Researchers Find Bats Use Tails to Assist Takeoff, Flight

Rick Adams

Bat researcher Rick Adams holds one of his favorite mammals. Related: photo gallery at end of article

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Super slow-motion video clips (no audio) taken with high-speed cameras during the research project.

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Researchers at the University of Northern Colorado have discovered that bats flap their tail membrane like a wing to produce potentially important thrust during takeoffs.

Using a high-speed video camera, Professor Rick Adams and his graduate students captured for the first time bats moving their tails above and below their bodies in a similar fashion to their hand-wings. This unique movement, indiscernible to the naked eye and previously undetected, is unlike that observed in any other flying vertebrate.

"This changes fundamental thinking not just for bats, but for vertebrate flight in general," said Adams, principle Investigator of the Bat Research Lab located in UNC's School of Biological Sciences.

Adams and his team spent two summers filming more than 100 bats across five species in Boulder County to study their flight as part of the UNC grant-funded project. Adams said it took "almost three years to analyze all the films and digitize all the motions" before being published Feb. 29 by the prestigious scientific journal PLoS ONE (Read the article).

The article is co-authored by UNC graduate student Emily Snode and Jason Shaw, a doctoral student at the time of the data collection and analysis who subsequently graduated.

"We decided on a whim to film our Colorado bats launching from a horizontal platform because this had never been done," said Adams, author of the award-winning book Bats of the Rocky Mountain West.

"Once we filmed them head-on flying into the camera, we could see that they were folding up the tail membrane on the upstroke to avoid down drafts and then opening it for the downstroke to push out air that would cause a rearward thrust — like fanning yourself with a piece of cardboard."

The tail-flapping motion, termed "Tail-Assisted-Flight-Thrust (TAFT)" by the researchers, is similar to the way that dolphins and manatees use their flukes to thrust through water, Adams said. The degree to which the tail flapping occurred related to body mass, agility and habitat-use patterns of each species.

More research is planned to determine the amount of thrust produced by the tail, which makes up about 20 percent of the total wing area in bats, and how many of the approximately 1,200 species of bats use this flight mode.

"Further investigation into how and when bats use the tail-wing will allow us to better understand how and why bats are the most agile aerial vertebrates on the Earth today," Adams said. "Also, for about a decade the military has been attempting to build a micro-aerial machine that flaps and moves like a bat. Our data may contribute to how these artificial machines are developed."

For more information about bat research at UNC, visit http://www.unco.edu/nhs/biology/faculty_staff/adams/LabPortal.htm

- UNC News Service