Nazca Boobies During Nesting Season on Genovesa

The indifference of the Galapagos fauna to human presence is quite unusual. You won’t find another experience like swimming with sea lions and turtles, who will treat you as part of their underwater world. On the most incredible Galapagos tour, you will have chances like these every day when visiting the most stunning islands in the archipelago (the only means to see some of the furthest islands and rarest unique species). This biology lesson will offer all you’ve always wanted to learn about the evolution and behaviors of Galapagos animals while observing them in their natural environment. While some of these behaviors resemble those of humans, others, like those of the Nazca booby (a Big15 species), follow more innate evolutionary tendencies.

The Insufferable Relative

Despite being closely related to both the well-known blue-footed booby and its red-footed cousin, Nazca boobies have unique physical traits and habits that set them apart from the latter two. They look beautiful with their pinkish-orange pointed beak, snow-white plumage, and black and covered eyes. Additionally, they can be very photogenic, much like any other Galapagos species. Regarding the concept of “survival of the fittest,” they are far more aggressive and territorial. Watch these animals throughout the period while they are nesting and hatching to see Darwin’s theory of evolution come to life!

Nazca Boobies During Nesting Season on Genovesa

Fernandina, Española, and Genovesa are home to Nazca boobies. Nazca boobies search for openings in cliffs and crevasses to build their “nest,” or guano ring, in contrast to blue-footed boobies, which search for comprehensive, level areas inland. Because there isn’t much room in these places, Nazca boobies compete fiercely for territory and will often peck viciously at other boobies that venture too near to their nest. But there’s something strange going on with the Nazca booby colony on Genovesa Island, which you can see on our Northern Itinerary. Because there is a small population of blue-footed boobies on this island, Nazca boobies have occupied some of the niches that their cousins would typically occupy. There is less competition and greater area, which is why some Nazca boobies have even exhibited behavior resembling that of the blue-footed booby. They have discovered an accessible biological niche to nest inland; thus, they are not copying their blue counterparts.

Siblicide Instinct

When a bird lays a single egg, it usually means that the egg has a 50% chance of surviving. For this reason, female Nazca boobies lay two eggs spread out by five-day. This way, if anything were to happen to the first egg, the second would take its place. If both eggs hatch, the first egg always hatches first and the second one hatches a little later. For this reason, the second one will always be smaller and weaker in comparison to its older sibling. They both grow up together until the first one has survived its critical period – the first 15 days after being born. The larger and more powerful one will begin driving the smaller one out of the guano ring as soon as this phase ends. The moment the hatchling leaves the guano ring, it becomes instant prey for predators, even though their blue-footed cousins don’t exhibit this behavior (for both species). The Nazca siblicide instinct is not unique; other maritime and coastal birds also regularly engage in this activity. It seems rather harsh, from an anthropomorphic standpoint, to push away a sibling and let them die while the parents do nothing about it. Darwin’s hypothesis, however, demonstrates that this instinct permits only the fittest and strongest individuals to survive, enhancing the population’s gene pool and guaranteeing its survival throughout time.