Image: Ben Tubby/Flickr
Penguins are probably the most universally endearing bird species, and it's at least partly due to their relatively monogamous and cooperative family structure. "They're just like us!" we say to ourselves, despite the fact that these creatures have webbed feet and a cloaca. But how do penguins choose their partners?The answer, at least for King penguins, lies in their beaks. King penguins have flashy orange spots on the sides of their beaks, plus ultraviolet spots invisible to human eyes. (Many bird species have cone cells that enable them to see UV rays.)Researchers from the Centre d'Ecologie Fonctionnelle et Evolutive examined King penguins that were still in the courtship stage, before they'd decided on a mate. They measured their beak colors with a spectrophotometer, as well as recording other variables. Then the penguin pairs were re-released.Apparently, the couples that most often went the distance and successfully co-parented had closely matching beak colors. And unlike most bird species where females have their pick of flashy males, each sex is sizing up the other, perhaps due to how both parents play equal roles in chick-rearing.If only choosing compatible human mates was that easy.