It’s hard to tell what will arouse a female bird and cause her to mate.

A female peahen looks long and hard at the tail feathers of the male peacock. If they are bright with lots of colorful circles, she is much impressed. Take away that showy tail and she is completely turned off.

Male blue-footed boobies are judged by the blueness of their feet. They will lift them up and spread out the webbing to impress the female. The darker the blue, the better chance for copulation. No blue – no...