|Adult on Española Island, Galapagos Islands|
The Nazca booby is a sea bird that form colonies on the islands it inhabits. It has a yellow iris, orange and pinkish beak, black facial skin in the form of a mask, and grey feet. Adults present white plumage with black tips of the wings and tail. The show sexual dimorphism, The female is bigger and heavier than the male, their beaks present a very slight difference in coloration, and the female squawk while the male whistles.The chicks stay in the nests for a long period of time, and their coloration is snow white and fluffy. When they make their first attempts to fly their feather coloration change to grey as well as their beak and feet. They nest near cliffs in bare terrains with little to no vegetation. Their nests are done on the bare floor.They are pelagic when they are out of their islands where they nest.
They were previously in the order Pelecaniformes, however they were recently placed in the Suliformes order, in the Sulidae family along with other 8 genres with 55 species. Because of their similarity with the masked boobies (Sula dactylatra) they were considered as members of the same species, however, further studies that looked to diferenciate the b-citocrome showed the existence of three different species: Nazca boobies, Central and oriental Pacific masked boobies, and Caribbean and Atlantic masked boobies. This groups are likely to have diverged in a short period of time, 400.000-500.000 years ago.
They feed by diving at high speed into the ocean and catching their prey. They mostly catch sardines, however they are known to also feed on flying fish, anchovies and squid, specially during the El Niño events. Because of their sexual dimorphism females tend to feed on bigger prey and dive deeper.
This birds have relatively long lifes, with a low annual reproduction and long periods of development on their Young. They tend to set their colonies in areas near or on cliffs, where the male will choose a territory to courtship the female, reproduce and care for their chicks.
After the female lays the eggs, she starts incubating, time during which the parents control the different factors that are involved in the development of the embryo, such as temperature. In other species this is accomplished thanks to the incubation patch, a layer of bare skin that allows birds to transmit heat into their eggs, however Suliformes, a group that includes the boobies, don’t have this characteristic. Sula granti transfers the heat on to the eggs through the webbed feet in addition to the heat they will transfer thru their breast. The webbed feet are very vascularized, especially during the nesting period. . Both the male and the female show parental care, in a biparental care. The nesting size is one or two eggs, due to the low hatching success, however when 2 eggs are laid and they both hatch, it is common for only one of the chicks to survive. Usually the chick that hatches first is bigger and becomes aggressive towards its sibling. The younger one is pushed from the nest, and therefore is not fed and dies. The energy investment on the parent’s part is very high, so their metabolic rates change during the nesting season. (Apanius et al. 2008) This causes both parents to loose similar amounts of body weight and a decline on their immune system activity
When there is no nesting season the parents show no energetic decline. This happens when the nesting conditions are not ideal, and this is crucial for the parents survival. A huge factor for the reproduction of Sula granti is the movement of sea currents. This causes climate and weather changes. El Niño for example causes less availability of food for sea birds, which causes them to migrate further south or north, change their diets or even stop the nesting process.
Both in the UICN red list and the BirdLife International list of endangered species, Sula granti is considered of least concern (LC). Allthough a population tendency to decrease is observable, this doesn't happen at a rate fast enough to cause concern. Some of the factors that influence the decrease of populations are over fishing and ocean contamination 
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|Wikispecies has information related to: Sula Granti|
- BirdLife International (2012). "Sula granti". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
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- Takasuka, Akinori; Oozeki, Yoshioki; Aoki, Ichiro (2007-05-01). "Optimal growth temperature hypothesis: Why do anchovy flourish and sardine collapse or vice versa under the same ocean regime?". Canadian Journal of Fisheries and Aquatic Sciences. 64 (5): 768–776. doi:10.1139/f07-052. ISSN 0706-652X.