Campbell Island shag (Phalacrocorax campbelli)

Description

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Campbell Island shag fact file

• Description
• Biology
• Range
• Habitat
• Status
• Threats
• Conservation
• Find out more
• Glossary
• References
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Campbell Island shag description

The name shag originates from the Old Norse word ‘skegg’ meaning beard, and refers to the crests of these birds ⁽³⁾; accordingly, the Campbell Island shag has a short, Mohican-like crest on the top of the head. It is therefore strange that the Latin name Phalacrocorax derives from two Greek words meaning bald raven. The plumage on the head, long neck, back and wings is black, with a metallic blue sheen; the chin and underparts are white, and it has a white stripe on its folded wings. The strong, webbed feet are pink, and the base of the bill is orangey-red ⁽⁴⁾. Adults that are not breeding can be distinguished by the lack of a crest, and juveniles are brown rather than black ⁽²⁾. During courtship, the male can be heard making a barking noise ⁽⁴⁾.

Size

Length: 63 cm ⁽²⁾

Wingspan: 105 cm ⁽²⁾

Weight

1.6 – 2 kg ⁽²⁾

Campbell Island shag biology

As a marine bird, the diet of the Campbell Island shag consists of fish and marine invertebrates. They feed in large flocks, sometimes up to 2000 birds, fanning out in a line before diving for prey ^{(2) (5)}. Pursuit-diving is the most common feeding method of the shag, whereby the bird dives from the surface and propels itself underwater using its powerful webbed feet ⁽²⁾. Shags, like penguins, are impressively agile at sea, but appear awkward on land ^{(2) (5)}. The behaviour of shags has given rise to many Māori sayings; someone obviously poised to leave is compared to a shag ready for flight, and the dejected air of a sitting shag gave rise to the phrase, ‘as miserable as a shag on a rock’ ⁽⁵⁾.

It nests on cliffs, on exposed rocky ledges, hollows, or in sea caves, either solitary or in colonies of up to 150 nests ^{(2) (4)}. Sometimes these colonies are mixed with gulls and terns ⁽²⁾. It is thought that the breeding season starts in August or September, and lasts until December ⁽²⁾, during which time two pale blue eggs are laid in a nest made mostly of tussock grass, with other plant matter and debris ^{(2) (5)}. The oldest Campbell Island shag known lived for 13 years ⁽⁴⁾.

Campbell Island shag range

As the name suggests, this bird breeds only on Campbell Island, south of New Zealand, and forages in seas within 10 km of the island ^{(2) (4)}.

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Campbell Island shag habitat

The Campbell Island shag is a marine species, found in open sea and coastal waters. It breeds on sea cliffs, stacks or islets ⁽²⁾.

Campbell Island shag status

Classified as Vulnerable (VU) on the IUCN Red List ⁽¹⁾.

Campbell Island shag threats

The number of Campbell Island shags is assumed to be stable ⁽⁴⁾, and they are not believed to be currently subject to any major threats ⁽²⁾. However, because it breeds on only one small island it is very vulnerable to any future threats or chance events. In the past, it is thought the shag may have been impacted by farming activities on the island. Sheep farming was abandoned in 1931 and the last remaining sheep were eradicated from the island in 1992 ⁽⁶⁾, but a number of introduced plant species from the days of agriculture remain.

Surveys suggest that introduced feral cats may have died out on the island, and the brown rat and Norweigan rat have also recently been eradicated from Campbell Island. Whilst the Norwegian rat was known to have decimated wildlife on the island, none of these introduced mammals are known to have had any impact on the shag ^{(2) (4)}. It is a native bird, the brown skua, which is certainly known to affect the Campbell Island shag, through predation on the eggs ⁽²⁾.

As shags spend the majority of their time at sea, they are very vulnerable to water pollution, particularly oil spills, and impacts from the fishing industry. Fisheries can affect the shag in two ways; over-harvesting of one species may alter marine ecology, possibly affecting the availability of food for the shag, or shags can become entangled in fishing nets. Abandoned nets pose a particular threat ⁽⁵⁾. An increase in the tourism industry in the region, if not properly managed, could pose a threat to the Campbell Island shag, through further accidental introductions ⁽⁶⁾, not all of which could be as harmless as those in the past.

Campbell Island shag conservation

Campbell Island is part of the New Zealand Subantarctic Islands World Heritage Site, a place recognized by UNESCO as having outstanding natural ecosystems and species ⁽⁶⁾. It was the location of a remarkably successful eradication programme, implemented in 2001, which removed around 200,000 Norwegian rats from the island ⁽⁷⁾. Whilst this programme was largely aimed at the reintroduction of the Campbell Island teal and Campbell Island snipe ⁽⁷⁾, the eradication of the rat, and other mammals in the past, could only be a good thing for the shag. Proposed conservation measures specific to the shag include conducting a census of the entire population ⁽⁴⁾. The last one was undertaken in 1975, and therefore a current survey would be useful in determining the status of the Campbell Island shag. It has also been suggested that the sea around Campbell Island should be designated a marine reserve, in which fishing is prohibited ⁽⁴⁾. Hopefully, with such measures in place, the Campbell Island shag will be spared the fate of many other island endemic birds.

View information on this species at the UNEP World Conservation Monitoring Centre.

Find out more

For further information on this species see:

• Birdlife International
  http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3688&m=0

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Glossary

Forages

Searches for food.

Invertebrates

Animals with no backbone.

References

1. IUCN Red List (January, 2007)
   http://www.iucnredlist.org
2. del Hoyo, J., Elliott, A. and Sargatal, J. (1992) Handbook of the Birds of the World. Vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona. .
3. Greenoak, F. (1979) All the birds of the air; the names, lore and literature of British birds. Book Club Associates, London.
4. Birdlife International (April, 2007)
   http://www.birdlife.org/datazone/species/index.html?action=SpcHTMDetails.asp&sid=3688&m=0
5. Te Ara – The Encylopedia of New Zealand (April, 2007)
   http://www.teara.govt.nz/EarthSeaAndSky/BirdsOfSeaAndShore/Shags/en
6. UNEP-WCMC (April, 2007)
   http://www.unep-wcmc.org/medialibrary/2011/06/23/cbb4a1ae/Sub-Antarctic%20Islands.pdf
7. Department of Conservation (April, 2007)
   http://www.doc.govt.nz/templates/page.aspx?id=33380