Blue-Footed Booby

## Description

The blue-footed booby (Sula nebouxii ) is a marine bird native to subtropical and tropical regions of the eastern Pacific Ocean. It is one of six species of the genus Sula – known as 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 them 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 up to 1.5 m (5 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 south along the western coasts of Central and South America to Peru. About half of all breeding pairs nest on the Galápagos Islands. Its diet mainly consists of fish, which it obtains by diving and sometimes swimming under water in search of its prey. It sometimes hunts alone, but usually hunts in groups.

The blue-footed booby usually lays one to three eggs at a time. The species practices asynchronous hatching, in contrast to many other species whereby incubation begins when the last egg is laid and all chicks hatch together. This results in a growth inequality and size disparity between siblings, leading to facultative siblicide in times of food scarcity. This makes the blue-footed booby an important model for studying parent–offspring conflict and sibling rivalry.

## Appearance

The Blue-footed booby is a marine bird native to subtropical and tropical regions of the eastern Pacific Ocean. It is easily recognizable by its distinctive bright blue feet which play a key role in courtship rituals with the male visually displaying his feet to attract mates during the breeding season.

## Distribution

Blue-footed boobies occur among the continental coasts of the eastern Pacific Ocean from California to the Galápagos Islands south into Peru. They spend most of the time in the inshore waters and only come out on land to nest, which they do along the rocky coasts with little vegetation.

## Behavior

Blue-footed boobies are active during the day and outside of the breeding season spend all their time in the water. They hunt by diving into the ocean after prey, sometimes from a great height, and can also swim underwater in pursuit of their prey. They can hunt singly, in pairs, or in larger flocks. Boobies travel in parties of about 12 to areas of water with large schools of small fish. When the lead bird sees a fish shoal in the water, it signals to the rest of the group, and they all dive in unison, pointing their bodies down like arrows. Prey is usually eaten while the birds are still under the water. Individuals prefer to eat on their own instead of with their hunting group, usually in the early morning or late afternoon. Males and females fish differently, which may contribute to why blue-foots, unlike other boobies, raise more than one young. The male is smaller and has a proportionally larger tail, which enables the male to fish in shallow areas and deep waters. The female is larger and can carry more food. Blue-footed boobies communicate with the help of raucous or polysyllabic grunts or shouts and thin whistling noises. The males may throw up their heads and whistle at a passing, flying female. Their ritual displays are also a form of communication.

## Diet

Blue-footed boobies have a carnivorous (piscivorous) diet. They are specialized fish eaters, feeding on small schooling fish such as sardines, anchovies, mackerel, and flying fish. They will also take squid and offal.

## Reproduction

Blue-footed boobies are monogamous and form pairs. They are opportunistic breeders and have a very interesting courtship ritual which includes the male flaunting his blue feet and dancing to impress the female. The male begins by showing his feet, strutting in front of the female. Then, he presents nest materials and finishes the mating ritual with a final display of his feet. The dance also includes "sky-pointing", which involves the male pointing his head and bill up to the sky while keeping the wings and tail raised. Blue-footed boobies nest in colonies. Each pair 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. The female lays 2 or 3 eggs and both parents take turns incubating the eggs, while the non-sitting bird keeps watching. The incubation period is 41-45 days and usually, only 1 or 2 chicks are hatched. The male provides food for the young in the first part of their lives because of his specialized diving. The female takes over when the demand is higher. Chicks feed off the regurgitated fish in the adult's mouth. If the parent does not have enough food for all of the chicks, it will only feed the biggest chick, ensuring that at least one will survive. Young females usually start breeding when they are 1 to 6 years old, while males attain reproductive maturity when they are 2 to 6 years old.

## Population

### Threats

Blue-footed boobies are not considered endangered at present, however, climate change and shortage of food may cause declines in their population in the future.

### Number

According to the Avian Conservation and Ecology resource the total population size of the Blue-footed booby is 6,423 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are stable.

## Fun Facts

The name booby comes from the Spanish word bobo which means "stupid", "foolish", or "clown"; this is because the Blue-footed booby is, like other seabirds, clumsy on land. They are also regarded as foolish for their apparent fearlessness of humans.

Since Blue-footed boobies prey on fish by diving headlong into the water, their nostrils are permanently closed, and the birds have to breathe through the corners of their mouth.

The blue color of the Blue-footed booby's webbed feet comes from carotenoid pigments obtained from its diet of fresh fish. The feet can range in color from pale turquoise to a deep aquamarine, and males and younger birds have lighter feet than females.

When hunting, Blue-footed boobies can do plunge-diving from heights of 10-30.5 m (33-100 ft) and even up to 100 m (330 ft). These birds hit the water around 97 km/h (60 mph) and can go to depths of 25 m (82 ft) below the water surface. Their skulls contain special air sacs that protect the brain from enormous pressure.

Mated Blue-footed boobies can recognize each other by their calls. Although calls differed between sexes, there are unique individual signatures that help boobies discriminate the calls of their mates from others.

Blue-footed boobies do not have a brooding patch so they use their feet to keep the eggs warm.

While nesting, the female Blue-footed booby constantly turns to face the sun throughout the day, so the nest is surrounded by excrement, called guano.