The Hawaiian Honeycreepers (subfamily Drepanidinae of family Fringillidae; sometimes treated as family Drepanididae) evolved and diversified in the Hawaiian Archipelago from a single ancestral colonist, almost certainly a cardueline finch resembling modern-day redpolls, goldfinches and siskins (Carduelis), or their close relatives. This group represents a classic example of adaptive radiation and when scientists first encountered the species from this radiation in the late 1700s, they were initially assigned to several different bird families based on their diverse morphology, behavior, and ecology. An unusual and important clue to their common ancestry was a shared distinctive musty aroma, apparent in both live birds and dead specimens, that was first reported in the literature by R.C.L. Perkins, a pioneering investigator of Hawaiian biodiversity. Morphological, behavioral, paleontological, and genetic investigations have now firmly established the monophyly of this group.
This group includes nearly two dozen extant species and at least 16 additional species that have gone extinct since 1600. These are small to medium sized (10-19 cm) passerines with highly varied morphology and colors ranging from dull olive green to bright red or yellow. Various honeycreeper species are found in wet and dry forests and even in atoll vegetation.
As a group, the Hawaiian Honeycreepers have not fared well in the face of human colonization of Hawaii. By the time Europeans first visited the islands, in 1778, virtually all the lowlands had been deforested, seabirds were breeding only on offshore islets, and half of the avifauna present prior to settlement by seafaring humans (Polynesians), including many honeycreepers, had already been driven to extinction. A rich record of non-mineralized "sub-fossils", some with recoverable DNA, has revealed that numerous honeycreeper species went extinct following Polynesian colonization of Hawaii but prior to European discovery of the islands. The arrival of Europeans unleashed a new wave of honeycreeper population declines and extinctions, mainly due to the introduction of alien species such as cattle, goats, and pigs, whose feral descendants devastated native habitats, as well as rats, cats, rabbits, and other species. The catastrophic surge of honeycreeper declines and extinctions that began in the late 19th century and continued into the 20th century was mystifying for decades, but has now been attributed in large part to avian malaria and avian pox transmitted by introduced mosquitos. The mosquitos were apparently established prior to the inadvertent delivery of the avian malaria parasite (Plasmodium relictum) in the blood of introduced birds.
As of 2010, all but two of the drepanidine species that survived into the 1980s were globally threatened, including nine that were critically endangered (several of these may already be extinct). The challenges faced by those working to conserve and recover honeycreeper populations are daunting, and the losses already behind us are tragic, but substantial tracts of suitable habitat are now protected and successful captive breeding programs for several species may buy time as investigators look for effective ways to protect the birds from disease.
Comprehensive reviews of the biology of this family have been provided by Pratt (2005, 2010); Pratt (2009) has compiled recordings of the songs and calls of Hawaiian honeycreepers.
(Pratt 2010 and references therein)
- Pratt, H.D. 2005. The Hawaiian Honeycreepers: Drepanidinae. Oxford University Press, Oxford, UK.
- Pratt, H.D. 2009. Voices of Hawaii's Birds. 2 CD-ROM and booklet. Hawaii Audubon Society and Cornell Laboratory of Ornithology, Honolulu, HI & Ithaca, NY.
- Pratt, H.D. 2010. Family Drepanididae (Hawaiian Honeycreepers). Pp. 618-659 in: del Hoyo, J., Elliott, A., and Christie, D.A., eds. Handbook of the Birds of the World. Volume 15. Weavers to New World Warblers. Lynx Edicions, Barcelona.
Molecular Biology and Genetics
Statistics of barcoding coverage
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Hawaiian honeycreepers are small passerine birds endemic to Hawaiʻi. Some authorities still categorize this group as a family Drepanididae, but in recent years most authorities consider them a subfamily, Drepanidinae, of Fringillidae, the finch family. The entire group is also called "Drepanidini" in treatments where buntings and American sparrows (Emberizidae) are included in the finch family; this term is preferred for just one sub-group of the birds today.
The group is divided into three tribes, but only very provisionally so. Several taxa appear to be too basal to really place into one of these, and others are best considered incertae sedis. Some unusual forms never seen alive by scientists, such as Xestospiza or Vangulifer, cannot easily be placed into any group.
Members of Psittirostrini, known as "Hawaiian finches," are granivorous with thick finch-like bills, and songs like those of cardueline finches. The group once covered the islands. Finch-billed drepanids include the Laysan Finch, the Nihoa Finch, the Maui Parrotbill and the Palila, which may be the last remaining species left alive in this group. Extinct species include the four Koa finches, the ʻŌʻū, and the Lānaʻi Hookbill.
Hemignathini includes the Hawaiʻi Creeper and its allies, such as the Nukupuʻu. These are generally green-plumaged birds with thin bills, and feed on nectar and insects. Members of this group usually have green, yellow, orange, red, and grey feathers.
Species in the tribe Drepanidini are nectarivorous, and their songs contain nasal squeaks and whistles. Members of this group often have red black, yellow, white and orange plumage. It includes the ʻIʻwi.
The male Hawaiian honeycreepers are more brightly coloured than the females in the Psittirostrini, but in the Hemignathini, they often look very similar. The flowers of the native ʻōhiʻa lehua (Metrosideros polymorpha) are favoured by a number of nectarivorous honeycreepers. Many species of this subfamily have been noted to have a plumage odor that has been termed the Drepanidine odor and suspected to have a role in making the bird distasteful to predators.
The wide range of bills in this group, from thick finch-like bills to slender downcurved bills for probing flowers have arisen through adaptive radiation, where an ancestral finch has evolved to fill a large number of ecological niches. Some 20 species of Hawaiian honeycreeper have become extinct in the recent past, and many more in earlier times, between the arrival of arrival of the Polynesians who introduced the first rats, chickens, pigs, dogs, and hunted and converted habitat for agriculture.
Genera and species
The term "prehistoric" indicates species that went extinct between the initial human settlement of Hawaiʻi (i.e., from the late 1st millennium AD on) and European contact in 1778.
- Tribe Drepanidini
- Genus Ciridops Newton, 1892 - finch-like, fed on fruit of Pritchardia species
- Genus Drepanis Temminck, 1820 - downcurved bills, nectarivores
- Genus Himatione - thin-billed nectarivore
- Genus Melamprosops Casey & Jacobi, 1974 - short pointed bill, browser and snail specialist
- Genus Palmeria Rothschild, 1893 - thin-billed nectarivore, favors Metrosideros polymorpha
- Genus Vestiaria Jarocki, 1821 - downcurved-bill nectarivore
- Tribe Hemignathini
- Genus Aidemedia Olson & James, 1991 - straight thin bills, insectivores
- Genus Hemignathus Lichtenstein, 1839 - pointed or long and downcurved bills, insectivorous or nectarivorous
- Hemignathus flavus Bloxam, 1827 - Oʻahu ʻAmakihi
- Hemignathus kauaiensis Pratt, 1989 - Kauaʻi ʻAmakihi
- Hemignathus lucidus Lichtenstein, 1839 - Nukupuʻu
- Hemignathus sagittirostris Rothschild, 1892 - Greater ʻAmakihi (extinct, 1901)
- Hemignathus virens Cabanis, 1851 - Common ʻAmakihi
- Hemignathus vorpalis James & Olson, 2003 - Giant ʻAmakihi (prehistoric)
- (Sub)Genus Akialoa
- Hemignathus ellisianus or Akialoa ellisiana Gray, 1859 - Oʻahu ʻAkialoa (extinct, 1940)
- Hemignathus lanaiensis or Akialoa lanaiensis Rothschild, 1893 - Maui Nui ʻAkialoa (extinct, 1892)
- Hemignathus obscurus or Akialoa obscura Cabanis, 1889 - Hawaiʻi ʻAkialoa (extinct, 1940)
- Hemignathus stejnegeri or Akialoa stejnegeri Wilson, 1889 - Kauaʻi ʻAkialoa (extinct, 1969)
- Hemignathus upupirostris or Akialoa upupirostris - Hoopoe-billed ʻAkialoa (prehistoric)
- (Sub)Genus Heterorhynchus
- (Sub)Genus Magumma
- Genus Loxops - small pointed bills with the tips offset a little horizontally, insectivores
- Genus Oreomystis Wilson, 1891 - short pointed bills, browsers
- Genus Paroreomyza - similar to Oreomystis
- Genus Vangulifer - flat rounded bills, possibly caught flying insects
- Tribe Psittirostrini
- Genus Chloridops Wilson, 1888 - thick-billed, Myoporum sandwicense and other hard seed specialist
- Genus Dysmorodrepanis Perkins, 1919 - pincer-like bill, possibly snail specialist
- Genus Loxioides Oustalet, 1877 - finch-like, Fabales seed specialists
- Genus Orthiospiza - large weak bill, possibly soft seed or fruit specialist?
- Genus Pseudonestor - parrot-like bill, probes decomposing wood for insect larvae
- Genus Psittirostra - slightly hooked bill, Freycinetia arborea fruit specialist
- Genus Rhodacanthis - large-billed legume specialists
- Rhodacanthis flaviceps Rothschild, 1892 - Lesser Koa-finch (extinct, 1891)
- Rhodacanthis forfex James & Olson, 2005 - Scissor-billed Koa-finch (prehistoric)
- Rhodacanthis litotes James & Olson, 2005 - Primitive Koa-finch (prehistoric)
- Rhodacanthis palmeri Rothschild, 1892 - Greater Koa-finch (extinct, 1896)
- Genus Telespiza Wilson, 1890 - finch-like, granivores, opportunistic scavengers
- Genus Xestospiza James & Oslon, 1991 - cone-shaped bills, possibly insectivores
- ^ Clements, J. 2007. The Clements Checklist of the Birds of the World. 6th ed. ISBN 978-0-7136-8695-1
- ^ Dickinson, E, ed (2003). The Howard and Moore Complete Checklist of the Birds of the World (3rd ed.). Princeton University Press. ISBN 9780691117010.
- ^ AOU Check-list of North American Birds Accessed 26 December 2007
- ^ Pratt, H Douglas (2002). The Hawaiian Honeycreepers. Oxford University Press. p. 46. ISBN 9780198546535. http://books.google.com/?id=h8cdPD-YsosC.
- ^ Weldon, Paul J; John H. Rappole (1997). "A Survey of Birds Odorous or Unpalatable to Humans: Possible Indications of Chemical Defense". Journal of Chemical Ecology (Springer Science+Business Media) 23 (11): 2609–2633. doi:10.1023/B:JOEC.0000006670.79075.92.
- ^ James, Helen F.; Olson, Storrs L (1991). "Descriptions of Thirty-Two New Species of Birds from the Hawaiian Islands: Part II. Passeriformes" (PDF). Ornithological Monographs 46: 1–92. http://elibrary.unm.edu/sora/om/om046.pdf.
- ^ Olson, Storrs L.; James, Helen F (1991). "Descriptions of Thirty-Two New Species of Birds from the Hawaiian Islands: Part I. Non-Passeriformes" (PDF). Ornithological Monographs 45: 1–91. http://elibrary.unm.edu/sora/om/om045.pdf.
- ^ James, Helen F; Storrs L. Olson (2003). "A giant new species of nukupuu (Fringillidae: Drepanidini: Hemignathus) from the island of Hawaii". The Auk 120 (4): 970–981. doi:10.1642/0004-8038(2003)120[0970:AGNSON]2.0.CO;2. http://www.bioone.org/doi/full/10.1642/0004-8038(2003)120%5B0970%3AAGNSON%5D2.0.CO%3B2.
- ^ James, Helen F.; Johnathan P. Prince (May 2008). "Integration of palaeontological, historical, and geographical data on the extinction of koa-finches". Diversity & Distributions 14 (3): 441–451. doi:10.1111/j.1472-4642.2007.00442.x. http://www.ingentaconnect.com/content/bsc/ddi/2008/00000014/00000003/art00001?crawler=true.
- Groth, J. G. 1998. Molecular phylogeny of the cardueline finches and Hawaiian honeycreepers. Ostrich, 69: 401.