray — which is the defining signature of dichromatic color vision. Recordings from single optic-nerve fibers and the flicker electroretinogram then identified the two cone classes behind it, with average peaks at about 444 nm and 543 nm, alongside a rod mechanism near 502 nm.
The consequence is a color axis running from blue through gray to yellow. Colors at the blue end excite the 444 nm cone, colors at the yellow end excite the 543 nm cone, and everything in the red-orange-green range lands on that same long cone, distinguishable by brightness but not by hue. A red bird feeder in a green tree is a brightness difference to a squirrel, not a color difference.
Most mammals are descended from small nocturnal ancestors and kept a rod-dominated retina; dogs, cats, deer and rabbits all follow that pattern. Squirrels went the other way. Tree squirrels kept a far higher share of cones than most mammals, and ground squirrels are the extreme case: in the ground squirrel retina, cones make up the great majority of photoreceptors. Tree squirrels are strictly diurnal, and their retinas are built for the bright, high-contrast task of judging a jump between branches.
This is the useful correction to the phrase color blind. A squirrel's color vision is limited to two dimensions, but its retina is built for bright light, contrast and motion in a way a dog's or a deer's is not. Being dichromatic did not make it a poor-sighted animal; it made it a daylight animal that happens not to separate red from green.
Squirrel eyes are large for the skull and sit high and to the sides, giving a wide field of view with a useful zone of binocular overlap in front for judging distances between branches. Ground squirrels, which live under open sky, often have a yellow-tinted lens that filters short-wavelength and ultraviolet light, sharpening the image at the cost of blue sensitivity.
The retina has a horizontal visual streak rather than a single fovea, a layout shared with many animals that scan a horizon. In a tree squirrel that streak supports the rapid, precise visual judgments that let it run along a fence top or leap a gap without hesitation.
The human analogue is again protanopia: an S cone plus a single cone in the middle-to-long range, and no third class. The squirrel's long cone at 543 nm sits between the human M cone at about 530 nm and the L cone at about 560 nm, slightly nearer M, so the palette above uses the protan simulation. As always, the model shows which color differences vanish and does not claim to show what the animal experiences.
A person with protanopia would recognize the squirrel's neutral point immediately: a wavelength near 500 nm that reads as gray is a classic finding in human dichromats too. If you want to know whether your own vision has a neutral point, the free screening on this site estimates your type, and the D-15 arrangement test shows the confusion axis directly.
The squirrel's column above is close to what a person with red-green color blindness sees. The free color blind test takes about two minutes and estimates whether you have a red-green deficiency and which type.
Screening only — results estimate color vision on an uncalibrated screen and are not a diagnosis.
Animal color vision
The full comparison table: dogs, cats, birds, fish and the mantis shrimp by cone count.
Are rabbits color blind?
A dusk-adapted dichromat with the opposite retina: rods almost everywhere.
Farnsworth D-15
See your own confusion axis, the human version of a neutral point.
Color blindness simulator
Run your own photo through the same Machado model used on this page.
Last reviewed September 12, 2026. Cone peak values are from electroretinogram or microspectrophotometry studies of the species named; behavioral claims are from the cited discrimination experiments. Simulations approximate the color differences lost, not the animal's experience.