(Phys.org)—BBC documentarians filming for a special called "Penguins: Spy in the huddle" have captured video of vampire bats feeding on juvenile Humboldt penguins in a cave in the Atacama Desert in southern Peru. Until now, such attacks had never been witnessed by human eyes, though scientists had good reason to believe they occurred—bite marks on the feet of juveniles are quite common.
It wasn't easy to capture the footage—the researchers had to hide themselves in the cave at night when it was almost completely dark. The cave is where the penguins live—it offers some degree of protection from their main predator, neighboring sea lions. To witness what was going on the filmmakers hid themselves some distance from the penguins and used infrared cameras, scanning the small crowd for evidence of bats among them. They knew something was afoot when the group began to grow agitated. As the vampire bats began flying over and around the group, the adults moved in ways that staved off being attacked, but the juveniles, still learning, were not able to do the same. The cameras captured the bats biting the feet of the young penguins, landing and licking their blood.
Contrary to popular folklore, vampire bats don't actually suck the blood from unsuspecting victims, though they do generally favor those that are sleeping—they swoop in, bite, and then retreat. Then, they land nearby, creep up on the still sleeping animal and lick the blood that seeps from the wound.
Scientists have long suspected that the vampire bats that live in the Atacama Desert were deviating from the norm and were attacking young awake penguins—bite marks on their feet offered ample proof. No one had ever seen such an attack however—the BBC team, led by producer Matthew Gordon set out to do just that. In speaking with BBC Nature, Gordon reported that the bats went for the juveniles because they seemed less able to take preemptive measures.
The attacks don't kill the penguins, the documentarians noted, or even harm them that much. The bites leave them open to infection, of course, or contracting rabies and the loss of blood can leave them weak, but most recover and grow to adulthood, where over time they apparently learn to ward off the hungry bats.
Explore further: Team offers first look at how bats land (w/Video)