Vampire Bat walking and running on its wings (2 videos)
A vampire bat runs on a treadmill. As the pace picks up, the bat shifts from its walking gait to bounding forward with its wings.
Vampire bats are bats whose food source is blood, a dietary trait called hematophagy. Three bat species feed solely on blood: the common vampire bat (Desmodus rotundus), the hairy-legged vampire bat (Diphylla ecaudata), and the white-winged vampire bat (Diaemus youngi). All three species are native to the New World, ranging from Mexico to Brazil, Chile, and Argentina.
While other bats have almost lost the ability to maneuver on land, 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. [via]
Looking at a vampire bat on a treadmill shows how the bat walks by stepping forward on one wing at a time.