That’s right. Vampire Finches.
Dracula has lots of company. Real world company. Blood sucking is not uncommon in nature. Three species of bats do it, many species of bugs — bedbugs, ticks, chiggers, female mosquitoes, leeches — all do it. Called sanguivores, they exist almost entirely on the blood of their victims, even if they don’t live forever because of it. Then there is the candiru, a/k/a the toothpick fish which lives in the Amazon and Orinoco rivers and has the fearsome, and perhaps unjustified reputation, of crawling up human urethras and sucking blood. Small catfish, they normally eat the blood of larger fish hosts.
Stealing blood isn’t an easy way to make a living. You have to be small enough to drink the blood of your host without your host knowing it. Otherwise, the host is sure to swat you dead. And because blood is about 95% sea water — really — there is a lot of useless bulk to get rid of before you get to the 5% which is protein, sugar and mineral.
Which is why the Vampire Finches, which live no where in the world except on two islands in the Galapagos, live mainly on nectar, seeds and stolen eggs. But they do peck at the Blue-footed Boobies with whom they share the islands. Pecking persistently at the Boobies’ wings and tails, they draw blood and drink.
Truly we do not make this stuff up. A new book, Dark Banquet, is about the blood suckers of nature. Natalie Angier wrote about the book and hematophagy in the New York Times. She also provided a brief essay about blood. The photo of the Vampire Finch came from this blog which has an informative essay about the finches which, of course, have their very own Wikipedia entry.