The scissor-billed koa finch or scissor finch (''Rhodacanthis forfex'') is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

species of

Hawaiian honeycreeper Hawaiian honeycreepers are a group of small, passerine birds endemic to Hawaii. They are closely related to the rosefinches in the genus ''Carpodacus'', but many species have evolved features unlike those present in any other finch. Their great ...

in the subfamily

Carduelinae The cardueline finches are a subfamily, Carduelinae, one of three subfamilies of the finch family Fringillidae, the others being the Fringillinae and the Euphoniinae. The Hawaiian honeycreepers are now included in this subfamily. Except for the ...

of the family

Fringillidae The true finches are small to medium-sized passerine birds in the family Fringillidae. Finches have stout conical bills adapted for eating seeds and nuts and often have colourful plumage. They occupy a great range of habitats where they are usua ...

. It is known from fossils on the islands of

Maui The island of Maui (; Hawaiian: ) is the second-largest of the islands of the state of Hawaii at 727.2 square miles (1,883 km2) and is the 17th largest island in the United States. Maui is the largest of Maui County's four islands, which ...

and

Kauaʻi Kauai, () anglicized as Kauai ( ), is geologically the second-oldest of the main Hawaiian Islands (after Niʻihau). With an area of 562.3 square miles (1,456.4 km2), it is the fourth-largest of these islands and the List of islands of th ...

Hawaii Hawaii ( ; haw, Hawaii or ) is a state in the Western United States, located in the Pacific Ocean about from the U.S. mainland. It is the only U.S. state outside North America, the only state that is an archipelago, and the only stat ...

Distribution

Scissor-billed koa finch fossils have been found on

and

Kauai Kauai, () anglicized as Kauai ( ), is geologically the second-oldest of the main Hawaiian Islands (after Niʻihau). With an area of 562.3 square miles (1,456.4 km2), it is the fourth-largest of these islands and the 21st largest island ...

. Based on its

disjunct distribution In biology, a taxon with a disjunct distribution is one that has two or more groups that are related but considerably separated from each other geographically. The causes are varied and might demonstrate either the expansion or contraction of a s ...

, the species might have occurred on all of the main islands (except the

island of Hawaii Hawaii ( ; haw, Hawaii ) is the largest island in the United States, located in the state of Hawaii. It is the southeasternmost of the Hawaiian Islands, a chain of volcanic islands in the North Pacific Ocean. With an area of , it has 63% of th ...

), although more fossils are needed for confirmation.

Diet

The scissor-billed koa finch was a

granivore Seed predation, often referred to as granivory, is a type of plant-animal interaction in which granivores (seed predators) feed on the seeds of plants as a main or exclusive food source,Hulme, P.E. and Benkman, C.W. (2002) "Granivory", pp. 13 ...

, that, like the other members of its genus, had a bill adapted to eat the hard

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s and pods of

legume A legume () is a plant in the family Fabaceae (or Leguminosae), or the fruit or seed of such a plant. When used as a dry grain, the seed is also called a pulse. Legumes are grown agriculturally, primarily for human consumption, for livestock f ...

Pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...

and

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

evidence indicates that ''Ka palupalu o Kanaloa'' ('' Kanaloa kahoolawensis'') and ''koaia'' (''

Acacia koaia ''Acacia koaia'', known as ''koaia'' or ''koaie'' in Hawaiian, is a species of acacia that is endemic to Hawaii. It is closely related to ''koa'' (''Acacia koa''), and is sometimes considered to be the same species. Description ''Acacia koaia ...

'') were probably important food sources, and it may have eaten

caterpillar Caterpillars ( ) are the larval stage of members of the order Lepidoptera (the insect order comprising butterflies and moths). As with most common names, the application of the word is arbitrary, since the larvae of sawflies (suborder Sym ...

s and ''aalii'' (''

Dodonaea viscosa ''Dodonaea viscosa'', also known as the broadleaf hopbush, is a species of flowering plant in the ''Dodonaea'' (hopbush) genus that has a cosmopolitan distribution in Tropics, tropical, Subtropics, subtropical and warm temperate regions of Africa ...

'')

berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

Extinction

The koa finches seem to have been driven to extinction by

habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...

, and not by climatic variation nor mosquito-vectored diseases. Koa finches were likely driven out of lowland habitat before or shortly after the time of western contact in 1778. The two species from

(the scissor-billed koa finch and

primitive koa finch The primitive koa finch (''Rhodacanthis litotes'') is an extinct species of Hawaiian honeycreeper in the subfamily Carduelinae of the family Fringillidae. It is known from fossils on the islands of Maui and Oʻahu in Hawaii. Description An adu ...

) might have survived in an upland refugium until the late 19th century, paralleling the fate of the two species from the

(the

lesser Lesser, from Eliezer (, "Help/Court of my God"), is a surname. Notable people with the surname include: * Adolf Lesser (1851–1926), German physician * Aleksander Lesser (1814–1884), Polish painter and art critic * Anton Lesser (born 1952), Bri ...

and greater koa finches). However, the only verified records of the Maui species are from fossils at a lower elevation.

References

{{Taxonbar, from=Q5494509 Rhodacanthis Holocene extinctions Endemic fauna of Hawaii Extinct birds of Hawaii Hawaiian honeycreepers Late Quaternary prehistoric birds Taxa named by Helen F. James