Endangered
Blue Duck
Hymenolaimus malacorhynchos
The blue duck or whio is a member of the duck, goose and swan family, Anatidae and is endemic to New Zealand.
Appearance
The plumage is a dark slate-grey with a greenish sheen on the head, a chestnut-flecked breast. The outer secondaries are tipped with white and the inner ones have black margins. The plumage of the two sexes are mostly the same, although the female has slightly less chestnut in the chest.
When ducklings learn to fly, they lose contact with their parent blue ducks that by then becomes flightless.
The blue duck is 50–55 cm (20–22 in) long and varies in weight by sex. Females are smaller than males, weighing 680–870 g (24–31 oz), whereas the males weigh 820–970 grams (29–34 oz).
Published measurements include mass about 897.
Range and habitat
After the human settlement when the forests were being cleared, its population started to decline. Charlie Douglas in 1891 surprised on the blue duck's quick disappearances during an exploration of Waiatoto River remarked that: The ferrets have not got among the birds on this river evidently, as kakapos are squealing about in hundreds. Historical evidence suggests that it once inhabited the offshore islands of New Zealand and not just the North Island and South Island.
There are two subspecies of the blue duck, one in North Island and the other in South Island. It was last commonly seen in New Zealand in the 1950s following that stoat predation caused its further population decline and limiting it to only North and South Island.
Pins are Wikidata “endemic to” fields. Orange dots, when present, are GBIF occurrence tiles — survey bias included.
Diet and breeding
The blue duck feeds almost entirely on aquatic invertebrate larvae. A study of blue ducks on the Manganuioteao River in the central North Island found the most common prey items were Chironomidae (midge) and cased caddisfly larvae, although cased caddisfly were less preferred and were only consumed so much because of their abundance.
Other prey included mayfly, Aoteapysche (net-building caddis) and stonefly larvae. While nesting, they usually lay six eggs and breed within one year.
In crisis
It is the only individual species belonging to the genus Hymenolaimus. The European voyages led to more human settlement in New Zealand, causing a loss of forests, and that started the decline of Blue duck in the country.
Blue Duck is Endangered on this catalog because that is the IUCN category stored on Wikidata. Confirm the official criteria and any later count on iucnredlist.org.
Sources
Written for this catalog from the English Wikipedia article on Blue Duck, Wikidata item Q420499. Family and order context is original field-guide writing about the group, not a copied assessment of this one species. Wikipedia text is CC BY-SA. Not an IUCN assessment. Counts, when quoted, can change — confirm them on the recovery programme and on iucnredlist.org.
