Red birds stand out more than birds of other hues, so they get eaten more often than their drab relatives. So is having red feathers a good idea? And what makes birds red in the first place?
Recent research indicates that there are, in fact, advantages to being red, and they go far beyond being pretty to look at. It has been known for some time that birds with red feathers often have extra-sensitive cones (color-sensing vision cells) in their retinas, which may make it possible for them to see food sources that other birds can't. Some red birds have also been found to have cells in their livers that help with detoxification of harmful substances, potentially allowing their owners to eat a wider variety of foods than non-red birds. Perhaps because of these two advantages, birds with red coloring are more desirable mates than their non-red buddies in multiple species.
So how does red happen?
Recent research from the University of Cambridge, published in the journal Current Biology, indicates that some Zebra Finches possess a gene that allows them to convert yellow pigments in their food, called carotenoids, into a red coloring in their beaks. Interestingly, the red pigment exists at lower—almost undetectable—levels in regular, yellow-beaked Zebra Finches.
A separate research team out of the Universidade do Porto of Portugal is working on the genetics of the red canary, a hybrid developed by canary fanciers about 100 years ago by interbreeding with the Red Siskin. One particularly intriguing finding is that the gene for carotenoid-to-red conversion exists in many, if not most, bird species, even if those birds don't appear red. The birds that aren't red still have the super-sensitive color vision and heavy-duty liver function conferred by the gene, but for some reason as yet unknown, they just don't have red skin or feathers.
Why research red coloration in birds? Two reasons. First, it's a trait that easy to track and manipulate. Second, it's beautiful.