Testosterone produces bright bird colors

SASKATOON, Saskatchewan, Nov. 28 (UPI) -- Canadian scientists say they've found high levels of testosterone in male birds create bright coloring on feathers, beaks and legs.

The researchers discovered that as the levels of testosterone decrease, so does the level of carotenoids -- the chemicals that create the bright coloring.

The scientists say the brilliant colors serve as indicators of the sexual health of the male bird, signaling to females that he is healthy and would serve as a potentially good mate.

Scientists already knew testosterone in male birds produces more activity, National Geographic News reported. But until the recent study by Julio Blas and colleagues at the University of Saskatchewan in Saskatoon, Canada, the relationship between bird coloring and testosterone had eluded biologists.

"A bird in good shape should be colorful and also should sing more," Blas told NGN. "Until now these lines of evidence have been researched independently of each other. What we did is connect these two lines of research."

The study appeared in last week's issue of the Proceedings of the National Academy of Sciences.