Yelkouan Shearwater
Encyclopedia
The Yelkouan Shearwater, Levantine Shearwater or Mediterranean Shearwater (Puffinus yelkouan) is a medium-sized shearwater
in the seabird
family Procellariidae
.
It is silent at sea, but at night the breeding colonies are alive with raucous cackling calls, higher pitched and more drawn out than the Manx Shearwater's.
The Yelkouan Shearwater has a more contrasted appearance than the Balearic Shearwater with which its winter range overlaps, since the latter species is brown above and dirty white below. It is very similar to the black-and-white Manx Shearwater of the Atlantic, and stray birds out of their usual range are very difficult to identify with certainty.
Also, at least one mixed breeding colony of the Yelkouan and the Balearic Shearwater exists on Minorca
. A study of these birds recommended that a combination of morphological
characteristics and DNA sequence
data should be required at least for scientific purposes to assign individual birds to either species.
of the Manx Shearwater
; see there for more on the Puffinus puffinus superspecies
. After the first split, it was the nominate subspecies of the so-called "Mediterranean Shearwater" for nearly ten more years; it is considered a monotypic
species nowadays, as the Balearic form mauretanicus has been separated as Balearic Shearwater
.
The Yelkouan Shearwater appears to belong to a group of Mediterranean and adjacent Atlantic shearwaters which includes the Balearic Shearwater and one to three prehistorically
extinct taxa, Hole's and possibly also Olson's Shearwater as well as an undescribed population of uncertain distinctness from Menorca. The two living Mediterranean lineages had probably separated before the end of the Pliocene
(c.2 million years ago), as indicated by molecular differences and putative direct ancestor of the Balearic Shearwater, the Ibiza
n fossil Puffinus nestori from the Late Pliocene or Early Pleistocene
.
the Atlantic
in late summer. This species nests in burrows which are only visited at night to avoid predation by large gull
s.
This is a gregarious species, which can be seen in large numbers from boats or headlands, especially in autumn. It is under some threat from the development of holiday resorts near its breeding sites, and also from animals such as cats and rats. The Yelkouan Shearwater feeds on fish
and molluscs. It follows fishing ships when offal is being thrown.
The study of the Minorcan colony concluded that at least in these westernmost birds, genetic variation was extremely low, suggesting that the Yelkouan Shearwater may have suffered a marked population decline historically and thus, while not threatened judging from its absolute numbers, could be vulnerable to adverse effects of inbreeding
.
It was formerly classified as a Species of Least Concern
by the IUCN. But new research has shown it to be rarer than it was believed. Consequently, it is uplisted to Near Threatened
status in 2008.
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...
in the 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...
family 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...
.
Description and identification
Yelkouan Shearwaters are 30–38 cm long, with a 76–89 cm wingspan. It has the typically "shearing" flight of the genus, dipping from side to side on stiff wings with few wingbeats, the wingtips almost touching the water. This bird looks like a flying cross, with its wing held at right angles to the body, and it changes from very dark brown to white as the dark upperparts and paler undersides are alternately exposed as it travels low over the sea.It is silent at sea, but at night the breeding colonies are alive with raucous cackling calls, higher pitched and more drawn out than the Manx Shearwater's.
The Yelkouan Shearwater has a more contrasted appearance than the Balearic Shearwater with which its winter range overlaps, since the latter species is brown above and dirty white below. It is very similar to the black-and-white Manx Shearwater of the Atlantic, and stray birds out of their usual range are very difficult to identify with certainty.
Also, at least one mixed breeding colony of the Yelkouan and the Balearic Shearwater exists on Minorca
Minorca
Min Orca or Menorca is one of the Balearic Islands located in the Mediterranean Sea belonging to Spain. It takes its name from being smaller than the nearby island of Majorca....
. A study of these birds recommended that a combination of 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....
characteristics and DNA 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 should be required at least for scientific purposes to assign individual birds to either species.
Systematics
It was formerly considered a subspeciesSubspecies
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 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...
; see there for more on the Puffinus puffinus superspecies
Superspecies
A superspecies is a group of at least two more or less distinctive species with approximately parapatric distributions. Not all species complexes, whether cryptices or ring species are superspecies, and vice versa, but many are...
. After the first split, it was the nominate subspecies of the so-called "Mediterranean Shearwater" for nearly ten more years; it is considered a monotypic
Monotypic
In biology, a monotypic taxon is a taxonomic group with only one biological type. The term's usage differs slightly between botany and zoology. The term monotypic has a separate use in conservation biology, monotypic habitat, regarding species habitat conversion eliminating biodiversity and...
species nowadays, as the Balearic form mauretanicus has been separated as Balearic Shearwater
Balearic Shearwater
The Balearic Shearwater is a medium-sized shearwater in the seabird family Procellariidae. It was long regarded a subspecies of the Manx Shearwater; see there for more on the Puffinus puffinus superspecies; following an initial split it was held to be a subspecies of the "Mediterranean Shearwater"...
.
The Yelkouan Shearwater appears to belong to a group of Mediterranean and adjacent Atlantic shearwaters which includes the Balearic Shearwater and one to three prehistorically
Prehistory
Prehistory is the span of time before recorded history. Prehistory can refer to the period of human existence before the availability of those written records with which recorded history begins. More broadly, it refers to all the time preceding human existence and the invention of writing...
extinct taxa, Hole's and possibly also Olson's Shearwater as well as an undescribed population of uncertain distinctness from Menorca. The two living Mediterranean lineages had probably separated before the end of the Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...
(c.2 million years ago), as indicated by molecular differences and putative direct ancestor of the Balearic Shearwater, the Ibiza
Ibiza
Ibiza or Eivissa is a Spanish island in the Mediterranean Sea 79 km off the coast of the city of Valencia in Spain. It is the third largest of the Balearic Islands, an autonomous community of Spain. With Formentera, it is one of the two Pine Islands or Pityuses. Its largest cities are Ibiza...
n fossil Puffinus nestori from the Late Pliocene or Early Pleistocene
Pleistocene
The Pleistocene is the epoch from 2,588,000 to 11,700 years BP that spans the world's recent period of repeated glaciations. The name pleistocene is derived from the Greek and ....
.
Ecology and status
Yelkouan Shearwaters breed on islands and coastal cliffs in the eastern and central Mediterranean. Most winter in that sea, but small numbers enterBird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
the Atlantic
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
in late summer. This species nests in burrows which are only visited at night to avoid predation by large gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s.
This is a gregarious species, which can be seen in large numbers from boats or headlands, especially in autumn. It is under some threat from the development of holiday resorts near its breeding sites, and also from animals such as cats and rats. The Yelkouan Shearwater feeds on 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...
and molluscs. It follows fishing ships when offal is being thrown.
The study of the Minorcan colony concluded that at least in these westernmost birds, genetic variation was extremely low, suggesting that the Yelkouan Shearwater may have suffered a marked population decline historically and thus, while not threatened judging from its absolute numbers, could be vulnerable to adverse effects of inbreeding
Inbreeding
Inbreeding is the reproduction from the mating of two genetically related parents. Inbreeding results in increased homozygosity, which can increase the chances of offspring being affected by recessive or deleterious traits. This generally leads to a decreased fitness of a population, which is...
.
It was formerly classified as 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. But new research has shown it to be rarer than it was believed. Consequently, it is uplisted to Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
status in 2008.