Geospiza difficilis septentrionalis, aka the Vampire Finch, is a small bird with a very unusual diet – other bird’s blood.

Found on only two small islands in the Galapagos Archipelago – Darwin and Wolf – the vampire finch is a subspecies of the sharp-beaked ground finch, a relatively small and harmless-looking bird. However, as the specie’s name suggests, it has a very sharp beak, which it sometimes uses to break through more than just fruits and nuts. The vampire finch got its name from its bizarre habit of pecking at larger birds’ skin and feeding on their blood whenever other food sources are scarce.

Photo: Joseph C. Boone/Wikimedia Commons

The Nazca and blue-footed booby are the two primary victims of the vampire finch. Interestingly, these two seabirds are much larger than their assailant, but rarely put up any resistance. Experts believe that is because this unusual diet evolved from a much more common behavior that finches are known for – pecking at parasites on the plumage and skin of larger birds. Basically, Nazca and boobies don’t perceive the finch’s pecking as a threat.

In case the vampire finch’s behavior needs explanation, the small bird lands on the back of its victim and uses its small, sharp beak to peck at the skin until it pierces it and starts feeding on the blood.

Although no one knows exactly how the vampire finch developed a taste for blood, it is believed that, through the ages, it occasionally pecked too hard at the skin of seabirds while feeding on their parasites and over time adapted to consuming blood as a dietary supplement.

Blood feeding is exceedingly rare among birds, and the behavior of the vampire finch is considered an adaptation unique to Darwin and Wolf islands.

It’s worth pointing out that as gruesome as the vampire finch’s feeding habit may seem, its primary diet is made up of seeds and invertebrates. Blood is something it only turns to when such food is scarce.