Red-billed tropicbird (Phaethon aethereus)

French: Phaéton à bec rouge
KingdomAnimalia
PhylumChordata
ClassAves
OrderPelecaniformes
FamilyPhaethontidae
GenusPhaethon (1)
SizeLength including tail streamers: 90 - 105 cm (2)
Wingspan: 99 - 106 cm (2)
Weightca. 700 g (2)

Classified as Least Concern (LC) on the IUCN Red List (1).

The red-billed tropicbird is the largest of the three tropicbird species (2), a group of graceful seabirds best known for the two extremely elongated central tail feathers (3) (4) (5), which can measure up to 56 centimetres in this species (2). Named for its crimson beak, which is stout and slightly downward-curving, the red-billed tropicbird has a mainly white body, and can be distinguished by its black wing tips and fine black barring on the upperparts. There is also a long black stripe through the eye. The male and female are similar in appearance, but the male may have longer tail streamers, while juveniles have a yellow beak, stronger barring on the back, eyestripes that meet on the back of the neck, and lack the long tail streamers (2) (3) (4) (5). The short legs are set far back on the body, and the feet are webbed (3). Three subspecies are recognised (2) (4) (6).

The red-billed tropicbird is found throughout tropical regions of the eastern Pacific, the Caribbean Sea, Atlantic, Red Sea, Arabian Gulf and Indian Ocean (4) (5) (7), with key populations occurring on the Galapagos and Cape Verde Islands (3) (7). Phaethon aethereus aethereus is found in the southern Atlantic Ocean, Phaethon aethereus mesonauta is found in the eastern Atlantic, Caribbean and eastern Pacific, and Phaethon aethereus indicus is found in the Red Sea, Persian Gulf and Arabian Sea (2) (6).

Like all tropicbirds, the red-billed tropicbird is highly pelagic (2) (5) (6), spending most of its time over the open ocean and only coming onto land to breed. Nesting usually occurs on small, remote oceanic islands, in holes in cliffs or beneath rocks, or sometimes amongst vegetation (2) (3).

The red-billed tropicbird has a strong, energetic flight, using rapid wing-beats rather than gliding or soaring, and it also swims well, with the long tail held up out of the water (3) (5). Usually foraging alone, it typically flies high above the water, sometimes hovering, before plunge-diving to catch fish or squid, or sometimes taking flying fish from the air (2) (3) (6). In contrast, it is extremely awkward on land, using the wings to push itself along on its belly (3) (6).

Breeding occurs in loose colonies, and may take place almost year-round in some areas. The nest is a mere scrape on the ground, and the site may be aggressively defended. A single egg is laid, hatching after 42 to 44 days (2) (3) (6), with the newly hatched chick having pale grey down and fledging after around 80 to 90 days, after which it is abandoned by the adults (2) (6). The red-billed tropicbird attains adult plumage at around two to three years, and first breeds at around five years (3) (6). Lifespan may be as much as 16 years (6). Although this species does not undergo a regular migration, both adults and juveniles disperse widely outside of the breeding season (2) (6).

Despite its large distribution, and relatively stable populations in the Galapagos and Cape Verde Islands, the red-billed tropicbird is thought to be the least abundant of the tropicbird species (2) (3), numbering only around 7,500 individuals (7). The main threat to this species is predation of adults, eggs and chicks by introduced mammals such as rats, cats and dogs (2) (6) (7) (8) (9), compounded by increasing development and tourism at breeding sites (9), and persecution by fishermen in some areas (2). The difficulty in censusing the red-billed tropicbird, with its dispersed population and generally inaccessible nest sites, has made it difficult to accurately assess its status (6) (9).

The red-billed tropicbird is listed under the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA), which calls upon parties to engage in a range of conservation actions to help protect and conserve bird species that are dependent on wetlands for at least part of their annual cycle (10). Protection of key breeding sites, such as on Jarnein Island in Abu Dhabi, United Arab Emirates, will also be essential for the long-term conservation of this graceful bird (11).

However, the conservation of the red-billed tropicbird is made difficult by a general lack of studies on this species. The scattered distribution of its nesting colonies, while buffering the species somewhat from problems that may otherwise affect the whole population, sometimes means that the importance of even relatively small colonies can be overlooked. Few red-billed tropicbird colonies occur in protected areas, and little other legislation is in place to protect this species. It has therefore been suggested that this and other tropicbird species should be regarded as high conservation priorities (9).

To find out more about the red-billed tropicbird see:

 

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  1. IUCN Red List (July, 2009)
    http://www.iucnredlist.org
  2. del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions, Barcelona.
  3. Nelson, J.B. (2005) Pelicans, Cormorants, and their Relatives. The Pelecaniformes. Oxford University Press, Oxford.
  4. Blake, E.R. (1977) Manual of Neotropical Birds. Volume 1: Spheniscidae (Penguins) to Laridae (Gulls and Allies). University of Chicago Press, Chicago and London.
  5. Hilty, S.L. and Brown, W.L. (1986) A Guide to the Birds of Colombia. Princeton University Press, Princeton, New Jersey.
  6. Nellis, D.W. (2001) Common Coastal Birds of Florida and the Caribbean. Pineapple Press, Florida.
  7. BirdLife International (July, 2009)
    http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3648&m=0
  8. Hellyer, P. and Aspinall, S. (2005) The Emirates: A Natural History. Trident Press Limited, London.
  9. Lee, D.S. and Walsh-McGehee, M. (2000) Population estimates, conservation concerns, and management of tropicbirds in the Western Atlantic. Caribbean Journal of Science, 36: 267 - 279.
  10. Agreement on the Conservation of African-Eurasian Migratory Waterbirds (July, 2009)
    http://www.unep-aewa.org
  11. Javed, S., Khan, S. and Shah, J.N. (2008) Breeding status of the red-billed tropicbird, Phaethon aethereus (Aves: Phaethontidae), on Jarnein Island, United Arab Emirates. Zoology in the Middle East, 44: 11 - 16.