The Christmas shearwater or ''aoū'' (''Puffinus nativitatis'') is a medium-sized shearwater of the

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

Central Pacific. It is a poorly known species due to its remote nesting habits, and it has not been extensively studied at sea either.Seto, N.W.H. (2001): Christmas Shearwater (''Puffinus nativitatis''). ''In:'' Poole, A. & Gill, F. (eds.): ''The Birds of North America'' 561. Academy of Natural Sciences, Philadelphia, PA &

American Ornithologists' Union The American Ornithological Society (AOS) is an ornithological organization based in the United States. The society was formed in October 2016 by the merger of the American Ornithologists' Union (AOU) and the Cooper Ornithological Society. Its ...

, Washington, D.C. (requires subscription) It is one member of a very ancient lineage of the small ''Puffinus'' species. Its only close living relative is the Galápagos shearwater (''P. subalaris'').

Taxonomy

The species was described and given its current

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

by the American naturalist Thomas Hale Streets in 1877. A genetic analysis using

mitochondrial A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is used ...

DNA has shown that the closest living relative is the Galápagos shearwater (''Puffinus subalaris'').

Description

The Christmas shearwater is a slender-bodied shearwater, about 36 cm long, with a wingspan of around 75 cm, and weighs around 350 g. It has dark

plumage Plumage () is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, there can b ...

all over, generally blackish-grey with a rusty-brown tinge, slightly paler on the underside of the bird, and with some small edging of white under the chin and pale fringes to the upperwing coverts. It has brown-grey feet and a dark bill and eyes. Both sexes are alike, as are the young after fledging. Nestlings are covered in dark grey

down feather The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and p ...

s.Seto (2001), Shirihai ''et al.'' (2009) The species closely resembles the sooty (''Puffinus griseus'') and

short-tailed shearwater The short-tailed shearwater or slender-billed shearwater (''Ardenna tenuirostris''; formerly ''Puffinus tenuirostris''), also called yolla or moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in A ...

s (''P. tenuirostris''), but has dark brown underwings and is smaller. The short tail of the Christmas shearwater does not appear blunt except when spread, but in flight usually tapers to a point, enhanced by the feet which protrude beyond the tail-tip. It often flies in a leisurely way like the related

Procellariidae The family (biology), family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prion (bird), prions, and the shearwaters. This family is part of the bird order (biology), orde ...

, and thus can be mistaken for a petrel. In particular, it can appear similar to the extremely rare Fiji petrel (''Pseudobulweria macgillivrayi''), a

gadfly petrel The gadfly petrels or ''Pterodroma'' are a genus of about 35 species of petrels, part of the seabird order Procellariiformes. The gadfly petrels are named for their speedy weaving flight, as if evading gadflies (horse-fly, horseflies). The flight ...

-like relative of the shearwaters. The two species share a similar

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines *Morphology (archaeology), study of the shapes or forms of artifacts *Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies, ...

and colouration, but the bulbous head and rather thin long bill – typical for shearwaters – distinguish ''P. nativitatis'' from the slim-headed thick-billed Fiji petrel.

Distribution and habitat

The Christmas shearwater nests on remote islands of the Central Pacific: the Northwestern Hawaiian Islands, Tuamotu, the

Marshall Islands The Marshall Islands, officially the Republic of the Marshall Islands, is an island country west of the International Date Line and north of the equator in the Micronesia region of the Northwestern Pacific Ocean. The territory consists of 29 c ...

Kiritimati Kiritimati (), also known as Christmas Island, is a Pacific Ocean atoll in the northern Line Islands. It is part of the Republic of Kiribati. The name is derived from the English word "Christmas" written in Gilbertese according to its phonol ...

(for which the species is named) and Sala-y-Gómez. It has become locally extinct on a number of islands, including

Wake Island Wake Island (), also known as Wake Atoll, is a coral atoll in the Micronesia subregion of the Pacific Ocean. The atoll is composed of three islets – Wake, Wilkes, and Peale Islands – surrounding a lagoon encircled by a coral reef. The neare ...

. Outside of the breeding season it ranges across the Pacific, having been recorded off the coast of Mexico and Guatemala in the east, and

Bonin Islands The Bonin Islands, also known as the , is a list of islands of Japan, Japanese archipelago of over 30 subtropical and Island#Tropical islands, tropical islands located around SSE of Tokyo and northwest of Guam. The group as a whole has a total ...

in the west. Further south it is rare, having been recorded off

Fiji Fiji, officially the Republic of Fiji, is an island country in Melanesia, part of Oceania in the South Pacific Ocean. It lies about north-northeast of New Zealand. Fiji consists of an archipelago of more than 330 islands—of which about ...

only twice (one time in early to mid-May).

Behaviour

Diet and feeding

Like its relatives it feeds at sea, predominantly on

squid A squid (: squid) is a mollusc with an elongated soft body, large eyes, eight cephalopod limb, arms, and two tentacles in the orders Myopsida, Oegopsida, and Bathyteuthida (though many other molluscs within the broader Neocoleoidea are also ...

, and fish, mostly

flying fish The Exocoetidae are a family (biology), family of Saltwater fish, marine Actinopterygii, ray-finned fish in the order (biology), order Beloniformes, known colloquially as flying fish or flying cod. About 64 species are grouped in seven genus, ge ...

(Exocoetidae) and

goatfish The goatfishes are ray-finned fish of the family Mullidae, the only family in the suborder Mulloidei of the order Syngnathiformes. The family is also sometimes referred to as the red mullets, which also refers more narrowly to the genus '' Mul ...

(Mullidae). It is highly

pelagic The pelagic zone consists of the water column of the open ocean and can be further divided into regions by depth. The word ''pelagic'' is derived . The pelagic zone can be thought of as an imaginary cylinder or water column between the sur ...

and is dependent on predatory fish such as

tuna A tuna (: tunas or tuna) is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae ( mackerel) family. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bul ...

driving prey to the surface. As mentioned above, it does not only have the dramatic stiff-winged "shearing" (

dynamic soaring Dynamic soaring is a flying technique used to gain energy by repeatedly crossing the boundary between air masses of different velocity. Such zones of wind gradient are generally found close to obstacles and close to the surface, so the technique is ...

) flight technique which gave the shearwaters their common name. In addition to it, it may use the

plesiomorph In phylogenetics, a plesiomorphy ("near form") and symplesiomorphy are synonyms for an ancestral Phenotypic trait, character shared by all members of a clade, which does not distinguish the clade from other clades. Plesiomorphy, symplesiomorph ...

ic flight technique of

petrel Petrels are tube-nosed seabirds in the phylogenetic order Procellariiformes. Description Petrels are a monophyletic group of marine seabirds, sharing a characteristic of a nostril arrangement that results in the name "tubenoses". Petrels enco ...

s and similar

, moving about with slow, leisurely wingbeats.

Breeding

The Christmas shearwater nests on sandy islands with good cover. It nests on the surface, underneath dense cover (such as naupakas, ''Scaevola''), or under rock outcroppings. It lays one white

egg An egg is an organic vessel grown by an animal to carry a possibly fertilized egg cell (a zygote) and to incubate from it an embryo within the egg until the embryo has become an animal fetus that can survive on its own, at which point the ...

, the timing of laying varying from island to island, on some islands breeding throughout the year. The egg is incubated for around 50 days. The time taken to

fledge Fledging is the stage in a flying animal's life between egg, hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnera ...

varies depending on the

season A season is a division of the year based on changes in weather, ecology, and the number of daylight hours in a given region. On Earth, seasons are the result of the axial parallelism of Earth's axial tilt, tilted orbit around the Sun. In temperat ...

, ranging from 60 to 100 days.

Status and conservation

Although few specific studies have been conducted on the Christmas shearwaters, petrels and shearwaters are threatened worldwide by

fishing Fishing is the activity of trying to catch fish. Fish are often caught as wildlife from the natural environment (Freshwater ecosystem, freshwater or Marine ecosystem, marine), but may also be caught from Fish stocking, stocked Body of water, ...

, ingestion of

plastic waste Plastic pollution is the accumulation of plastic objects and particles (e.g. plastic bottles, bags and microbeads) in the Earth's environment that adversely affects humans, wildlife and their habitat. Plastics that act as pollutants are cate ...

, and habitat degradation. For example, on Laysan Island the introduced

rabbit Rabbits are small mammals in the family Leporidae (which also includes the hares), which is in the order Lagomorpha (which also includes pikas). They are familiar throughout the world as a small herbivore, a prey animal, a domesticated ...

s degraded the scrub cover, leaving adults, chicks and eggs vulnerable to overheating, and introduced

black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...

s took eggs and chicks. In 1985, the population on Sala-y-Gómez, a nature

sanctuary A sanctuary, in its original meaning, is a sacred space, sacred place, such as a shrine, protected by ecclesiastical immunity. By the use of such places as a haven, by extension the term has come to be used for any place of safety. This seconda ...

, was estimated at 5,000. With its wide range and considerable numbers, the Christmas shearwater is considered a species of

least concern A least-concern species is a species that has been evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...

by the

IUCN The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...

.Seto (2001), BLI (2009)

Footnotes

References

* Austin, Jeremy J. (1996): Molecular Phylogenetics of ''Puffinus'' Shearwaters: Preliminary Evidence from Mitochondrial Cytochrome ''b'' Gene Sequences. '' Mol. Phylogenet. Evol.'' 6(1): 77–88. (HTML abstract) * Seto, N.W.H. (2001): Christmas Shearwater (''Puffinus nativitatis''). ''In:'' Poole, A. & Gill, F. (eds.): ''The Birds of North America'' 561. Academy of Natural Sciences, Philadelphia, PA &

, Washington, D.C. (requires subscription) * Shirihai, Hadoram; Pym, Tony; Kretzschmar, Jörg; Moce, Kolinio; Taukei, Amania & Watling, Dick (2009): First observations of Fiji Petrel ''Pseudobulweria macgillivrayi'' at sea: off Gau Island, Fiji, in May 2009. '' Bull. B.O.C.'' 129(3): 129–148
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{{Taxonbar, from=Q1269689 Christmas shearwater Christmas shearwater Birds of the Pacific Ocean Christmas shearwater Christmas shearwater