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Teaching resource - Threatened birds

Threatened birds

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Black stilt/kakī.
Black stilt/kakī

Black stilt/kakī

Status: Threatened – nationally critical

The kakī (Himantopus novaezelandiae) is regarded by Ngāi Tahu as a taonga species. Now confined to the Mackenzie Basin, kakï are one of the rarest waders in the world. The braided riverbeds, swamps and tarns of the Mackenzie Basin are its last feeding and breeding grounds.

Most riverbed birds migrate to warmer coastal environments in winter, but kakī usually stay in the Mackenzie Basin and feed on the parts of river and delta that do not freeze over. Kakī can wade out into deeper, slower-moving water than most riverbed birds. They reach down to catch insects, such as mayfly and caddisfly larvae, on the river bottom. Sometimes they dart at insects and small fish in shallow rapids or muddy areas. Unlike pied stilts and other waders, kakī can also feed by ‘feeling’ insects under stones.

If kakī cannot find a kakī mate, they tend to breed with the pied stilt, a close relative. Each pair of kakī defends a territory, and nests alone. They rely on camouflage to protect their eggs and chicks and actively defend their nests. Within hours, newly hatched chicks can hunt for food and swim if necessary.

The Department of Conservation has a management programme based in Twizel to increase kakī numbers. This programme has been successful and kakī numbers have increased significantly from 31 adult birds in 1999 to 93 in 2008.

Black-fronted tern/tarapirohe. Photo: D Veitch.
Black-fronted tern/tarapirohe

Black-fronted tern/tarapirohe

Status: Threatened – nationally endangered

Most terns are sea birds, but the black-fronted tern (Chlidonias albostriatus) lives and breeds inland, only visiting the coast to feed in autumn and winter. Black-fronted terns feed on the wing over main channels, catching insects in the air, or swooping down on fish and insects at the water's surface. They sometimes feed on insects and lizards from surrounding farmland, especially in ploughed fields.

Black-fronted terns nest in loose colonies on open shingle, often on river islands. Their eggs and chicks are well camouflaged. Unlike many other river birds, young terns must remain near the nest, relying on parents to bring them food. To defend their eggs and chicks from intruders, they dart at them, calling loudly while swooping past. Terns often desert their nests if people or predators disturb them.

Of the remaining 5,000 black-fronted terns, 60 percent nest on the rivers and wetlands of the Mackenzie Basin. In the 2008–09 breeding season 762 black-fronted terns were counted in the Tekapo and Ohau riverbeds. At present they are declining in numbers because of loss of suitable habitat and high levels of predation.

Black-billed gull/tarāpuka. Photo: R Morris.
Black-billed gull/tarāpuka

Black-billed gull/tarāpuka

Status: Threatened – nationally endangered

Unlike the common coastal red-billed gull, the endangered black-billed gull (Larus bulleri) visits the coast only in the winter after the breeding season. During the rest of the year, the black-billed gull is found inland, breeding and feeding in colonies on shingle islands in rivers. Nests are found on open shingle areas.

Colonies vary in size and location, because the gulls do not choose the same sites or the same rivers for breeding each year. Young gulls, like terns, rely on their parents to bring food until they can fly and hunt for themselves. Black-billed gulls feed on the wing over the main river channels, catching insects in the air, or scooping fish and insects from the water's surface. They sometimes feed on insects from surrounding farmland.

Wrybill/ngutu pare. Photo: D Veitch.
Wrybill/ngutu pare

Wrybill/ngutu pare

Status: Threatened – nationally vulnerable

Wrybills (Anarhynchus frontalis) are small birds that are well camouflaged amongst the stones of braided riverbeds. They are probably the most specialized braided river wading bird, but sadly, wrybill numbers continue to decline as they are affected by high levels of predation and habitat loss. Wrybills require open shingle habitat to nest in, and feed along the shallow margins of braid channels. Aggressive colonising weeds occupy nesting habitat and stabilise the braids making channel margins too deep for feeding. Reduction in river flows compounds the weed encroachment problem and can make nesting and feeding sites more accessible to predators. Of the remaining 5000 wrybills, approximately 15 percent nest in the Mackenzie Basin. In the 2008–09 breeding season 143 wrybill were counted in the Tasman riverbed.

Wrybill pairs defend a territory and nest alone. They will nest only on flat expanses of gravel, bare of vegetation. They rely on camouflage and distraction behaviours to protect their nest, eggs and chicks. Chicks are active soon after hatching.

Wrybills feed in shallow channels, shallow rapids, and the edges of pools. They are the only bird in the world with a bill that curves to the right. The bill is specially adapted to reach under stones for mayfly larvae. In winter, they migrate to North Island harbours and feed in flocks on the mudflats.

Banded dotterel/turiwhatu. Photo: P Morrison.
Banded dotterel/turiwhatu

Banded dotterel/turiwhatu

Status: Threatened – nationally vulnerable

In the North Island, banded dotterel (Charadrius bicinctus bicinctus) breed mostly on harbours and coastal beaches. However, in the South Island, many live inland on braided rivers and sparsely vegetated river terraces, where they are the most numerous wading bird. While some South Island banded dotterels move to the coasts of both islands during winter, many migrate to the warmer climate of Australia.

Banded dotterels feed on moths, flies and beetles found among scattered low vegetation on the high parts of the riverbed and along the muddy edges of lakes and rivers. While feeding, they show a distinctive run-stop-peck-run movement.

Each banded dotterel pair defends a territory and nests alone. Chicks can leave the nest soon after hatching to follow parents as they forage for food. In the 2008–09 breeding season 847 banded dotterel were counted in the Tasman riverbed.

South Island pied oystercatcher/tōrea. Photo: D Veitch.
South Island pied oystercatcher/tōrea

South Island pied oystercatcher/tōrea

Status: At risk – declining

South Island pied oystercatchers (Haematopus ostralegus) establish territories in South Island riverbeds and surrounding farmland in late July. Between September and January the birds breed. Breeding pairs are very territorial and display with shrill piping calls when other birds or people come too close to their nests.

The pied oystercatcher's long bill allows it to probe deep into mud, sand or under pebbles, to find worms and insects in riverbeds, pasture and ploughed land. During the winter they flock to harbours of both the North and South Islands to feed.

Other braided river birds

Caspian terns/taränui (Threatened – nationally vulnerable), and pied stilts/poaka (At risk – declining), also breed on braided rivers and their side channels and wetlands. Caspian terns are infrequent visitors to upper Waitaki rivers, but pied stilts often make use of shallow braid channels or ponds with low vegetation in rivers and wetlands for feeding and nesting. At least sixteen other bird species, including various shags/kawau, gulls, terns/tara, and herons/matuku, breed and forage in Canterbury's braided rivers and adjacent wetlands.

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For more information contact your local DOC office or email conservED@doc.govt.nz