The Heard Island shag (''Leucocarbo nivalis''), or Heard Island cormorant, is a marine cormorant native to the Australian territory comprising the Heard and McDonald Islands in the

Southern Ocean The Southern Ocean, also known as the Antarctic Ocean, comprises the southernmost waters of the World Ocean, generally taken to be south of 60° S latitude and encircling Antarctica. With a size of , it is regarded as the second-small ...

, about 4100 km south-west of

Perth Perth is the capital and largest city of the Australian state of Western Australia. It is the fourth most populous city in Australia and Oceania, with a population of 2.1 million (80% of the state) living in Greater Perth in 2020. Perth i ...

Western Australia Western Australia (commonly abbreviated as WA) is a state of Australia occupying the western percent of the land area of Australia excluding external territories. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to th ...

Taxonomy

The Heard Island shag is one of the

blue-eyed shag ''Leucocarbo'' is a genus of birds in the family Phalacrocoracidae with the members commonly known as blue-eyed shags. This is a group of closely related cormorant taxa. Many have a blue, purple or red ring around the eye (not a blue iris); othe ...

s, sometimes placed in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

''Leucocarbo'', and a subspecies of the

imperial shag The imperial shag or imperial cormorant (''Leucocarbo atriceps'') is a black and white cormorant native to southern South America, primarily in rocky coastal regions, but locally also at large inland lakes. Some taxonomic authorities, including ...

. Others place it in the genus Phalacrocorax. It is now usually considered to be a full species.

Distribution and habitat

The Heard Island shag is restricted to the

subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...

Heard and

McDonald Islands The McDonald Islands () are an uninhabited archipelago in the southern Indian Ocean in the vicinity of Heard Island (). Together with Heard Island, they make up the Australian external Territory of Heard Island and McDonald Islands. The McDona ...

, and is only known to breed on Heard Island. Apart from breeding and roosting, its

habitat In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...

is marine.

Description

The Heard Island shag has largely black upperparts and white underparts. The cheeks and ear-coverts are white; there are white bars on the wings, a black, recurved crest over the forehead, and pink feet.Marchant & Higgins (1991), p.854. A breeding adult has a pair of orange caruncles above the base of the

bill Bill(s) may refer to: Common meanings * Banknote, paper cash (especially in the United States) * Bill (law), a proposed law put before a legislature * Invoice, commercial document issued by a seller to a buyer * Bill, a bird or animal's beak Plac ...

in front of the eyes as well as blue eye-rings. It is about 77 cm in length, with a

wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan o ...

of 120 cm and a weight of 3 kg.

Behaviour

Heard Island shags are gregarious, roosting in groups of from 10-20 birds up to several hundred.

Breeding

The birds are present year round at Heard Island, where they breed annually in

colonies In modern parlance, a colony is a territory subject to a form of foreign rule. Though dominated by the foreign colonizers, colonies remain separate from the administration of the original country of the colonizers, the '' metropolitan state'' ...

. Courtship takes place from late August to early October. Nests are mounds built largely of the stipes,

root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the su ...

s and adhering soil of the

tussock grass Tussock grasses or bunch grasses are a group of grass species in the family Poaceae. They usually grow as singular plants in clumps, tufts, hummocks, or bunches, rather than forming a sod or lawn, in meadows, grasslands, and prairies. As perenni ...

Poa cookii ''Poa cookii'', sometimes called Cook's tussock-grass or bluegrass, is a species of tussock grass native to various subantarctic islands. The specific epithet honours British explorer James Cook who visited the Kerguelen Islands in 1776. Desc ...

'' and average about 22 cm high, with a minimum distance between nests of 50 cm. The clutch of two or three eggs is laid mainly between mid-September and November, hatching from November to February. The chicks fledge from January to March.DEWHA website

Feeding

The birds forage locally in shallow coastal waters, with the diet consisting primarily of

polychaetes Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made ...

and

fish Fish are aquatic, craniate, gill-bearing 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. Approximately 95% of ...

.Green, K., and Williams, R. (1997). ''Biology of the Heard Island Shag Phalacrocorax nivalis. 3. Foraging, Diet and Diving Behaviour.'' Emu 97: 76-83 The proportion of fish in the diet is higher when the birds are feeding chicks.

Status and conservation

The Heard Island shag population is estimated to comprise about 1000 breeding pairs. It is listed as Vulnerable under Australia's

Environment Protection and Biodiversity Conservation Act 1999 The ''Environment Protection and Biodiversity Conservation Act 1999'' (Cth) is an Act of the Parliament of Australia that provides a framework for protection of the Australian environment, including its biodiversity and its natural and cult ...

, because the population is small, localised and subject to fluctuations in breeding success due to weather conditions and food availability. A potential threat is

climate change In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to ...

affecting sea temperatures and thus food supply.Garnett & Crowley (2000).

Notes

References

* * * * * * * * {{Taxonbar, from=Q1261443

Heard Island shag The Heard Island shag (''Leucocarbo nivalis''), or Heard Island cormorant, is a marine cormorant native to the Australian territory comprising the Heard and McDonald Islands in the Southern Ocean, about 4100 km south-west of Perth, Wester ...

Fauna of Heard Island and McDonald Islands

Birds of Australia