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5/15/2015
Blue duck/whio: Wetland and river birds
Printed from: http://www.doc.govt.nz/whio
Blue duck/whio
The whio/blue duck is only found in New Zealand. It is a nationally vulnerable species and faces a risk of
becoming extinct.
Population: Under 3000
Threat status: Nationally vulnerable
Found in: Clean, fast­flowing rivers in the North and South Islands
Facts
The blue duck is one of a handful of torrent duck species worldwide. It is a river specialist which inhabits clean,
fast flowing streams in the forested upper catchments of New Zealand rivers. Nesting along the riverbanks, they
are at high risk of attack from stoats and rats.
Their Maori name is whio whio, and they are found nowhere else in the world.
They are believed to have appeared at a very early stage in evolutionary history. Their blue duck's isolation in
New Zealand has meant that it has a number of unique anatomical and behavioural features.
The whio features on our $10 note, and are rarer than some species of
kiwi.
Predator plague
Blue duck/whio is at risk from a predator plague caused by high levels of
seed production ('beech mast') in 2014.
Battle for our Birds protects whio and other native species from
predators.
Whio Forever
Genesis Energy is partnering with DOC to save whio/blue duck through
the Whio Forever Project.
Genesis’ contribution over the next five years will ensure that all aspects
of the Whio Recovery Plan 2009­2019 can be implemented. This will
effectively double the level of work at recovery sites. Genesis is also
providing technical expertise and staff support for the recovery and
monitoring work.
Whio/blue duck have a number of
unique anatomical and behavioural
features
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Blue duck/whio: Wetland and river birds
Whio/blue duck are mainly active
during early morning and late
evening periods
Whio and chicks
More about whio/blue duck
Territory
Blue duck establish exclusive territories. 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.
Where are they found?
The pre­European 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
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Blue duck/whio: Wetland and river birds
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.
Physical features
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.
The male makes a distinctive high­pitched aspirate sound – “whio”, contrasting with the guttural and rattle­
like call of the female.
Adult length: 530mm; males 1000g; females 800g
Blue ducks moult between December and May.
Behaviour
They are mainly active during early morning and late evening periods, hiding during the day in log­jams,
caves and other such places – some populations have adopted an almost nocturnal existence.
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.
Whio/blue ducks have unique features such as streamlined head and large webbed feet to enable them to
feed in fast moving water
Nesting
Blue ducks nest between August and October, laying 4­9 creamy white eggs. The female incubates the eggs for
35 days and chicks can fly when about 70 days old.
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 down­lined scrapes in caves, under river­side vegetation or in log­jams, 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
Habitat
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.
A few reasons why the whio is so unique:
It is one of only three species amongst the world’s other 159 waterfowl that live year round on fast­flowing
rivers. The others are found in South America and New Guinea.
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.
Where blue ducks still reside in middle­river habitats, population densities and productivity are much
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Blue duck/whio: Wetland and river birds
higher than in typical headwaters. It is likely therefore that the upper­river habitats where blue duck are
mostly found today are not preferred but sub­optimal habitats.
Threat classification
The Department of Conservation species threat classification of blue duck/whio is "Nationally vulnerable".
Blue duck are recorded by the International Union of Conservation for Nature (IUCN) as "Endangered" because it
has a very small and severely fragmented population which is undergoing a rapid decline owing to a variety of
factors, most notably the affects of introduced predators.
Find out more about threats to whio and how you can help.
Blue duck/whio sound recording
Blue duck/whio song (MP3, 1,342K)
1 minute 24 second recording of a blue duck/whio adult pair swimming in a stream communicating and answering
tape recorded calls.
Note: Bird songs may be reused according to our copyright terms. Get help on opening files.
Related links
Whio/blue duck factsheet (PDF, 247K)
Whio surf the rapids (PDF, 5,100K)
Feisty whio (PDF, 3,800K)
Whio still need our help; Being born a whio (PDF, 5,400K)
Spot the whio (PDF, 5,880K)
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Related
Whio video
Watch this video to find out why the highly endangered blue duck or whio is thriving on the Whakapapa
River.
Blue duck/whio fun facts posters
This is a series of posters which contain a heap of fun facts about whio under the title 'We're not
quackers'.
Whio Field Day video
In this video we visit a Wanganui farmer’s Field Day, where the locals sample some pretty tasty goat
curry, learn about predators and find out how they can involved and help protect wildlife.
Whiotastic! video
This video is about how whio or blue duck in Te Urewera Mainland Island after ten years of predator
control. Monitoring whio is a great way of measuring how effective pest control can be.
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