One-third of the world’s shag species are found in New Zealand, where they are icons of lake and coastal landscapes. The diverse shorelines and rich marine and freshwater resources offer many habitats for these elegant, straight-flying birds.
Often seen perched on rocks or trees drying their outspread wings, shags are large birds with long hooked bills, snaky elastic necks, and powerful webbed feet for underwater hunting. Of the world’s 36 shag species, 12 are found in New Zealand. Eight of these are endemic – they are found nowhere else. The remaining four are native to other countries as well as New Zealand. All except the black shag are fully protected by law in New Zealand, and it too is protected except in special circumstances.
The various shag species have evolved to specialise in different environments. Some are coastal, and have adapted to feed in either shallow or deeper water. Others are found inland, where they dive for fish and other prey in lakes and rivers. Several that live on offshore islands have probably evolved into new species through isolation.
Members of the shag family belong to three groups, based on the colour of their feet: black, yellow or pink. Outside New Zealand, the black-footed shags are better known as cormorants.
Shags capture and eat fish larger than would seem possible. The New Zealand naturalist Edgar Stead observed a black shag catching a 60-centimetre eel:
[T]he Shag is able to hold it without difficulty, for the edges of its bill are so sharp they can cut into the eel’s skin and so give a good grip … I have seen an eel half swallowed by a Shag give (no doubt when its head came into contact with the bird’s gastric juices) such a convulsive heave that it flipped itself clean out of the bird’s throat. 1
Shags capture their prey by chasing it underwater (pursuit diving), propelling themselves with powerful webbed feet. They can stay underwater for an extraordinary length of time. A king shag in the Marlborough Sounds was clocked diving for 190 seconds in search of prey, while a pied shag lasted 220 seconds before coming up for air. But although they might be agile at sea, shags are as awkward as penguins on land.
Compared to other seabirds such as penguins or petrels, shags have less fat to keep them warm. In addition, so that they can dive better to catch their prey, their feathers are less oily, and can become partially waterlogged. As a result they are at risk of hypothermia if they are in the water too long. Studies show that shags in cold waters catch fish at a very fast rate. At the end of a fishing expedition, they characteristically hang out or flap their wings to dry and get warm again.
Of the four species of black-footed shag (Phalacrocorax genus) living in New Zealand, the best known and most widespread is the black shag or kawau (Phalacrocorax carbo novaehollandiae). This subspecies, found in Australia and New Guinea as well as New Zealand, belongs to a species which is also found extensively elsewhere – in Europe, Asia, Africa and North America – where it is known as the great cormorant. In some parts of the world, such as China and Japan, it has been trained to capture fish for humans; a ring around the neck prevents the bird swallowing its catch.
At 88 centimetres long (from bill tip to tail tip) and weighing 2.2 kilograms, the black shag is the largest. Found both on the coast and in fresh water inland, it feeds on fish, crustaceans and invertebrates. Black shags are fairly common in New Zealand, with a population estimated at 5,000–10,000 breeding pairs. They nest mostly in trees but occasionally on rock ledges, laying two to five blue-green eggs from June to October. The young fledge at about seven weeks. They are thought to live for up to 20 years.
The black shag has a reputation among fishermen for robbing them of trout. As a result, between 1890 and 1940, acclimatisation societies put a price on them and many shag colonies were destroyed. In his 1945 publication The shag menace, angler H. G. Williams demanded a wholesale destruction of the black shag in order to ‘make the Dominion’s waters worthy of the claim to be the anglers’ Paradise.’ 1
Anglers the world over share this view of the black shag’s appetite for sport fish, and in Denmark and other countries, hunters are allowed to shoot them. But in New Zealand, after studies showed that shags have little impact on fish stocks, the black shag was partially protected in 1986. A landowner can still kill them if they damage crops or commercial property. During the duck season, hunters still shoot them, sometimes failing to distinguish between common and rare shags.
Crew on the Tangaroa, a government research vessel, observed unusual behaviour by immature black shags on a cross-Tasman trip in 1978. Some of the shags followed the ship, and came on board at night, sleeping among the anchor gear. Sometimes during the day they would perch in the rigging. It appeared that having only recently learned to fly, they were at times exhausted, and grateful for the nearby roost.
Conspicuously dressed with greenish-black plumage and a dazzling white front, the pied shag (Phalacrocorax varius) typically breeds in pōhutukawa or pine trees overhanging the sea. They are primarily coastal, preferring warm sheltered sites such as harbours, and feeding on fish and eels. They are found in the north of the North Island and the south of the South Island and Stewart Island. Despite feeding only in coastal waters, some nest on freshwater lakes.
Slightly smaller than the black shag, the pied shag measures about 80 centimetres long and weighs about 2 kilograms. In terms of population size, breeding, fledging and lifespan, it is similar to the closely related black shag.
Found in other parts of Australasia, the little black shag (Phalacrocorax sulcirostris) was first reported in New Zealand in 1840 and since then has expanded to most of the North Island. It is only occasionally seen in the South Island. It likes to feed in packs; scores or even hundreds of the birds herd and trap small fish against a barrier in a frenzy of feeding. Adapted to both freshwater and coastal environments, its main foods are fish, bullies, whitebait and freshwater crayfish. It is fully protected.
As the name implies, the little black shag is smaller than the black and pied shags, just 60 centimetres long and weighing 800 grams. There are between 1,000 and 5,000 breeding pairs. Like the other black-footed shags they lay two to five blue-green eggs, but breed later, in November–December. The life span is around nine years.
At two-thirds the size of the black and the pied shag, the little shag is New Zealand’s smallest, measuring 56 centimetres long and weighing 700 grams. The species Phalacrocorax melanoleucos is found in Australia and other parts of the east Pacific; the subspecies Phalacrocorax melanoleucos brevirostris is found throughout New Zealand, where it is protected. There are between 5,000 and 10,000 breeding pairs.
Known to Māori as kawaupaka, it comes in a variety of plumages: juveniles are all black, whereas adults are black on the back with various white front markings – sometimes just at the throat, or covering the whole front, or a mix of the two. It is equally at home in fresh or salt water, and eats fish, freshwater crayfish, smelt, bullies, and sometimes frogs and tadpoles. It tends to feed close to shore in shallow waters.
Little shags live for up to six years. They live in large colonies of about 200 nests, laying two to five pale blue-green eggs between August and February. Nests are usually built in large trees.
Pink-footed shags belong to the Leucocarbo genus. They are part of a group of cold-water shags found on islands in the Southern Ocean, on the Antarctic Peninsula and the south coasts of Australia and South America. They all feed at sea. The six New Zealand species are found nowhere else. They nest on rock rather than in trees, which are absent in many of their habitats.
The largest of the group is the king shag (Leucocarbo carunculatus) – 76 centimetres long and weighing 2.5 kilograms. It is known to Māori as kawau pateketeke. When the Resolution anchored in the Marlborough Sounds on Captain James Cook’s second voyage in 1772, the German naturalist Johann Reinhold Forster and his son Georg took a specimen of this striking black and white bird.
Breeding in colonies, they spend months building twiggy nests on rock, and lay one to three eggs between May and June. They tend to feed in sea water that is 20–40 metres deep, taking flounder, sand eels, cod and other fish as well as crayfish and crabs from the sea floor. Their dives last from 45 to 90 seconds.
A count in 2001 found there were just 650 king shags. Considered to be among the world’s rarest seabirds, the king shag has been rated ‘vulnerable’ by the World Conservation Union. It was once widespread (fossil bones dating between 2,000 and 3,000 years old have been found in Northland and elsewhere), but is now found only on islands around the Marlborough Sounds; most likely their numbers were reduced by Māori through hunting. Nelson Māori used to lower men over cliffs by ropes to capture the big birds on their roosting sites.
More than most shags, the king shag is very easily frightened. It is scared off by people landing on the islands where it breeds, and is disturbed by boats that approach closer than 100 metres.
Closely related to the king shag is the Stewart Island shag (Leucocarbo chalconotus), which breeds from North Otago down to Stewart Island. Breeding and roosting in flocks on steep cliffs and rugged offshore islets, this shag has two distinct colour phases or forms – one wholly black with a greenish gloss (in this form the bird is sometimes named the bronze shag), and the other black and white – giving rise to the belief that they are two separate species.
The Stewart Island shag is smaller than the king shag, measuring 68 centimetres, but similar in weight at 2.5 kilograms. It is considered rare, with the population estimated at 1,600–1,800 breeding pairs. Twiggy nests are built in cliffs, and one to three pale blue eggs are laid from September to November. The shags feed on bullies, as well as fish, crabs, shrimps and octopus taken from the sea floor in water less than 30 metres deep.
Mere specks in a vast ocean, New Zealand’s southern offshore islands are home to four species of pink-footed shags, whose ancestors probably colonised the islands by chance. As they were not well adapted for long-distance flight, they remained separated and evolved into distinct species. All four are classified as rare, and are not found outside each group of islands.
The Chatham Island shag (Leucocarbo onslowi) is endemic to the Chatham Islands. It is similar in size to the Stewart Island shag, and has a population of 500–1,000 breeding pairs. Pale blue eggs are laid from August to December in nests perched on high rocky sites. The birds feed mainly in deep offshore waters, taking fish (flounder, bullies), octopus, squid and cuttlefish.
The Bounty Islands are a small, isolated group of bare granite rocks in the Southern Ocean, 820 kilometres east of Stewart Island. The Bounty Island shag is found only on these islands, which it shares with thousands of other seabirds and many seals. A survey in 1997–98 found 368 shags. On average they are 71 centimetres long and weigh 2.5 kilograms. They build nests on rock using seaweed they collect by diving to depths of 10 metres. Two or three pale blue eggs are laid in October–November. Food includes fish, squid, isopods (slater-like crustaceans) and sea urchins.
In Māori sayings, someone obviously poised to leave is compared to a shag (kawau) ready for flight: ‘Ka maro te kaki o te kawau’ (the shag’s neck is stretched out). People on a determined course of action are ‘me kawau ka tuku ki roto i te aro maunga’ (like a shag making for a mountain face). Shags also symbolise tenacity: ‘E kore te kawau e neke i tona tumu tu’ (the shag will not move from his stump).The dejected air of a sitting shag gave rise to the Kiwi phrase, ‘as miserable as a shag on a rock’.
The Auckland Island shag (Leucocarbo colensoi) breeds on the subantarctic Auckland Islands. This is a medium-sized species, at 63 centimetres long and 2 kilograms in weight. There are fewer than 1,000 breeding pairs. Nests are mostly built on ledges or tall basalt columns along the cliffs, preferably under an overhang for protection from skuas. Three pale blue eggs are laid between November and February, and incubation is around 28 days. Their diet is fish and marine invertebrates.
Campbell Island is 700 kilometres south of New Zealand. The Campbell Island shag (Leucocarbo campbelli) is also 63 centimetres long and 2 kilograms in weight. There are about 1,000 breeding pairs on the island. Two pale blue eggs are laid between November and February. One bird on this island was recorded living at least 13 years. The birds feed in large flocks, fanning out in a line before diving. They forage in harbours as well as far out to sea, and feed on fish and marine invertebrates.
Yellow-footed shags belong to the Stictocarbo genus, which is found only in New Zealand. The birds are remarkable for their spotted plumage and brightly coloured facial patches when breeding.
Spotted shags (Stictocarbo punctatus) are best known for their striking breeding plumage, double crest and bright green facial skin. The pale grey front and light brown back and wings differ from the more common black and white shag colours. The Māori name is parekareka, and in Canterbury they are locally known as ‘flip-flaps’, from their laboured take-off from the water.
Spotted shags are of medium size – 70 centimetres long and weighing 1.2 kilograms. There are about 30,000 breeding pairs, and they nest in colonies of up to 700 pairs on rocky islets or coastal cliffs. They feed further offshore than many other shags, preferring rocky zones. They are found in two areas of the North Island (near Auckland and in Wellington Harbour), and around much of the South Island. A south-western South Island and Stewart Island subspecies is known as the blue shag (Stictocarbo punctatus steadi).
They lay one to four pale blue eggs, and laying times vary throughout the country. The young leave the nest at around two months. To feed they travel up to 15 kilometres from the shore and take small fish and marine invertebrates. The oldest recorded age is 10 years.
This shag (Stictocarbo featherstoni) is found only on Pitt Island and nearby Chatham Island. The population of around 650 breeding pairs is scattered in small colonies of up to 20 pairs, usually away from the pink-footed Chatham Island shags. They lay one to four pale blue eggs from August to December. They feed alone, mainly on small fish and marine invertebrates.
Ell, Gordon. Seashore birds of New Zealand. Auckland: Bush Press, 1984.
Heather, Barrie D., and Hugh A. Robertson. The field guide to the birds of New Zealand. Rev. ed. Auckland: Viking, 2000.
Higgins, P. J., and others, eds. Handbook of Australian, New Zealand and Antarctic birds. 6 vols. Melbourne: Royal Australasian Ornithologists Union and Oxford University Press, 1990–2002.
Reader’s Digest complete book of New Zealand birds. Auckland: Reed, 1985.
http://www.doc.govt.nz/upload/documents/science-and-technical/TSOP16.pdf
This online article in PDF format (236 pages, 1.89 MB download) by Graeme A. Taylor is part of the Department of Conservation’s series on threatened species.
http://www.doc.govt.nz/upload/documents/science-and-technical/TSOP17.pdf
A second article in PDF format (203 pages, 1.6 MB download) by Graeme A. Taylor, discussing non-threatened seabirds, their habitat, and conservation issues.
http://www.nzbirds.com/birds/kawau.html
This page on the NZ Birds site presents a commentary on shags by site manager Narena Olliver. The website has information on many New Zealand species, as well as news and links to related sites.