Drepanididae
Drepanidini[verification needed] (see text)
Drepaniidae
Drepanidinae
Hawaiian honeycreepers are a group of small birds
endemic to
Hawaiʻi. They are members of the
finch family Fringillidae, closely related to the
rosefinches (Carpodacus), but many species have evolved features unlike those present in any other finch. Their great morphological diversity is the result of
adaptive radiation in an insular environment. Many have been driven to
extinction since the
first humans arrived in Hawaii, with extinctions increasing over the last two centuries following European discovery of the islands, with
habitat destruction and especially
invasive species being the main causes.[1][2]
Taxonomy
Before the introduction of molecular phylogenetic techniques, the relationship of the Hawaiian honeycreepers to other bird species was controversial. The honeycreepers were sometimes categorized as a
familyDrepanididae,[3] other authorities considered them a
subfamily, Drepanidinae, of Fringillidae, the
finch family. The entire group was also called Drepanidini in treatments where buntings and
American sparrows (
Passerellidae) were included in the finch family; this term is preferred for just one subgroup of the birds today.[4][5] Most recently, the entire group has been subsumed into the finch subfamily
Carduelinae.[2][6]
The Hawaiian honeycreepers are the
sister taxon to the Carpodacus rosefinches. Their ancestors are thought to have been from
Asia and diverged from Carpodacus about 7.2 million years ago, and they are thought to have first arrived and radiated on the
Hawaiian Islands between 5.7-7.2 million years ago, which was roughly the same time that the islands of
Ni'ihau and
Kauai formed. The lineage of the recently extinct
po'ouli (Melamprosops) was the most ancient of the Hawaiian honeycreeper lineages to survive to recent times, diverging about 5.7-5.8 million years ago. The lineage containing Oreomystis and Paroreomyza was the second to diverge, diverging about a million years after the po'ouli's lineage. Most of the other lineages with highly distinctive morphologies are thought to have originated in the mid-late
Pliocene, after the formation of
Oahu but prior to the formation of
Maui. Due to this, Oahu likely played a key role in the formation of diverse morphologies among honeycreepers, allowing for cycles of colonization and speciation between Kauai and Oahu.[7]
A
phylogenetic tree of the recent Hawaiian honeycreeper lineages is shown here. Genera or clades with question marks (?) are of controversial or uncertain taxonomic placement.[7][8]
The classification of Paroreomyza and Oreomystis as
sister genera and forming the second most
basal group is based on
genetic and
molecular evidence, and has been affirmed by numerous studies; however, when
morphological evidence only is used, Paroreomyza is instead the second most basal genus, with Oreomystis being the third most basal genus and more closely allied with the derived Hawaiian honeycreepers, as Oreomystis shares traits with the derived honeycreepers, such as a squared-off tongue and a distinct musty odor, that Paroreomyza does not. This does not align with the genetic evidence supporting Paroreomyza and Oreomystis as sister genera, and it would be seemingly impossible for only Paroreomyza to have lost the distinctive traits but Oreomystis and all core honeycreepers to have retained or convergently evolved them, thus presenting a taxonomic conundrum.[8]
Viridonia (containing the
greater ʻamakihi) may be associated with or even synonymous with the genus Aidemedia (containing the prehistoric icterid-like and sickle-billed gapers), and has the most debated taxonomy; it was long classified within the "greater Hemignathus" radiation (a now-
paraphyletic grouping containing species formerly lumped within Hemignathus, including Hemignathus, Akialoa, and Chlorodrepanis) and while some sources speculate it as being sister to Chlorodrepanis (containing the
lesser ʻamakihis), other sources speculate it may be a sister genus to the genus Loxops (containing the
'akepas,
ʻakekeʻe and
ʻalawī).[8]
Characteristics
Nearly all species of Hawaiian honeycreepers have been noted as having a unique odor to their plumage, described by many researchers as "rather like that of old canvas tents".[9][10]
Today, the flowers of the native ʻōhiʻa (Metrosideros polymorpha) are favored by a number of
nectarivorous honeycreepers. The wide range of bill shapes in this group, from thick, finch-like bills to slender, down-curved 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, following the arrival of humans who introduced
non-native animals (ex: rats, pigs, goats, cows) and converted habitat for agriculture.[11][12]
Genera and species
The term "prehistoric" indicates species that became extinct between the initial human settlement of Hawaiʻi (i.e., from the late 1st millennium AD on) and European contact in 1778.
Hawaiian honeycreepers were formerly classified into three
tribes – Hemignathini, Psittirostrini, and Drepanidini – but they are not currently classified as such.
Hawaiian honeycreepers (
Fringillidae), of the
subfamilyCarduelinae, were once quite abundant in all forests throughout
Hawai'i.[16] This group of birds historically consisted of at least 51 species. Less than half of Hawaii's previously
extant species of honeycreeper still exist.[16] Threats to species include habitat loss, avian malaria, predation by non-native mammals, and competition from non-native birds.[17]
^Beolens, Bo; Watkins, Michael; Grayson, Michael (2014).
The Eponym Dictionary of Birds. Johns Hopkins University Press.
ISBN9781472905741. The genus Aidemedia is named in honor of Joan Aidem.
^Jacobi, James D.; Carter T. Atkinson (September 28, 2000).
"Hawaii's Endemic Birds". U.S. Department of the Interior. Archived from
the original on 2007-07-11. Retrieved 2007-04-26.
Other references
Groth, J. G. 1998. Molecular phylogeny of the cardueline finches and Hawaiian honeycreepers. Ostrich, 69: 401.
External links
Wikimedia Commons has media related to
Drepanidinae.