These are the fastest powered flight speeds documented yet in any vertebrate that is, in bats or birds.
Brazilian free-tailed bats are not “faster than a speeding bullet,” but they’ve recently been clocked in tests at 100 mile per hour (160 km per hour), making them faster than a speeding bird … in fact, faster than all speeding birds on Earth.
What makes these Brazilian free-tailed bats (Tadarida brasiliensis) so fast? For one thing, they live not in Brazil but in Texas, where everything is bigger and faster. The bats migrate north from Mexico to spend their summers breeding in the Frio Bat Cave in Concan, Texas, 80 miles east of San Antonio. The Frio Bat Cave holds the second largest bat population in the world (and the largest one open to the public). That’s where Gary McCracken, professor of Ecology & Evolutionary Biology at the University of Tennessee at Knoxville, found the world’s fastest flying vertebrate.
McCracken’s research team dragged an airplane tracking device to the Frio Bat Cave and measured the ground speeds of seven bats. All of them hit 100 km/ph (62 mph) and one reached 160 km/ph. That beats the speed of the world’s fastest bird – the common swift – which has been clocked at 112 km/ph (70 mph). That speed shocked McCracken
Most of the time, these animals are moving at moderate speeds, but what we see here is that they exceed these expectations and quite dramatically for brief periods of time.
The team took the measurements on a still night and only on level-flying bats to avoid the influence of tailwinds or gravity. So what gives them their incredible speed? It could be that free tail, which makes up half of their body length. Combined with their long and narrow but angular wings, they’re built for fast flight, says Sharon Swartz, team member and co-author of their report in the journal Royal Society Open Science.
The skin of bat wings is full of muscles that can change the skin’s stiffness, unlike bird or insect wings, which are stiff, much like the planes we build.
More study is needed to fully understand how these bats fly like a bat out of hell. Where did that expression come from anyway? Turns out it dates back to 414 BC to The Birds by the Greek playwright Aristophanes.
Near by the land of the Sciapodes there is a marsh, from the borders whereof the unwashed Socrates evokes the souls of men. Pisander came one day to see his soul, which he had left there when still alive. He offered a little victim, a camel, slit his throat and, following the example of Odysseus, stepped one pace backwards. Then that bat of a Chaerephon came up from hell to drink the camel's blood.
Now it’s tied to the famous song by Meat Loaf, who probably ignores all of the people who fly away like a bat out of hell when he starts to sing it.