The Blue-Footed Booby: Built for Spectacle

The name alone tells you something. “Bobo” means foolish or clownish in Spanish. Early Spanish sailors gave the birds the name because of their unusual behavior. They would waddle past sleeping sailors on shore, seemingly unbothered by people. They could even be picked up by hand while resting. To hungry crews short on provisions, that made them easy prey. The name had stuck.

The feet, however, are anything but a joke. Their brilliant blue color comes from carotenoid pigments, which the birds obtain through their diet of fresh fish. The more recently a male has eaten, the brighter his feet tend to be. After several days without enough food, the color can visibly fade.

Females don’t choose the brighter feet simply because they look better. They can distinguish relatively subtle differences in foot color, which provides information about a male’s recent nutritional condition. A brightly colored male is likely to be well-fed and in good condition, qualities that can matter when choosing a mate and raising chicks. The courtship display is, in effect, a sign of health on two blue feet.

Age adds another layer. Younger birds tend to have lighter-colored feet, while older birds generally develop deeper, more saturated blue coloration, provided they are well fed. Females also tend to have darker blue feet than males of the same age, setting them apart when courting pairs stand together.

The other thing blue-footed boobies are famous for is their spectacular way of feeding. You can even sometimes watch it from the deck of a boat. A group will circle above a school of fish, then suddenly start diving. Rather than going in one at a time, several birds can hit the water within seconds of each other, creating a series of overlapping splashes.

From up high, a booby folds its wings back just before entering the water, giving its body an efficient shape for diving. They can plunge from heights of up to 30 metres. Their bodies have adapted for these repeated dives, their skull reinforced and their nostrils positioned to keep water from rushing in when they hit the surface.

Watching a whole group dive together is a spectacular wildlife encounter you can have in the Galápagos. The water seems to erupt around the fish, and a few seconds later the birds start popping back up with their catch. Cruise passengers sometimes see this from a Zodiac while travelling between the ship and shore, an unplanned wildlife experience.

Another detail that surprises many visitors is how blue-footed boobies incubate their eggs. Instead of sitting directly on the eggs like many other birds, they place their warm, well-vascularized feet over the eggs and young. There isn’t much of a nest either. It’s usually just a cleared patch of ground, sometimes surrounded by a ring of droppings marking the territory. The same blue feet that are used to attract a mate are used to keep their eggs warm.

The nest can barely be considered a nest. Blue-footed boobies clear a patch of open ground, sometimes surrounding it with a ring of droppings. They lay their eggs directly on the ground, without using sticks or leaves. Usually one to three eggs are laid, and the parents keep them warm by placing their well-vascularized feet over them.

Both parents take turns incubating the eggs. The chicks are altricial, meaning they are completely helpless when they hatch, depending on their parents for warmth, protection, and food.

The number of eggs they lay also depends on food availability. When sardines are plentiful, a pair may successfully raise two or three chicks. When food is scarce, they may not breed at all. Over longer periods, changes in sardine availability can therefore have a noticeable effect on the population.