The white-capped albatross (''Thalassarche cauta steadi'') is a

mollymawk The mollymawks are a group of medium-sized albatrosses that form the genus ''Thalassarche''. The name has sometimes been used for the genus ''Phoebetria'' as well, but these are usually called sooty albatrosses. They are restricted to the Sout ...

that breeds on the islands off of New Zealand. Not all experts agree that this form should be recognized as a separate species from the shy albatross, ''Thalassarche cauta''. It is a medium-sized black, slate gray, and white albatross and is the largest of the mollymawks.

Taxonomy

Mollymawks are a type of albatross that belong to family

Diomedeidae Albatrosses, of the biological family Diomedeidae, are large seabirds related to the procellariids, storm petrels, and diving petrels in the order Procellariiformes (the tubenoses). They range widely in the Southern Ocean and the North Pacifi ...

of the order

Procellariiformes Procellariiformes is an order of seabirds that comprises four families: the albatrosses, the petrels and shearwaters, and two families of storm petrels. Formerly called Tubinares and still called tubenoses in English, procellariiforms are of ...

, along with

shearwater Shearwaters are medium-sized long-winged seabirds in the petrel family Procellariidae The family Procellariidae is a group of seabirds that comprises the fulmarine petrels, the gadfly petrels, the diving petrels, the prions, and the shearwa ...

fulmar The fulmars are tubenosed seabirds of the family Procellariidae. The family consists of two extant species and two extinct fossil species from the Miocene. Fulmars superficially resemble gulls, but are readily distinguished by their flight on ...

storm petrel Storm-petrel may refer to one of two bird families, both in the order Procellariiformes, once treated as the same family. The two families are: * Northern storm petrels (''Hydrobatidae'') are found in the Northern Hemisphere, although some speci ...

s, and

diving petrel The diving petrels form a genus, ''Pelecanoides'', of seabirds in the family Procellariidae. There are four very similar species of diving petrels, distinguished only by small differences in the coloration of their plumage, habitat, and bill con ...

s. They share certain identifying features. First, they have nasal passages that attach to the upper bill called

naricorns A nostril (or naris , plural ''nares'' ) is either of the two orifices of the nose. They enable the entry and exit of air and other gasses through the nasal cavities. In birds and mammals, they contain branched bones or cartilages called turbi ...

. 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 seven and nine horny plates. Finally, they produce a

stomach oil Stomach oil is the light oil composed of neutral dietary lipids found in the proventriculus (fore-gut) of birds in the order Procellariiformes. All albatrosses, procellarids (gadfly petrels and shearwaters) and northern and austral storm petrel ...

made up of

wax ester A wax ester (WE) is an ester of a fatty acid and a fatty alcohol. Wax esters comprise the main components of three commercially important waxes: carnauba wax, candelilla wax, and beeswax.. Wax esters are formed by combining one fatty acid with o ...

s and

triglycerides A triglyceride (TG, triacylglycerol, TAG, or triacylglyceride) is an ester derived from glycerol and three fatty acids (from ''tri-'' and ''glyceride''). Triglycerides are the main constituents of body fat in humans and other vertebrates, as we ...

that is stored in the

proventriculus The proventriculus is part of the digestive system of birds.Encarta World English Dictionary orth American Edition(2007). ''Proventriculus''. Source: (accessed: December 18, 2007) An analogous organ exists in invertebrates and insects. Birds Th ...

. This is used against predators as well as an energy rich food source for chicks and for the adults during their long flights. They also have a

salt gland The salt gland is an organ for excreting excess salts. It is found in the cartilaginous fishes subclass elasmobranchii (sharks, rays, and skates), seabirds, and some reptiles. Salt glands can be found in the rectum of sharks. Birds and reptiles ...

that is situated above the nasal passage and helps desalinate their bodies, due to the high amount of ocean water that they imbibe. It excretes a high saline solution from their nose. The white-capped albatross is part of a greater complex of albatrosses consisting of the

shy albatross The shy albatross, also known as shy mollymawk, (''Thalassarche cauta'', formerly ''Diomedea cauta''), is a medium-sized albatross that breeds on three remote islands off the coast of Tasmania, Australia, in the southern Indian Ocean. Its li ...

, ''Thasassarche cauta'', Salvin's albatross, ''Thalassarche salvini'', and

Chatham albatross The Chatham albatross (''Thalassarche eremita''), also known as the Chatham mollymawk or Chatham Island mollymawk,Robertson, C. J. R. (2003) is a medium-sized black-and-white albatross which breeds only on The Pyramid, a large rock stack in th ...

, ''Thalassarche eremita''. In 1998, Robertson and Nunn recommended a four-way split,Robertson C. J. R. & Nunn G. B. (1998) some experts agreed.

BirdLife International BirdLife International is a global partnership of non-governmental organizations that strives to conserve birds and their habitats. BirdLife International's priorities include preventing extinction of bird species, identifying and safeguarding ...

agreed in 2007,BirdLfie International (2008a) ACAP agreed in 2006,ACAP (2006) and Brooke agreed in 2004.Brooke, M. (2004) The SACC agreed to a three-way split, leaving ''steadi'', the white-capped albatross grouped with the

.Remsen Jr., J. V. (2004)Remsen Jr., J. V. (2005)Remsen Jr., J. V. (2008) The

Clements taxonomy ''The Clements Checklist of Birds of the World'' is a book by Jim Clements which presents a list of the bird species of the world. The most recent printed version is the sixth edition (2007), but has been updated yearly, the last version in 2022 ...

Cornell Lab of Ornithology (2018) has yet to agree on any of these splits. Finally, following Brooke, this species was shifted from ''Diomedea'' to ''Thalassarche'', which was generally agreed upon by most experts.

Description

The white-capped albatross averages in length, with a wingspan of .Dunn, Jon L. & Alderfer, Jonathan (2006) It weighs It has a bold white cap that contrasts with a pale silver gray face and a darker brow. Some adults have a white back with brown tipped feathers.Watkins, B. (2008) They have a dark gray mantle and a black tail. Most of the rest of the body is white. Its bill is pale gray to blue with a yellow tip. Juveniles have a gray bill with a dark tip, and their head is darker, with gray to the collar.

Range and habitat

They are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

to the islands off the coast of New Zealand, with a population of 75,000 breeding pairs, estimated in 2007,Gales, R., et al. (1998)Baker, G. B., et al. (2007) and 350,000 to 375,000 total birds.

Disappointment Island Disappointment Island is one of seven uninhabited islands in the Auckland Islands archipelago, in New Zealand. It is south of the country's main South Island and from the northwest end of Auckland Island. It is home to a large colony of white ...

has 72,000 pairs,

Auckland Island Auckland Island ( mi, Mauka Huka) is the main island of the eponymous uninhabited archipelago in the Pacific Ocean. It is part of the New Zealand subantarctic area. It is inscribed in the UNESCO World Heritage list together with the other New ...

has 3,000 pairs, Adams Island (

Auckland Islands The Auckland Islands (Māori: ''Motu Maha'' "Many islands" or ''Maungahuka'' "Snowy mountains") are an archipelago of New Zealand, lying south of the South Island. The main Auckland Island, occupying , is surrounded by smaller Adams Island, ...

) has 100 pairs,Taylor, G. A. (2000)Croxall, J. P. & Gales, R. (1998) and

Bollons Island Bollons Island () is a small island in New Zealand's subantarctic Antipodes Islands group. It is the second largest island in the group behind Antipodes Island. Geography The island is roughly crescent-shaped, and has an area of . It lies to the ...

(

Antipodes Islands The Antipodes Islands ( Maōri: Moutere Mahue; "Abandoned island") are inhospitable and uninhabited volcanic islands in subantarctic waters to the south of – and territorially part of – New Zealand. The 21 km2 archipelago lies 860 ...

) has 100 pairs.Tennyson, A., et al. (1998) Juvenile and non-breeding birds are believed to forage in the southwestern

Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...

White, R. W., et al. (2002)) and a recent DNA test of a South Georgia bird confirmed it.Phalan, B., et al. (2004) Also, using different techniques, scientists have proven that they forage off the coast of southwestern

Africa Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 6% of Earth's total surface area ...

.Abbott, C. L., et al. (2006)Thompson, D. R. & Sagar, P. M. (2007)Robertson, C. J. R., et al. (2003) Juveniles are also believed to go as far as the south

and the southwestern

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

Behavior

Feeding

They are a surface feeder, but may utilize shallow dives for their food which is fish,

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

tunicate A tunicate is a marine invertebrate animal, a member of the subphylum Tunicata (). It is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time ca ...

s, and crustacea.

Reproduction

The white-capped albatross breeds annually on rocks on small islands.

Conservation

The

IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...

classifies this species as

near threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...

, with an occurrence range of and a breeding range of . The largest threat for this bird is longline and trawl fisheries. Net monitor cables were responsible for large numbers of deaths; however, they were phased out in 1992. Commercial exploitation of squid in

Bass Strait Bass Strait () is a strait separating the island state of Tasmania from the Australian mainland (more specifically the coast of Victoria, with the exception of the land border across Boundary Islet). The strait provides the most direct waterwa ...

may present a threat by reducing the food supply. Also, pigs on

reduced nesting from 1972–1982, and feral cats also take small number of chicks.Thompson, D. R. & Sagar, P. M. (2006) Since 2006,

birds have been tracked, and this will continue.

Footnotes

References

* * * * * * * * * * * * * * * * * * * * * * *Watkins, B. (2008) ''in litt'' *

External links

{{taxonbar, from=Q5437614

white-capped albatross The white-capped albatross (''Thalassarche cauta steadi'') is a mollymawk that breeds on the islands off of New Zealand. Not all experts agree that this form should be recognized as a separate species from the shy albatross, ''Thalassarche caut ...

Birds of the Auckland Islands