The idea of an animal having a “favorite color” is complex, requiring an understanding of how the animal perceives color. For humans, a favorite color is an aesthetic choice, but for animals, a strong reaction to a color is usually rooted in survival and the unique structure of their eyes. To determine if a color is “liked,” one must first examine the physical limitations and enhancements of a species’ visual system. The answer lies in the function of color within an animal’s life.
The Biological Basis of Color Vision
Color perception begins with photoreceptor cells in the retina, primarily the cones, which are active in brighter light and distinguish different wavelengths of the visual spectrum. The number of cone types an animal possesses dictates the range of colors it can see, known as the dimensionality of its color vision. Humans are trichromatic, meaning we have three cone types that allow us to perceive a wide spectrum including red, green, and blue light.
Many mammals are dichromatic, having only two cone types, which significantly limits their ability to discriminate between certain colors. By contrast, some birds, reptiles, and insects are tetrachromatic, possessing four cone types, which extends their vision beyond the human range. The physical presence of these cones determines the colors an animal can register as distinct.
Mammalian Perception and Learned Preference
Most non-primate mammals, including dogs and cats, are dichromatic, meaning their visual world is primarily composed of blues and yellows. They struggle to distinguish between the longer wavelengths of light that humans see as red, orange, and green. These colors often appear as muted shades of yellow or gray to them.
For these animals, what appears to be a “favorite” color is often a learned association with a color that provides the highest contrast and brightness. A dog may seem to prefer a red ball, but the ball is likely a highly visible shade of yellow or gray that stands out against green grass. Research suggests that dog toys in blue and yellow are the most easily visible and engaging because these colors provide the best contrast for their dichromatic vision. This preference is functional, allowing them to track an object against a background, rather than an aesthetic choice.
Avian and Invertebrate Color Attraction
In contrast to mammals, birds, reptiles, and many insects possess a more expansive color vision system, leading to a hardwired attraction or repulsion to certain hues. Birds are tetrachromatic, with a fourth cone type sensitive to ultraviolet (UV) light, which is invisible to the human eye. This UV vision is used for immediate, instinctual biological functions, such as identifying mates or marking territories.
Feathers that appear plain white to humans often have complex UV patterns that signal a bird’s health and desirability to potential partners. Similarly, invertebrates like bees use UV light to navigate and find food. Flowers that look uniformly yellow often display a “bullseye” pattern in the UV spectrum, which acts as a nectar guide to direct the insect pollinator toward the reward. This immediate response, driven by evolutionary survival, is closer to an innate “favorite” than a mammal’s learned preference.
Applying Our Knowledge of Animal Color
Understanding how different species perceive color has practical applications in conservation and product design. For instance, the superior color vision of birds is used to prevent window strikes, a common and deadly hazard. Decals or films applied to glass are often treated with UV-reflective materials, which create a visible barrier to a tetrachromatic bird but remain nearly transparent to humans.
In the pet industry, manufacturers design dog toys in blue and yellow to maximize visibility and engagement for the dichromatic canine eye. In fishing, the color of a lure is chosen based on the complex and sometimes adaptable vision of fish, who may change their color sensitivity depending on the water conditions. By moving beyond our own visual experience, we can create environments and tools optimized for an animal’s unique way of seeing the world.