Many bird species have vision that extends to the ultraviolet range. Special light-sensitive proteins and light-filtering pigments allow birds to discern visual details and gradations of visible color that are invisible to humans and even to some other types of birds. Birds with this ability use it to avoid danger, hunt for food, and evaluate potential mates.
Like humans, birds have light-sensitive cells in their eyes that account for seeing color. Called photoreceptors, they fall into categories of rods and cones. Human eyes have cones that are red-, green- and blue-sensitive. According to Star Tribune, these cones allow humans to see as many as a thousand different colors.
Birds have a fourth type of cone in their eyes, a modified blue cone that is sensitive to violet and ultraviolet light, or UV light, according to Phys.org. This modified blue cone is the result of carotenoids, which are light-filtering, fat-soluble yellow-to-orange pigments that naturally occur in things such as autumn leaves, tomatoes, and carrots. Birds obtain carotenoids through their diets, and their bodies process the pigments in such a way that gives their ocular photoreceptors the ability to absorb shorter or longer light wavelengths.
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Mechanisms within the blue cone and light-sensitive proteins called opsins in the violet and UV cones share a special relationship. They coordinate and move in sync so that UV vision is even and crisp. With the power to see violet and UV light, birds are able to see more colors and details to a factor of 10. They can detect fruits and other edible items that reflect UV light when at the peak of ripeness.
Female birds rely on UV vision to evaluate the fitness of potential mates. Among single females in many birds species, males with the brightest, fullest, most colorful plumage are the most eligible. Birds also use their UV vision to detect and avoid possible predators and other dangers.
Superior vision is but one of many amazing traits that birds have. Watch this video to discover some other amazing bird powers.Whizzco