What makes the Blue-Footed Booby's feet blue?

This is the question that our expert naturalist guides are asked most about these delightful creatures! Rather like the feather color of flamingos, the source of the booby's blue feet is their diet. In the blue-footed boobies, it’s from pigments called carotenoids, which come from 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, the females are selecting well nourished and healthy partners.