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Red-footed Booby Sula sula

Justification
Although this species may have a restricted range, it is not believed to approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: #http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls#.
Christidis, L.; Boles, W. E. 2008. Systematics and taxonomy of Australian birds. CSIRO Publishing, Collingwood, Australia.
del Hoyo, J.; Collar, N. J.; Christie, D. A.; Elliott, A.; Fishpool, L. D. C. 2014. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Barcelona, Spain and Cambridge UK: Lynx Edicions and BirdLife International.
SACC. 2006. A classification of the bird species of South America. Available at: #http://www.museum.lsu.edu/~Remsen/SACCBaseline.html#.

Distribution and population
This species winters on tropical islands in most oceans, excluding the eastern Atlantic. It winters at sea in the same area, just ranging north of the Tropic of Cancer, and just south of the Tropic of Capricorn (del Hoyo et al. 1992).

Population justification
The global population is estimated to number > c.1,000,000 individuals (del Hoyo et al. 1992), while national population sizes have been estimated at < c.100 breeding pairs and < c.50 individuals on migration in Taiwan and < c.100 breeding pairs and < c.50 individuals on migration in Japan (Brazil 2009).

Trend justification
The population is suspected to be in decline owing to habitat loss, predation by invasive species and unsustainable levels of exploitation.

Ecology
This species is strictly marine and largely pelagic. It feeds mainly on flying-fish and squid with a mean prey length of 8.8 cm. Prey are caught by plunge-diving, but flying fish are also taken in flight especially when chased by underwater predators. It often rests on boats using them as vantage points. Breeding is not seasonal in most of its range. Individuals form large colonies, nesting and roosting mainly in trees or on islets with abundant vegetation (del Hoyo et al. 1992).

Related state of the world's birds case studies

References
Brazil, M. 2009. Birds of East Asia: eastern China, Taiwan, Korea, Japan, eastern Russia. Christopher Helm, London.

del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Vandenbosch, R. 2000. Effects of ENSO and PDO events on seabird populations as revealed by Christmas Bird Count data. Waterbirds 23: 416-422.

Further web sources of information
Explore HBW Alive for further information on this species

Search for photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Ekstrom, J., Butchart, S., Calvert, R.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2014) Species factsheet: Sula sula. Downloaded from http://www.birdlife.org on 31/10/2014. Recommended citation for factsheets for more than one species: BirdLife International (2014) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 31/10/2014.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

ARKive species - Red-footed booby (Sula sula) 0

Key facts
Current IUCN Red List category Least Concern
Family Sulidae (Gannets, Boobies)
Species name author (Linnaeus, 1766)
Population size mature individuals
Population trend Decreasing
Distribution size (breeding/resident) 32,500 km2
Country endemic? No
Links to further information
- Additional Information on this species