If optimists see the world through rose-colored lenses, some birds see it through ultraviolet ones. Avians have evolved ultraviolet vision quite a few times in history, a new study finds.
Birds depend on their color vision for selecting mates, hunting or foraging for food, and spotting predators. Until recently, ultraviolet vision was thought to have arisen as a one-time development in birds. But a new DNA analysis of 40 bird species, reported Feb. 11 in the journal BMC Evolutionary Biology, shows the shift between violet (shorter wavelengths on the electromagnetic spectrum) and ultraviolet vision has occurred at least 14 times.