H�STAD, O.*; �DEEN, A.: Different avian color vision in predator and prey

Birds see more than twice the number of colors compared to humans, and individual colors may appear very different, even to different bird species. We have developed a molecular marker that can be used for determining the type of color vision. The eyes of most birds are tetrachromatic, that is, the retina contains four distinct classes of cones, where in humans there are only three. There are two main types of color vision described from the retina of birds. The most important difference between these is whether the maximum absorbance position (λ-max) of the opsin in the fourth cone is in the UV or violet range. If we want to understand the evolution of plumage coloration, predator-prey interactions and foraging behavior of birds we need to take their four-dimensional color space into consideration and acknowledge that birds see the world differently from us, and sometimes, from other birds. Due to the relative complexity of the currently used method, microspectrophotometry, only a small number of bird species have been examined to date. Since our method does not require keeping or killing the bird, it facilitates large screenings including rare and endangered species. From our results we conclude that, as expected, the only bird taxa including species with UV type of color vision are the Psittaciforms and the oscine Passeriforms. Surprisingly, the suboscine Brown-crested Flycatcher did not share this character with other Passeriforms. The Falconiforms are of the violet type giving them a vision system different from their Passeriform prey. This enables UV type birds to signal with colors that are bright to members of their own species, but dull or cryptic to raptors.