The
Nazca Booby,
Sula granti, is a
boobyA booby is a seabird in the Sula genus, part of the Sulidae family. Boobies are closely related to the gannets , which were formerly included in Sula....
which is found in the eastern
Pacific OceanThe Pacific Ocean is the largest of the Earth's oceanic divisions. Its name is derived from the Latin name Tepre Pacificum, "peaceful sea", bestowed upon it by the Portuguese explorer Ferdinand Magellan. It extends from the Arctic in the north to Antarctica in the south, bounded by Asia and...
, namely on the
Galápagos IslandsThe Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, 972 km west of continental Ecuador...
where it can be seen by
eco-touristsEcotourism is travel to fragile, pristine, and usually protected areas that strives to be low impact and small scale. It helps educate the traveler; provides funds for conservation; directly benefits the economic development and political empowerment of local communities; and fosters respect for...
, and on
Clipperton IslandClipperton Island is a nine-square-kilometre coral atoll in the Eastern Pacific Ocean, southwest of Mexico and west of Central America, at...
. The
Revillagigedo IslandsThe Revillagigedo Islands are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem...
off
Baja CaliforniaBaja California is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California peninsula, north...
which possibly constitute its northeasternmost limit of its breeding range.
It was formerly regarded as a
subspeciesSubspecies in biological classification, is 1) a taxonomic rank subordinate to species, or 2) a taxonomic unit, a taxon in that rank...
of the
Masked BoobyThe Masked Booby, Sula dactylatra, is a large seabird of the gannet family, Sulidae. This species breeds on islands in tropical oceans, except in the eastern Atlantic; in the eastern Pacific it is replaced by the Nazca Booby, Sula granti, which was formerly regarded as a subspecies of Masked Booby...
but the Nazca Booby is now recognized as a separate
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
. They differ in regard to
ecologicalEcology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....
and
morphologicalIn biology morphology is the form, structure and configuration of an organism.This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs...
as well as mtDNA
cytochrome bCytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequenceA DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology....
data.
The
Nazca Booby,
Sula granti, is a
boobyA booby is a seabird in the Sula genus, part of the Sulidae family. Boobies are closely related to the gannets , which were formerly included in Sula....
which is found in the eastern
Pacific OceanThe Pacific Ocean is the largest of the Earth's oceanic divisions. Its name is derived from the Latin name Tepre Pacificum, "peaceful sea", bestowed upon it by the Portuguese explorer Ferdinand Magellan. It extends from the Arctic in the north to Antarctica in the south, bounded by Asia and...
, namely on the
Galápagos IslandsThe Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, 972 km west of continental Ecuador...
where it can be seen by
eco-touristsEcotourism is travel to fragile, pristine, and usually protected areas that strives to be low impact and small scale. It helps educate the traveler; provides funds for conservation; directly benefits the economic development and political empowerment of local communities; and fosters respect for...
, and on
Clipperton IslandClipperton Island is a nine-square-kilometre coral atoll in the Eastern Pacific Ocean, southwest of Mexico and west of Central America, at...
. The
Revillagigedo IslandsThe Revillagigedo Islands are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem...
off
Baja CaliforniaBaja California is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North Territory of Baja California. It has an area of , or 3.57% of the land mass of Mexico and comprises the northern half of the Baja California peninsula, north...
which possibly constitute its northeasternmost limit of its breeding range.
Taxonomy
It was formerly regarded as a
subspeciesSubspecies in biological classification, is 1) a taxonomic rank subordinate to species, or 2) a taxonomic unit, a taxon in that rank...
of the
Masked BoobyThe Masked Booby, Sula dactylatra, is a large seabird of the gannet family, Sulidae. This species breeds on islands in tropical oceans, except in the eastern Atlantic; in the eastern Pacific it is replaced by the Nazca Booby, Sula granti, which was formerly regarded as a subspecies of Masked Booby...
but the Nazca Booby is now recognized as a separate
speciesIn biology, a species is:* a taxonomic rank or* a unit at that rank ....
. They differ in regard to
ecologicalEcology is the interdisciplinary scientific study of the interactions between organisms and the interactions of these organisms with their environment....
and
morphologicalIn biology morphology is the form, structure and configuration of an organism.This includes aspects of the outward appearance as well as the form and structure of the internal parts like bones and organs...
as well as mtDNA
cytochrome bCytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequenceA DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information as described by the central dogma of molecular biology....
data. The Nazca Booby co-occurs with the Masked Booby on Clipperton Island, where they may rarely hybridize.
Behaviour
Nazca boobies are known for practicing obligate
siblicideSiblicide , the death of an individual by its close relatives may occur directly between siblings or indirectly across the parent-offspring relationship and is seen to have beneficial indirect results for the genetic viability of a population or direct results for the recipient individuals.Cattle...
(Anderson, 1990). They lay two
eggsIn most birds and reptiles, an egg is the zygote, resulting from fertilization of the ovum. To enable incubation the egg is usually kept within a favourable temperature range as it nourishes and protects the growing embryo. When the embryo is adequately developed it breaks out of the egg in the...
, several days apart. If both eggs hatch, the elder chick will push its sibling out of the
nestA nest is a place of refuge to hold an animal's eggs and/or provide a place to live or raise offspring. They are usually made of some organic material such as twigs, grass, and leaves; or may simply be a depression in the ground, or a hole in a tree, rock or building...
area, leaving it to die of thirst or cold. The parent booby will not intervene and the younger chick will inevitably die. It is believed that two eggs are laid so that one remains an insurance in case the other gets destroyed or eaten, or the chick dies soon after hatching. In a study published in PLoS ONE (June 18, 2008), biologists linked the murderous behavior to high levels of
testosteroneTestosterone is a steroid hormone from the androgen group. In mammals, testosterone is primarily secreted in the testes of males and the ovaries of females, although small amounts are also secreted by the adrenal glands. It is the principal male sex hormone and an anabolic steroid.In men,...
and androgens found in the hatchlings. According to the study, the high hormone levels also cause the surviving chicks to behave like bullies after they grow up. Adults that have failed to breed frequently seek out nestlings in their colony, and during those visits they often bite, preen and even try to copulate with chicks. This behaviour is known as NPAV, which stands for Non Parental Adult Visitor; the causes of this behavior are not fully understood (Anderson, 2004).