Listen to a talk by a biology professor discussing birds.
As we discussed, the human eye has three different types of color receptors that respond to three basic colors---red, green and blue, or other colors are seem to combination for these different types of the receptors. Birds, however, have receptors for these three basic colors and for ultraviolet or UV light. Thus they have much greater color range. What’s really interesting though is the role that UV light plays in a bird’s life. Scientists have discovered that the bird’s eye is extremely sensitive to ultraviolet light. In one experiment robins were able to distinguish between two objects: one completely unlit and one lit by very dim ultraviolet light. Even with the very dim UV light the object was very apparent to the robins. In another experiment female birds wax gold to two male birds. One was behind the filter transparent UV light and one was behind the filter that blocked UV light. The female bird prefers the male bird behind the transparent filter. Those birds’ feather may have appeared more colorful. Hunting birds use UV light to track down small animals. This is possible because small animals use urine to mark their trails and urine observed UV light. The hunting birds can use the UV light to follow the trail to their prey.
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