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Our human eyesight does not allow us to perceive the world as most birds do, and that they at times might be responding to visual clues literally beyond our ken. For example, are the ultraviolet "tear-drops" on the cheeks of a Mourning Dove an important visual "target" for close-up courtship, or are they perhaps important for stimulating preening by its mate? It would be interesting to modify or eliminate these small marks, and see what behavioral effects might result. Two individual male birds that, to human eyes, might appear identical, may be of quite differing attraction to females, depending upon their feathers' levels of UV reflectance. It has also been found that putting UV-reflectant leg bands on a bird can have social effects on other birds in ways we might not anticipate (Hunt et al., 1997; McGraw et al., 1999). The potential importance of recognizing the possible effects of avian UV light perception should not be under-estimated by students of bird behavior hoping to understand and perhaps experimentally manipulate their research subjects.