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 i ...

formerly known as the Stewart Island shag 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, 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 shags (''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, func ...

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 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 finally confirmed in ...

, 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 Otago. 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.

Distribution and conservation

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

, 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 rai ...

, 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 Southla ...

. 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 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

* Otago shag discussed on RadioNZ ''Critter of the Week''
4 March 2016
{{Taxonbar, from=Q27074618 Otago shag Birds of the South Island Otago shag Otago shag Endemic birds of New Zealand