The medium tree finch (''Camarhynchus pauper'') is a critically endangered species of

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

in the

Darwin's finch Darwin's finches (also known as the Galápagos finches) are a group of about 18 species of passerine birds. They are well known for their remarkable diversity in beak form and function. They are often classified as the subfamily Geospizinae or t ...

group of the

tanager The tanagers (singular ) comprise the bird family Thraupidae, in the order Passeriformes. The family has a Neotropical distribution and is the second-largest family of birds. It represents about 4% of all avian species and 12% of the Neotrop ...

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Thraupidae The tanagers (singular ) comprise the bird family Thraupidae, in the order Passeriformes. The family has a Neotropical distribution and is the second-largest family of birds. It represents about 4% of all avian species and 12% of the Neotrop ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found els ...

to the

Galápagos Islands The Galápagos Islands ( es, Islas Galápagos) are an archipelago of volcanic islands in the Eastern Pacific, located around the Equator west of the mainland of South America. They form the Galápagos Province of the Republic of Ecuador, with ...

where it is only found on

Floreana Island Floreana Island (Spanish: ''Isla Floreana'') is an island of the Galápagos Islands. It was named after Juan José Flores, the first president of Ecuador, during whose administration the government of Ecuador took possession of the archipelago ...

. Its name is derived from the fact that the bird's beak is intermediate in size between that of the

small tree finch The small tree finch (''Camarhynchus parvulus'') is a species of bird in the Darwin's finch group of the tanager family Thraupidae. It has a grasping beak with curved culmens. Its natural habitats are subtropical or tropical dry forests an ...

and the large tree finch. Because it has a very small range on a single island, and because of the introduction of a parasitic fly which kills the nestlings, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natur ...

has rated the medium tree finch as " critically endangered".

Distribution

This species is only found on

at elevations above 250 meters in moist highland forest habitats. Prime breeding habitat is dominated by ''

Scalesia ''Scalesia'' is a genus in the family Asteraceae endemic to the Galapagos Islands. It contains fifteen species that grow as shrubs or trees. This is unusual, because tree species are uncommon in Asteraceae. The genus ''Scalesia'' resulted from a ...

pedunculata'' trees.

Ecology

The diurnal Galapagos

short-eared owl The short-eared owl (''Asio flammeus'') is a widespread grassland species in the family Strigidae. Owls belonging to genus ''Asio'' are known as the eared owls, as they have tufts of feathers resembling mammalian ears. These "ear" tufts may or ...

is its only remaining natural predator. Medium tree finches generally lay two to three eggs. Eggs are incubated for approximately 12 days, and nestlings are fed by both parents at the nest for approximately 14 days before becoming fledglings. The range of beak sizes of the medium tree finch on Floreana and the large tree finch, ''Camarhynchus psittacula'', on Isabela is roughly the same. This reflects the fact that the two species feed on the same type and size of insect. The beak of the medium tree finch is intermediate in size between the

and large tree finch. All three species are found in the same habitat country and area.

Status

The medium tree finch is threatened by introduced predators such as rats, mice, cats and the

smooth-billed ani The smooth-billed ani (''Crotophaga ani'') is a bird in the cuckoo family. It is a resident breeding species from southern Florida, the Caribbean, parts of Central America, south to western Ecuador, Brazil, northern Argentina and southern Chile. ...

, as well as

habitat loss 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 ...

, which has occurred through clearance for agriculture. The introduced fly ''

Philornis downsi ''Philornis downsi'', also known as the avian vampire fly, is a species of fly (Diptera, Muscidae) that was first recorded in Trinidad and Brazil in the 1990s. It has been accidentally introduced to the Galapagos Islands ( Ecuador). Adults ...

'' is a significant threat to the survival of this species. Parasitic larvae of this fly live in the nest material and feed on the blood and body tissues of nestlings. ''P. downsi'' causes high nestling mortality in the medium tree finch. Because of this, and because it has a very small range on a single island, the

has rated the medium tree finch as " critically endangered".

References

*O’Connor JA, Sulloway FJ, Kleindorfer S (2010). Avian population survey in the Floreana highlands: Is Darwin's medium tree finch declining in remnant patches of Scalesia forest? ''Bird Conservation International.'' *O’Connor JA, Sulloway FJ, Robertson J, Kleindorfer S (2010). ''Philornis downsi'' parasitism is the primary cause of nestling mortality in the critically endangered Darwin's medium tree finch (''Camarhynchus pauper''). ''Biodiversity and Conservation.'' 19:853-866.

External links

BirdLife Species Factsheet.
{{Taxonbar, from=Q1125857 medium tree finch Endemic birds of the Galápagos Islands medium tree finch Taxa named by Robert Ridgway Taxonomy articles created by Polbot Taxobox binomials not recognized by IUCN