Looking at Birds in a Whole New Spectrum

Shipud writes "Historically, bird species are classified using may different indicators, including plumage colors. Also, plumage variation has figured heavily in description of similarity between species. In a recent article in PNAS, Robert Bleiweiss shows that if we look in the ultra violet spectrum, birds species which seem similar, or are even considered related based on plumage colors, appear quite different. Quite a few theories regarding supposedly sympatric (sibling) species would have to be re-checked now. And yes, birds can see in the near UV spectrum, which is invisible to humans."