The Otago shag, (''Leucocarbo chalconotus''), together with the

Foveaux shag The Foveaux shag (''Leucocarbo stewarti''), together with the Otago shag formerly known as the Stewart Island shag and in its dark phase as the bronze shag, is a species of shag endemic to Stewart Island/Rakiura and Foveaux Strait, from which it ...

formerly known as the

Stewart Island shag Stewart Island shag or Stewart shag was the former name of a species of cormorant that was split into two species as a result of genetic studies. The two resulting species are: * Otago shag, ''Leucocarbo chalconotus'', which is endemic to coastal ...

and in its dark phase as the bronze shag, is a species of

shag Shag, or Shagged, or Shagger, or Shagging, 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 People Pseudonym ...

now found only in coastal

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

, New Zealand.

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, weigh about 2–3 kg, and are slightly larger than

s. They can be distinguished from Foveaux shags by their facial ornamentation in the breeding season: Foveaux shags have dark orange papillae on their face, whereas Otago shags have both papillae and small bright orange facial caruncles above the base of the bill.

Classification

Until 2016, Otago shags and the closely related shags living around Stewart Island and Foveaux Strait were considered to be a single species, called the Stewart Island shag. Mitochondrial DNA suggests Otago shags are actually more closely related to

Chatham shag The Chatham shag (''Leucocarbo onslowi''), also known as the Chatham Island shag, is a species of bird in the cormorant and shag family, Phalacrocoracidae. It is endemic to the Chatham Islands of New Zealand. For a long time the species was plac ...

s (''Leucocarbo onslowi''), and

osteological Osteology () is the scientific study of bones, practised by osteologists. A subdiscipline of anatomy, anthropology, and paleontology, osteology is the detailed study of the structure of bones, skeletal elements, teeth, microbone morphology, funct ...

and genetic differences supported separating off

s as a distinct species, ''L. stewarti''. Foveaux and Otago shags probably diverged when populations were split up by lower sea levels in the

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological Epoch (geology), epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fina ...

, and the

Chatham Islands The Chatham Islands ( ) (Moriori: ''Rēkohu'', 'Misty Sun'; mi, Wharekauri) are an archipelago in the Pacific Ocean about east of New Zealand's South Island. They are administered as part of New Zealand. The archipelago consists of about te ...

were subsequently colonised by shags from

. Other taxonomists have kept the Otago shag and the Foveaux shag conspecific. A recent taxonomic revision argues that ''Leucocarbo'' is a distinct genus, which would contain amongst other species the Otago, Foveaux, and Chatham shags. Others place it in the genus

Phalacrocorax ''Phalacrocorax'' is a genus of fish-eating birds in the cormorant family Phalacrocoracidae. Members of this genus are also known as the Old World cormorants. Taxonomy The genus ''Phalacrocorax'' was introduced by the French zoologist Mathurin ...

Distribution and conservation

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

Marlborough Marlborough may refer to: Places United Kingdom * Marlborough, Wiltshire, England ** Marlborough College, public school * Marlborough School, Woodstock in Oxfordshire, England * The Marlborough Science Academy in Hertfordshire, England Austral ...

, 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 ( mi, Muaūpoko) 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 sou ...

, 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 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 mouth. It ...

, as far north as

Oamaru Oamaru (; mi, Te Oha-a-Maru) 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 coast; State Highway 1 and the railway ...

, and as far south as the

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

. 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. Otago shags breed colonially from May to September, making raised cup nests out of organic material and

guano Guano (Spanish from qu, wanu) is the accumulated excrement of seabirds or bats. As a manure, guano is a highly effective fertilizer due to the high content of nitrogen, phosphate, and potassium, all key nutrients essential for plant growth. G ...

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 Taiaroa Head is a headland at the end of the Otago Peninsula in New Zealand, overlooking the mouth of the Otago Harbour. It lies within the city limits of Dunedin. The nearest settlement, Otakou, lies three kilometres to the south. The cape is h ...

, 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

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

Otago shag The Otago shag, (''Leucocarbo chalconotus''), together with the Foveaux shag formerly known as the Stewart Island shag and in its dark phase as the bronze shag, is a species of shag now found only in coastal Otago, New Zealand. Description ...

Birds of the South Island

Endemic birds of New Zealand