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Red-footed booby

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Red-footed booby
Temporal range: Holocene – recent[1]
White morph, Philippines
Brown morph, male, Galápagos Islands
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Suliformes
Family: Sulidae
Genus: Sula
Species:
S. sula
Binomial name
Sula sula
(Linnaeus, 1766)
Synonyms
  • Pelecanus sula Linnaeus, 1766
  • Pelecanus piscator Linnaeus, 1758
  • Sula piscator (Linnaeus, 1758)

The red-footed booby (Sula sula) is a large seabird of the booby family, Sulidae. Adults always have red feet, but the colour of the plumage varies. They are powerful and agile fliers, but they are clumsy in takeoffs and landings. They are found widely in the tropics, and breed colonially in coastal regions, especially isolated islands such as St. Brandon, Mauritius (Cargados Carajos shoals). The species faces few natural or man-made threats, although its population is declining; it is considered to be a least-concern species by the International Union for Conservation of Nature (IUCN).

Taxonomy

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The red-footed booby was formally described by the Swedish naturalist Carl Linnaeus in 1766, in the twelfth edition of his Systema Naturae. He gave it the binomial name Pelecanus sula and described it based on a specimen from Barbados.[3][4] The present genus Sula was introduced by the French scientist Mathurin Jacques Brisson in 1760.[5] The word Sula is Norwegian for a gannet.[6]

There are three subspecies:[7]

  • S. s. sula (Linnaeus, 1766) – Caribbean and southwest Atlantic islands
  • S. s. rubripes Gould, 1838 – tropical Pacific and Indian Oceans
  • S. s. websteri Rothschild, 1898 – eastern central Pacific

Description

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The red-footed booby is the smallest member of the booby and gannet family at about 70 cm (28 in) in length and with a wingspan of up to 152 cm (60 in).[8] The average weight of 490 adults from Christmas Island was 837 g (1.845 lb).[9] It has red legs, and its bill and throat pouch are coloured pink and blue. This species has several morphs. In the white morph the plumage is mostly white (the head often tinged yellowish) and the flight feathers are black. The black-tailed white morph is similar, but with a black tail, and can easily be confused with the Nazca and masked boobies. The brown morph is overall brown. The white-tailed brown morph is similar, but has a white belly, rump, and tail. The white-headed and white-tailed brown morph has a mostly white body, tail and head, and brown wings and back. The morphs commonly breed together, but in most regions one or two morphs predominates; for example, at the Galápagos Islands, most belong to the brown morph, though the white morph also occurs.

The sexes are similar, and juveniles are brownish with darker wings, and pale pinkish legs, while chicks are covered in dense white down.

Distribution

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The red-footed booby is widespread throughout the tropics of the Atlantic, Pacific, and Indian Oceans. In the Atlantic, they mainly live in the Caribbean islands.[10] In the Pacific, populations can be found in the Galapagos Islands, mostly on Genovesa and San Cristobal[11] and in Hawaii, on Kauai.[12] In the Indian Ocean, it is found on Aldabra, the Seychelles, Rodrigues, the Maldives, the Chagos Archipelago, the Cocos (Keeling) Islands, and Christmas Island.[13]

The red-footed booby has been extirpated from a large number of islands due to a combination of introduced predators and human predation, including the Glorioso Islands, Assumption Island, Tikopia, Henderson Island, the Marquesas Islands, the Society Islands, and Desecheo Island.[13] The species is a vagrant to Sri Lanka,[14] New Zealand,[15] and the United Kingdom.[16]

Ecology and behaviour

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Breeding

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This species breeds on islands in most tropical oceans. When not breeding it spends most of the time at sea, and is therefore rarely seen away from breeding colonies. It nests in large colonies, laying one chalky blue egg in a stick nest, which is incubated by both adults for 44–46 days. The nest is usually placed in a tree or bush, but rarely it may nest on the ground. It may be three months before the young first fly, and five months before they make extensive flights.

Red-footed booby pairs may remain together over several seasons. They perform elaborate greeting rituals, including harsh squawks and the male's display of his blue throat, also including short dances.

Diet

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The diet of red-footed boobies consists mostly of fish (such as Exocoetidae flying fish and Gempylidae escolars) and squid.[17] Studies of the red-footed booby on Christmas Island have found that most fish eaten are 6–15 cm (2.4–5.9 in) long, with a maximum length of 20 cm (7.9 in), and most squid are 6–10 cm (2.4–3.9 in), with a maximum length of 15 cm (5.9 in). On Aldabra, the proportion of fish and squid in the diet varies between seasons; squid make up 21% of the diet by mass in the wet season and 1% in the dry season. They generally catch prey by diving into the ocean vertically from heights of 4 to 8 m (13 to 26 ft), although flying fish may be caught while in the air.[13]

Predators and parasites

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Adult red-footed boobies are known to be hunted by coconut crabs; the crabs use their powerful claws to break the wings of boobies or catch them by their legs. One booby attacked while asleep on a low branch was killed by six coconut crabs over a period of several hours, while another caught after landing near the entrance to a crab burrow was dragged inside.[18] Red-footed booby nestlings and eggs are also attacked by a variety of predators, including rats, cats, pigs,[13] raptors,[19] and Micronesian starlings,[20] although introduced mammalian predators have a limited impact as the booby nests in trees.[13] However, the booby's habit of breeding on remote islands may be an adaptation to avoid predation;[13] on the Galápagos Islands, the red-footed booby does not nest on any islands inhabited by the Galapagos hawk, even when they have suitable conditions, and has been observed colonizing islands soon after the hawk is extirpated on them.[21] Humans eat both red-footed booby adults and nestlings; boobies will bite humans trying to catch them near their nest.[13]

Parasites recorded from the species include the tick Ornithodoros capensis in nests and the bird louse Pectino pygus in adults.[13]

Conservation

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The International Union for Conservation of Nature (IUCN) lists the red-footed booby as a species of least concern, though the population worldwide is decreasing.[2] The warm phase (El Niño) of the El Niño–Southern Oscillation in 1982 and 1983 negatively affected breeding on Christmas Island as higher water temperatures reduced food supply. Where usually 6000 pairs nested, 30 pairs and the around 60 pairs attempted breeding in 1982 and 1983 respectively.[22]

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References

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  1. ^ "Sula sula Linnaeus 1766 (red-footed booby)". PBDB.
  2. ^ a b BirdLife International (2018). "Sula sula". IUCN Red List of Threatened Species. 2018: e.T22696694A132589278. doi:10.2305/IUCN.UK.2018-2.RLTS.T22696694A132589278.en. Retrieved 12 November 2021.
  3. ^ Linnaeus, Carl (1766). Systema naturae : per regna tria natura, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis [The system of nature: through the three kingdoms of nature, according to classes, orders, genera, species, with characters, differences, synonyms, places] (in Latin). Vol. 1, part 1 (12th ed.). Stockholm: Laurentii Salvii. p. 218.
  4. ^ Grant, Claude H. B.; Mackworth-Praed, C. W. (1933). "The Correct Type-locality of the Red-footed Booby, Sula sula sula (Linnæus)". Bulletin of the British Ornithologists' Club. 53: 185–187.
  5. ^ Brisson, Mathurin Jacques (1760). Ornithologie, ou, Méthode contenant la division des oiseaux en ordres, sections, genres, especes & leurs variétés (in French and Latin). Vol. 1. Paris: Jean-Baptiste Bauche. Vol. 1 p. 60, Vol. 6 p.494.
  6. ^ Jobling, James A. (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 373. ISBN 978-1-4081-2501-4.
  7. ^ Gill, Frank; Donsker, David, eds. (2017). "Hamerkop, Shoebill, pelicans, boobies & cormorants". World Bird List Version 7.3. International Ornithologists' Union. Retrieved 20 November 2017.
  8. ^ "Red-footed Booby". All About Birds. Cornell Lab of Ornithology. Retrieved May 28, 2020.
  9. ^ CRC Handbook of Avian Body Masses, 2nd Edition by John B. Dunning Jr. (Editor). CRC Press (2008), ISBN 978-1-4200-6444-5.
  10. ^ "Birds Connect Our World – Day 49". Birds Caribbean. 20 October 2022. Retrieved 13 June 2024.
  11. ^ "Red-footed booby". Galapagos Conservation Trust. Retrieved 13 June 2024.
  12. ^ "Red-footedBooby Overview". All About Birds. Retrieved 13 June 2024.
  13. ^ a b c d e f g h Schreiber, Elizabeth A.; Schreiber, R. W.; Schenk, G. A. (2020-03-04). Billerman, Shawn M.; Keeney, Brooke K.; Rodewald, Paul G.; Schulenberg, Thomas S. (eds.). "Red-footed Booby (Sula sula)". Birds of the World. Cornell Lab of Ornithology. doi:10.2173/bow.refboo.01. Retrieved 2024-04-01.
  14. ^ Amarasinghe, Chamara Jayaba; Bandara, Imesh Nuwan. "Third confirmed record of the red-footed booby Sula sula from Sri Lanka". academia.
  15. ^ "'Astonishing' first ever NZ sighting of red-footed booby". 23 January 2017. Retrieved 2017-08-01.
  16. ^ Digital, Douglass. "Changes to the British List (16 August 17)". British Ornithologists' Union. Retrieved 2022-07-05.
  17. ^ "Red-footed Booby Life History". All about birds. Retrieved 2024-04-21.
  18. ^ Laidre, Mark E (2017). "Ruler of the atoll: the world's largest land invertebrate". Frontiers in Ecology and the Environment. 15 (9): 527–528. Bibcode:2017FrEE...15..527L. doi:10.1002/fee.1730. ISSN 1540-9295.
  19. ^ Raine, André F.; Vynne, Megan; Driskill, Scott (2019). "The impact of an introduced avian predator, the Barn Owl Tyto alba, on Hawaiian seabirds" (PDF). Marine Ornithology. 47: 35.
  20. ^ Reichel, James D.; Glass, Philip O. (1990). "Micronesian Starling Predation on Seabird Eggs". Emu - Austral Ornithology. 90 (2): 135–136. Bibcode:1990EmuAO..90..135R. doi:10.1071/MU9900135. ISSN 0158-4197.
  21. ^ Anderson, David J. (1991). "Apparent predator-limited distribution of Galápagos Red-footed Boobies Sula sula". Ibis. 133 (1): 26–29. doi:10.1111/j.1474-919X.1991.tb04805.x. ISSN 0019-1019.
  22. ^ Schreiber, Ralph W.; Schreiber, Elizabeth Anne (1984). "Central Pacific Seabirds and the El Niño Southern Oscillation: 1982 to 1983 Perspectives". Science. 225 (4663): 713–716. Bibcode:1984Sci...225..713S. doi:10.1126/science.225.4663.713. JSTOR 1693159. PMID 17810291. S2CID 40459951.
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