Tristan Albatross
Encyclopedia
The Tristan Albatross, Diomedea dabbenena, is a large seabird
from the albatross
family
. One of the great albatross
es of the genus
Diomedea, it was only widely recognised as a full species
in 1998.
order, along with Shearwater
s, Fulmar
s, Storm-petrel
s, and Diving-petrels. They share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the Albatross are on the sides of the bill. The bills of Procellariiformes are also unique in that they are split into between 7 and 9 horny plates. Finally, they produce a stomach oil made up of wax ester
s and triglycerides that is stored in the proventriculus
. This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights.
While not all scientists believe it is a full species with some retaining it as a subspecies
of the Wandering Albatross
, a 2004 study of the mitochondrial DNA
of the Wandering Albatross species complex
supported the split. Other studies have shown it to be the most genetically
distinct member of the Wandering Albatross superspecies. This may be due to it díverging from their common ancestor before all its relatives, or because it underwent particularly strong genetic drift
. Among the major experts, BirdLife International has split this species, Jeff Clements has not yet, and the SACC
has a proposal on the table to split it.
, whose companions turned to birds.
of the Wandering Albatross, and its bill is about 25 mm (0.984251968503937 in) shorter.
They breed biennially and will nest in wet heath from 400 to 700 m (1,312.3 to 2,296.6 ft) in elevation. They are monogamous, and don't start breeding until they are about 10 years old.
and females to the east towards Africa
. They have been sightings near Brazil
and also off the coast of Australia
.
The Tristan Albatrosses are endemic
to the islands of the Tristan da Cunha
group and more specifically Gough Island
. The majority of the world's population nest on Gough Island
, around 1500 pairs. On some years a pair breeds on Inaccessible Island
.
, rats, cats and pigs, but these have now been removed
from their breeding islands. However, this resulted in the population of mice, Mus musculus
, increasing to the point where they would eat and kill albatross chicks en masse. Even though the chicks are huge compared to the mice, they do not know how to defend themselves appropriately. Today the main threat to the species is believed to be long-line fishing
and these mice.
Formerly classified as an endangered species
by the IUCN, it was suspected to be more threatened than generally assumed and undergoing a marked decline. Following the evaluation of its status, this was found to be correct, and the Tristan Albatross was consequently uplisted to Critically Endangered
status in 2008. They have an occurrence range of 14000000 km² (5,405,430.2 sq mi) and a breeding range of 80 km² (30.9 sq mi).
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 albatross
Albatross
Albatrosses, of the biological family Diomedeidae, are large seabirds allied to the procellariids, storm-petrels and diving-petrels in the order Procellariiformes . They range widely in the Southern Ocean and the North Pacific...
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...
. One of the great albatross
Great albatross
The great albatrosses are seabirds in the genus Diomedea in the albatross family. The genus Diomedea formerly included all albatrosses except the sooty albatrosses, but in 1996 the genus was split with the mollymawks and the North Pacific albatrosses both being elevated to separate genera...
es of the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Diomedea, it was only widely recognised as a full 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...
in 1998.
Taxonomy
Albatrosses belong to Diomedeidae family and come from the ProcellariiformesProcellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...
order, along with 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, Fulmar
Fulmar
Fulmars are seabirds of the family Procellariidae. The family consists of two extant species and two that are extinct.-Taxonomy:As members of Procellaridae and then the order Procellariiformes, they share certain traits. First, they have nasal passages that attach to the upper bill called...
s, Storm-petrel
Storm-petrel
Storm petrels are seabirds in the family Hydrobatidae, part of the order Procellariiformes. These smallest of seabirds feed on planktonic crustaceans and small fish picked from the surface, typically while hovering. The flight is fluttering and sometimes bat-like.Storm petrels have a cosmopolitan...
s, and Diving-petrels. They share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the Albatross are on the sides of the bill. The bills of Procellariiformes are also unique in that they are split into between 7 and 9 horny plates. Finally, they produce a stomach oil made up of wax ester
Wax ester
An ester of a fatty acid and a long-chain alcohol. These oils have similar properties as triglycerides, but are indigestible. They are found in some fish such as orange roughy, oilfish, escolar, black oreo, smooth oreo and other deep water fish. They are also present in marine copepods. Wax...
s and triglycerides that is stored in the proventriculus
Proventriculus
The proventriculus is part of the digestive system of birds, invertebrates and insects.-Birds:The proventriculus is a standard part of avian anatomy...
. This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights.
While not all scientists believe it is a full species with some retaining it 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 the Wandering Albatross
Wandering Albatross
The Wandering Albatross, Snowy Albatross or White-winged Albatross, Diomedea exulans, is a large seabird from the family Diomedeidae, which has a circumpolar range in the Southern Ocean. It was the first species of albatross to be described, and was long considered the same species as the Tristan...
, a 2004 study of the mitochondrial DNA
Mitochondrial DNA
Mitochondrial DNA is the DNA located in organelles called mitochondria, structures within eukaryotic cells that convert the chemical energy from food into a form that cells can use, adenosine triphosphate...
of the Wandering Albatross 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 ....
supported the split. Other studies have shown it to be the most genetically
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
distinct member of the Wandering Albatross superspecies. This may be due to it díverging from their common ancestor before all its relatives, or because it underwent particularly strong genetic drift
Genetic drift
Genetic drift or allelic drift is the change in the frequency of a gene variant in a population due to random sampling.The alleles in the offspring are a sample of those in the parents, and chance has a role in determining whether a given individual survives and reproduces...
. Among the major experts, BirdLife International has split this species, Jeff Clements has not yet, and the SACC
American Ornithologists' Union
The American Ornithologists' Union is an ornithological organization in the USA. Unlike the National Audubon Society, its members are primarily professional ornithologists rather than amateur birders...
has a proposal on the table to split it.
Etymology
Diomedea antipodensis breaks into Diomedea referring to DiomedesDiomedes
Diomedes or Diomed is a hero in Greek mythology, known for his participation in the Trojan War.He was born to Tydeus and Deipyle and later became King of Argos, succeeding his maternal grandfather, Adrastus. In Homer's Iliad Diomedes is regarded alongside Ajax as one of the best warriors of all...
, whose companions turned to birds.
Description
It is, however, practically indistinguishable from the Wandering Albatross at sea; the Tristan Albatross is smaller and has a slightly darker back. The Tristan Albatross is 110 cm (43.3 in) and has a wingspan of up to 3.5 m (11.5 ft). The Tristan Albatross also never attains the full white plumagePlumage
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...
of the Wandering Albatross, and its bill is about 25 mm (0.984251968503937 in) shorter.
Behavior
The Tristan Albatross feeds on fish and cephalopods.They breed biennially and will nest in wet heath from 400 to 700 m (1,312.3 to 2,296.6 ft) in elevation. They are monogamous, and don't start breeding until they are about 10 years old.
Range and habitat
Due to the difficulty in distinguishing them from Wandering Albatrosses, their distribution at sea is still not fully known, but the use of satellite tracking has shown that they forage widely in the South Atlantic, with males foraging west of the breeding islands towards South AmericaSouth America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
and females to the east towards Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
. They have been sightings near Brazil
Brazil
Brazil , 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...
and also off the coast of Australia
Australia
Australia , 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...
.
The Tristan Albatrosses are endemic
Endemic (ecology)
Endemism is the ecological state of being unique to a defined geographic location, such as an island, nation or other defined zone, or habitat type; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, all species of lemur are endemic to the...
to the islands of the Tristan da Cunha
Tristan da Cunha
Tristan da Cunha is a remote volcanic group of islands in the south Atlantic Ocean and the main island of that group. It is the most remote inhabited archipelago in the world, lying from the nearest land, South Africa, and from South America...
group and more specifically Gough Island
Gough Island
Gough Island , also known historically as Gonçalo Álvares or Diego Alvarez, is a volcanic island in the South Atlantic Ocean. It is a dependency of Tristan da Cunha and part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha...
. The majority of the world's population nest on Gough Island
Gough Island
Gough Island , also known historically as Gonçalo Álvares or Diego Alvarez, is a volcanic island in the South Atlantic Ocean. It is a dependency of Tristan da Cunha and part of the British overseas territory of Saint Helena, Ascension and Tristan da Cunha...
, around 1500 pairs. On some years a pair breeds on Inaccessible Island
Inaccessible Island
Inaccessible Island is an extinct volcano, 14 km² in area, rising out of the South Atlantic Ocean 45 km southwest of Tristan da Cunha. Inaccessible Island is located at . It is part of the archipelago of Tristan da Cunha, which is part of the overseas territory of the United Kingdom,...
.
Conservation
They were formerly threatened by introduced speciesIntroduced 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...
, rats, cats and pigs, but these have now been removed
Island restoration
The ecological restoration of islands, or island restoration, is the application of the principles of ecological restoration to islands and island groups. Islands, due to their isolation, are home to many of the world's endemic species, as well as important breeding grounds for seabirds and some...
from their breeding islands. However, this resulted in the population of mice, Mus musculus
House mouse
The house mouse is a small rodent, a mouse, one of the most numerous species of the genus Mus.As a wild animal the house mouse mainly lives associated with humans, causing damage to crops and stored food....
, increasing to the point where they would eat and kill albatross chicks en masse. Even though the chicks are huge compared to the mice, they do not know how to defend themselves appropriately. Today the main threat to the species is believed to be long-line fishing
Long-line fishing
Longline fishing is a commercial fishing technique. It uses a long line, called the main line, with baited hooks attached at intervals by means of branch lines called "snoods". A snood is a short length of line, attached to the main line using a clip or swivel, with the hook at the other end....
and these mice.
Formerly classified as an endangered species
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
by the IUCN, it was suspected to be more threatened than generally assumed and undergoing a marked decline. Following the evaluation of its status, this was found to be correct, and the Tristan Albatross was consequently uplisted to Critically Endangered
Critically Endangered
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered means that a species' numbers have decreased, or will decrease, by 80% within three generations....
status in 2008. They have an occurrence range of 14000000 km² (5,405,430.2 sq mi) and a breeding range of 80 km² (30.9 sq mi).