Iiwi
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Iiwi ( Drepanis coccinea ) |
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| ( Forster , 1780) |
The Iiwi or Iiwikleidervogel ( Drepanis coccinea , syn .: Vestiaria coccinea ) is a songbird from the tribe of the clothes birds (Drepanidini). The species endemic to the Hawaiian Islands is the last surviving member of the genus Mamos . The small but strikingly colored and vocal Iiwi was an integral part of Hawaiian mythology , but its continued existence is threatened today by various factors.
features
The Iiwi is a medium-sized representative of the clothes birds, which when fully grown reaches a size of about 15 cm with a weight between 16 and 20 g. The males are generally slightly larger than their female conspecifics, but there is no more extensive sexual dimorphism that could be used to differentiate between the sexes. The plumage of the Iiwi shows a bright vermilion on the body and head , while the wings and tail are glossy black. For many individuals, the head appears generally lighter than the rest of the body. This is due to the fact that moulting begins on the belly and ends on the head, which means that even older, duller-looking feathers from the previous year sometimes contrast with the other, more shiny feathers. There is a white spot on the inner secondary feathers of the wings, which contrasts strongly with the black of the surrounding feathers. Around the eyes there is a yellowish or pale orange eye ring that is only visible up close. The iris of the eye shows various shades of brown. In addition to the plumage, the 25 to 28 mm long, sickle-shaped, peach- to salmon-colored beak is the most striking feature of the species. The legs sit quite far back on the body and appear rather slender, their coloration roughly corresponds to that of the beak.
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Until the first complete moult, juvenile birds have a completely different color than the adult representatives of the species. The contour feathers on the head and shoulders are greenish-yellow to mustard-yellow and streaked with black stripes and spots. The chin is orange. The wings show shiny black to gray tones, while yellowish colors dominate on the chest, which are replaced by gray and brown tones towards the belly. The beak is initially rather inconspicuous brown and only takes on the characteristic bright color of the adult birds over time.
Confusion with the superficially similar Apapane ( Himatione sanguinea ), which is also native to Hawaii, can occur, in addition to less obvious differences in the red tones of the plumage, however, the significantly shorter and less curved beak of the Apapane and the Iiwi missing white contour feathers on the underside as separating features are used. A study from 2014 was able to show that hybridization takes place between the two species .
behavior
Outside the breeding season, Iiwis spend most of the year alone, but can occasionally be found in small flocks of up to nine birds of their own species or together with other species in mixed flocks. The species does not show any pronounced territorial behavior, only breeding birds defend the area around the nest from approaching conspecifics. However, abundant food sources are defended against other iiwis as well as other birds. While iiwis were originally dominated by various honey-eaters and larger mummies when foraging , today they are at the forefront of the native nectar-eating species in almost all places due to the extinction of various Hawaiian species. Only the entrained Japanese white-eye ( Zosterops japonicus ) and on Maui the crested bird clothes ( Palmeria dolei ) they must submit to continue. The species is considered a resident bird , but sometimes covers long distances in search of food, but whether migrations between the individual islands of the archipelago are also undertaken has not yet been conclusively clarified.
nutrition
Iiwis feed mainly on nectar of flowers of various Hawaiian plant species, with preference being given to the iron wood belonging Ohiabaum and the legume counting Art Sophora chrysophylla be consulted. When taking in the nectar, the birds hang upside down on the flower-bearing branch directly below the inflorescence , so that the long, curved beak points upwards and can be inserted into the petal of the flower with one quick movement . Dozens of flowers can be approached within a few minutes. The menu is supplemented by small invertebrates such as butterflies, moths, grasshoppers and spiders. When feeding the young, caterpillars in particular play a bigger role. Most of the fluid requirements are met by ingesting the nectar, but the birds occasionally drink smaller amounts of water that has collected on leaves or flowers. Foraging takes place exclusively during the day, with the birds being most active in the first two hours after sunrise and the last two hours before sunset. In captivity, Iiwis also accept fruit in addition to artificial nectar. In these cases, the food is usually supplemented with additional protein.
Reproduction
During each breeding season, Iiwis form monogamous pairs, which, however, separate again after the offspring have fledged. During courtship , the male pursues the female he has chosen in flight and then tries to win over the potential partner through loud chants. Here the male hops from branch to branch, flaps his wings and slowly rocks back and forth, these performances are interrupted again and again by short flights. Once couples have found each other, the bond is strengthened through regular feeding of the partner. The female shows her willingness to copulate by a crawling posture and a trembling of the lowered wings. If it comes to nest building, this takes place preferably in the crown of an ohia tree at a height of about seven meters. Both partners participate in the construction of the nest, with the majority of the work being done by the female. The round nest, almost 10 cm in diameter, consists of ohia branches and mosses, in the middle there is an approximately 3.5 cm deep recess in which the eggs are ultimately laid. It is lined with lichen as well as leaves and bark. About one to five days after the nest is completed, the female begins laying eggs, with only one egg being laid per day in the early morning hours. The clutch size is rather small, between one and three eggs, with two eggs being the most common. These are on average about 20 mm long and about 15.5 mm wide. They are predominantly white in color, and chocolate-brown spots of varying degrees can appear, especially at the wider end. The eggs are only incubated at night and in heavy rainfall, and exclusively by the female. The male adult bird does not approach the nest again until the young have hatched, but regularly calls the female from a distance to hand over the food. The incubation period is around 14 days, and immediately after hatching, the young birds are still naked and completely helpless. Their beaks are initially short and straight, only over time do they take on the elongated and curved shape. The eyes open after about five days and the first contour feathers can be seen after a week. After just under two weeks, the nestlings react to disturbances with a quick escape from the nest, but return for a few more days as soon as the danger has passed. They finally fledge after 21 to 22 days, but follow one of the parents for a period of about four months and continue to beg for food before they can finally fend for themselves. Iiwis become sexually mature after just one year and begin to produce offspring themselves.
Vocalizations
The most commonly heard chant of the iiwi is described as "jarring" and "like a rusty hinge". The singing that rises towards the end sounds like ii - wi or ee - vee , which is what gave the species its common name . There are also contact and alarm calls that are supposed to sound like ta - weet , eek or coo - eek . Iiwis are also known to mimic the chants of other species. Both sexes sing all year round, but are particularly heard at the beginning of the breeding season from October to December. The chants are only performed in the hours between sunrise and sunset, with a focus on the early morning and late afternoon. A characteristic feature of the Iiwi is the whirring noise that its flight feathers make in flight and that can still be heard from a distance of 50 to 100 m.
Spread and endangerment
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The Iiwi is an endemic inhabitant of the Hawaiian archipelago, where it is still found today in greater density and distribution on the islands of Hawaii , Maui and Kaua'i . On Oʻahu there are still remnants in the mountains of the Waiʻanae and Koʻolau ranges, while only a few sightings have been reported from Molokaʻi since the 1980s. The species was last reliably detected on Lānaʻi in 1929 and is therefore considered extinct there. Historically, the Iiwi was one of the most common forest birds in Hawaii and could be found on all islands with sufficient forest cover into the lowlands and also in the coastal regions. With a few exceptions, however, the species has now disappeared from all areas below 1000 m above sea level, only in more humid forest areas from around 1500 m do the birds still occur in significant population density. In addition to the advanced deforestation of the lower-lying regions of the islands, the main reason for this is the spread of bird malaria and birdpox , which are spread by mosquitos that are introduced but rarely or not at all in higher-lying areas. The Iiwi is particularly susceptible to bird malaria; birds bitten by mosquitoes infected with the pathogen Plasmodium relictum show a mortality rate of more than 90%. The Iiwi's natural predators include short-eared owls ( Asio flammeus ) and Hawaiian buzzards ( Buteo solitarius ), and feral domestic cats regularly chase after the birds. In addition, Japanese goggles originally introduced to Hawaii for pest control compete with the native Iiwi for food, which also has a negative impact on the species' populations. Clutches and young birds regularly fall victim to introduced predators such as house rats , Pacific rats , brown rats and small mongooses . The IUCN classified the species as "endangered" (status vulnerable ) as of 2016 . The most recent data on the population development come from the early 1990s, when the organization still assumed around 350,000 adult specimens on the islands. Since then, however, a persistently negative population development has been assumed, only two populations - on the windward side of Maui and in the Hakalau Forest National Wildlife Refuge in Hawaii - seem to be largely stable in their population.
Systematics
The German naturalist Georg Forster described the species for the first time in 1780 under the scientific name Certhia coccinea and initially classified it as a tree creeper . For his first description he had several copies that had been collected a few years earlier on James Cook's last great voyage of discovery. The species is considered monotypical today, a subspecies D. c. Postulated by the American zoologist Outram Bangs in 1911 . suavis from the island of Molokaʻi was not recognized. Geographical variations are also missing, which indicates a certain gene exchange between the populations of individual islands in the archipelago. The Iiwi is the last recent representative of its genus. The closest living relatives of the species are the crested birds and the Apapane.
Iiwi and human
The iiwi had a firm place in the religion of the Hawaiian natives due to its striking appearance and its unmistakable song. It is said to have received its red coloring from the demigod Māui , who, according to a legend, is said to have shown the ancient Hawaiians for the first time the beauty of birds - which they themselves could only hear, but not see. The feathers of the iiwi were considered valuable in Hawaiian culture, their red color symbolizing a form of holiness. James Cook reports in his discovery report that the Hawaiians are said to have offered him and his team large quantities of these feathers as commodities. In addition, the indigenous people of the islands used the iiwi feathers and those of other clothes birds to make artistic clothing such as capes, helmets and coats. Some of these pieces consisted of hundreds of thousands of individual feathers. The feathers were also used in the production of religious works of art, such as depictions of Hawaiian gods.
literature
- Harold Douglas Pratt: The Hawaiian Honeycreepers: Drepanidinae . Oxford University Press, Oxford 2005, ISBN 0-19-854653-X , pp. 269–273 ( limited preview in Google Book search).
- Steven G. Fancy, C. John Ralph: 'I'iwi (Vestiaria coccinea) . In: A. Poole, F. Gill (Eds.): The Birds of North America . No. 327 . Philadelphia, PA 1998. (available as PDF at fs.fed.us )
Web links
- Recordings of vocalizations at xeno-canto.org
Individual evidence
- ↑ Pratt, pp. 269-270.
- ↑ Pratt, p. 270.
- ↑ Jessie L. Knowlton, David J. Flaspohler, NC Rotzel Mcinerney, Robert C. Fleischer: First Record of Hybridization in the Hawaiian Honeycreepers: 'I'iwi (Vestiaria coccinea) ×' Apapane (Himatione sanguinea) . In: The Wilson Journal of Ornithology . tape 126 , no. 3 , 2014, p. 562-568 , doi : 10.1676 / 13-054.1 .
- ↑ Pratt, pp. 271-272.
- ^ Fancy & Ralph, pp. 3-4.
- ↑ Pratt, p. 271.
- ↑ a b Fancy & Ralph, p. 5.
- ↑ a b Pratt, p. 272.
- ^ Fancy & Ralph, pp. 2-3.
- ↑ Stephen Mountainspring, J. Michael Scott: Interspecific Competition Among Hawaiian Forest Birds . In: The Wilson Journal of Ornithology . tape 55 , no. 2 , 1985, pp. 219-239 , doi : 10.2307 / 1942558 .
- ^ Fancy & Ralph, p. 7.
- ^ Iiwi Drepanis coccinea. In: iucnredlist.org/. BirdLife International, 2016, accessed April 30, 2020 .
- ↑ a b Fancy & Ralph, p. 3.
- ↑ Pratt, p. 269.
- ↑ 'I'iwi in Hawaiian Culture. In: mauiforestbirds.org. Maui Forest Bird Recovery Project, 2018, accessed May 5, 2020 .
- ↑ Pratt, pp. 278-284.