Nazca Booby

Nazca Booby
Adult with chick and unhatched egg
Conservation status
Least Concern (IUCN 3.1)[1]
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Pelecaniformes
Family:	Sulidae
Genus:	Sula
Species:	S. granti
Binomial name
Sula granti Rothschild, 1902

Española Island, Galapagos Islands

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^[2].

Taxonomy

It was formerly regarded as a subspecies of the Masked Booby but the Nazca Booby is now recognized as a separate species. They differ in regard to ecological and morphological^[3] as well as mtDNA cytochrome b sequence data.^[4] The Nazca Booby co-occurs with the Masked Booby on Clipperton Island, where they may rarely hybridize.^[4]

Behavior

Nazca boobies are known for practicing obligate siblicide.^[5] 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.^[6] 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.^[7] This behaviour is known as NPAV, which stands for Non Parental Adult Visitor; the causes of this behavior are not fully understood.^[8]

Gallery

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  Dorsal view

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  Ventral view

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  Nazca Booby portrait

See also

• Vampire Finch

References

1. ^ BirdLife International (2004). Sula granti. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 12 May 2006. Database entry includes justification for why this species is of least concern
2. ^ Brattstrom, Bayard H.; Howell, Thomas R. (1956), "The Birds of the Revilla Gigedo Islands, Mexico", Condor 58 (2): 107–20, doi:10.2307/1364977, JSTOR 1364977, http://elibrary.unm.edu/sora/Condor/files/issues/v058n02/p0107-p0120.pdf.  DjVu fulltext
3. ^ Pitman, R.L. & Jehl, J.R. (1998). "Geographic variation and reassessment of species limits in the "Masked" Boobies of the eastern Pacific Ocean". Wilson Bull. 110 (2): 155–70. http://elibrary.unm.edu/sora/Wilson/v110n02/p0155-p0170.pdf.  DjVu fulltext
4. ^ ^{a b} Friesen, V.L.; Anderson, D.J.; Steeves, T.E.; Jones, H. & Schreiber, E.A. (2002). "Molecular Support for Species Status of the Nazca Booby (Sula granti)" (in English with Spanish abstract) (^{[dead link]}). Auk 119 (3): 820–6. doi:10.1642/0004-8038(2002)119[0820:MSFSSO]2.0.CO;2. http://www.nmnh.si.edu/vert/birds/pdf/eas1.pdf. 
5. ^ Anderson, J. David (December 1990). "The evolution of Obligate Siblicide in boobies". Evolution. 
6. ^ Müller MS, Brennecke JF, Porter ET, Ottinger MA, Anderson DJ (June 2008). Helle, Samuli. ed. "Perinatal Androgens and Adult Behavior Vary with Nestling Social System in Siblicidal Boobies". PLoS ONE 3 (6): e2460. doi:10.1371/journal.pone.0002460. PMC 2413419. PMID 18560542. http://www.plosone.org/article/fetchArticle.action?articleURI=info:doi/10.1371/journal.pone.0002460. 
7. ^ High Hormone Levels in Seabird Chicks Prepare Them to Kill Their Siblings Newswise, Retrieved on July 1, 2008.
8. ^ Anderson DJ, Porter ET, Ferree ED (2004). "Non breeding Nazca boobies(Sula Granti) show social and sexual interest in chicks: behavioral and ecological aspects". Behavior 141 (8): 959–77. doi:10.1163/1568539042360134.