When most people think of animals moving at high speed, they envision cheetahs or swiftly diving raptors, but probably not small and unfamiliar nocturnal flying mammals.
When most people think of animals moving at high speed, they envision cheetahs or swiftly diving raptors, but probably not small and unfamiliar nocturnal flying mammals. Yet, a new study suggests that Brazilian free-tailed bats (Tadarida brasiliensis) may achieve speeds of up to 160 kilometers (99.42 miles) per hour in level flight. This ranks this species of bats faster than any previously documented bird or bat in level flight.
“These are the fastest powered flight speeds documented yet in any vertebrate that is, in bats or birds,” Explains Gary McCracken of the University of Tennessee in Knoxville New Scientist. “We didn’t expect these results, even though the Brazilian free-tailed bats are known for their exceptional fast flight.”
This may be due to their aerodynamic body shape and longer-than-average wings compared to other bat species. Animals with long and narrow wings are typically built for faster flight. Consider the fastest bird on record for level flight, the common swift (Apus apus), which can reach speeds around 112 km/h. Peregrine falcons can reach speeds of up to 300 kilometers per hour, but only when diving.
“Most of the time, these animals [Brazilian free-tailed bats] are moving at moderate speeds, but what we see here is that they exceed these expectations and quite dramatically for brief periods of time,” McCracken says.
McCracken and colleagues at the Max Planck Institute for Ornithology used an airplane tracking method to document moderate flight speeds of the Brazilian free-tailed bats, and observed bouts of very rapid flight.
“We don’t know the behavioral context of why these bats are doing this, but they must have a good reason as flight is the most expensive form of animal locomotion,” McCracken says.
A small radio transmitter was attached to the backs of the bats and was tracked using a mobile receiver on a small aircraft. The scientists also evaluated data from nearby weather stations to note wind conditions at the time of the studied flights.
This study sheds new light on the mystery of bats and may help reshape public perception of these elusive mammals.
Bracken Cave is the summer maternity roost of more than 15 million Mexican free-tailed bats, a subspecies of the Brazilian free-tailed bat.