This audio story is brought to you by BirdNote, a partner of the 探花精选. BirdNote episodes air daily on public radio stations nationwide. 9127 Transcript: This is BirdNote. Male Northern Cardinals, Scarlet Tanagers, and House Finches all have striking red plumage that’s thought to play a role in attracting mates. To develop red feathers, they need to eat seeds or fruit containing pigment molecules called yellow carotenoids. Their bodies then change those pigments from yellow to red. Males with the brightest red feathering tend to have the best luck with the females. Scientists think that a male’s redness signals to females that he has just what it takes to help produce superior offspring. But just because a male is a brilliant shade of red, does that mean he’s stronger or more fit than his duller-colored competitors? Scientists think one answer may lie in a male’s mitochondria, the energy powerhouses inside the body’s...