Credit for the photo: Wilder Rodrìguez Arteaga (Peru)

Review: Abdel Rahman El Gamal (Founder of the website)

Introduction

The blue-footed booby, Sula nebouxii is a tropical marine bird that belongs to the family Sulidae. The bird got its name “booby” from the Spanish “bobo”, or “bubi” that means stupid. This name was probably given by early European colonists who got by these clumsy and unwary birds. Even though, the naming of the bird seems unfair especially to Spainsh speakers, it will continue carrying this silly name. These goose-sized birds can live as long as 17 years.

Geographic range

This species is found on the western coast of the Americas, ranging from north-westMexico and Panama to north Peru and the Galapagos Islands, Ecuador. The bird is native to Chile;Colombia; Costa Rica; Ecuador (Galápagos); El Salvador; Honduras; Mexico; Nicaragua; Panama; Peru;United States. It is believed that the Galápagos Islands population includes about half of all breeding pairs of blue-footed boobies.

Key descriptions

The blue-footed booby has an average of about 80 cm long and about 1.5 kg weigh. The female is slightly larger than the male and can measure up to 90 cm long with pointed wings that can measure an average 1.5 m across.

The most notable characteristic of the bird is its blue-colored feet which come from carotenoid pigments obtained from the bird’s diet of fresh fish. It is believed that blue color of bird’s feet indicates the current health condition and the individual’s immunological state of the bird.

The feeding habits of the bird is reflected in its physical make-up as shown in its excellent binocular vision through its side eyes, its tapered bill with serrated edges that enable the bird to tightly grasp fish. The bird feeding through diving, its nostrils are permanently closed while the bird breathing takes place through mouth corners. Moreover, their skulls contain special air sacs that protect the brain from enormous pressure through diving.

Feeding habits

The blue-footed booby is a specialized fish eater, feeding on small fish such as sardines, anchovies, mackerel, and flying fish as well as on squids. In Peru where this photo is taken, their favorite fish is the Peruvian anchovy while their principal diet in the Galapagos Islands is sardines.

Once the prey fish schools are in sight, the birds whether singly or in larger flocks dive into the ocean from heights of 10–30 which can reach up to 100 m and can dive to depths of 20-25 m and for a period longer than 30 seconds. However, their common dives are shallower and shorter. The foraging activity of blue-footed boobies is restricted to daylight hours.

In addition to being exceptional divers, the blue-footed booby is skilled hunter in the air as thebirds are known to catch flying fish when they are still in the air.

The smaller size of the blue-footed male as well as its proportionally larger tail enables the bird to stick and fish with shallow dives closer to shore. On the other hand, heavier females make deeper dives offshore and may catch bigger fish. The regurgitation feeding of the chicks is done by both male and female parent.

Reproduction and life history

The age of first breeding in the Blue-footed Booby is almost 4 years of age with a breeding cycle which occurs every 8 to 9 months at any time of the year.

The blue feet play a key role in the courtship and breeding of blue-footed booby with the male flaunting his brilliant blue feet and presenting nest materials to attract the female. Male dance and display are a part of the courtship that including a “sky-pointing” dance. A brief courtship flight follows, after which the male proudly flashes his blue feet to the female once more. Then, mating follows.

A female of blue-footed boobies usually lays one to threepale blue or green eggs at a time with about four to five days apart. Eggs are laid in shallow depressions on flat ground, far away from other nests. Both male and female take turns incubating the eggs, while the non-sitting bird keeps watch.

Since the blue-footed booby does not have brooding patches of skin to incubate the eggs, the bird uses its webbed feet to cover and keep the eggs warm especially their blue feet have an excellent blood supply.

The incubation period is about 45 days. Usually, one to two chicks are hatched from the eggs originally laid. The bird is characterized by its asynchronous hatching. After the first egg is laid, it is immediately incubated leading to sequential hatching of chicks. In other words, the first chick enjoys a four-day head start in growth compared to its younger sibling.

Parental care:Both parents share parental responsibilities feeding the chicks with regurgitated fish through their bills. The male will provide food for the young in the first part of their life because of his specialized diving. The female will take over when the demand is higher. Hatched chicks lack feathers and stay in the nest near parents for a 2-3 month until fledging.

Predation:On the Galápagos Islands, the predator of the nestling boobies during day time is the Galapagos Hawk (Buteo galapagoensis).  Typically, the nestlings are typically attended by at least one parent at night, providing protection from the nocturnal predator, the Short-eared Owl (Asio flammeus).

References:Animal Diversity Web, Animal Corner, Nature Works, Neotropical, National geographic, MarineBio, Wikipedia