Kakī, or black stilt (Himantopus novaezelandiae), is a native wading bird only found in New Zealand. It is regarded by Māori as a taonga species – a living treasure.

Once common throughout New Zealand, kakī is now restricted to the braided rivers and wetlands of the Mackenzie Basin, South Island.

Facts about the black stilt/kakī

Black stilt on nest

What do they look like?

Kakī have completely black plumage and long red legs. Young kakī have black and white plumage until 18 months old, when they become all black.

Where are they found?

Once common throughout New Zealand, kakī are now restricted to the braided rivers and wetlands of the Mackenzie Basin, South Canterbury. At the time of European settlement, kakī were found in many of New Zealand’s rivers and wetlands. There was plenty of habitat and the risk of predation was low. As European settlement intensified, New Zealand’s environment began to change. Settlers introduced foreign plants and animals, drained wetlands for development, and channelised rivers. With the spread of new predators and extensive modification of their habitat, by 1981 kakī numbers declined to a low of just 23 birds.

Kakī facts

• Kakī are critically endangered.  
• Kakī are found in braided riverbeds, side streams, swamps and tarns and sometimes on lake margins and irrigated paddocks if there is good feed available. Most riverbed birds migrate to the coast in winter, but kakī usually continue to feed on the parts of river and delta which do not freeze over.
• Kakī first breed when aged two or three years, and are known to mate for life. If they cannot find a kakī mate, they may sometimes breed with the pied stilt, a close relative.
• Each pair of kakī defends a territory, and nest alone, on stable banks near the water in braided riverbeds, side streams and swamps. They rely on camouflage to protect their eggs and chicks, and actively defend their nests.
• Incubation is shared equally by the parents and takes 25 days. Within hours, newly hatched chicks can hunt for food and swim if necessary.
• Kakī are opportunistic feeders, mostly taking aquatic insects, molluscs and small fish.
• They can wade out into deeper, slower moving water than most riverbed birds, reaching 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, they can also feed by using a scything motion with their bill.

Blue duck/whio

The blue duck (or whio; Hymenolanimus malacorhynchos) is a unique threatened species of waterfowl endemic to New Zealand. It is the only member of its genus and has no close relative anywhere in the world.

Facts about blue duck/whio

The Blue Duck (Maori name: "Whio Whio") is a river specialist which inhabits clean, fast flowing streams in the forested upper catchments of New Zealand rivers. They occur nowhere else in the world.

Blue duck establish exclusive territories of up to a kilometre long. Strong pair bonding results in individual pairs occupying the same stretch of river year after year which they aggressively defend against other blue duck, as well as grey duck, paradise duck and even shags or gulls. The larger (1,000 gram) males can live for up to 12 years but smaller (750 gram) females are generally much shorter lived. Nesting and egg incubation of four to seven eggs is undertaken by the female while the male stands guard. Nests are shallow, twig, grass and down-lined scrapes in caves, under river-side vegetation or in log-jams, and are therefore very prone to spring floods. For this, and other reasons, their breeding success is extremely variable from one year to the next.

Blue duck require bouldery rivers and streams within forested catchments which provide high water quality, low sediment loadings, stable banks and abundant and diverse invertebrate communities. With such habitat requirements, blue duck are key indicators of river system health. The higher the number of breeding pairs of blue duck on a given stretch of river, the greater the life supporting capacity of that river.

The pre-European fossil record suggests that blue duck were once throughout New Zealand. They are currently considerably less widespread being limited to the less modified catchments of the Urewera, East Cape and central areas of North Island, and along the West Coast of South Island from Nelson to Fiordland.

There is growing concern for the species as most studies suggest that this already reduced range is continuing to contract. Remaining populations tend to be fragmented and isolated, have low reproductive success and are increasingly dominated by males. It is estimated that about 640 pairs remain on North Island while just under 700 pairs remain on South Island giving a total population of between 2,000 and 3,000 individuals.

This situation has resulted in a Department of Conservation species threat classification of "Nationally Endangered" – similar to kiwi and kokako. Blue duck are recorded by the International Union of Conservation for Nature (IUCN) as "Vulnerable".

Features and ecology

 
A blue duck family in rapids

• Blue ducks have unique features such as streamlined head and large webbed feet to enable them to feed in fast moving water.
• The upper bill has a thick semicircular, fleshy ‘lip’ that overlaps the lower bill allowing them to scrape off insect larvae that cling to rocks, without wear and tear.
• It is one of only three species amongst the world’s other 159 waterfowl that live year round on fast-flowing rivers. The others are found in South America and New Guinea.
• The male makes a distinctive high-pitched aspirate sound – “whio”, contrasting with the guttural and rattle-like call of the female.
• In contrast to other waterfowl, blue ducks obtain all their food (consisting almost exclusively of aquatic insect larvae) and even rear their young, in the fast moving rapids and riffles of their home territories.
• Blue ducks vigorously defend their river territories all the year round. The size of each pair’s territory can vary (average is about 1.5km) depending on the quality of the habitat and food available.
• Blue ducks nest between August and October, laying 4-9 creamy white eggs. The female incubates the eggs for 35 days and chicks can fly when about 70 days old.
• Blue ducks moult between December and May.
• Adult length: 530mm; males 1000g; females 800g
• They are mainly active during early morning and late evening periods, hiding during the day in log-jams, caves and other such places – some populations have adopted an almost nocturnal existence.
• Recent research has found that where blue ducks still reside in middle-river habitats, population densities and productivity are much higher than in typical headwaters. It is likely therefore that the upper-river habitats where blue duck are mostly found today are not preferred but sub-optimal habitats.

Threats to blue duck/whio

Historically, one of the major causes of blue duck decline was habitat loss. Forest clearance for agriculture and poor riparian (river-side) management resulted in reduced water quality. In many other rivers, flows are now manipulated for hydro-electric power generation or irrigation, which has changed the characteristics of the rivers making them unsuitable for blue duck.

Whilst habitat loss still remains a threat to blue duck, other threats are also very important. Even where high quality river habitat remains, predation by introduced mammalian predators is now playing a significant role in the decline of the species. Stoats are perhaps the greatest danger. They attack females on the nest, steal eggs, and take young ducklings from the river’s edge. Feral cats, domestic dogs and ferrets are also known predators of blue duck, while rats and possums have been recorded at nests and are likely to take eggs.

Another as yet un-quantified threat to blue duck is human disturbance. As New Zealand and overseas tourists increasingly utilise wilderness rivers for recreational activities, like white water rafting and kayaking, there is some evidence that disturbance of family groups during the breeding season may have an adverse effect on populations. The use of river courses by hunters and anglers, especially if they have companion or hunting dogs, may also be an issue when the ducks are either breeding or moulting (a period in summer when the ducks lose their feathers to grow a new set - during which time they cannot fly).

Fight for survival

The blue duck is classified as a nationally endangered species, with current populations declining, and unless the causes for its decline are remedied (or reduced), the species faces a very real risk of becoming extinct.

A recent estimate, based on surveys and site records, provided a national figure of approximately 2500 individuals and declining. Blue ducks have been adversely affected by many human induced changes.

In particular:

• The direct loss of suitable riverine habitats due to the clearance of vegetation from stream and river banks, water diversions, poor water quality and damming for hydro-electric and irrigation schemes;
• Increased mortality caused by introduced predators and human disturbance. More recently, research has found that stoats are a major predator of blue ducks, and probable cause of population declines through decreased recruitment of juveniles.
• Possums, cats and dogs are also threats to whio.

Unlike some endangered bird species, blue ducks cannot simply be transferred to off-shore islands to ensure their viability, because they rely on large areas of quality, fast flowing riverine habitat that is unavailable on islands. The continued survival of this species is therefore largely dependent on the protection of secure source populations throughout mainland New Zealand.

Brown Teal, or pateke, is a small dabbling duck species endemic to New Zealand.

They were distributed throughout the lowland freshwater wetlands, forests, and historically the Chatham Islands.

Facts about the brown teal/pateke

Brown teal swimming

The Pateke’s omnivorous diet, restricted annual range and mainly terrestrial lifestyle give it a unique ecological niche among waterfowl, somewhat akin to a wetland rodent, and it serves as a classic example of the influence of selective forces that operated on birds in pre-human New Zealand.

The Pateke were once widespread throughout New Zealand but are now rare and restricted to Great Barrier Island and coastal valleys of eastern Northland plus several predator free islands.

The species has suffered an ongoing decline in numbers and range since the late nineteenth century.

There are currently fewer than 1000 Pateke living in a wild state in New Zealand, making it New Zealand’s rarest waterfowl species on the mainland.

Pateke: features and ecology

• They now number around 1000 birds nationally concentrated in two remnants, Great Barrier Island (where approximately 700 reside) and Northland (where around 300 reside)
• Their habitat is within broad lowland valleys comprising of short-grass pasture, streams, wetlands, estuaries and associated riparian vegetation
• They feed at night on invertebrates, fruits, seeds, and vegetation.  These are generally found in damp or flooded pasture, lawns, drains, shallow wetlands, estuaries, and wet forest habitats
• Pateke nest in winter and spring in rushes, sedges or under banks.