It has been proposed that the name "booby" comes from the spanish word "bobo" meaning stupid or dunce and refers to the bird's characteristic lack of fear of man.
Due to the fact that this particular bird lives in isolated oceanic areas, and often spends much of its time very far from land, it does not have many predators.
Sula sula is the smallest booby, and is well suited for its long flights out to sea in search of prey. It has strong neck muscles, and a wedge-shaped tail. It has a long, tapering bill with serrated cutting edges to help catch and eat its prey. Its external nostrils are closed to allow for plunge-diving, but it has developed secondary nostrils beside the mouth which are automatically covered by flaps when it plunges. The skin around its face is generally bare. The eyes are beside the bill, face forward, and have very pale irises. The wings are long, pointed, and situated fairly far back on the body. They help the bird to fly in high winds (which it does by alternating powerful flaps with gliding) and also to dive. When diving, the wings close around the body of the bird, making it more aerodynamic. The legs are short and strong, and the feet are large and totipalmate (webbed between all four toes). The feet are highly vascular because it is through the feet that heat is transmitted from the parent to the offspring. The legs are set far back on the body, helping it to swim. The feet and legs are also red, thus giving the bird its name. Sula sula is very buoyant, having developed a series of air-sacs which are extensions of the bronchi. They help in its plunge-diving.
The plumage of Sula sula must serve two purposes, camouflage and body temperature maintenance. The underpart of the bird is generally white, so as to provide countershading to help prevent its prey from seeing it. Also, "in an environment where both salt and the sun intensify the effects of feather abrasion, dark, melanin-rich feathers on the upper parts help to provide stronger resistance" (del Hoyo et al., 1992). The plumage is molted continuously so as not to hinder the bird's flight capability at any one time, however, molt is suspended during breeding. Feathers are renewed 1 to 2 times yearly. Sula sula lacks a brood patch because it would interfere with streamlining and insulation. There are several morphs of this bird, often making it difficult to identify without noting the color of its feet. The morphs are: the white-tailed brown morph, the white headed and white tailed brown morph, the white morph (which has black on its wings), the black-tailed white morph (found on the Galapagos Islands), and the golden white morph (found on the Christmas Islands).
Red-footed boobies are 70 to 71 cm long, on average and have a wingspan of 91 to 101 cm. They weigh from 900 to 1003 g. Females tend to be slightly larger than males.
Range mass: 900 to 1003 g.
Range length: 64 to 76 cm.
Average length: 70-71 cm.
Range wingspan: 91 to 101 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry ; polymorphic
Sexual Dimorphism: female larger
Red-footed boobies live as sexually reproductive adults for approximately 23 years but can live for more than 40 years.
Range lifespan
Status: wild: 40 (high) years.
Average lifespan
Status: wild: 23 years.
Average lifespan
Status: wild: 275 months.
Red-footed boobies make their nests in the tops of trees on islands and coasts in tropical regions. They may also nest in low scrub. They inhabit islands and coastal regions in the tropics, because they prey on fish in pelagic regions of the ocean.
Habitat Regions: tropical ; terrestrial ; saltwater or marine
Terrestrial Biomes: scrub forest
Aquatic Biomes: pelagic ; coastal
Red-footed boobies are found in tropical and sub-tropical waters across the globe (they are found in the Oriental, Ethiopian, Neotropical, and Australian regions; they are also found on oceanic islands). They take long hunting trips of up to 150 km from their breeding grounds but do not migrate. One of the largest populations is on the Galapagos Islands.
Biogeographic Regions: oriental (Native ); ethiopian (Native ); neotropical (Native ); australian (Native ); oceanic islands (Native )
Sula sula preys on fish. It is known to hunt up to 150 km out to sea, much farther than other Sulids. It plunge-dives to moderate depths (approximately 4 to 10 m) in order to acquire fish, which it catches and swallows on its return to the surface. Red-footed boobies can fly higher than other Sulids (10 to 30 m) when searching for food because of their binocular vision. Once prey are sighted, the bird will dive straight down into the water, reaching its top speed just before entry. The larger females can often catch food that is deeper than the smaller males because of their weight. Sometimes it will also use its wings to swim deeper underwater (15 to 20 m) to reach prey. Red-footed boobies can also catch prey in midflight, due to their smaller size and better agility than other species of booby. This is a particularly effective method for hunting flying fish as they jump out of the water. They are also known to hunt squid at night, as their large eyes allow effective nocturnal hunting. Red-footed boobies are communal hunters and once one bird has spotted food, all will dive. The food is swallowed before the bird emerges from the water; this prevents other individuals from stealing it.
Two favorite foods of red-footed boobies are flying fish, which they are often able to catch in midflight, and squid (that they catch during night hunting). However, they will eat whatever fish are available.
Animal Foods: fish; mollusks
Primary Diet: carnivore (Piscivore )
Red-footed boobies play an important role in their ecosystem; they have an impact on the fish that they prey on. They do not interact with many other organisms, as they live in such isolated marine areas, often staying far out to sea.
In some areas people rely on red-footed boobies as a food source. In the past, people who hunted them were always aware of the detrimental effects of their hunting, and as such were cautious not to overhunt the populations. Today, people collect sulids and their eggs and sell them across the world. This has gotten out of control and the exploitation has become a concern.
Conservation parks have been established so that people can visit and enjoy these birds without harming them.
Positive Impacts: food ; ecotourism
There are no known adverse affects of red-footed boobies on humans.
The Red-Footed Booby lays a single egg. The eggs are a pale color, and are covered in a chalky residue. The parent keeps the egg warm by placing its feet on the egg. As the parent stands on the egg, it is usually very strong. The egg is generally 5% of the mother's total weight. Incubation lasts for 41-45 days, and the parents take turns guarding/warming it in stints which last anywhere from 12-60 hours. Upon hatching, the chick is near-naked, having no feathers. It broods on the feet of its parents for the first few days, and is not left unattended until is is approximately one month old when it can regulate its own body temperature. Chicks are generally a whitish-brown color. The young feed from the parent, eating from it's mouth. The fledgling phase lasts from 100-139 days, and post-fledgling care lasts for about 190 days. Juveniles are brown or grayish-brown with yellow-gray legs. Red-Footed Boobies molt several times per year, going through several stages between the brown juvenile and the white adult. They are ready to breed at 2-3 years.
(del Hoyo, 1992; Nelson, 1978.)
Sula sula is not globally threatened, because it is so widely dispersed. It is one of the most abundant and widespread of all the Sulids. Despite this, the population size has been decreasing steadily over recent centuries. The biggest threats to these birds are deforestation and the fishing industry. Because they live in trees, deforestation destroys their habitat/nesting grounds, and the fishing industry depletes their food source.
While they are not threatened on a global level, in some areas human pressure on their habitats is threatening specific populations. In addition, people collect sulids and their eggs and sell them across the world. This has gotten out of control and the exploitation has become a concern. Red-footed boobies are protected in some areas now. Conservation parks have been set up so that people can visit and enjoy these birds without harming them. Red-footed boobies are protected under the US Migratory Bird Treaty Act.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
There are a variety of calls used by red-footed boobies. Male and female calls are different, due to structural differences in the trachea and syrinx. The male produces mild, plaintive whistles while the female produces trumpeting honks or quacks. The juveniles sound like females. The posturing that is typically used in courtship is also a form of communication.
Communication Channels: visual ; acoustic
Other Communication Modes: choruses
Perception Channels: visual ; tactile ; acoustic ; chemical
Since red-footed boobies are colonial and highly social, mating/courtship rituals and displays are very important. The higher the population density, the more ritualized their behavior. They show off their wings and feet, and display postures. Movement is displayed by the "Bill-Up-Face-Away" posture. The "Facing-Away" and "Bill Tucking" postures inhibit aggression. Males posture with their tails, beaks, and wings facing upward and call for mates. Once a monogamous pair mates, they will return to the same nest year-to-year to mate.
Mating System: monogamous
Red-footed boobies mate approximately once every 15 months, depending on food availability. They are known for their somewhat flimsy, unstable nests which are often damaged by storms. They often build their nests in trees. Their choice of nest location may be a way to avoid competition for space, since other species of boobies nest on the ground. Pairs mate and lay one egg at a time, raising that egg to maturity. Incubation lasts between 41 and 45 days and the young fledge as young as 91 days old. In El Niño Southern Oscillation years (when food is scarce) fledging may occur at more than 139 days old (Schreiber et al., 1996). Red-footed boobies reach maturity in two to three years.
Breeding interval: Breeding occurs every 15 months.
Breeding season: Breeding is not seasonal.
Range eggs per season: 1 to 1.
Range time to hatching: 41 to 45 days.
Range fledging age: 91 to >139 days.
Range age at sexual or reproductive maturity (female): 2 to 3 years.
Range age at sexual or reproductive maturity (male): 2 to 3 years.
Key Reproductive Features: iteroparous ; year-round breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous
Average eggs per season: 1.
Red-footed boobies nest colonially with hundreds of mating pairs together in one location. Pairs mate and lay one egg at a time, raising that egg to maturity. Incubation lasts between 41 and 45 days and the young fledge in one month. Both the male and female red-footed booby care for the altricial young. If food is scarce the parents may abandon the young in order to ensure their own survival, but if food is abundant they may care for the juvenile for a long time, teaching it how to hunt. Because this bird has such a long lifespan, it can afford to raise one juvenile at a time, and still produce many young during its lifetime.
Parental Investment: no parental involvement; altricial ; pre-hatching/birth (Protecting); pre-weaning/fledging (Provisioning: Male, Female); pre-independence (Provisioning: Male, Female)
The red-footed booby (Sula sula) is a large seabird of the booby family, Sulidae. Adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings. They are found widely in the tropics, and breed colonially in coastal regions, especially islands. The species faces few natural or man-made threats, although its population is declining; it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN).
The first formal description of the red-footed booby was by the Swedish naturalist Carl Linnaeus in 1766 in the twelfth edition of his Systema Naturae. He introduced the binomial name Pelecanus sula.[4] The type locality is Barbados in the West Indies.[5] The present genus Sula was introduced by the French scientist Mathurin Jacques Brisson in 1760.[6] The word Sula is Norwegian for a gannet.[7]
There are three subspecies:[8]
The red-footed booby is the smallest member of the booby and gannet family at about 70 cm (28 in) in length and with a wingspan of up to 152 cm (60 in).[9] The average weight of 490 adults from Christmas Island was 837 g (1.845 lb).[10] It has red legs, and its bill and throat pouch are coloured pink and blue. This species has several morphs. In the white morph the plumage is mostly white (the head often tinged yellowish) and the flight feathers are black. The black-tailed white morph is similar, but with a black tail, and can easily be confused with the Nazca and masked boobies. The brown morph is overall brown. The white-tailed brown morph is similar, but has a white belly, rump, and tail. The white-headed and white-tailed brown morph has a mostly white body, tail and head, and brown wings and back. The morphs commonly breed together, but in most regions one or two morphs predominates; for example, at the Galápagos Islands, most belong to the brown morph, though the white morph also occurs.
The sexes are similar, and juveniles are brownish with darker wings, and pale pinkish legs, while chicks are covered in dense white down.
The species has been recorded three times from Sri Lanka.[11]
In March 2016, footage of a red-footed booby being caught and killed by a coconut crab was recorded on the Chagos Archipelago.[12] After the coconut crab killed the bird, five others were observed being drawn to the site, where they competed over the meat.[13]
In September 2016, a male red-footed booby was found washed up on a beach in East Sussex, UK, 5,000 miles from its nearest usual habitat. It was the first of its species ever recorded in the UK. The bird, later named Norman, was exhausted and malnourished.[14] He was brought back to health before being transported by plane to an environmental center in the Cayman Islands in December 2016, where he subsequently died before ever being released into the wild.[15] As a result of Norman's appearance, the red-footed booby was formally added to the British List by the British Ornithologists' Union on 16 August 2017.[16][17]
In January 2017, a red-footed booby was sighted on the New Zealand mainland for the first time.[18]
This species breeds on islands in most tropical oceans. When not breeding it spends most of the time at sea, and is therefore rarely seen away from breeding colonies. It nests in large colonies, laying one chalky blue egg in a stick nest, which is incubated by both adults for 44–46 days. The nest is usually placed in a tree or bush, but rarely it may nest on the ground. It may be three months before the young first fly, and five months before they make extensive flights.
Red-footed booby pairs may remain together over several seasons. They perform elaborate greeting rituals, including harsh squawks and the male's display of his blue throat, also including short dances.
Red-footed boobies dive into the ocean at high speeds to catch prey. They mainly eat small fish (such as flying fish)[19][20] or squid which gather in groups near the surface.
The International Union for Conservation of Nature (IUCN) lists the red-footed booby as a species of least concern, though the population worldwide is decreasing.[3] The warm phase (El Niño) of the El Niño–Southern Oscillation in 1982 and 1983 negatively affected breeding on Christmas Island as higher water temperatures reduced food supply. Where usually 6000 pairs nested, 30 pairs and the around 60 pairs attempted breeding in 1982 and 1983 respectively.[21]
Red footed booby in flight over Half Moon Caye, Belize
Juvenile red-footed booby poking his head out of his nest on Half Moon Caye, Belize
Red-footed booby
Egg, Collection Museum Wiesbaden
The red-footed booby (Sula sula) is a large seabird of the booby family, Sulidae. Adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings. They are found widely in the tropics, and breed colonially in coastal regions, especially islands. The species faces few natural or man-made threats, although its population is declining; it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN).
