The ʻIʻiwi (Vestiaria coccinea), pronounced ee-EE-vee, is a "hummingbird-niched" species of Hawaiian honeycreeper and the only member of the genus Vestiaria. It is one of the most plentiful species of this family, many of which are endangered or extinct. The ʻIʻiwi is a highly recognizable symbol of Hawaiʻi. The ʻIʻiwi is the third most common native land bird in the Hawaiian Islands. Large colonies of ʻIʻiwi inhabit the islands of Hawaiʻi and Kauaʻi, with smaller colonies on Molokaʻi and Oʻahu. ʻIʻiwi were extirpated from Lānaʻi in 1929. Altogether, the remaining populations total 350,000 individuals, but are decreasing.
Description and uses
The adult ʻiʻiwi is mostly scarlet , with black wings and tail and a long, curved, salmon-colored bill used primarily for drinking nectar. The contrast of the red and black plumage with surrounding green foliage makes the ʻIʻiwi one of Hawaiʻi's most easily-seen birds. Younger birds have a golden plumage with more spots and ivory bills and were mistaken for a different species by early naturalists.
Even though it was used in the feather trade, was less affected than the Hawai'i mamo because it was not as sacred to Hawaiians. The ʻIʻiwi's feathers were highly prized by Hawaiian aliʻi (nobility) for use in decorating ʻahuʻula (feather cloaks) and mahiole (feathered helmets), and such uses gave the species its scientific name: vestiaria, which comes from the Latin for clothing, while coccinea means scarlet-colored. The bird is often mentioned in Hawaiian folklore. The Hawaiian song "Sweet Lei Mamo" includes the line "The i'iwi bird, too, is a friend".
The bird is capable of hovering, much like hummingbirds. Its peculiar song consists of a couple of whistles, the sound of balls dropping in water, the rubbing of balloons together, and the squeaking of a rusty hinge. At one time the difference in appearance between adults and young gave rise to the belief that they were separate species. Observations of young birds moulting into adult plumage resolved this confusion.
The long bill of the ʻIʻiwi assists it to extract nectar from the flowers of the Hawaiian lobelioids, which have decurved corollas. From 1902 the lobelioid population declined dramatically, and the ʻIʻiwi shifted to nectar from the blossoms of ʻōhiʻa lehua (Metrosideros polymorpha) trees. ʻIʻiwi also eat small arthropods.
These birds are altitudinal migrants; they follow the progress of flowers as they develop grow at increasing altitudes throughout the year. Seeking food at low elevation exposes it to low elevation disease organisms and high mortality. The birds are able to migrate between islands and it is because of this that the ʻIʻiwi has not gone extinct on smaller islands such as Molokaʻi.
In the early winter in January to June, the birds pair off and mate as the ʻōhiʻa plants reach their flowering maximum. The female lays two to three eggs in a small cup shaped nest made from tree fibers, petals, and down feathers. These bluish eggs hatch in fourteen days. The chicks are yellowish-green marked with brownish-orange. The chicks fledge in twenty-four days and soon attain adult plumage.
Linguists derive the Hawaiian language word ʻIʻiwi from Proto-Nuclear Polynesian *kiwi, which in central Polynesia refers to Numenius tahitiensis, the Bristle-thighed Curlew, a migratory bird. The long decurved bill of the curlew somewhat resembles that of the ʻIʻiwi.
Threats and conservation
|This section needs additional citations for verification. (February 2012)|
Although ʻIʻiwi are still fairly common on most of the Hawaiian islands, they are rare on Oʻahu and Molokai and no longer found on Lānaʻi. Most of the decline was from loss of habitat, as native forests were cleared for farming, grazing and development.
Plentiful in two parts of its range, it is listed as a threatened species because of small populations in some of its range and its susceptibility to fowlpox and avian influenza. Ninety percent of all exposed ʻIʻiwi died and the other ten percent were weakened but survived. Habitat restoration projects removed non-native/invasive plants and animal species, including on the Island of Hawaiʻi, around Mauna Kea. Smaller lobelia populations forced ʻIʻiwi to target ʻōhiʻa trees.
Introduced diseases, particularly avian malaria (Plasmodium relictum) spread by mosquitoes. In a series of challenge experiments involving avian malaria, more than half of the ʻIʻiwi tested died from a single infected mosquito bite. ʻIʻiwi generally survive at higher elevations where temperatures are too cool for mosquitoes. Many disease-susceptible endemic birds became rare to absent at lower elevations, even in relatively intact native forest. The ʻIʻiwi were also removed when forests were replaced with farms, plantations, towns, and alien forests.
Altitudinal migration complications population assessment.
On Molokaʻi, The Nature Conservancy preserved habitat by fencing off areas within several nature reserves to keep out pig populations. The pigs create wallows which serve as incubator sites for mosquito larvae, which in turn spread avian malaria.
ʻIʻiwi was formerly classified as a Near Threatened species by the IUCN, but recent research has proven that it was rarer than previously believed. Consequently, it was uplisted to Vulnerable status in 2008. iwi birds...
- BirdLife International (2012). "Vestiaria coccinea". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013.
- Hirai, Lawrence T. (1978). "Native Birds of Lanai, Hawaii" (PDF). Western Birds 9: 71–77.
- Elbert, Samuel H; Noelani Mahoe (1970). Ne Mele o Hawaiʻi Nei: 101 Hawaiian Songs. University of Hawaii Press. p. 92. ISBN 978-0-87022-219-1.
- Smith, Thomas B.; Leonard A. Freed; Jaan Kaimanu Lepson; John H. Carothers (February 1995). "Evolutionary Consequences of Extinctions in Populations of a Hawaiian Honeycreeper". Conservation Biology (Society for Conservation Biology) 9 (1): 107–113. doi:10.1046/j.1523-1739.1995.09010107.x. JSTOR 2386392.
- "ʻIʻiwi" (PDF). Hawaii's Comprehensive Wildlife Conservation Strategy. State of Hawaiʻi. 2005-10-01.
- Polynesian Lexicon Project Online, entry kiwi.1. pollex.org.nz
- BirdLife International (2012). Vestiaria coccinea. In: IUCN 2012. IUCN Red List of Threatened Species. Version 2012.2.