The Galapagos is well known to be the home of great number of endemic species. One of the rarest and most interesting creatures is the vampire finch (Geospiza difficilis). This unusual bird is a subspecies of the sharp-beaked ground finch that lives on Darwin and Wolf Islands and has some striking behavioral differences from other sharp-beaked ground finches. In order to understand the biological adaptation of these finches that use the resource “blood” of seabirds during the dry season, the Galapagos National Park (GNP) initiated a new investigation concerning the unusual behavior of these individuals of this specie of finch that inhabits the islands Darwin and Wolf, at the northern end of the archipelago.

One of the park rangers in charge of this research, explained that the finches of the sharp-beaked ground finch species also found in Pinta, Genovesa, Santiago and Fernandina islands normally feed on seeds and insects, but such things can often be in short supply on Darwin and Wolf islands. Only in these two small and remote islands, this finch feed on blood (hematophagy) of other birds. For this reason, during the rainy season (January and February), specialists conducted a monitoring where samples of saliva, blood and ecological data were collected in order to understand the behavior of the vampire finches.

Through the analysis of these samples, the research team hopes to confirm or rule out a case of “convergent evolution”, as developed by vampires, mosquitoes and ticks that despite being distant species have evolved the same molecules (proteins-enzymes) in saliva that help digest the blood anticoagulant and anesthetic properties. Vampire finches peck at boobies’ feathers and skin with their sharp beaks until they suck blood, and drink nutrient-rich blood to enrich their diet when seeds and insects are scarce. Strangely, the boobies don't seem to mind the vampire finches drinking their blood. It is believed that this behavior evolved from the blood-sucking finches preying on parasites from the feathers of boobies.

The finches’ blood-drinking habits have allowed them to thrive even in the driest months, becoming the most numerous birds on the island. At peak feeding times, finches can be seen lining up behind a victim, patiently waiting their turn to dine. This bird is sexually dimorphic. The males are black whereas the females are greyish with brown streaks. As an adaption to its characteristic way of life, the vampire finch has evolved the largest and most pointed beak of all the sharp-beaked ground finch subspecies.