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The white-chinned petrel (''Procellaria aequinoctialis'') also known as the Cape hen and shoemaker, is a large shearwater in the family Procellariidae. It ranges around the Southern Ocean as far north as southern Australia, Peru and Namibia, and breeds colonially on scattered islands. The white-chinned petrel was formerly considered to be conspecific with the
spectacled petrel The spectacled petrel (''Procellaria conspicillata'') is a rare seabird that nests only on the high western plateau of Inaccessible Island in the South Atlantic Tristan da Cunha group. It is one of the largest petrels that nests in burrows. This ...
(''Procellaria conspicillata'').


Taxonomy

In 1747 the English naturalist George Edwards included an illustration and a description of the white-chinned petrel in the second volume of his ''A Natural History of Uncommon Birds''. He used the English name "The great Black Peteril" and based his hand-coloured etching on a preserved specimen that had been brought to London. He believed that it had been collected near the
Cape of Good Hope The Cape of Good Hope ( af, Kaap die Goeie Hoop ) ;''Kaap'' in isolation: pt, Cabo da Boa Esperança is a rocky headland on the Atlantic coast of the Cape Peninsula in South Africa. A common misconception is that the Cape of Good Hope is t ...
. When in 1758 the Swedish naturalist Carl Linnaeus updated his ''
Systema Naturae ' (originally in Latin written ' with the ligature æ) is one of the major works of the Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the system, now known as binomial nomen ...
'' for the tenth edition, he placed the white-chinned petrel with the other petrels in the genus '' Procellaria''. Linnaeus included a brief description, coined the
binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called nomenclature ("two-name naming system") or binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, bot ...
''Procellaria aequinoctialis'' and cited Edwards' work. There are two subspecies: * ''P. a. aequinoctialis'' - breeds on islets of the temperate and subantarctic South Atlantic and South Indian Oceans, winters throughout them * ''P. a. steadi'' - breeds on the subantarctic islands of New Zealand, winters throughout the
South Pacific The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...
Ocean Both subspecies were formerly considered synonymous with each other, but were recognized as distinct by the International Ornithological Congress in 2022 based on strong genetic distinctiveness. The genus name ''Procellaria'' is from the Latin ''procella'' meaning "storm" or "gale. The specific epithet ''aequinoctialis'' is Latin meaning ''equinoctial'' (''aequinoctium'' is the Latin word for "equinox"). The word ''petrel'' is derived from Saint Peter and the story of his walking on water, referring to their appearing to run on the water's surface when taking to the air.Gotch, A. T. (1995) Other English names for this species are Cape hen and shoemaker. The white-chinned petrel is a member of the family Procellariidae, and the
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
Procellariiformes. As a member of the Procellariiformes, they share certain identifying features. First, they have nasal passages that attach to the upper bill called naricorns. Although the nostrils on the petrel are on top of the upper bill. The bills of Procellariiformes are also unique in that they are split into between seven and nine horny plates. 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 esters and triglycerides that is stored in the proventriculus. This can be sprayed out of their mouths as a defence against predators and as an energy rich food source for chicks and for the adults during their long flights. Finally, they also have a salt gland 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.


Description

The white-chinned petrel measures in length and has a wingspan of . Males are heavier and average whereas females weigh around . Not only is it the largest ''Procellaria'' petrel but is also the largest species in its family outside of the giant petrels. This large petrel is sooty-black and has some white on its throat and chin, more so in the Indian Ocean sector than the Atlantic. Its primaries can have a silvery appearance underneath. Its bill may be horn or yellow with some black between the nostrils. It has black legs and feet. When it flies, it mixes slow wing beats with glides. Although normally quiet, it will rattle or groan while at its colony.


Distribution and habitat

The white-chinned petrel utilises many islands during the breeding season. 2,000,000 pairs breed on
South Georgia South Georgia ( es, Isla San Pedro) is an island in the South Atlantic Ocean that is part of the British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. Stretching in the east†...
, Between 175,000 and 226,000 pairs are on the
Kerguelen Islands The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic constituting one of the two exposed parts of the Kerguelen Plateau, a large ...
, and 100,000 pairs on Disappointment Island. Some also breed on the
Crozet Islands The Crozet Islands (french: ÃŽles Crozet; or, officially, ''Archipel Crozet'') are a sub-Antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarcti ...
, Prince Edward Islands, Campbell Islands, Auckland Islands, Antipodes Islands, and the Falkland Islands. During the non-breeding season, the petrels fly from the
Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...
pack ice to the
subtropics The subtropical zones or subtropics are geographical and climate zones to the north and south of the tropics. Geographically part of the temperate zones of both hemispheres, they cover the middle latitudes from to approximately 35° north and ...
.


Behaviour


Breeding

Both sexes help to build a nest, and will help incubate the egg. Upon hatching, both sexes again will assist in feeding and protecting the young.Maynard, B. J. (2003)


Feeding

Their diet is composed mainly of krill followed by fish. White-chinned petrels feed by surface seizing and by undertaking shallow dives, and they will readily follow ships to collect fisheries discards,Cherel, Y, et al. (1996) making them vulnerable to
longline Long line or longline may refer to: *''Long Line'', an album by Peter Wolf *Long line (topology), or Alexandroff line, a topological space *Long line (telecommunications), a transmission line in a long-distance communications network *Longline fish ...
fisheries.


Conservation

A 2004 estimate placed the adult population at 7,000,000 with an occurrence range of . Mortality of both adults and chicks due to
longline Long line or longline may refer to: *''Long Line'', an album by Peter Wolf *Long line (topology), or Alexandroff line, a topological space *Long line (telecommunications), a transmission line in a long-distance communications network *Longline fish ...
fisheries has caused 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 ...
to classify it as
vulnerable Vulnerable may refer to: General * Vulnerability * Vulnerability (computing) * Vulnerable adult * Vulnerable species Music Albums * ''Vulnerable'' (Marvin Gaye album), 1997 * ''Vulnerable'' (Tricky album), 2003 * ''Vulnerable'' (The Used album) ...
. An overall decline in population is inferred by a drop in
burrow An Eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of sh ...
occupancy rates of 28% at Bird Island, and an 86% reduction in population at Prydz Bay. Also, monitoring on
Marion Island The Prince Edward Islands are two small uninhabited islands in the sub-Antarctic Indian Ocean that are part of South Africa. The islands are named Marion Island (named after Marc-Joseph Marion du Fresne, 1724–1772) and Prince Edward Island ...
has shown of 14.5% reduction, and a 37% reduction on the
Crozet Islands The Crozet Islands (french: ÃŽles Crozet; or, officially, ''Archipel Crozet'') are a sub-Antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarcti ...
. Unintentional death at the hands of longline fisheries has proven to be a major contributor to the overall population decline. Nearly all of the
bycatch Bycatch (or by-catch), in the fishing industry, is a fish or other marine species that is caught unintentionally while fishing for specific species or sizes of wildlife. Bycatch is either the wrong species, the wrong sex, or is undersized or juve ...
from the Namibian hake are white-chinned petrels. 10% of the South African pelagic longline bycatch and 55% of the
demersal The demersal zone is the part of the sea or ocean (or deep lake) consisting of the part of the water column near to (and significantly affected by) the seabed and the benthos. The demersal zone is just above the benthic zone and forms a layer of ...
. Also, the white-chinned petrel has suffered at the hands of invasive species such as the brown rat, ''Rattus novegicus'', and the
black rat The black rat (''Rattus rattus''), also known as the roof rat, ship rat, or house rat, is a common long-tailed rodent of the stereotypical rat genus ''Rattus'', in the subfamily Murinae. It likely originated in the Indian subcontinent, but is n ...
, ''Rattus rattus''.BirdLife International (2009) Several of the breeding islands are protected areas. Ongoing studies and population monitoring are occurring at
South Georgia South Georgia ( es, Isla San Pedro) is an island in the South Atlantic Ocean that is part of the British Overseas Territory of South Georgia and the South Sandwich Islands. It lies around east of the Falkland Islands. Stretching in the east†...
, the Prince Edward Islands,
Kerguelen Islands The Kerguelen Islands ( or ; in French commonly ' but officially ', ), also known as the Desolation Islands (' in French), are a group of islands in the sub-Antarctic constituting one of the two exposed parts of the Kerguelen Plateau, a large ...
, and
Crozet Islands The Crozet Islands (french: ÃŽles Crozet; or, officially, ''Archipel Crozet'') are a sub-Antarctic archipelago of small islands in the southern Indian Ocean. They form one of the five administrative districts of the French Southern and Antarcti ...
. Finally, they are a part of ACAP Annex I, and CMS Appendix II. To assist in reversing the decline in population it has been proposed to continue and extend monitoring studies, trying to eliminate most invasive species, promote adoption of best practice mitigation measures at all fisheries within the range via ACAP, FAO, CCAMLR.


References


Sources

* * * * * * * *


External links


BirdLife species factsheet
* Whitechinned Petrel
Species text in The Atlas of Southern African Birds
{{Taxonbar, from=Q276206 white-chinned petrel white-chinned petrel Birds of the Southern Ocean Birds of South Australia Birds of New Zealand Birds of Southern Africa Birds of islands of the Atlantic Ocean Birds of subantarctic islands Vulnerable fauna of Australia Fauna of the Crozet Islands Birds of the Indian Ocean Fauna of the Prince Edward Islands white-chinned petrel white-chinned petrel