Sharp-beaked ground finch
|Sharp-beaked ground finch|
|Female, Genovesa Island|
The sharp-beaked ground finch (Geospiza difficilis) is a species of bird in the Darwin's finch group of the tanager family Thraupidae. It is classified as a least-concern species by the International Union for Conservation of Nature and it is native to the Galápagos Islands in Ecuador. It has a mass of around 20 grams (0.71 oz) and the males have black plumage, while females have streaked brown plumage. This finch was described by Richard Bowdler Sharpe in 1888.
This relatively small, slender-billed finch is endemic to the Galápagos Islands, where it is found on Fernandina, Santiago, Pinta, Genovesa, Darwin, and Wolf Islands. On the first three islands, it breeds in the humid highlands and disperses afterwards, but on the remaining smaller and lower islands the sharp-beaked ground finch is found in the arid zone year-round. Due to habitat destruction its range has decreased. It was formerly also present in the highlands of several other islands, and it is possible it still occurs on Isabela.
The subspecies on the islands of Darwin and Wolf has gained a level of notoriety due to its habit of feeding on blood of large birds, notably boobies, gaining it the common name vampire finch (Geospiza difficilis septentrionalis). It also feeds on the eggs of other birds. Other subspecies do not exhibit this behavior, instead feeding mainly on insects. Specimens located on islands of high altitude devour both seeds and invertebrates, while those on low-altitude islands have mainly seed-based diets. At high altitudes, it occurs in locations with Zanthoxylum fagara abundance.