Colorblindness is relative. Just as we can perceive hues that dogs can’t, hummingbirds can see colors that humans can’t. Whereas the three types of color-sensitive cone cells in our eyes allow us to see red, green, and blue light, hummingbirds (and most other birds) have a fourth type of cone attuned to ultraviolet light. In addition to UV light, birds may even be able to see combination colors like ultraviolet+green and ultraviolet+red — something we mere humans can only imagine. Having four types of cones cells, known as tetrachromacy, is also common in fish and reptiles, and researchers believe that dinosaurs possessed it as well. Some very special humans also seem to have a fourth type of cone — about 1% of the population.
Being able to see this way is especially useful for hummingbirds, whose endless quest for sugar is aided by their ability to discern different-colored flowers — including “nonspectral” colors that combine hues from widely different parts of the color spectrum. Purple is the only nonspectral color we humans can perceive (it involves both blue and red, or both short and long wavelengths of light), but some birds might see as many as five: purple, ultraviolet+red, ultraviolet+green, ultraviolet+yellow, and ultraviolet+purple. That certainly sounds worth singing about.
Media Release/InterestingFacts
