The Tuscaloosa News Some backyard birds, like cardinals and bluebirds, are becoming more colorful right now for a reason. Males of many species take on brighter, more eye-catching plumage in spring for a single purpose: to attract females. Ornithologist Peter Stangel notes that male American goldfinches are “neon yellow and jet black when advertising to females, but more modest yellow-green the rest of the year.” He further notes that in some situations “color intensity signals health to potential mates. A brighter male goldfinch probably has better access to food, which is appealing to...