Whether you think of squirrels as cute furballs that chase each other across treetops or pests that occasionally invade your attic and chew their way through everything, squirrels are very interesting creatures. My personal fascination with squirrels is old news of course. So when I was reading about how animals see differently from humans, the first question that popped into my head was whether squirrels have good eyesight? Here’s what I found:
Yes, squirrels have good daylight eyesight. In fact, compared to other rodents, they fare extremely well in the vision department. Squirrels have great focal eyesight and their peripheral vision is equally sharp. This means that squirrels can see what is next to them or above them without having to move their heads. This helps a squirrel stay alert to changes in its environment, making it easier to detect predators. Squirrels have a hard time seeing in dark, night time conditions.
Why Do Squirrels Have Good Vision?
A squirrel’s vision plays an important role in their survival. Other rodents like mice and rats are nocturnal in nature. Since rats spend most of their time running around in the dark they tend to have poor vision and use their whiskers as a navigation tool. The squirrel, on the other hand, is active and running around in the day and has to rely upon their vision to spot daytime predators.
The physiological differences between the visual abilities of squirrels and rats is seen in the fact that the visual brain areas for squirrels are larger and more well developed than in other rodents.
Squirrels enhance and protect their vision with a pale yellow pigment found on their lenses. The pigment acts like a pair of sunglasses and reduces the glare from the sun. More recent studies have suggested that this yellow pigment may also block UV light and protect a squirrel’s retina from damage.
There are two types of photo receptors in a squirrel’s retina, rods and cones. The ability to see in low light conditions is enabled by the presence of rods and the concentration of rods varies between the different types of squirrels. The receptors Ground squirrels have a rod density of 10%, while grey squirrels have a rod density of about 40% and the nocturnal flying squirrel having a rod density of nearly 100%.
Thus the ability for squirrels to see at night varies greatly among the different types of squirrels.
The exception to these comments rests with albino squirrels. Albino animals lack the ability to produce a key pigment called melanin. Melanin is needed for color development but is also an important component for the proper development of components of the eye including the retina. As animals with these traits tend to have poorly developed eyes, albino squirrels have vision problems. (One reference suggests that albino grey squirrels maintain good vision. However, no supporting links or data were provided to support this claim.)
To sum it up, squirrels definitely have very sharp eyesight. What about colors, though? Let’s find out.
A Squirrel’s World in Color
Compared to other animals, a squirrel’s vision does include colors. Early studies of a squirrel’s retina suggested that squirrels have the ability to see colors. More recent studies showed squirrels to have a dichromatic vision, which helps them distinguish between yellow and blue color tones. However, they cannot tell apart red and green hues, which means that squirrels are color blind. A red object will appear yellow-green to a squirrel. Most squirrel species have cone-dominated retinas and have dichromatic color vision that is mediated by green and blue cones.
One interesting study, however, showed squirrels being able to distinguish green and red biscuits. They also appeared to be capable of discriminating between color intensity. This was completely contrary to the information available about a squirrel’s vision capacity. However, it was suggested that they may just be responding to the brightness or smell of the biscuits and not the colors.
Squirrel vs. Human Vision
Squirrels have good vision, but is it better than human vision? Yes and no. There are certainly a lot of similarities between the visual perception of squirrels and humans. Humans can also suffer from color-blindness. What’s more is that at the micro-level, color-blindness pretty much functions in the same way for humans as it does for squirrels. This means that people suffering from color blindness confuse the same color spots as squirrels do.
That said, squirrels have a better visual focus than humans do. A human retina has a very small area where the vision is the sharpest. For squirrels, this area is spread over their entire retina. This means that humans can focus on one object at a time and their peripheral vision is poor. Squirrels, as already mentioned above, have excellent peripheral vision.
To Sum It Up
In spite of being color blind, squirrels have good vision. They are also aided by things like excellent peripheral vision and the yellow pigment in their eyes. These factors can help a squirrel survive in the wild and I imagine they are particularly useful when fighting off a predator attack.
Before you go, take a quick look at this fun video that captures the world from a squirrel’s point of view: