Brown Booby

(Sula Leucogaster)

The Brown Booby (Sula leucogaster) is a large seabird commonly found along the beaches of the Pacific, especially near the surf. It is distinguished by its steep-angle dives. It nests in colonies on marine islands, placing its nests on the ground. Adults have brown heads, necks, and upper parts, with white bellies. Males in the Pacific may have white heads. Juveniles have mottled brown bellies. Its diving and feeding behavior is vital to the coastal marine ecosystem.

Behavior

The Brown Booby is a diving seabird that hunts for food. It nests in colonies on islands, building ground nests. It is territorial and monogamous during breeding. It lives in dense colonies for cooperation and protection. Some migrate seasonally, and juveniles disperse after fledging.

Size & shape

The Brown Booby measures between 70-75 cm in length with a wingspan of 130-150 cm. It has an aerodynamic body, with brown heads and upper parts, white bellies, and short, strong legs.

Location

The Brown Booby inhabits tropical and subtropical regions of the Pacific and Atlantic, including the coasts and islands of Central and South America, and the Caribbean.

The Brown Booby has adapted to a variety of marine environments, demonstrating great flexibility and adaptability in its habits. It inhabits diverse coastal, insular, and oceanic zones in tropical and subtropical regions.

Coastal and Beach Areas

Proximity to the coast: These birds are often seen near Pacific and Atlantic beaches, especially in areas near the surf, where they can find abundant food.
Rocky and sandy beaches: They can be seen on both sandy beaches and rocky coasts, where they rest between hunting periods.

Oceanic Islands

Nesting on remote islands: They prefer to nest on remote marine islands, away from human activity, building their nests directly on the ground. Islands like the Galapagos in the Pacific and some in the Caribbean are common nesting sites.
Dense colonies: They form large nesting colonies on these islands, providing mutual protection and facilitating cooperation among individuals.

Open Marine Zones

Feeding in open sea: They spend much of their time in the open sea, hunting for food. They are expert divers, catching fish and squid in areas of high marine productivity.
Tropical and subtropical waters: They prefer the warm, productive waters of tropical and subtropical regions, which offer abundant food necessary for their survival.

Habitat Factors

Food accessibility: Their habitat is influenced by food availability. They move along marine currents that concentrate prey like fish and squid.
Absence of predators: They prefer nesting on islands free of terrestrial predators, increasing the survival of their chicks.
Climate and temperature: Warm, stable climates are essential for their reproduction and chick-rearing, avoiding extreme climates that could affect their reproductive success.

Diet

Fish: Their main food source is fish, which they catch in large quantities. They prefer small to medium-sized species that swim in schools near the surface.
Squid: Squid also form a significant part of their diet. These cephalopods are captured in deeper waters during dives.
Crustaceans and other marine invertebrates: Though less common, they may also feed on small crustaceans and other marine invertebrates when available.

Feeding Techniques

Plunge diving: The Brown Booby is known for its ability to plunge dive. It launches from considerable heights and enters the water at a sharp angle to catch its prey with precision.
Group hunting: These birds often hunt in groups, which allows them to surround schools of fish and increase their chances of success.

Feeding Patterns

Daily diet: Brown Boobies need to feed several times a day to meet their energy needs. The abundance and availability of prey influence their feeding patterns and movements.
Hunting distances: They can travel considerable distances from their nesting colonies to find food, sometimes traveling several kilometers offshore.

Nesting is a carefully coordinated process that maximizes the survival chances of chicks in a challenging environment. Their choice to nest on remote islands and their cooperative behavior are key strategies for reproductive success.

Nest Location

Remote islands: They prefer nesting on oceanic islands away from human activity, where they find a safe environment free from terrestrial predators.
Dense colonies: They form large nesting colonies, with numerous nests close to each other, facilitating cooperation and mutual protection.

Nest Construction

Ground nests: They build their nests directly on the ground, using available materials like stones, dry vegetation, and feathers.
Simplicity: The nests are simple depressions in the ground, often reinforced with small rocks or shells for greater stability.

Nesting Season

Seasonality: The nesting season varies by location, but generally occurs during periods of greater food availability.
Synchronization: In some regions, nesting is synchronized with the rainy seasons, ensuring an adequate food supply for the chicks.

Reproduction and Rearing

Eggs: The female typically lays 1-2 eggs, although usually only one chick survives due to competition and resource availability.
Incubation: Both parents share the responsibility of incubating the eggs, taking turns to keep them warm and protect them from predators.
Parental care: After hatching, both parents feed and care for the chicks, bringing them regurgitated food to ensure their growth and development.

Chick Development

Growth period: Chicks stay in the nest for several weeks, completely dependent on their parents for food and protection.
First flight: Once young birds develop enough feathers and strength, they leave the nest to make their first flights and begin hunting on their own.

Territorial Behavior

Nest defense: During the breeding season, Brown Boobies are very territorial, aggressively defending their nests against intruders and other colony members.
Courtship rituals: Adults perform complex courtship rituals before nesting, including head movements and synchronized flight displays.

The Brown Booby (Sula leucogaster) is notable for its versatile and cooperative behavior. This species stands out for its ability to dive from great heights, plunging into the water to capture fish and squid. They often hunt in groups, which allows them to surround and catch schools of fish more effectively.

During the breeding season, the Brown Booby nests in large colonies on remote islands, where it builds simple ground nests. They are very territorial during this period, aggressively defending their nests against intruders. They generally form monogamous pairs seasonally, and both parents participate in incubating the eggs and caring for the chicks, feeding them regurgitated fish. They live in dense colonies, which facilitates communication, cooperation, and mutual protection. They use a variety of vocalizations and visual displays to communicate, especially during breeding.

Some populations migrate seasonally, while juveniles disperse widely after leaving the nesting colonies. Adapted to maximize efficiency in capturing prey, Brown Boobies adjust their feeding patterns to the availability of resources, showing high resilience and adaptability to different environmental conditions. Their presence and reproductive success are indicators of marine environment health and resource abundance.

The Brown Booby (Sula leucogaster) is classified as of “Least Concern” by the IUCN, but faces threats such as habitat loss, climate change, pollution, and overfishing.

According to “Partners in Flight,” it has a conservation concern score of 13, indicating moderate concern. The estimated global population is approximately 300,000 individuals. Although not in immediate danger, it is essential to maintain and strengthen conservation measures to protect this species.

Brown Booby

The Brown Booby (Sula leucogaster) emits a variety of sounds, especially during the breeding season. Their vocalizations include grunts, growls, and squawks used to communicate with each other, defend their territories, and during courtship rituals. Males and females have distinctive calls, with males emitting higher-pitched sounds and females producing deeper vocalizations.

Isla Contoy Experience · Brown Booby (Sula leucogaster)

Cool facts

Curious Name: The name “Booby” comes from the Spanish word “bobo,” meaning “fool” or “clown.” This name is due to their seemingly clumsy behavior on land, where they are less agile than in water or air.
Courtship Rituals: During the breeding season, Brown Boobies perform elaborate courtship rituals that include head movements, wing displays, and coordinated vocalizations. These rituals help strengthen pair bonds and ensure compatibility.
Spectacular Dives: They are known for their impressive dives. They can plunge from heights of up to 30 meters, entering the water at sharp angles and reaching high speeds to capture their prey with precision.
Adapted Eyes: Their eyes are adapted to see clearly both in the air and underwater, allowing them to locate and track their prey with great accuracy, a crucial hunting skill.
Noisy Colonies: In nesting colonies, Brown Boobies are very vocal. The colonies can be quite noisy due to constant calls and territorial disputes among individuals, creating a very dynamic and active environment.

Reference source

Birds of the world