Brighter colors on certain birds may have evolved so the birds can see each other in darker habitats, according to a UC Davis researcher. In a recent paper in the journal Nature, doctoral student Karen Marchetti also reports that flashier colors on male birds seem to impress other males more than females, which have been thought to prefer mates with colorful markings. Correlating the relative brightness of eight species of warblers in Kashmir, India, Marchetti found the brightest birds in the darkest woods and the dullest birds in the well-lighted habitats of meadows and above timberline. By experimentally manipulating the colors of the birds -- painting brighter yellow markings on some and duller green camouflage on other birds -- Marchetti showed that the brightest males won territories about twice as big as the dullest males within the same habitat.