Why are cardinals so red?
Northern cardinals are well known for their vibrant and alluring plumage, and are the official state bird in more US states (seven) than any other species. But how do these beauties, a common sight across the eastern USA, get their fabulous colours? Male cardinals are bright red, while females are paler brown, with red found only around their wings, tail and crest. Carotenoid pigments are responsible for the red coloration. These pigments are not produced automatically, but instead obtained through dietary sources, much as flamingos famously do. In the case of cardinals, they come from carotenoid-rich fruits, berries and seeds, and certain other plant parts.
It has been suggested that the reddest males attract higher quality females and manage to pair up earlier in the season, while also obtaining higherquality territories.