Most of the birds I see in the Minnesota backyard in the winter are variations of black and white, perhaps with a bit of chestnut, yellow-tan, or reddish accents: chickadees, nuthatches, woodpeckers, house finches, goldfinches, etc. But one bird really stands out in the winter scene, the Northern Cardinal, the male of which advertises his bright red colors all year. Forget camouflage, this bird flaunts his feathery spectacle every day; it’s the one cheery spot in the monotonous gloom of winter white, gray, and brown.
That red advertisement in the presence of a number of predators that would love to eat him really begs the questions: why are cardinals so red, and why are they red all year?
Let’s start with the argument recently elaborated by Yale ornithologist Richard Prum in his delightful new book: “The Evolution of Beauty” (2017). Prum advances the Darwinian argument for sexual selection (as opposed to natural selection), more specifically, the role of female choice in mate selection, as the basis for why some males are so ornately decorated or colorful.
The adaptationist (via natural selection) argument for why male peacocks have such long tails with intricate patterns is that this feather display proves the male is 1) stronger (able to fly away from and evade predators), 2) healthier (more energy devoted to his ornaments), and 3) more vigorous (long periods of strutting around showing off those feathers while evading predation). Prum instead argues that it is female choice of the “most beautiful” males that has driven them to become so gaudy; that is, only the extravagantly bright and showy males will pass on their genes through successful matings.
Does this help explain why Cardinals are red? What do you think?
I’ll add my thoughts to the discussion tomorrow.