The blue-footed booby (Sula nebouxii) is a marine bird in the family Sulidae, which includes ten species of long-winged seabirds. Blue-footed boobies belong to the genus Sula, which comprises six species of boobies. It is easily recognizable by its distinctive bright blue feet, which is a sexually selected trait. Males display their feet in an elaborate mating ritual by lifting their feet up and down while strutting before the female. The female is slightly larger than the male and can measure up to 90 cm (35 in) long with a wingspan of up to 1.5 m (4.9 ft). The natural breeding habitats of the blue-footed booby are the tropical and subtropical islands of the Pacific Ocean. It can be found from the Gulf of California down along the western coasts of Central and South America down to Peru . Approximately one half of all breeding pairs nest on the Galápagos Islands. Its diet mainly consists of fish, which it obtains by diving and sometimes swimming underwater in search of its prey. While it sometimes hunts alone, the blue-footed booby mainly hunts in groups. The blue-footed booby usually lays one to three eggs at a time. The species practices asynchronous hatching, which means that eggs that are laid first are hatched before the consequent eggs, resulting in a growth inequality and size disparity between siblings. This results in facultative siblicide in times of food scarcity, making the blue-footed booby an effective model for studying parent-offspring conflict and sibling rivalry. The blue-footed booby is on average 81 cm (32 in) long and weighs 1.5 kg (3.3 lb), with the female being slightly l arger than the male. Its wings are long and pointed, and are brown in color. The neck and head of the blue-footed booby are light brown with white streaks while the belly and underside exhibit pure white plumage. Its eyes are placed on either side of its bill and oriented towards the front, enabling excellent binocular vision. Its eyes are a distinctive yellow, with the male having more yellow in its iri ses than the female. Blue-footed booby chicks have black beaks and feet and are clad in a layer of soft white down. 1Since the blue-footed booby frequently obtains fish by diving headlong into the water, it has permanently closed no strils for this purpose, necessitating breathing through the corners of its mouth. Its most notable characteristic is its blue-colored feet, which can range in color from a pale turquoise to a deep aquamarine. Males and younger birds have lighter feet while females have darker feet. Its blue feet play a key role in courtship rituals and breeding, with the male visually displaying its feet to attract mates during the breeding season. The blue-footed booby is distributed among the continental coasts of the eastern Pacific Ocean from California to t he Galápagos Islands down into Peru. It is strictly a marine bird. Its only need for land is to breed and rear young, which it does along the rocky coasts of the eastern Pacific. A booby may use and defend two or three nesting sites, which consist of bare black lava in small divots in the ground, until they develop a preference for one a few weeks before the eggs are laid. These nests are created as parts of large colonies. While nesting, the female will turn to face the sun throughout the day, so the nest is surrounded by excretion.