The blue duck or whio (Hymenolaimus malacorhynchos ) is a member of the duck, goose and swan family Anatidae endemic to New Zealand. It is the only member of the genus Hymenolaimus. Its exact taxonomic status is still unresolved, but it appears to be most closely related to the tribe Anatini, the dabbling ducks.
The whio is depicted on the reverse side of the New Zealand $10 banknote.
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CrepuscularCrepuscular animals are those that are active primarily during twilight (that is, the periods of dawn and dusk). This is distinguished from diurnal...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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InsectivoresAn insectivore is a carnivorous plant or animal that eats insects. An alternative term is entomophage, which also refers to the human practice of e...
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SemiaquaticSemiaquatic animals are those that are primarily or partly terrestrial but that spend a large amount of time swimming or otherwise occupied in wate...
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WaterfowlWaterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans. They ...
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PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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Island endemicIsland endemic animals are found in a single defined geographic location, such as an island. Animals or organisms that are indigenous to a place ar...
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NatatorialNatatorial animals are those adapted for swimming. Some fish use their pectoral fins as the primary means of locomotion, sometimes termed labriform...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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Not a migrantAnimals that do not make seasonal movements and stay in their native home ranges all year round are called not migrants or residents.
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starts withThe Blue duck is a native of New Zealand, where its Maori name is “whio”. It is the only member of the family Hymenolaimus. It inhabits fast-flowing inland streams, nesting along the riverbanks, where predation is a threat. It is a powerful swimmer and generally reluctant to fly. The Blue duck has dusky blue-grey plumage and chestnut markings on the chest. This species is rare and is listed as endangered.
The Blue duck lives only in the North and South Islands of New Zealand, in the west of the South Island, especially in Otago and Southland, as well as in the central North Island within national parks. It usually occurs in alpine river regions, favoring cascading, bush-fringed rivers, as well as streams within gorges. It is rarely seen on open or side creeks but lives only on fast-flowing rivers, which supply all its food.
Blue ducks feed while swimming, by dipping their head and neck beneath the surface of the water. They also dive well and dabble, upending, pecking in the shallow water, and taking insects from rocks. This bird can detect its prey by sight, due to its wide binocular field of vision, and it can also see directly forwards. It forages early in the morning and in the late afternoon, sometimes by night. This species is commonly seen in pairs, remaining in the same section of river and shore for the whole year and often for life. The birds are very terrestrial and will usually chase all intruders away from their area. Its blue-gray plumage blends well into its surroundings, and only its pale bill is visible when it moves its head. When disturbed, it dives into the fast-flowing current and swims rapidly away or it flattens onto rocks and waits, looking out for an intruder or predator. The male makes high-pitched whistling as advertising calls and when defending territory. With intruders, a short “whi” or “whio” is heard, and the female will give guttural, rasping growls when disturbed or threatened.
Blue ducks are carnivores (insectivores), they mainly eat invertebrates: caddis-fly larvae, aquatic insects and grubs that fall from trees. Algae and berries are also eaten, especially in autumn.
This species is monogamous. They are thought to remain in a pair for life and to defend the same territory during their nesting period. Pairs will defend small territories of a size of 0.7 to 1 km beside a river. These birds are solitary nesters and once the breeding season is over, they stay in family groups. From August to December is the breeding season. Birds nest near water, under overhanging rocks, on banks under thick vegetation, in a hollow log, a rock crevice or a small cave, no more than 30 m from the water, where there is a threat from spring floods. 4-7 creamy white eggs are laid, incubated by the female for 33-35 days while her mate remains in close vicinity. Soon after hatching, the young can swim and dive. They stay with their family group within the territory for 70-80 days, tended by both parents. The adults molt while their young are unable to fly. Most females mate when they are one year old but males do not breed until they are two years old.
Blue duck numbers have declined due to habitat loss and disturbance, predation, particularly by non-native mammals, competition with introduced trout, and population fragmentation. Human recreational activity and hydroelectric dams on rivers also disturb this species.
According to the IUCN Red List, the total Blue duck population size is 1,800 individuals, including 1,200 mature individuals. According to the New Zealand Birds Online resource, there are unlikely to be over 1,000 pairs in the total breeding population. Currently this species is classified as Endangered (EN) on the IUCN Red List and its numbers today are decreasing.
Blue ducks are important in their riverine habitats as predators of aquatic insects, thus controlling their populations.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...