What is the origin of the name 'Brown Booby'?

You might think it's because they eat bonito, but Brown Boobies do not actually eat bonito. Then why are they called 'Brown Booby'? The term originates from the behavior of bonito, which primarily feeds on smaller fish. These smaller fish, trying to escape the bonito, come up near the surface where the Brown Booby can easily catch them. Hence, fishermen started calling it the 'Brown Booby' because it helps them locate schools of fish like bonito.

Ironically, from the bonito’s perspective, it might feel like its meal is being stolen. Even though the small fish believe they are escaping to safety, they end up being prey for another. Besides, this method of following larger fish to catch the smaller ones they disturb is also practiced by other birds, which were all collectively referred to as 'Brown Booby' by fishermen. Over time, this name became exclusively associated with this particular bird.

Why does the Brown Booby live there?

Brown Boobies are seabirds that inhabit tropical and subtropical oceans. They nest in inclined areas such as island cliffs or rocky outcrops. For example, in the Ogasawara Islands, there is an uninhabited island named after these birds where colonies of more than 20 individuals may form and nest together.

Being migratory birds that come to Japan for breeding, you might spot them flying around from spring to autumn.

What does the Brown Booby eat?

As previously mentioned, Brown Boobies primarily feed on fish chased by bonito, including sardines, flying fish, mackerel, and squids. They spot their prey from the air and dive spectacularly from heights to catch them, plunging from the sky straight into the water, sometimes reaching depths of 10 to 30 meters.

They are also known to follow ships, not for fun but to catch flying fish startled by the vessels. While older birds do this strategically, younger boobies often approach out of curiosity.

How does the Brown Booby reproduce?

Brown Boobies breed in colonies. They usually build nests on slight inclines on cliffs using dried grass and seaweed, creating territorial boundaries. If an intruder enters their territory, they might react aggressively, much like a windshield wiper motion, swaying their heads vigorously from side to side.

They lay one to two eggs per breeding attempt, which both parents incubate alternately. After about 43 days, the chicks hatch and engage in a brutal survival strategy where the stronger chick may kill or push out the weaker sibling from the nest.

This harsh behavior ensures that the surviving chick gets all the resources it needs to grow stronger. The surviving chick feeds on regurgitated food from its parents until it fledges, which can take about 85 to 105 days. Given their size, Brown Boobies have a longer incubation and fledging period compared to other birds.

How does the Brown Booby fly?

Despite their proficiency in diving and swimming, Brown Boobies are also skilled fliers. They utilize their long wings and tails to glide straight across the sea surface. When the wind picks up, they use it to ascend and glide, a technique known as 'soaring' which allows them to remain airborne for extended periods.

However, taking off and landing are challenging for them due to their body weight. They need a lot of effort to lift off from land, often using slopes for a running start, and they approach landings with extreme caution to avoid injury.

Is it true that Brown Boobies can become blind?

Remember how Brown Boobies dive into the water from great heights? The impact upon entering the water can be as severe as hitting concrete, which over time, can damage their eyes, eventually leading to blindness.

Once they lose their sight, they can no longer hunt effectively and are likely to die. Moreover, incorrect diving techniques can lead to broken necks or wings, which can also be fatal. Such dangerous dives are sometimes called 'death dives.'

What is the lifespan of a Brown Booby?

Despite the risks involved in their hunting techniques, Brown Boobies are long-lived birds, with lifespans ranging from 20 to 30 years. This longevity is attributed to their large size and the lack of natural predators.

For instance, a Brown Booby at Tennoji Zoo lived for 11 years and 6 months. Their ability to survive so long in the wild shows their resilience and adaptiveness.

Is it true that Brown Boobies are mascots for a brand?

Are you familiar with the brand 'CHUMS'? If so, you might think of their mascot as a penguin, but it’s actually a Brown Booby!

Their mascot, known as 'Booby Bird', is specifically modeled after the Red-footed Booby, a type of Brown Booby with distinctive red feet, similar to the mascot. The choice of the Brown Booby as a mascot was influenced by the desire to be a beloved brand, akin to how the bird is perceived as endearing and a bit goofy ('booby' in Spanish means 'silly but cute'). This reflects the brand's playful and friendly image.

Is it true that Brown Boobies are designated as natural monuments?

It’s not the Brown Boobies themselves but their breeding sites that are designated as natural monuments. In 1972, Nakano Kami Island was designated as a natural monument to protect the seabird breeding sites there.

Although Brown Boobies are not currently at risk of extinction and continue to breed successfully, such protections help ensure their survival and conservation.