Nazca Booby
Encyclopedia
The Nazca Booby, Sula granti, is a booby
which is found in the eastern Pacific Ocean
, namely on the Galápagos Islands
where it can be seen by eco-tourists
, and on Clipperton Island
. The Revillagigedo Islands
off Baja California
which possibly constitute its northeasternmost limit of its breeding range.
of the Masked Booby
but the Nazca Booby is now recognized as a separate species
. They differ in regard to ecological
and morphological
as well as mtDNA cytochrome b
sequence
data. The Nazca Booby co-occurs with the Masked Booby on Clipperton Island, where they may rarely hybridize.
. They lay two eggs
, several days apart. If both eggs hatch, the elder chick will push its sibling out of the nest
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 testosterone
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.
Booby
A booby is a seabird in the genus Sula, part of the Sulidae family. Boobies are closely related to the gannets , which were formerly included in Sula.-Description:...
which is found in the eastern Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
, namely on the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
where it can be seen by eco-tourists
Ecotourism
Ecotourism is a form of tourism visiting fragile, pristine, and usually protected areas, intended as a low impact and often small scale alternative to standard commercial tourism...
, and on Clipperton Island
Clipperton Island
Clipperton Island is an uninhabited nine-square-kilometre coral atoll in the eastern Pacific Ocean, southwest of Mexico and west of Central America, at...
. The Revillagigedo Islands
Revillagigedo Islands
The Revillagigedo Islands or Revillagigedo Archipelago are a group of four volcanic islands in the Pacific Ocean, known for their unique ecosystem...
off Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
which possibly constitute its northeasternmost limit of its breeding range.
Taxonomy
It was formerly regarded as a subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of the Masked Booby
Masked Booby
The Masked Booby, Sula dactylatra, is a large seabird of the booby 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 species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
. They differ in regard to ecological
Ecology
Ecology is the scientific study of the relations that living organisms have with respect to each other and their natural environment. Variables of interest to ecologists include the composition, distribution, amount , number, and changing states of organisms within and among ecosystems...
and morphological
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
as well as mtDNA cytochrome b
Cytochrome b
Cytochrome 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 :...
sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data. The Nazca Booby co-occurs with the Masked Booby on Clipperton Island, where they may rarely hybridize.
Behavior
Nazca boobies are known for practicing obligate siblicideSiblicide
Siblicide is the killing of an infant individual by its close relatives . It may occur directly between siblings or be mediated by the parents. The evolutionary drivers may be either indirect benefits for the genetic viability of a population or direct benefits for the perpetrators...
. They lay two eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, several days apart. If both eggs hatch, the elder chick will push its sibling out of the nest
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
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 testosterone
Testosterone
Testosterone is a steroid hormone from the androgen group and is found in mammals, reptiles, birds, and other vertebrates. 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...
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.