What Makes the Blue-Footed Booby's Feet Blue?

Just like the color of flamingos' feathers, the source of the blue color in the booby's feet comes from their diet. In blue-footed boobies, it comes from pigments called carotenoids, which are found in the fish they eat. Scientists have also shown that the feet become an even brighter blue the healthier the bird is.

So by choosing a mate with the bluest feet, females are selecting well-nourished and healthy partners.Their "booby" name refers to the fact that these birds are a bit clumsy when on land. They are also known as blue-footed gannet, blue-footed booby, or blue-footed pelican.