Scarlet Hawaiian Honeycreeper, 'I'wi (Vestiaria coccinea) - Wiki
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[Photo] Iiwi (Vestiaria coccinea). Quelle: von U.S. Geological Survey (http://biology.usgs.gov/s+t/SNT/noframe/pi179.htm bzw. http://biology.usgs.gov/s+t/SNT/noframe/pi179f25.htm ), laut dieser Quelle von J. Jeffrey, U.S. Fish and Wildlife Service, zur Verf??gung gestellt
The 'I'iwi (Vestiaria coccinea) or Scarlet Hawaiian Honeycreeper is a Hawaiian bird of the family Drepanididae, and the only member of the genus Vestiaria. (species Vestiaria coccinea), Hawaiian songbird, one of the commoner members of the Hawaiian honeycreeper family, Drepanididae, order Passeriformes.The 'I'iwi (ee-EE-vee) is one of the most beautiful birds in Hawai'i. A nectar-feeder, named for its squeaky call (“ee-ee-vee”), it is 15 cm (6 inches) long, with a red body, black wings with small white patches, black tail, and sickle-shaped red bill. One of the most plentiful species of this family, which includes many endangered or extinct species, the 'I'iwi is a highly recogizable symbol of Hawai'i. It is found on most the main islands of Hawai'i; however, since the late 1800s, its range has become far more restricted due to introduced diseases. Now the 'I'iwi survives at higher elevations where temperatures are generally too cool for mosquitoes and the diseases they carry.The prime breeding habitat of the 'I'iwi is dominated by the 'ohia-lehua and koa trees with an understory of tree ferns. They forage yet seldom nest in the dryer mamane/naio forests at higher elevations. Like many disease-susceptible endemic birds, they are rare to absent at lower elevations even in relatively intact native forest. The species had a very high mortality rate from avian malaria (Plasmodium relictum) in a series of challenge experiments: more than half of the birds died from a single infected mosquito-bite. The Ibis, a British ornithological journal, which published chapters of a book that was in progress, called Aves Hawaiiensis: The Birds of the Hawaiian Islands.
Description, and Uses
The brilliant scarlet body plumage of the 'I'iwi is perfectly matches the black wings and tail. Their long decurved salmon pink-colored bills are specialized for sipping nectar from tubular flowers. They are small birds, 15 cm long and are 16-20 grams in weight when fully grown. Although the sexes are similar in appearance, males are slightly larger. Immature birds are a paler yellow splotched with brown. Their plain brown bills brighten in color with maturity. 'I'iwis can produce a wide variety of sounds from strange metallic squeaks to clear flute-like calls. The iiwi is one of more than 50 species of honeycreepers that are believed to have evolved from a single ancestral species which colonized the Islands millions of years ago. The birds were caught by professional bird catchers who smeared tree sap onto a branch next to a flower blossom.Sometimes the bird catcher would imitate a bird's song, or recite a special chant to lure more birds. When the bird landed on the branch to sip the flower nectar, it was caught. The feathers were highly prized by Hawaiian ali'i (nobles) for use in decorating 'ahu'ula (capes) and mahiole (helmets), and such uses gave the species its scientific name: vestiaria comes from the Latin for clothing, and coccinea means scarlet-colored. The bird is also often mentioned in Hawaiian folklore. Feeding Habits Although the long bill of the 'I'iwi apparently evolved for feeding from long curved flowers, the bird now depends on nectar from '??hi'a trees, which have tiny flowers.The long decurved bill of the 'I'iwi is beautifully adapted to sip nectar from the long tubular flowers of the native Hawaiian lobelioids. They will pierce a hole in the base of the flower and extract the nectar with their brushy tipped tubular tongues. They are important pollinators for many species of native plants. 'I'iwis also clean insects and spiders off the foliage. They forage high above the ground in the mid to upper canopy, and will defend a feeding territory in a heavily flowering tree. As the lobelioids have declined through habitat loss and extinction, 'I'iwis have shifted to feeding more on other native flowers such as the 'ohia-lehua, koa, naio, and mamane. They will also feed on the flowers of the introduced banana-poka vine, an aggressive alien weed that is choking out native vegetation throughout the islands. These flowers have shorter corollas than the endangered lobelioids. This dietary shift may be reflected in the slight (0.5 mm) reduction in average bill length seen over the past century.
The 'I'iwi is locally common in high elevation (above 1,500 m) mesic and wet forests on Hawaii, Maui, and Kaua'i. They were once found on all of six largest forested islands in the Hawaiian chain but are disappearing rapidly on the lower elevation islands of Molokai and O'ahu. Extensive surveys on O'ahu from 1994 to 1996 located only eight individuals. They have been extinct on Lanai since 1929.Recent research has also confirmed that these birds perform seasonal altitudinal migrations within the island of Hawai'i.
'I'iwis maintain a monogamous pair bond throughout the breeding season. Courtship includes singing, swaying rhythmically on a perch, and wing-fluttering by the displaying male. The female will also take food from the male in a courtship feeding ritual that helps maintain the pair bond. Breeding is timed to coincide with the maximum flowering of the 'ohia trees. The female, with some assistance from her mate, builds a cup nest, made up of twigs, mosses, and lichens high in the top of an 'ohia tree. She lays two whitish eggs with chocolate brown speckles and splotches concentrated at the large end of the egg. Incubation lasts for 14 days. The altricial chicks have bright orange-pink skin covered with white or pale gray down. Both parents feed the young a diet of insects. They grow rapidly and are able to hop out of the nest into the surrounding foliage by 2 weeks of age. They fledge a week later.
Threats to the 'I'iwi
A variety of factors have played a role in the rapid range contraction and dwindling populations of the 'I'iwi and other native Hawaiian birds. Most of the decline is blamed on loss of habitat, as native forests are cleared for farming, grazing, and development. Habitat destruction began with the arrival of the Polynesians and accelerated with the advent of European colonization. Forest habitat loss ranges from 50% on the big island of Hawaii to over 85% on O'ahu. Perhaps the most devastating blow to the Hawaiian honeycreepers came when Culex mosquitoes were accidently introduced to the islands in the 1820s by a ship cleaning out its water casks in an island stream. These mosquitoes carry avian pox and avian malaria, diseases previously unknown to the island's birds. Native birds have virtually no immunity to these diseases. Studies on 'I'iwis have shown that a single bite from an infected mosquito causes death more than 90% of the time. Culex mosquitoes have virtually extirpated many native birds from the lower elevations, but fortunately they are less tolerant of the cooler temperatures of the high altitude forests. Numerous introduced species of birds thrive in the relatively predator free environment and provide a reservoir for avian diseases. Introduced livestock such as pigs, goats, and cattle contribute to habitat destruction. They facilitate the spread of the mosquitoes by destroying the tree fern understory, leaving the hollow decaying trunks of the ferns on the forest floor to fill with rainwater and provide breeding habitat for mosquitoes. Introduced feral cats and black rats prey directly on native birds. Conservation efforts are concentrating on controlling introduced ungulates by direct hunting and fencing projects that exclude them from prime native habitats. Research is underway to identify disease resistant birds that could be used as founders for restored populations.
The Nature Conservancy on Moloka'i has particular interest in preserving the 'I'iwi and other native Hawaiian birds. In order to defend the territory of all native birds, the Conservancy has fenced areas within the Kamakou and Pelekunu Preserves to keep down the pig population. The problem with pigs is their penchant for wallowing, which creates depressions in the rainforest forest floor where water stands. Standing water becomes the incubator for mosquito larva and mosquitoes carry avian malaria, which kills many species of native Hawaiian birds. I`iwi are fairly common on Kaua`i, Maui, and the island of Hawai`i. Their declines on Moloka`i, Lana`i, and O`ahu are likely due to habitat loss, introduced diseases and predation by rats. Although the I`iwi population on the island of Hawai`i is still fairly large, recent evidence indicates that it might be seriously declining. I`iwi appear to be especially succeptible to introduced diseases and it is suspected that their long migrations in search of nectar may lead them into mosquito infested areas where they contract avian malaria and avian poxvirus.
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