Christmas Shearwater
Encyclopedia
The Christmas Shearwater, Puffinus nativitatis, is a medium-sized shearwater
of the tropical Central Pacific
. It is a poorly known species due to its remote nesting habits, and it has not been extensively studied at sea either.
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), as indicated by mtDNA cytochrome b
sequence
data and morphology
. Until recently, that species was considered conspecific with Audubon's Shearwater
.
, about 36 cm long, with a wingspan of around 75 cm, and weighs around 350 g. The Christmas Shearwater has dark plumage
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
s.
The species closely resembles the Sooty
("Puffinus" griseus) and Short-tailed Shearwater
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. The Christmas Shearwater often flies in a leisurely way like related Procellariidae
, and thus can be mistaken for a petrel. In particular, a very similar species is the extremely rare Fiji Petrel
(Pseudobulweria macgillivrayi), a gadfly petrel
-like relative of the shearwaters. It looks very similar in habitus
and coloration, but the bulbous head and rather thin long bill – typical for shearwaters – distinguish P. nativitatis from the slim-headed thick-billed Fiji Petel.
The Christmas Shearwater nests on remote islands of the Central Pacific: the Northwestern Hawaiian Islands
, Tuamotu, the Marshall Islands
, Kiritimati
(for which the species is named) and Sala-y-Gómez. It has become locally extinct on a number of islands, including Wake Island
. 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 in the west. Further south it is rare, having been recorded off Fiji
only twice (one time in early-mid May).
Like its relatives it feeds at sea, predominantly on squid
, and fish
, mostly flying fish (Exocoetidae) and goatfish
(Mullidae). It is highly pelagic and is dependent on predatory fish such as tuna
driving prey species to the surface. As mentioned above, it does not only have the dramatic stiff-winged "shearing" (dynamic soaring
) flight technique which gave the shearwaters their common name. In addition to it, it may use the plesiomorphic flight technique of petrel
s and similar Procellariidae
, moving about with slow, leisurely wingbeats.
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
, 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
varies depending on the season
, ranging from 60 to 100 days.
, ingestion of plastic
waste
, and habitat degradation. For example on Laysan Island the introduced
rabbit
s degraded the scrub cover, leaving adults, chicks and eggs vulnerable to overheating, and introduced black rat
s took eggs and chicks. In 1985, the population on Sala-y-Gómez, a nature sanctuary, was estimated at 5,000. With its wide range and considerable numbers, the Christmas Shearwater is considered a Species of Least Concern
by the IUCN.
Shearwater
Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...
of the tropical Central Pacific
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...
. It is a poorly known species due to its remote nesting habits, and it has not been extensively studied at sea either.
It is one member of a very ancient lineage of the small Puffinus species. Its only close living relative is the Galápagos Shearwater
Galápagos Shearwater
The Galápagos Shearwater, Puffinus subalaris is a small shearwater. Until recently it was considered to be a subspecies of Audubon's Shearwater, but it is actually one of two members of a very ancient lineage of the small Puffinus species, the other being, as indicated by mtDNA cytochrome b...
(P. subalaris), as indicated by mtDNA cytochrome b
Cytochrome b
Cytochrome b/b6 is the main subunit of transmembrane cytochrome bc1 and b6f complexes. In addition, it commonly refers to a region of mtDNA used for population genetics and phylogenetics.- Function :...
sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
data and morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
. Until recently, that species was considered conspecific with Audubon's Shearwater
Audubon's Shearwater
Audubon's Shearwater, Puffinus lherminieri, is a common tropical seabird from the family Procellariidae. Sometimes called Dusky-backed Shearwater, the scientific name of this species commemorates the French naturalist Félix Louis L'Herminier....
.
Description
It is a slender-bodied shearwaterShearwater
Shearwaters are medium-sized long-winged seabirds. There are more than 30 species of shearwaters, a few larger ones in the genus Calonectris and many smaller species in the genus Puffinus...
, about 36 cm long, with a wingspan of around 75 cm, and weighs around 350 g. The Christmas Shearwater has dark plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...
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
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
. Nestlings are covered in dark grey down feather
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 padding, used in goods such as jackets, bedding,...
s.
The species closely resembles the Sooty
Sooty Shearwater
The Sooty Shearwater is a medium-large shearwater in the seabird family Procellariidae. In New Zealand it is also known by its Māori name tītī and as "muttonbird", like its relatives the Wedge-tailed Shearwater and the Australian Short-tailed Shearwater The Sooty Shearwater (Puffinus griseus) is...
("Puffinus" griseus) and Short-tailed Shearwater
Short-tailed Shearwater
The Short-tailed Shearwater or Slender-billed Shearwater , also called Yolla or Moonbird, and commonly known as the muttonbird in Australia, is the most abundant seabird species in Australian waters, and is one of the few Australian native birds in which the chicks are commercially harvested...
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. The Christmas Shearwater often flies in a leisurely way like related Procellariidae
Procellariidae
The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes , which also includes the albatrosses, the storm-petrels, and the diving petrels.The procellariids are...
, and thus can be mistaken for a petrel. In particular, a very similar species is the extremely rare Fiji Petrel
Fiji Petrel
The Fiji Petrel , also known as MacGillivray's Petrel, is a small, dark gadfly petrel.The Fiji Petrel was originally known from one immature specimen found in 1855 on Gau Island, Fiji by naturalist John MacGillivray on board 'HMS Herald' who took the carcass to the British Museum in London...
(Pseudobulweria macgillivrayi), a gadfly petrel
Gadfly petrel
The gadfly petrels are seabirds in the bird order Procellariiformes. These medium to large petrels feed on food items picked from the ocean surface....
-like relative of the shearwaters. It looks very similar in habitus
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....
and coloration, but the bulbous head and rather thin long bill – typical for shearwaters – distinguish P. nativitatis from the slim-headed thick-billed Fiji Petel.
Range and ecology
Northwestern Hawaiian Islands
The Northwestern Hawaiian Islands or the Leeward Islands are the small islands and atolls in the Hawaiian island chain located northwest of the islands of Kauai and Niihau. They are administered by the U.S. state of Hawaii except Midway Atoll, which has temporary residential facilities and is...
, Tuamotu, the Marshall Islands
Marshall Islands
The Republic of the Marshall Islands , , is a Micronesian nation of atolls and islands in the middle of the Pacific Ocean, just west of the International Date Line and just north of the Equator. As of July 2011 the population was 67,182...
, Kiritimati
Kiritimati
Kiritimati or Christmas Island is a Pacific Ocean raised coral atoll in the northern Line Islands, and part of the Republic of Kiribati....
(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
Wake Island is a coral atoll having a coastline of in the North Pacific Ocean, located about two-thirds of the way from Honolulu west to Guam east. It is an unorganized, unincorporated territory of the United States, administered by the Office of Insular Affairs, U.S. Department of the Interior...
. Outside of the breeding season it ranges across the Pacific, having been recorded off the coast of Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
and Guatemala
Guatemala
Guatemala is a country in Central America bordered by Mexico to the north and west, the Pacific Ocean to the southwest, Belize to the northeast, the Caribbean to the east, and Honduras and El Salvador to the southeast...
in the east, and Bonin Islands in the west. Further south it is rare, having been recorded off Fiji
Fiji
Fiji , officially the Republic of Fiji , is an island nation in Melanesia in the South Pacific Ocean about northeast of New Zealand's North Island...
only twice (one time in early-mid May).
Like its relatives it feeds at sea, predominantly on squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...
, and fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
, mostly flying fish (Exocoetidae) and goatfish
Goatfish
Goatfishes are tropical marine perciform fish of the family Mullidae. Seldom found in brackish waters, goatfish are most associated with the reefs of the Atlantic, Indian, and Pacific Oceans...
(Mullidae). It is highly pelagic and is dependent on predatory fish such as tuna
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...
driving prey species to the surface. As mentioned above, it does not only have the dramatic stiff-winged "shearing" (dynamic soaring
Dynamic soaring
Dynamic soaring is a flying technique used to gain energy by repeatedly crossing the boundary between air masses of significantly different velocity...
) flight technique which gave the shearwaters their common name. In addition to it, it may use the plesiomorphic flight technique of petrel
Petrel
Petrels are tube-nosed seabirds in the bird order Procellariiformes. The common name does not indicate relationship beyond that point, as "petrels" occur in three of the four families within that group...
s and similar Procellariidae
Procellariidae
The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the prions, and the shearwaters. This family is part of the bird order Procellariiformes , which also includes the albatrosses, the storm-petrels, and the diving petrels.The procellariids are...
, moving about with slow, leisurely wingbeats.
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
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...
, 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
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
varies depending on the season
Season
A season is a division of the year, marked by changes in weather, ecology, and hours of daylight.Seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earth's axis relative to the plane of revolution...
, 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 fishingFishing
Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....
, ingestion of plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
waste
Waste
Waste is unwanted or useless materials. In biology, waste is any of the many unwanted substances or toxins that are expelled from living organisms, metabolic waste; such as urea, sweat or feces. Litter is waste which has been disposed of improperly...
, and habitat degradation. For example on Laysan Island the introduced
Introduced species
An introduced species — or neozoon, alien, exotic, non-indigenous, or non-native species, or simply an introduction, is a species living outside its indigenous or native distributional range, and has arrived in an ecosystem or plant community by human activity, either deliberate or accidental...
rabbit
Rabbit
Rabbits are small mammals in the family Leporidae of the order Lagomorpha, found in several parts of the world...
s degraded the scrub cover, leaving adults, chicks and eggs vulnerable to overheating, and introduced black rat
Black Rat
The black rat is a common long-tailed rodent of the genus Rattus in the subfamily Murinae . The species originated in tropical Asia and spread through the Near East in Roman times before reaching Europe by the 1st century and spreading with Europeans across the world.-Taxonomy:The black rat was...
s took eggs and chicks. In 1985, the population on Sala-y-Gómez, a nature sanctuary, was estimated at 5,000. With its wide range and considerable numbers, the Christmas Shearwater is considered a Species of Least Concern
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the IUCN.