I vant to suck your blood: vampire finches, vampire moths and oxpeckers

October 12, 2016 9:54 AM

Vampirism — piercing or cutting animal skin to suck or lap up blood — is known throughout the animal kingdom. Mosquitoes come to mind, plus ticks, mites, vampire bats, and the vampire finch of the Galapagos Islands. But … vampire moths? Wait, let's take a step back, did you say the vampire finch of the Galapagos Islands? Yes. They're a subspecies of the sharp-beaked ground finch that outnumber every other finch species on all of the islands combined. While they don't seem to bother the adult Boobies whose blood they drink, they may be fatal to chicks* and even crack open eggs. Right, what of those vampire moths?

* From the Wired article Absurd Creature of the Week: The Tiny Blood-Slurping Bird That Terrorizes the Galapagos

... although Petren saw them swarming dead chicks, he hesitates to conclude that the finches were responsible for the deaths. Life in this hot, dry environment is tough, so mortality rates for seabirds are quite high as it is, and he has no direct observations of finches actively hunting the babies.

Vampire finches aren't the only small bird to feast on the blood of larger animals. Oxpeckers are more aggressive, eating ticks off of and drawing blood from large mammals, including hippos, buffaloes, antelopes and giraffes. Endemic to the savanna of Sub-Saharan Africa, these birds may have evolved or adapted in a similar fashion to the vampire finches of the Galapagos islands, starting out by eating insects off of larger animals, then happening to find that drinking blood is a lot more convenient. Many recent studies have shown that classic examples of mutualism are either far more complicated than originally believed, or that they are not mutualisms at all.

In comparison, species within the vampire moth genus Calyptra are nuisances at worst. Discovered in Siberia in 2008, the bloodsuckers may have evolved from a purely fruit-eating species, male moths can use their hook and barb-lined tongues to pierce skin. Even though they're not skilled blood-suckers like mosquitoes, and may just be drinking your blood for its salt content, they don't stab their victims repeatedly to get at the juices inside.

posted by filthy light thief (4 comments total)

Where there's a niche, there's a way.
posted by little onion at 10:29 AM on October 12, 2016

How much blood does the vampire finch draw from each peck? If that is its only diet then there is a lot of pecking it must do.
posted by dov3 at 11:28 AM on October 12, 2016

It eats like a bird.
posted by XMLicious at 11:33 AM on October 12, 2016 [1 favorite]

How much blood does the vampire finch draw from each peck? If that is its only diet then there is a lot of pecking it must do.

According to the Wired article in the FPP,

"Blood and eggs are just two of the many items on the vampire finch’s menu, though. It’s a generalist, also taking seeds and even drinking up the vomit of other birds, because why the hell not. The vampire’s wickedly sharp beak is perfectly adapted for this lifestyle, allowing it to not only pierce flesh but to also open up fruits and drink nectar. It has to be creative on this unforgiving island, especially during droughts, when finch populations can crash by as much as 90 percent, according to Petren."

Natural selection at its finest. The "vampire finch" sub-species in particular is endemic to such a small geographic area that very unusual feeding strategies would absolutely be necessary to survive. Especially in such a rocky and desolate place.

Thanks, filthylightthief, for a great biology post!
posted by strelitzia at 3:40 PM on October 12, 2016