Small Ground-Finch
Geospiza fuliginosa
A small, widespread Galápagos finch. Bill is longer than it is deep, appears somewhat pointed, and has only a slight curve to the upper edge. Lower edge of bill is mostly straight. Bill size varies among individuals, and not all birds can be accurately identified. Bill is black on breeding male and dull orange on female and nonbreeding male. Male’s plumage is sooty-black; female is brown with paler underparts that are streaked with gray. Medium Ground-Finch has thicker, less pointed bill. Sharp-beaked Ground-Finch has bill that is slightly more pointed and is less rounded on the upper edge. Found in a wide variety of habitats on most islands, but absent from Genovesa, Darwin, and Wolf.
Identification
The small ground finch is the smallest of the ground finches, measuring 11 cm (4.3 in) in length. Its beak is short and pointed, with a slightly curved culmen. On average, its beak is smaller than that of the medium ground finch, but there is a significant overlap in size between the two, particularly on islands where only one of the two species exists. On islands where the two species compete directly, the difference between their beaks are greater. The male is black with white-tipped undertail coverts, while the female and young are brown with streaked underparts. There are observable phenotypic differences between finches that live in lowlands and ones that live in highlands, and this change is most likely attributed to adaptation. The finches seen in highlands have larger, more pointed beaks and smaller feet and claws compared to the lowland variety. These finches are on a cline (series of biocommunities on a continuous gradient), and individuals in the hybrid zone have intermediate traits. This is an example of parapatric speciation, where the elevation gradient of 560 meters causes differentiation in traits, but hybrids are well adapted in their “hybrid zone.”
Taxonomy
The small ground finch is one of Darwin's finches, a group of closely related birds which evolved on the Galápagos Islands. The group is related to the Tiaris grassquits, which are found in South America and the Caribbean.<p>When Charles Darwin first collected the species in 1835, he thought it was a finch. John Gould, who officially described Darwin's specimens, agreed, placing it in the genus Fringilla with the Old World finches. By 1841, Gould had changed his mind, moving this and five other species into the new genus Geospiza — still a genus of finches, but distinct from those of the Old World. DNA research has now shown that all of Darwin's "finches" are actually tanagers.<p>The name Geospiza is a combination of the Greek words geo-, meaning "ground-", and spiza, meaning finch. The specific name fuliginosa is late Latin for "sooty".<p>It is known to hybridize (rarely) with the medium ground finch.
- Scientific name
- Geospiza fuliginosa
- Authority
- Gould, 1837
- Order
- Passeriformes
- Family
- Thraupidae
- Genus
- Geospiza
Range and habitat
Like all but one of the other Darwin's finches, the small ground finch is endemic to the Galápagos Islands. Abundant and widespread, it is found on every island in the archipelago except for the Genovesa, Wolf and Darwin islands. It is most common in arid coastal and transition areas, though it moves into the highlands following the breeding season.
- Migration
- Vertical migration
Behavior
Like the other Galápagos ground finches, the small ground finch is an omnivore with a preference for vegetable matter. It feeds primarily on the ground or in low vegetation, eating seeds, buds, flowers, leaves and the occasional insect. It forms symbiotic relationships with Galápagos tortoises and both marine and Galápagos land iguanas by gleaning parasites from their skins.<p>The small ground finch's song is rapid and weak and is transcribed as "twichooo-twichooo" or "teur-weee".
Conservation
Although the population size of the small ground finch has not been quantified, it is described as common across the Galápagos, and the International Union for Conservation of Nature lists it as a species of Least Concern. Its numbers seem to be stable, and neither its population size nor its range size appear to approach thresholds for concern. However, like all endemic wildlife on the Galápagos Islands, it is impacted by some human activities, including fires, overgrazing by domestic and feral animals, and the introduction of exotic species. It is found in ten of the Important Bird Areas established on the islands. The species suffers from high mortality rates from the parasitic fly, ranging from 16% to 95% over a four-year period (2002–2006).
- Population trend
- stable
Photos
Distribution
Bird Calls
Other Birds
Tepui Redstart
Myioborus castaneocapilla
Small, active bird of highland forests. Generally yellow below and grayish above with a chestnut cap and white outer tail feathers. White eyering is more extensive in birds from western part of range, where it forms distinct spectacles. Found only in forests of the tepui highlands (above 1000 m), where typically encountered singly or in pairs. Forages actively, gleaning insects from leaves and bark or making acrobatic sallies to catch them mid-air. Usually keeps tail partially spread, revealing white outer feathers. Song is a rapid, chippering trill, recalling Tropical Parula but without strongly accented notes, and dropping slightly in pitch. Told from Slate-throated Redstart by entirely yellow underparts (including throat) and more prominent chestnut crown.
White-headed Starling
Sturnia erythropygia
A distinctive starling with white head, white breast, and gray back. Note the yellow legs and pale bill. The vent, outer tail feathers, and lower back are grayish-white on birds in the Andamans and reddish-brown on birds in the Nicobars. An active species that usually occurs in flocks with other starlings and insectivores in plantations, paddyfields, open woodlands, and forest edges.
Cut-throat
Amadina fasciata
A small, gray-brown, heavily scaled and barred waxbill. The male has a characteristic red crescent throat band that the female and juvenile lack. Pairs and flocks are resident in arid thorn scrub, dry broadleaf woodland, and grassy scrub. The species joins flocks with other seedeaters in the non-breeding season. The female Red-headed Finch looks similar to the smaller female Cut-throat, but differs in its plain (not barred) head and its white-tipped outer tail.
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