A study of the ability of vampire bats (
Desmodus rotundus) to run on the ground was just published:
Nature. 2005 Mar 17;434(7031):292.
Biomechanics: independent evolution of running in vampire bats.
Riskin DK, Hermanson JW.
Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA. dkr8@cornell.edu
Most tetrapods have retained terrestrial locomotion since it evolved in the Palaeozoic era, but bats have become so specialized for flight that they have almost lost the ability to manoeuvre on land at all. Vampire bats, which sneak up on their prey along the ground, are an important exception. Here we show that common vampire bats can also run by using a unique bounding gait, in which the forelimbs instead of the hindlimbs are recruited for force production as the wings are much more powerful than the legs. This ability to run seems to have evolved independently within the bat lineage.
Pubmed link.
There is a free article covering the study at another site, for those that don't have access to
Nature:
Yikes! Vampire Bats Can Run, Too.The article includes images of a bat running on a treadmill from the original report.
Since the vampire bat is the only bat species known to have the ability to run (and essentially maneuver at all) along the ground, the study begs an interesting question regarding the selective force for this trait.
This is all the speculation the authors give us in the original paper:
But despite detailed knowledge of their roosting and foraging behaviour, the selective benefit of running for these bats in the wild is not known. Presumably, vampire bats are most likely to run when manoeuvring around prey animals while feeding, and they may have used the gait more before the introduction of domestic livestock to the Americas in the sixteenth century.
Cornell also has a news story on their website; from that:
However, running may help them avoid being stepped on, Riskin suggests. More likely, the researchers say, the ability to run evolved long ago, when vampire bats had to prey on faster South American athletes such as the agouti, a rodent about the size of a hare, which might wake up and take a swipe at the nocturnal visitor. It remains unclear exactly what the native prey were before the introduction of cattle, he adds...
Riskin explains, "The vampire bat is good on the ground because when you feed on the hoof of an animal that weighs 14,000 times more than you do, it's dangerous."
Cornell link with movie.
If nothing else, when and where else would you get to see a bat run on a treadmill?
Enjoy!