Wedge-tailed shearwater

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Wedge-tailed shearwater
Pair "singing", Lady Elliot Island, Queensland, Australia

Least Concern  (IUCN 3.1)[1]
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Procellariiformes
Family: Procellariidae
Genus: Ardenna
Species:
A. pacifica
Binomial name
Ardenna pacifica
(Gmelin, JF, 1789)
  Nonbreeding
  Breeding
Synonyms

Procellaria pacifica (

protonym
) Puffinus pacificus

The wedge-tailed shearwater (Ardenna pacifica) is a medium-large

Islas Revillagigedo, the Hawaiian Islands, the Seychelles, the Northern Mariana Islands, and off Eastern and Western Australia
.

Taxonomy

The wedge-tailed shearwater was

sister to Buller's shearwater.[9]

Description

The pale morph and dark morphs side by side

The wedge-tailed shearwater is the largest of the tropical shearwaters. The two colour morphs of the species are dark and pale; the pale morphs predominate in the North Pacific, the dark morph elsewhere. However, both morphs exist in all populations, and bear no relation to sex or breeding condition. The pale morph has grey-brown plumage on the back, head, and upper wing, and whiter plumage below. The darker morph has the same dark grey-brown plumage over the whole body. The species' common name is derived from the large, wedge-shaped tail, which may help the species glide. The bill is dark and legs are salmon pink, with the legs set far back on the body (in common with the other shearwaters) as an adaptation for swimming.

This species is related to the pan-Pacific Buller's shearwater, which differs much in colour pattern, but also has a wedge tail and a thin, black bill.

superspecies of the large shearwaters that were for a long time included in the genus Puffinus.[12][13]

Behaviour and ecology

Food and feeding

Wedge-tailed shearwaters feed

pelagically on fish, squid, and crustaceans. Their diet is 66% fish, of which the most commonly taken is goatfish. The species was thought to mostly take food from surface feeding, but observations of feeding wedge-tails suggested that contact-dipping, where birds flying close to the surface snatch prey from the water was the most commonly used hunting technique. However, a 2001 study which deployed maximum depth recorders found that 83% of wedge-tails dived during foraging trips with a mean maximum depth of 14 m (46 ft) and that they could achieve a depth of 66 m (217 ft).[14]

Breeding

Egg, Muséum de Toulouse)

The wedge-tailed shearwater breeds in

colonies on small tropical islands. Breeding seasons vary depending on location, with synchronised breeding seasons more common at higher latitudes. Northern Hemisphere birds begin breeding around February, and Southern Hemisphere birds begin around September. Wedge-tailed shearwaters display natal philopatry
, returning to their natal colony to begin breeding at the age of four.

Chick in burrow, Kilauea Point National Wildlife Refuge

Wedge-tailed shearwaters are

nocturnally
, although nonbreeding wedge-tails are often seen at the surface throughout the day and breeding birds rest outside their burrows before laying.

Both sexes undertake a prelaying exodus to build up energy reserves; this usually lasts around 28 days. A single egg is laid, if that egg is lost, then the pair will not attempt another that season. After laying, the male usually undertakes the first incubation stint. Both sexes incubate the egg, in stints that can last up to 13 days. Incubation takes around 50 days. After hatching, the chick is brooded for up to 6 days, until it is able to

thermoregulate, after which it is left alone in the nest while both parents hunt for food. It is initially fed with stomach oil, an energy-rich, waxy oil of digested prey created in the parent's gut; later, it is fed both solids and stomach oil. Like many procellariids, wedge-tailed shearwater parents alternate long and short trips to provide food, with the parents alternating between short foraging trips (1–4 days) and long trips (about 8 days), the two parents coordinating their feeding effort. Chicks increase in size to 560 g (20 oz) (larger than the adults), then drop to around 430 g (15 oz) before fledging
. Fledging occurs after 103–115 days, after which the chick is independent of the adult.

Known breeding colonies include:

Gallery

  • Juvenile, Kilauea, Kauai, Hawaii
    Juvenile, Kilauea, Kauai, Hawaii
  • Profile in flight, Hawaiian Islands
    Profile in flight, Hawaiian Islands

References

  1. doi:10.2305/IUCN.UK.2018-2.RLTS.T22698175A132631353.en
    . Retrieved 13 November 2021.
  2. ^ Gmelin, Johann Friedrich (1789). Systema naturae per regna tria naturae : secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis (in Latin). Vol. 1, Part 2 (13th ed.). Lipsiae [Leipzig]: Georg. Emanuel. Beer. p. 560.
  3. ^ Latham, John (1785). A General Synopsis of Birds. Vol. 3, Part 2. London: Printed for Leigh and Sotheby. p. 416, No. 22.
  4. ^ Mayr, Ernst; Cottrell, G. William, eds. (1979). Check-List of Birds of the World. Vol. 1 (2nd ed.). Cambridge, Massachusetts: Museum of Comparative Zoology. p. 91.
  5. ^ Mathews, Gregory M. (1912). The Birds of Australia. Vol. 2. London: Witherby. p. 80.
  6. ^ Hellmayr, C.E.; Conover, B. (1928). Catalogue of Birds of the Americas and the Adjacent Islands in Field Museum of Natural History. Field Museum Natural History Publication 242. Zoological Series. Volume 13, Part 1 No. 2. p. 66, Note.
  7. ^ Reichenbach, H. G. Ludwig (1853). Avium systema naturale. Dresden and Leipzig: Expedition der vollständigsten naturgeschichte. p. IV. The title page has 1850 (original title page missing in the BHL scan but available from BSB). The Preface is dated 1852 but Mayr 1979 gives the year as 1853.
  8. ^
    Rasmussen, Pamela, eds. (August 2022). "Petrels, albatrosses"
    . IOC World Bird List Version 12.2. International Ornithologists' Union. Retrieved 15 November 2022.
  9. hdl:2445/193747
    .
  10. PMID 8812308
    .
  11. doi:10.1642/0004-8038(2004)121[0847:AGMPOT]2.0.CO;2
    .
  12. doi:10.1071/MU01060
    .
  13. ^ "Proposal (647) to South American Classification Committee: Split Ardenna from Puffinus". South American Classification Committee. Retrieved 23 January 2016.
  14. doi:10.1642/0004-8038(2001)118[0755:DDOS]2.0.CO;2
    .

Further reading

External links
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