Audubon's Shearwater
Encyclopedia
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
.
Certain populations are also known as Baillon's Shearwater or Tropical Shearwater, Bannerman's Shearwater, Mascarene Shearwater and Persian Shearwater; some of these are considered distinct species by various authors. If they are all placed in P. lherminieri, the North Atlantic Little Shearwater
(otherwise often separated as P. baroli) is generally included here too. Thus, these small shearwater
s form a cryptic species complex
.
is around 4 cm in length. In general appearance, it is a small shearwater
, black above and white below and hard to distinguish from its relatives at first glance.
The upperparts, rectrices and undertail coverts are blackish-brown, as are at least the distal undersides of the remiges
, but sometimes the entire feathers. The rest of the underparts are white, as is the head below eye level. The iris
is dark, the feet are dull pink with a black wash and black toenails, and the bill is grey, darker towards the tip, and with a pinkish hue.
Males and females look alike. Immature birds do not have a distinct plumage, while the nestlings are covered with down feather
s, grey above and whitish on the belly.
It can be confused with the Manx Shearwater
(P. puffinus), which has white undertail coverts and in direct comparison a longer bill. Other similar-looking species are usually completely allopatric
, though the largely subantarctic
Little Shearwater
(P. assimilis) may occasionally range into waters where P. lherminieri is normally found. It has more white on the face and underwing, a smaller bill and greyish-blue feet.
Its twittering calls and mewing are often only heard at night in the breeding colonies.
north to the Arabian Sea
, throughout the northwest and central Pacific, in the Caribbean
, and parts of the eastern Atlantic. It is a species of tropical
waters; only some Atlantic populations and Bannerman's Shearwater of the Ogasawara Islands
occur farther north. Unlike the larger shearwater
s, adult Audubon's Shearwaters are not thought to wander much or undertake great migrations, although their young birds do so before breeding, and western Indian Ocean
birds may gather in large numbers at the upwelling
zone in the Arabian Sea.
It is adaptable as regards its preferred marine habitat; it can be found in pelagic, offshore and inshore waters. It feeds in a variety of methods, mainly diving out of flight, plunging underwater from a swimming position, and picking up food less than a bill's length underwater while "pattering" as if it were walking across the waves. It eats small fish
, squid
and plankton
ic crustacean
s. Unlike other shearwaters, it is not commonly a ship-follower, though it may attend small fishing boats; it is also sometimes met with as part of a mixed-species feeding flock
.
The species is colonial, nesting in small burrows and crevices in rocks and on earthy slopes on atoll
s and rocky islets. The breeding season varies according to location and subspecies, but how precisely is not very well-studied. Both parents share the responsibility of incubating the single white egg (measurements of 52.5 by 36.2 mm and a weight of 37 g have been recorded for one specimen of average size), each incubating for periods of 2 to 10 days until the egg hatches after 49–51 days of incubation. The nestlings are brooded for half a week to one week, after which time the parents will leave it mostly alone in the burrow and spend most of their time foraging and feeding their voracious offspring, which become very fat. Time from hatching to fledging
is 62–75 days. Audubon's Shearwaters take about 8 years to reach breeding age. As typical for Procellariiformes
they are long-lived for their size, one bird ringed
as an adult was still alive 11 years later; it must have been more than 15 years old at that time.
While some small populations are threatened, the species as a whole (in the present sense, i.e. unsplit) is not considered to be globally threatened.
. The taxonomy
of this species is extremely confusing. It is occasionally listed as a subspecies
of P. assimilis (the Little Shearwater
), but they do not appear to be that closely related. Rather, P. lherminieri seems to belong to an ill-resolved clade
also including such species as the Little Shearwater, the Manx Shearwater
(P. puffinus) or the Black-vented Shearwater
(P. opisthomelas).
The little-known Heinroth's Shearwater
(P. heinrothi) is sometimes considered a subspecies of either Audubon's or the Little Shearwater. Though it is likely to be another member of that close-knit group, its actual relationships remain uncertain due to lack of specimens.
Audubon's Shearwater itself has around 10 subspecies. Several have at one time or another been suggested to constitute separate species. For example, the Galápagos Islands
population has turned out to be a very distinct species, the Galápagos Shearwater
(P. subalaris); it is apparently related to the Christmas Shearwater
(P. nativitatis) and together with it constitutes an ancient lineage without other close relatives in the genus. Other taxa were initially assigned to the Little Shearwater and later moved to Audubon's. Analysis of mtDNA cytochrome b
sequence
data – which is of somewhat limited value in procellariiform birds however – indicates that at least 3 major clade
s can be distinguished:
The former two have more white on the face and bluish feet like the Little Shearwater, with which they were formerly placed and are considered a distinct species
(Barolo Shearwater, P. baroli) by some, depending on whether biogeography
and morphological
differences or the genetic similarity are considered more significant, and what other lineages are considered distinct from P. lherminieri in a particular treatment. The southern Caribbean birds were separated as P. l. loyemilleri, but are not distinct.
These form another distinct clade as indicated by mtDNA sequences, and have for some time been proposed as a distinct species, Persian Shearwater (P. persicus). From the molecular data alone, this seems fairly warranted, but the ranges of the two taxa are quite far apart, separated by forms of the third clade. It is quite obvious that on the basis of such contradicting data as presently available, no decision can be taken regarding the taxonomic status of these birds. Possibly, they do form a distinct species separated from the third clade by a different circannual rhythm, as is known from other procellariiform birds. They are phenotypically distinct, with a longer bill, a dark rump, and more extensive dark on the underwing, including some mottling in the normally white area.
If P. bailloni is accepted as a distinct species but P. persicus is not, then this latter group would have to be included in P. bailloni.
This group is the most confusing of all. The subspecies dichrous occurs in two areas which appear to be separated by the whole of Indonesia
and the seas surrounding it; the Pacific subpopulation includes the proposed subspecies polynesiae (Ta‘ū, American Samoa
) and possibly gunax (see below), whereas the geographically separated Indian Ocean subpopulation contains the birds formerly separated as nicolae (NW Indian Ocean, from Aldabra to the Maldives
) and colstoni (Aldabra
, Arabian Sea).
There appear to be no significant genetical or morphological differences between these birds, which is quite amazing given that the Pacific and Indian Ocean subpopulations must have been isolated for a fairly long time, and that no less than three unequivocally distinct subspecies (bailloni, persicus and temptator) occur within the range of Indian Ocean dichrous. On the other hand, the supposed species Mascarene Shearwater ("P. atrodorsalis") is inseparable morphologically and genetically from bailloni.
Clearly, some mechanism blocking gene flow
is at work, but what this is exactly remains unknown – though as remarked above, separate breeding seasons seem a reasonable assumption and are tentatively supported by the available field data. In addition, it is entirely mysterious why such a mechanism should apply in the rather limited and ecologically homogenous northwestern Indian Ocean range, but not in the ecologically more diverse and by far larger Pacific range of dichrous.
These unresolved problems nonwithstanding, this clade – possibly including the preceding one – has been proposed to constitute a separate species, the Tropical Shearwater or Baillon's Shearwater, Puffinus bailloni.
These taxa could not be included in the most recent studies due to lack of material. The case of gunax seems fairly straightforward – as certainly as this can possibly be said in the absence of new data, it belongs to the bailloni clade either as a distinct subspecies, or, more likely, as yet another synonym of dichrous.
The case of the more distinct bannermani, the range of which is parapatric to that of the Pacific dichrous, is more complicated. It has for some time been proposed as a distinct species, Bannerman's Shearwater (P. bannermani). In the absence of more recent data to investigate this claim, its status continues to be altogether unresolved, though the case for it being at least a distinct subspecies in the bailloni clade seems good.
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...
from the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
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...
. Sometimes called Dusky-backed Shearwater, the scientific name of this species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
commemorates the French naturalist Félix Louis L'Herminier
Félix Louis L'Herminier
Félix Louis L'Herminier was a French pharmacist and naturalist who was born in Paris. He studied chemistry and natural history in Paris, and in 1798 travelled to Guadeloupe, where he studied the flora and fauna of the island until 1829, when he returned to France.He published several works on...
.
Certain populations are also known as Baillon's Shearwater or Tropical Shearwater, Bannerman's Shearwater, Mascarene Shearwater and Persian Shearwater; some of these are considered distinct species by various authors. If they are all placed in P. lherminieri, the North Atlantic Little Shearwater
North Atlantic Little Shearwater
The Barolo Shearwater , also known as the North Atlantic Little Shearwater or Macaronesian Shearwater, is a small shearwater which breeds in the North Atlantic....
(otherwise often separated as P. baroli) is generally included here too. Thus, these small shearwater
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...
s form a cryptic species complex
Cryptic species complex
In biology, a cryptic species complex is a group of species which satisfy the biological definition of species—that is, they are reproductively isolated from each other—but whose morphology is very similar ....
.
Description
Audubon's Shearwaters are on average 30 cm (12 in) in length—about half the size of the Greater Shearwater (Puffinus gravis)—and weigh 170 g. There is some variation between populations and the normal size and weight range is 27–33 cm and 150–230 g. The wingspan is 64–72 cm, the tail is around 8.5 cm long, the exposed culmen measures 3 cm or slightly less, and the tarsusTarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
is around 4 cm in length. In general appearance, it is a small shearwater
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...
, black above and white below and hard to distinguish from its relatives at first glance.
The upperparts, rectrices and undertail coverts are blackish-brown, as are at least the distal undersides of the remiges
Flight feather
Flight feathers are the long, stiff, asymmetrically shaped, but symmetrically paired feathers on the wings or tail of a bird; those on the wings are called remiges while those on the tail are called rectrices . Their primary function is to aid in the generation of both thrust and lift, thereby...
, but sometimes the entire feathers. The rest of the underparts are white, as is the head below eye level. The iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
is dark, the feet are dull pink with a black wash and black toenails, and the bill is grey, darker towards the tip, and with a pinkish hue.
Males and females look alike. Immature birds do not have a distinct plumage, while the nestlings are covered with 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, grey above and whitish on the belly.
It can be confused with the Manx Shearwater
Manx Shearwater
The Manx Shearwater is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx Shearwaters were called Manks Puffins in the 17th century. Puffin is an Anglo-Norman word for the cured carcasses of nestling shearwaters...
(P. puffinus), which has white undertail coverts and in direct comparison a longer bill. Other similar-looking species are usually completely allopatric
Allopatric speciation
Allopatric speciation or geographic speciation is speciation that occurs when biological populations of the same species become isolated due to geographical changes such as mountain building or social changes such as emigration...
, though the largely subantarctic
Subantarctic
The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...
Little Shearwater
Little Shearwater
The Little Shearwater is a small shearwater in the seabird family Procellariidae.mtDNA cytochrome b sequence data indicates that the former North Atlantic Little Shearwater group is closer to Audubon's Shearwater , and myrtae being closer to the Newell's and possibly Townsend's Shearwater...
(P. assimilis) may occasionally range into waters where P. lherminieri is normally found. It has more white on the face and underwing, a smaller bill and greyish-blue feet.
Its twittering calls and mewing are often only heard at night in the breeding colonies.
Range and ecology
If not split into several species, Audubon's Shearwater ranges across the Indian OceanIndian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
north to the Arabian Sea
Arabian Sea
The Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by the Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui in northeastern Somalia and Kanyakumari in India...
, throughout the northwest and central Pacific, in the Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
, and parts of the eastern Atlantic. It is a species of tropical
Tropics
The tropics is a region of the Earth surrounding the Equator. It is limited in latitude by the Tropic of Cancer in the northern hemisphere at approximately N and the Tropic of Capricorn in the southern hemisphere at S; these latitudes correspond to the axial tilt of the Earth...
waters; only some Atlantic populations and Bannerman's Shearwater of the Ogasawara Islands
Ogasawara Islands
The Bonin Islands, known in Japan as the are an archipelago of over 30 subtropical and tropical islands, some directly south of Tokyo, Japan. Administratively, they are part of Ogasawara Municipality of Ogasawara Subprefecture, Tokyo...
occur farther north. Unlike the larger shearwater
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...
s, adult Audubon's Shearwaters are not thought to wander much or undertake great migrations, although their young birds do so before breeding, and western Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...
birds may gather in large numbers at the upwelling
Upwelling
Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. The increased availability in upwelling regions results in high levels of primary...
zone in the Arabian Sea.
It is adaptable as regards its preferred marine habitat; it can be found in pelagic, offshore and inshore waters. It feeds in a variety of methods, mainly diving out of flight, plunging underwater from a swimming position, and picking up food less than a bill's length underwater while "pattering" as if it were walking across the waves. It eats small 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...
, 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 plankton
Plankton
Plankton are any drifting organisms that inhabit the pelagic zone of oceans, seas, or bodies of fresh water. That is, plankton are defined by their ecological niche rather than phylogenetic or taxonomic classification...
ic crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
s. Unlike other shearwaters, it is not commonly a ship-follower, though it may attend small fishing boats; it is also sometimes met with as part of a mixed-species feeding flock
Mixed-species feeding flock
A mixed-species feeding flock, also termed a mixed-species foraging flock, mixed hunting party or informally bird wave, is a flock of usually insectivorous birds of different species, that join each other and move together while foraging...
.
Atoll
An atoll is a coral island that encircles a lagoon partially or completely.- Usage :The word atoll comes from the Dhivehi word atholhu OED...
s and rocky islets. The breeding season varies according to location and subspecies, but how precisely is not very well-studied. Both parents share the responsibility of incubating the single white egg (measurements of 52.5 by 36.2 mm and a weight of 37 g have been recorded for one specimen of average size), each incubating for periods of 2 to 10 days until the egg hatches after 49–51 days of incubation. The nestlings are brooded for half a week to one week, after which time the parents will leave it mostly alone in the burrow and spend most of their time foraging and feeding their voracious offspring, which become very fat. Time from hatching to 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...
is 62–75 days. Audubon's Shearwaters take about 8 years to reach breeding age. As typical for Procellariiformes
Procellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...
they are long-lived for their size, one bird ringed
Bird ringing
Bird ringing or bird banding is a technique used in the study of wild birds, by attaching a small, individually numbered, metal or plastic tag to their legs or wings, so that various aspects of the bird's life can be studied by the ability to re-find the same individual later...
as an adult was still alive 11 years later; it must have been more than 15 years old at that time.
While some small populations are threatened, the species as a whole (in the present sense, i.e. unsplit) is not considered to be globally threatened.
Systematics
Audubon's Shearwater belongs to the Puffinus sensu stricto group of mid-sized and small shearwaters, which is related to the genus CalonectrisCalonectris
Calonectris is a genus of seabirds. It comprises three large shearwaters. There are two other shearwater genera. Puffinus, which comprises about twenty small to medium-sized shearwaters, and Procellaria with another four large species...
. The taxonomy
Taxonomy
Taxonomy is the science of identifying and naming species, and arranging them into a classification. The field of taxonomy, sometimes referred to as "biological taxonomy", revolves around the description and use of taxonomic units, known as taxa...
of this species is extremely confusing. It is occasionally listed as a subspecies
Subspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
of P. assimilis (the Little Shearwater
Little Shearwater
The Little Shearwater is a small shearwater in the seabird family Procellariidae.mtDNA cytochrome b sequence data indicates that the former North Atlantic Little Shearwater group is closer to Audubon's Shearwater , and myrtae being closer to the Newell's and possibly Townsend's Shearwater...
), but they do not appear to be that closely related. Rather, P. lherminieri seems to belong to an ill-resolved clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
also including such species as the Little Shearwater, the Manx Shearwater
Manx Shearwater
The Manx Shearwater is a medium-sized shearwater in the seabird family Procellariidae. The scientific name of this species records a name shift: Manx Shearwaters were called Manks Puffins in the 17th century. Puffin is an Anglo-Norman word for the cured carcasses of nestling shearwaters...
(P. puffinus) or the Black-vented Shearwater
Black-vented Shearwater
The Black-vented Shearwater is a species of seabird. The bird is 30–38 cm in size, with a 76–89 cm wingspan. Formerly considered a subspecies of the Manx Shearwater, its actual relationships are unresolved....
(P. opisthomelas).
The little-known Heinroth's Shearwater
Heinroth's Shearwater
Heinroth's Shearwater is a poorly known seabird in the family Procellariidae. Probably a close relative of the Little Shearwater or Audubon's Shearwater , it is distinguished by a long and slender bill and a brown-washed underside.This species is restricted to the seas around the Bismarck...
(P. heinrothi) is sometimes considered a subspecies of either Audubon's or the Little Shearwater. Though it is likely to be another member of that close-knit group, its actual relationships remain uncertain due to lack of specimens.
Audubon's Shearwater itself has around 10 subspecies. Several have at one time or another been suggested to constitute separate species. For example, the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...
population has turned out to be a very distinct species, 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); it is apparently related to the Christmas Shearwater
Christmas Shearwater
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....
(P. nativitatis) and together with it constitutes an ancient lineage without other close relatives in the genus. Other taxa were initially assigned to the Little Shearwater and later moved to Audubon's. Analysis of 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 – which is of somewhat limited value in procellariiform birds however – indicates that at least 3 major clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...
s can be distinguished:
The lherminieri clade (Atlantic Ocean, Caribbean)
- Puffinus lherminieri lherminieri Lesson, 1839 – breeds throughout the Caribbean, on the Bahamas and formerly on BermudaBermudaBermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
; ranges throughout the Caribbean and up the North American Atlantic coast up to southern CanadaCanadaCanada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, with vagrants having been recorded off northeastern Canada. A small breeding colony found in 1993 in the Itatiaia Islands off Vila VelhaVila VelhaVila Velha is a coastal town in Espírito Santo, Brazil. It lies across from Vitória, the state capital. Its population was 396,323 and its area is 208.82 km².Vila Velha forms part of the Greater Vitória metropolitan area...
(Espírito SantoEspírito SantoEspírito Santo is one of the states of southeastern Brazil, often referred to by the abbreviation "ES". Its capital is Vitória and the largest city is Vila Velha. The name of the state means literally "holy spirit" after the Holy Ghost of Christianity...
, BrazilBrazilBrazil , officially the Federative Republic of Brazil , is the largest country in South America. It is the world's fifth largest country, both by geographical area and by population with over 192 million people...
) probably belongs to this subspecies. Includes loyemilleri. - Puffinus lherminieri baroli (Bonaparte, 1857) – breeds on AzoresAzoresThe Archipelago of the Azores is composed of nine volcanic islands situated in the middle of the North Atlantic Ocean, and is located about west from Lisbon and about east from the east coast of North America. The islands, and their economic exclusion zone, form the Autonomous Region of the...
and Canary IslandsCanary IslandsThe Canary Islands , also known as the Canaries , is a Spanish archipelago located just off the northwest coast of mainland Africa, 100 km west of the border between Morocco and the Western Sahara. The Canaries are a Spanish autonomous community and an outermost region of the European Union...
(E Atlantic); ranges throughout E Atlantic around (but mostly north of) the Tropic of CancerTropic of CancerThe Tropic of Cancer, also referred to as the Northern tropic, is the circle of latitude on the Earth that marks the most northerly position at which the Sun may appear directly overhead at its zenith...
. - Puffinus lherminieri boydi Mathews, 1912 – breeds on Cape Verde Islands (E Atlantic); ranges throughout E Atlantic around (but mostly south of) the Tropic of Cancer.
The former two have more white on the face and bluish feet like the Little Shearwater, with which they were formerly placed and are considered a distinct species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
(Barolo Shearwater, P. baroli) by some, depending on whether biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...
and morphological
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....
differences or the genetic similarity are considered more significant, and what other lineages are considered distinct from P. lherminieri in a particular treatment. The southern Caribbean birds were separated as P. l. loyemilleri, but are not distinct.
The persicus clade (West Indian Ocean)
- Puffinus lherminieri persicus Hume, 1837 – breeds on Khuriya Muriya IslandsKhuriya Muriya IslandsThe Khuriya Muriya Islands are a group of five islands in the Arabian Sea, off the southeastern coast of the Sultanate of Oman. The islands form part of the province of Shalim and the Hallaniyat Islands in the governorate of Dhofar....
(Arabian SeaArabian SeaThe Arabian Sea is a region of the Indian Ocean bounded on the east by India, on the north by Pakistan and Iran, on the west by the Arabian Peninsula, on the south, approximately, by a line between Cape Guardafui in northeastern Somalia and Kanyakumari in India...
); ranges throughout the Arabian Sea. - Puffinus lherminieri temptator Louette & Herremans, 1985 – breeds on MohéliMohéliMohéli, also known as Mwali, is one of the three islands which make up the nation of Comoros. Mohéli is located in the Indian Ocean off the coast of Africa. It is by far the smallest of the Comoros islands. Its population, as of 2006, is about 38,000. Its capital city is Fomboni...
(ComorosComorosThe Comoros , officially the Union of the Comoros is an archipelago island nation in the Indian Ocean, located off the eastern coast of Africa, on the northern end of the Mozambique Channel, between northeastern Mozambique and northwestern Madagascar...
); ranges in W Indian Ocean around the northern end of MadagascarMadagascarThe Republic of Madagascar is an island country located in the Indian Ocean off the southeastern coast of Africa...
.
These form another distinct clade as indicated by mtDNA sequences, and have for some time been proposed as a distinct species, Persian Shearwater (P. persicus). From the molecular data alone, this seems fairly warranted, but the ranges of the two taxa are quite far apart, separated by forms of the third clade. It is quite obvious that on the basis of such contradicting data as presently available, no decision can be taken regarding the taxonomic status of these birds. Possibly, they do form a distinct species separated from the third clade by a different circannual rhythm, as is known from other procellariiform birds. They are phenotypically distinct, with a longer bill, a dark rump, and more extensive dark on the underwing, including some mottling in the normally white area.
If P. bailloni is accepted as a distinct species but P. persicus is not, then this latter group would have to be included in P. bailloni.
The bailloni clade (Indian and Pacific oceans)
- Puffinus lherminieri bailloni (Bonaparte, 1857) – breeds on Mascarene IslandsMascarene IslandsThe Mascarene Islands is a group of islands in the Indian Ocean east of Madagascar comprising Mauritius, Réunion, Rodrigues, Cargados Carajos shoals, plus the former islands of the Saya de Malha, Nazareth and Soudan banks...
(SW Indian Ocean); ranges throughout the SW Indian Ocean to the north of the Tropic of CapricornTropic of CapricornThe Tropic of Capricorn, or Southern tropic, marks the most southerly latitude on the Earth at which the Sun can be directly overhead. This event occurs at the December solstice, when the southern hemisphere is tilted towards the Sun to its maximum extent.Tropic of Capricorn is one of the five...
, and vagrant birds seen off South AfricaSouth AfricaThe Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...
probably belong to this subspecies. Includes atrodorsalis. - Puffinus lherminieri dichrous Finsch & Hartlaub, 1867 – breeds throughout central PolynesiaPolynesiaPolynesia is a subregion of Oceania, made up of over 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are termed Polynesians and they share many similar traits including language, culture and beliefs...
and possibly MelanesiaMelanesiaMelanesia is a subregion of Oceania extending from the western end of the Pacific Ocean to the Arafura Sea, and eastward to Fiji. The region comprises most of the islands immediately north and northeast of Australia...
(Pacific) and the NW Indian Ocean up to the Arabian Sea; ranges throughout the W Indian Ocean around the EquatorEquatorAn equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....
, and in the C Pacific from the equatorial region to the Tropic of Capricorn. Includes colstoni, nicolae, polynesiae and maybe gunax; vagrants seen off AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
could belong to dichrous or gunax (if valid), while vagrants recorded from GuamGuamGuam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
and RotaRota (island)Rota also known as the "peaceful island", is the southernmost island of the United States Commonwealth of the Northern Mariana Islands and the second southernmost of the Marianas Archipelago. It lies approximately 40 miles north-northeast of the United States territory of Guam...
(Marianas) might be dichrous or bannermani.
This group is the most confusing of all. The subspecies dichrous occurs in two areas which appear to be separated by the whole of Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...
and the seas surrounding it; the Pacific subpopulation includes the proposed subspecies polynesiae (Ta‘ū, American Samoa
American Samoa
American Samoa is an unincorporated territory of the United States located in the South Pacific Ocean, southeast of the sovereign state of Samoa...
) and possibly gunax (see below), whereas the geographically separated Indian Ocean subpopulation contains the birds formerly separated as nicolae (NW Indian Ocean, from Aldabra to the Maldives
Maldives
The Maldives , , officially Republic of Maldives , also referred to as the Maldive Islands, is an island nation in the Indian Ocean formed by a double chain of twenty-six atolls oriented north-south off India's Lakshadweep islands, between Minicoy Island and...
) and colstoni (Aldabra
Aldabra
Aldabra, the world's second largest coral atoll, is in the Aldabra Group of islands in the Indian Ocean that form part of the Seychelles. Uninhabited and extremely isolated, Aldabra is virtually untouched by humans, has distinctive island fauna including the Aldabra Giant Tortoise, and is...
, Arabian Sea).
There appear to be no significant genetical or morphological differences between these birds, which is quite amazing given that the Pacific and Indian Ocean subpopulations must have been isolated for a fairly long time, and that no less than three unequivocally distinct subspecies (bailloni, persicus and temptator) occur within the range of Indian Ocean dichrous. On the other hand, the supposed species Mascarene Shearwater ("P. atrodorsalis") is inseparable morphologically and genetically from bailloni.
Clearly, some mechanism blocking gene flow
Gene flow
In population genetics, gene flow is the transfer of alleles of genes from one population to another.Migration into or out of a population may be responsible for a marked change in allele frequencies...
is at work, but what this is exactly remains unknown – though as remarked above, separate breeding seasons seem a reasonable assumption and are tentatively supported by the available field data. In addition, it is entirely mysterious why such a mechanism should apply in the rather limited and ecologically homogenous northwestern Indian Ocean range, but not in the ecologically more diverse and by far larger Pacific range of dichrous.
These unresolved problems nonwithstanding, this clade – possibly including the preceding one – has been proposed to constitute a separate species, the Tropical Shearwater or Baillon's Shearwater, Puffinus bailloni.
Undetermined
- Puffinus lherminieri bannermani Mathews & Iredale, 1915 – breeds on Ogasawara IslandsOgasawara IslandsThe Bonin Islands, known in Japan as the are an archipelago of over 30 subtropical and tropical islands, some directly south of Tokyo, Japan. Administratively, they are part of Ogasawara Municipality of Ogasawara Subprefecture, Tokyo...
(NW Pacific); ranges throughout the NW Pacific from JapanJapanJapan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
ese waters to the equatorial region. Vagrants recorded from GuamGuamGuam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
and RotaRota (island)Rota also known as the "peaceful island", is the southernmost island of the United States Commonwealth of the Northern Mariana Islands and the second southernmost of the Marianas Archipelago. It lies approximately 40 miles north-northeast of the United States territory of Guam...
(Marianas) might be dichrous or bannermani. - Puffinus lherminieri gunax Mathews, 1930 – breeds on Banks IslandsBanks IslandsThe Banks Islands are a group of islands in northern Vanuatu.Together with the Torres Islands to the northwest, they make up the northernmost province of Torba. The group lies about north of Maewo, and includes Gaua and Vanua Lava, two of the 13 largest islands in Vanuatu...
of VanuatuVanuatuVanuatu , officially the Republic of Vanuatu , is an island nation located in the South Pacific Ocean. The archipelago, which is of volcanic origin, is some east of northern Australia, northeast of New Caledonia, west of Fiji, and southeast of the Solomon Islands, near New Guinea.Vanuatu was...
(SW Pacific); ranges throughout the SW Pacific between the equatorial region and the Tropic of Capricorn. Might belong in dichrous; vagrants seen off AustraliaAustraliaAustralia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
could belong to either taxonTaxon|thumb|270px|[[African elephants]] form a widely-accepted taxon, the [[genus]] LoxodontaA taxon is a group of organisms, which a taxonomist adjudges to be a unit. Usually a taxon is given a name and a rank, although neither is a requirement...
.
These taxa could not be included in the most recent studies due to lack of material. The case of gunax seems fairly straightforward – as certainly as this can possibly be said in the absence of new data, it belongs to the bailloni clade either as a distinct subspecies, or, more likely, as yet another synonym of dichrous.
The case of the more distinct bannermani, the range of which is parapatric to that of the Pacific dichrous, is more complicated. It has for some time been proposed as a distinct species, Bannerman's Shearwater (P. bannermani). In the absence of more recent data to investigate this claim, its status continues to be altogether unresolved, though the case for it being at least a distinct subspecies in the bailloni clade seems good.
Further reading
- Snow, D.W. (1965). "The breeding of the Audubon's Shearwater Puffinus lherminieri in the Galapagos." The Auk 82(4)