Blue Duck
Saumschnabelente - the beak end of the dark membrane is seen
The Saumschnabelente ( Hymenolaimus malacorhynchos ), and Blue Duck, Blue Scaup or onomatopoeic called after the call of the male Whio, is a species in the order of the ducks. The majority of insects live duck is the only species belonging to the genus Saumschnabelenten and ranks along with the Laysan, Bernier and Madagascar duck of the rarest species of ducks in the world. Their occurrence is restricted to fast flowing, clear and rubble -filled streams and rivers in New Zealand. The population numbers have declined markedly in recent years. The reasons for habitat loss, an increased predation pressure from introduced in New Zealand species such as weasels, martens and feral cats and possibly a food competition is one of the also introduced rainbow trout. The IUCN classifies the Saumschnabelente one as endangered ( endangered ) and estimates the backlog at 1,200 mature individuals.
Similar to other endangered New Zealand bird species such as the kakapo, the Südinseltakahe and the Kiwis are tried in New Zealand by various measures to increase the stock figures again.
- 5.1 Food and foraging
- 7.1 Literature
- 7.2 External links
- 7.3 footnotes
Appearance
Appearance of adult Saumschnabelenten
Saumschnabelenten are lighter and smaller than the European Mallard. The average body weight of an adult drake is 890, that of an adult female at 750 grams .. The wing length is 23.5 to 25 inches.
The plumage of drake and duck resembles to a large extent. Ducks are only slightly smaller than the drakes generally. The plumage on the front body top, called the coat is blue-gray with gray-brown Sprenkseln. The breast is mottled red-brown and blue-gray. For individuals doing outweigh the russet hues. The blue-gray shoulder feathers, called Scapulare are thin lined black. The tail-coverts, flanks, and the wings are plain blue-gray. Neck and head feathers are feathered uniformly dark blue - gray. The region between the eyes and the beak beginning shimmers greenish. The feet and legs are flesh-colored. The iris is yellow to orange. The beak is pale flesh-colored to yellowish, the beak end is black.
At their lives in fast-flowing waters Saumschnabelenten adapted by several features. The eyes of the Saumschnabelente are as in the skull, that the field is aligned for breeds of ducks unusually far forward. Some ornithologists this is interpreted as an adaptation for their hunt for aquatic insects. The beak of these breeds of ducks has at its end on a dark and soft membrane that protects the mouth from injury when the ducks are on the growth of stones for insects.
Saumschnabelenten swim relatively high in the water. This allows them to stay in very choppy waters above.
Appearance of the chicks and not yet fully grown ducks
The chicks are black gray on top of the head, back, wings, thighs and belly sides. The face is white-gray, over the eyes, which are in contrast to the adult birds are dark in color, runs a dark reins. The white- gray eyes About strips are separated on the forehead by a thin black stripes. The chest, the body bottom, the front neck and the rear edge of the wing are also feathery white gray. The bill is still in the chicks from dark gray blue color. With about eight weeks to change the chicks in the first juvenile plumage.
Not yet fully grown Saumschnabelenten differ from the adult ducks by an overall duller plumage coloration. When they miss the red-brown Brustfleckung or is less pronounced. It also lacks the black Federsäume the Scapulare. The beak is still bright blue graun, the iris dark brown in color. The typical adult Saumschnabelenten flesh-colored beak color and the bright yellow to orange-colored iris have young ducks on from her ninth month of life.
Flight image
Saumschnabelenten regarded as one of the ducks, fly up very reluctant. They move mostly gone swimming and running. Already, however, very young chicks have high bounce, which allows them to jump on protruding from the water boulders. Despite the low flight attitude are Saumschnabelenten powerful flier, where one has counted up to 480 wing beats per minute. Single observations of this so far inadequately studied breeds of ducks suggest that the ducks flying patrol their territory at dawn. During flight, the Saumschnabelenten in flight image neck and head stretch horizontally forward. They fly mostly just above the water surface.
Voice
The drake give loud, shrill whistles of himself that can be heard over the roar of the mountain streams and rivers. The calls are like a " whio " which coined the onomatopoeic names that have given this breeds of ducks, the Maori. Of these females whistles are not heard. To respond to the calls of the male with a quieter, darker in tone rumble.
Dissemination
Saumschnabelenten are limited in their distribution to New Zealand and are found on both the South and the North Island.
Originally came breeding populations of Saumschnabelenten on both islands of New Zealand wherever there before, where the shores clear rubble rich, fast-flowing and shallow waters were covered with a dense forest. Typical Saumschnabelentenreviere had a partly shaded watercourse and a largely stable water level, as strongly fluctuating water levels and especially flood entrains the algae and Moooswuchs, in settling the important food for aquatic insects. Where the rivers kept their fast-flowing character and the shore was wooded, the ducks populated the rivers up to their estuary on the coast. Most rivers reported such suitable habitats only at its upper and middle reaches. Saumschnabelenten were to be found here up to the alpine timberline. The forest surrounding these sections or in natural regions still surrounds it, was the endemic deciduous forest - tree fern forest in New Zealand. The population density along such rivers and streams could be very high. Even in the 1960s was an employee of a New Zealand Conservation Authority, who traveled along two rivers running through pristine forests, every few hundred meters a set with a pair Saumschnabelente breeding grounds.
Several factors have led to the number of stations, the Saumschnabelenten provide suitable habitat, has significantly decreased. Even the settlement of New Zealand Maoris by about eight hundred years ago meant that the forests of New Zealand reduced by a quarter. The Maori arrived dogs and the Polynesian rat to New Zealand, which are both potential predators of Saumschnabelente. Archaeological investigations at waste heaps of Maori suggest that Saumschnabelenten only occasionally were among their prey.
Since the settlement of New Zealand by Europeans about 200 years ago, the forest cover has declined by a further quarter. Logging has also changed the structure of these forests, the construction of hydroelectric power plants has destroyed a number of habitats. At least as serious as the reduction of the forest has been carried out on the fauna of New Zealand associated with European settlement, introduction of a variety of invasive species. Among the introduced species include the red fox, marten, weasels, domestic cats, deer, opossum, the brushtail possum, ovine, swine and goats, Canada Goose and rainbow trout.
The introduction of these species and the change in the forests have endemic species was threatening implications for a number in New Zealand. Among the best known examples is the owl parrot Kakapo or whose survival we try to ensure that, by trying to locate the Remainder in imported animals are still free islands.
Stock
The Saumschnabelente was up in the 1990s as one of the endemic species in New Zealand, their potential settlement area had indeed reduced and their stocks were significantly decreased. Saumschnabelenten but were not considered a directly endangered species the survival of the species was seen backed up, because there was apparently a sufficient number of suitable habitats. The specialized ducks ornithologist Hartmut Kolbe gave the stock figures of this kind yet for 1995, with 2,000 to 4,000 individuals and as a distribution area the interior of the North Island of New Zealand as well as the entire western half of the South Island. Already Kolbe Hartmut pointed out, however, that increasingly suitable habitats remained vacant when the adult birds died.
Since the beginning of the new millennium, the assessment has changed over the inventory status of Saumschnabelenten. 2003 has been classified as highly endangered, the World Conservation Union, the kind. The main reason for this assessment is the recognition that Saumschnabelenten exist today in each other isolated populations, between which there is no exchange. Each of these isolated populations of which is threatened with extinction by natural disasters such as forest fires or other habitat destruction. The increased pressure from introduced predators and competitors for food has also led to a change in the habits of the Saumschnabelenten which endanger the recovery. This also applies to the New Zealand areas that have been preserved apparently still largely in original condition and is now considered to be the areas with the densest Saumschnabelentenpopulation. The organization now operates the Te Urewera National Park, the largest area of unspoilt forests in the North Island and New Zealand's largest National Park, Tongariro National Park, the West Coast of the South Island and the New Zealand Fiordland and the area around Mount Taranaki and the Kahurangi National Park.
Way of life
Saumschnabelenten belong to the so far relatively little studied species of ducks. First intensive field studies conducted in the late 1960s by the British ornithologist Janet Kear, which belonged to the Wildfowl Trust. Most of the findings are still valid today date back to these investigations.
Food and foraging
Saumschnabelenten eat the larvae of caddis, stone and ephemera. This they collect from partially submerged by the boulders in the river or stream bed. Saumschnabelenten are also able to catch adult and capable of flying insects from the air. During the New Zealand winter half- year, they also eat a variety of berries.
The aquatic insects, which constitute the bulk of the food of the Saumschnabelente be eaten by the introduced rainbow trout in New Zealand preferred. The effect of rainbow trout on the stock of Saumschnabelenten is so far not been adequately studied.
System
The Saumschnabelente is allocated together with the mirror geese, the goose bumps gloss, the shelduck, the Spatelschnabelente, the torrent duck and the steamer ducks of the subfamily of half- goose