The Blue-footed Booby is a specie from the Sula genus. The natural breeding habitat of the Blue-footed Booby is tropical and subtropical islands off the Pacific Ocean, most famously, the Galápagos Islands, Ecuador. This fish-eating bird has drab plumage but bright blue feet. During his courtship display, the male raises his tail and parades in front of the female, lifting his feet as high as he can with each step. This comical march persuades the female to mate.
The Blue-footed Booby is on average 81 cm (32 in) long and weighs 1.5 kg (3.3 lb), with the females slightly larger than the males. It has long pointed wings and a wedge shaped tail. They have strong, thick necks. The booby's eyes are placed on either side of their bill and oriented towards the front. They have excellent binocular vision. The Blue-footed Booby's eyes are yellow. The male has more yellow on its iris than the female. The Blue-footed Booby has permanently closed nostrils made for diving. They breathe through the corners of their mouths. Their feet range from a pale turquoise to a deep aquamarine. Males and younger birds have lighter feet than females do.
The brightness of male foot colour is dependent on access to food. The male's foot colouration is extremely sensitive, with changes perceivable by female birds within a 48 hour period. As the Blue-footed Booby is a monogamous species with biparental care, the female is able to make day-by-day alterations to her investment in the pairing, dependent on male quality, which makes male foot colour a secondary sexual characteristic. During egg laying, the female is able to alter her reproductive investment through changing egg size, dependent on the perceived quality of her male partner.