The Stewart Island shag (''Leucocarbo chalconotus''; ) is a species of

shag Shag or Shags may refer to: Animals * Shag or cormorant, a bird family ** European shag, a specific species of the shag or cormorant family ** Great cormorant another species of the family Persons * Shag (artist), stage name of the American a ...

found on New Zealand's

South Island The South Island ( , 'the waters of Pounamu, Greenstone') is the largest of the three major islands of New Zealand by surface area, the others being the smaller but more populous North Island and Stewart Island. It is bordered to the north by ...

and

Stewart Island Stewart Island (, ' glowing skies', officially Stewart Island / Rakiura, formerly New Leinster) is New Zealand's third-largest island, located south of the South Island, across Foveaux Strait. It is a roughly triangular island with a la ...

. The Stewart Island shag has sometimes been split into two species, the Foveaux shag and the Otago shag.

Taxonomy

The Stewart Island shag was formally described and illustrated in 1845 by the English zoologist George Gray based on a specimen collected by Percy Earl in the

Otago Otago (, ; ) is a regions of New Zealand, region of New Zealand located in the southern half of the South Island and administered by the Otago Regional Council. It has an area of approximately , making it the country's second largest local go ...

region of New Zealand's

. Gray placed the new species in the genus ''Gracalus'' and coined the

binomial name In taxonomy, binomial nomenclature ("two-term naming system"), also called binary nomenclature, is a formal system of naming species of living things by giving each a name composed of two parts, both of which use Latin grammatical forms, altho ...

''Gracalus chalconotus''. The specific epithet is from

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

χαλκονωτος/''khalkonōtos'' meaning "bronze-backed". The Stewart Island shag is now one of the 15 shags placed in the genus ''

Leucocarbo ''Leucocarbo'' is a genus of birds in the family Phalacrocoracidae. Several species within the genus are collectively known as blue-eyed shags. This is a group of closely related cormorant taxa. Many have a blue, purple or red ring around the ey ...

'', which was introduced in 1856 by the French naturalist

Charles Lucien Bonaparte Charles Lucien Jules Laurent Bonaparte, 2nd Prince of Canino and Musignano (24 May 1803 – 29 July 1857) was a French naturalist and ornithology, ornithologist, and a nephew of Napoleon. Lucien and his wife had twelve children, including Cardinal ...

. Two

subspecies In Taxonomy (biology), biological classification, subspecies (: subspecies) is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (Morphology (biology), morpholog ...

are recognised: * ''L. c. chalconotus'' ( Gray, GR, 1845) – east

(New Zealand) * ''L. c. stewarti'' ( Ogilvie-Grant, 1898) – south South Island and

(New Zealand) The Stewart Island shag has sometimes been split into two species with the subspecies ''L. c. chalconotus'' known as the Otago shag and the subspecies ''L. c. stewarti'' known as the Foveaux shag. The species was split based on a molecular phylogenetic study published in 2016 but were then re-lumped when a later study by some of the same ornithologists found that the two species were separated by only a shallow genetic divergence.

Description

The species is dimorphic, with two plumages. Roughly one quarter of the individuals are pied, with dark and white feathers, and the rest, known as bronze shags, are dark all over. Both morphs breed together. These large, chunky birds are about 70 cm long and weigh about 2–3 kg. Stewart Island shags vary in their facial ornamentation in the breeding season. Roughly half of breeding individuals have dark orange papillae on their face, while the other half have small bright orange caruncles above the base of the bill instead. Gular pouch colour in the breeding season also varies, from bright orange to dark orange to purple.

Distribution and conservation

Archaeological evidence shows that Stewart Island shags were formerly found along the entire east coast of the South Island up to

Marlborough Marlborough or the Marlborough may refer to: Places Australia * Marlborough, Queensland * Principality of Marlborough, a short-lived micronation in 1993 * Marlborough Highway, Tasmania; Malborough was an historic name for the place at the sou ...

, but when humans arrived the population was devastated, reduced by 99 percent within 100 years with a corresponding loss of genetic diversity. It became restricted to the rocky offshore islets off the

Otago Peninsula The Otago Peninsula () is a long, hilly indented finger of land that forms the easternmost part of Dunedin, New Zealand. Volcanic in origin, it forms one wall of the eroded valley that now forms Otago Harbour. The peninsula lies south-east of Ot ...

, and has scarcely recovered since that time. There are less than 2500 Otago shags remaining, but they can be seen at

Otago Harbour Otago Harbour is the harbor, natural harbour of Dunedin, New Zealand, consisting of a long, much-indented stretch of generally navigable water separating the Otago Peninsula from the mainland. They join at its southwest end, from the harbour m ...

, as far north as

Oamaru Oamaru (; ) is the largest town in North Otago, in the South Island of New Zealand, it is the main town in the Waitaki District. It is south of Timaru and north of Dunedin on the Pacific Ocean, Pacific coast; State Highway 1 (New Zealand), Sta ...

, and as far south as the

Catlins The Catlins (sometimes referred to as The Catlins Coast) comprise an area in the southeastern corner of the South Island of New Zealand. The area lies between Balclutha, New Zealand, Balclutha and Invercargill, straddling the boundary between ...

. Restricted to a small area, and having little or no genetic variation, they require conservation efforts tailored to these extinction risk factors; this could include reintroduction to part of their former range. Stewart Island shags breed colonially from May to September, making raised cup nests out of organic material and

guano Guano (Spanish from ) is the accumulated excrement of seabirds or bats. Guano is a highly effective fertiliser due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. Guano was also, to a le ...

on islands and sea cliffs. Colonies are large enough to be strikingly visible, and are used year after year. One notable colony is on the northern shore of Taiaroa Head, at the mouth of the Otago Harbour. They feed in coastal waters less than 30 m deep and are rarely if ever seen inland or far out to sea.

References

External links

* Stewart Island shag discussed on RadioNZ ''Critter of the Week''
4 March 2016
{{Taxonbar, from=Q27074618

Otago shag The Stewart Island shag (''Leucocarbo chalconotus''; ) is a species of shag found on New Zealand's South Island and Stewart Island. The Stewart Island shag has sometimes been split into two species, the Foveaux shag and the Otago shag. Taxon ...

Birds of the South Island

Endemic birds of New Zealand