As if it were not enough that vampire bats can swoop down from the sky to get a blood dinner from their victims, it turns out that they also can run on the ground to sneak up on them.
The finding is surprising because no other bat has been shown to run.
In fact, most can barely walk, shuffling awkwardly from a sprawled position.
Daniel Riskin of the College of Veterinary Medicine at Cornell University and his colleagues made the discovery at a ranch in Trinidad, where they trapped five adult male vampire bats using cows as bait. They placed the animals on a treadmill inside a plexiglass cage and photographed them with a high-speed camera while the speed of the treadmill was increased.
They were surprised to find that, at higher speed, the animals broke into a full-fledged run. Their stride fulfills the definition of running, Riskin said, because all four limbs lose contact with the ground simultaneously – just as is the case when horses, for example, run.
But their running style is unique, the team reported in last week’s issue of the journal Nature. Other four-legged animals depend on their hind legs for most of their power. But because bats’ front limbs – their wings – are much more powerful than their rear legs, most of the propulsion comes from them.
Bats, the only mammals that fly, lost the ability to run long ago, so Riskin believes the vampire bats re-evolved the ability. But neither he nor anyone else knows why.
Perhaps it just makes it easier for them to get out of the way when cows and other quarry kick at them, or perhaps it helps them chase smaller prey, he said.
