The secret of the vampire finches of the Galapagos islands is in their saliva

April 21, 2021 00:00
Fernando Criollo

Photo: Courtesy Jaime Chaves / San Francisco State University

The only species of birds in the world inhabits the Galapagos that, in addition to feeding on blood, is responsible for wounding other living animals to extract the liquid. The vampire finch is a clear example of evolution on the islands. It has developed characteristics that differentiate it from other finches and that make it similar to bats.

Birgit Fessl, a researcher at the Charles Darwin Foundation, explains that these birds use their long, pointed beaks to reach the base of the feathers of other species, make a hole and obtain their blood. In Africa there is a record of other birds that have this diet, but the difference is that they take advantage of the wounds made previously by ticks or other insects to absorb their food.

Jaime Chaves, professor at San Francisco State University of California and visiting professor and researcher at the San Francisco University of Quito, says that blood is an option for these animals during the dry season.

In the wet season, vampire finches mainly consume insects and seeds, which become scarce when the weather changes. This has led the species to seek the blood of masked and red-footed boobies to survive, especially during the dry season.

These birds do not kill their victims nor do they consume their bodies when they have died. Fessl says their attitude resembles that of parasites, causing enough damage to ensure they get food without unduly harming the host.

Vampire finches generally attack live boobies in groups of three or four. These climb on the back of the largest bird and begin to peck it until they cause the wounds and obtain the blood. Other finches observe the scene, learn how to make the holes and wait their turn to get on the booby.

These behaviors have piqued the curiosity of researchers. Chaves says that, together with specialists from CalTech, UMiami, Occidental College, U Cambridge, UC Davis and the Galapagos Science Center, studies have been carried out on the bacteria that allow vampire finches to feed on blood.

The first thing they found is that these animals have very different bacteria than those found in the other 17 species of finches, but some are similar to those that exist in scavengers. After this result, the second step was to compare their organism with that of other species that feed only on blood, such as vampire bats.

Chaves explains that some bacteria are in both animals, but the fuso bacteria, which are what differentiate these finches from the rest of the birds in their group, are not found in vampire bats. On the other hand, although the bacteria of the two are different, they have the same function.

Now, researchers are looking to solve other unknowns about how these bacteria got to the Galapagos or if there are proteins in the saliva of vampire finches that are similar to those of bats. The latter have anesthetics and painkillers in their saliva, therefore their prey do not notice when they are drawing their blood.

The vampire finch is an example of evolutionary processes that these animals live under special conditions. The species is endemic to the islands of Darwin and Wolf, which are found in the north of the archipelago. This means that they are the only places on the planet where you can see these animals. Any disturbance in their habitat could lead to extinction .

Read the original coverage from El Comercio at https://www.elcomercio.com/tendencias/secreto-pinzones-vampiro-islas-galapagos.html

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