Scarlet plumage has long posed a mystery to scientists—but now they've finally solved it.
How did cardinals get those bright red feathers? (Constantine
The Gene That Paints Birds Red - The Atlantic
Red Bird Strategic
Red, white and blue birds of Pennsylvania
The Facts and Myths About Cardinal Birds – Natural History Society
Indiana's State Bird: The Northern Cardinal - WonderLab
Red Bird Strategic
Two studies find one gene for red beaks and feathers - BBC News
Where Red Birds Get Their Vibrant Hues, Smart News
Solving the mystery of what causes bald cardinals - Farm and Dairy
Red Bird Plumage » How And Why Does It Get That Way? - Bird Buddy Blog
Why Do Some Birds Have Red Eyes? – Nature Blog Network
What's Behind Those Lustrous Red Feathers?
Lammergeiers rub iron rich soil into their feathers to dye them