If you could find the whitest bird near the shoreline, it has to be a Nazca Booby. Formerly known as Masked (White) Booby, this native sea bird has one of the most intriguing behaviours in the animal world. Nazca Boobies belong to the Sulidae family (Order Pelicaniformes), and are part of the three gannet species of the archipelago.
Size wise, it is also the largest of all three. Nesting occurs right on the ground, and their “guano rings” are easily observed. This species of booby nests mainly along the edges of the shoreline, although nesting areas like Tower Island, may have them as far as 100 metres inland (some 300 feet). Unlike blue-footed boobies, they have a fixed mating season with one peculiar situation: sibling murder.
Siblicide is not uncommon in avian life. In fact, herons, cranes, and even egrets perform it. The complete evolutionary set of advantages has not been completely deciphered, but there are definite clues that lead us to believe, these birds are taking the “insurance policy” concept to the limit.
It seems the reason for siblicide lies in the rigidity of their fixed mating season. Producing an egg is hard to start with, more so if two are laid. If they lay only one egg, and something happens to that single egg, there will be an uphill climb if you are to lay another one and rear it successfully. You may not finish in time. Therefore, ethics forgotten, siblicide seems to be the key for survival and a clear evolutionary advantage.
This system works in a non-conflict environment, since the laying of the two eggs is about 4-5 days apart (thus, the hatching of the eggs is at different days). Chicks will have different sizes where the older is larger by about 30%. This makes a crucial difference at feeding time, since the larger chick has a clear advantage versus its smaller sibling. Pushing the younger one out of the nest (siblicide) gets rid of the potential competition, but more so, it increases the survival ratio of the staying sibling by 50%.
Cruel or not, it doesn’t matter. Survival matters; and it is the only mechanism that allows species to have a chance to pass on their genes to a next generation. Best nesting colonies for observing Nazca Boobies: Genovesa (Tower), Hood (Española), and Floreana
Galapagos Islands. Best time of the year to observe them: anytime of the year.
Authors This article was developed by Metropolitan Touring, for their newsletter, and was wrote by a team of travelers, field guides, operations and marketing staff inside the company, all of them has more than 10 years working in the
Galapagos cruises & tours guiding and sales, Sylvia Moncayo, Francisco Dousdebés, Santiago Tamayo, Gonzalo Alvarez are the team who produce our articles, Email info@metropolitan-touring.com Article Copyright Metropolitan Touring Corporation 2005 - 2006 Source: