In species exhibiting strong sexual dichromatism, what causes the bright coloration in males?

Answer

Carotenoid pigments

The vibrant yellows and reds commonly seen in brightly colored male finches are derived from carotenoid pigments, with the intensity often signaling the quality of the male's diet.

In species exhibiting strong sexual dichromatism, what causes the bright coloration in males?
birdanimaldescriptionfinch