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Finches are well known for their seed-foraging skills and hardiness in harsh climates. What lengths will a finch go to in order to survive during the most difficult times to find food? Darwin’s Finches are on the case.
13 species of tanagers, widely known as Darwin’s Finches, reside on the Galapagos Islands. These islands of the Pacific Ocean lie close to the equator. For much of the year, the islands enjoy a surprisingly cold drizzle. A subspecies of Darwin’s Finches, the Vegetarian Finch, manages to maintain an entirely seed-filled diet. During dry times, food can be difficult or impossible to find for these birds. Most finches will leave inhospitable areas in search of food, but two of the Galapagos islands are particularly arid. The subspecies of finch that resides here must go to great lengths in order to survive.
Known as Vampire Finches, these particular birds regularly supplement their usual plant diet by feasting on blood. When times aren’t too difficult, these finches will eat parasites from the backs of iguanas and tortoises. They even poop on their hosts after eating; this sounds like a rude practice, but it’s an easy method to inform other finches all the food is gone. During the dryest of seasons, the Vampire Finch will feed upon blood from seabirds.
How do they get away with this vampiric practice? These finches don’t kill other birds outright. Their strategy is to peck at existing wounds on other larger seabirds’ backs and tails. They’ll do so in order to keep blood available and flowing, but these Vampire Finches aren’t enough of a nuisance that the larger birds will fight or fly away. Sometimes a Vampire Finch will create a wound, but they prefer to open existing ones. The small birds take a sip of blood every few seconds, and sometimes other Vampire Finches will wait in line for their turn at the altar.
On Wolf island (about 120 miles north of the main Galapagos Archipelago), these Vampire Finches are particularly active, as the island remains dry for most of the year. The Vampire Finch (and its wholly vegetarian counterpart) stand as examples of evolution in action, which seems proper for a species called Darwin’s Finch.