A Mexican free-tailed bat hunts a corn earworm moth.
A Mexican free-tailed bat hunts a corn earworm moth.

While researching our QUEST TV story on Northern California’s bats, I discovered these stunning videos of bats in mid flight produced by the labs of biologists Sharon Swartz and Kenny Breuer, at Brown University, in Rhode Island.

Using high-speed video equipment that has become affordable for scientists in the past five years, Breuer and Swartz created the movies as a research tool to investigate the flight mechanics of bats. They coax the bats to fly inside wind tunnels using food rewards.

Lesser dog-faced fruit bat.

The videos reveal the intricacies of how bats use their wings.

“One thing we found is that the movements of the wing are extremely complex compared to birds and insects,” said Swartz. “They have many, many joints they can control independently.”

Their complex wings enable bats to make sharp turns that birds can’t manage.

“They don’t necessarily turn fast,” said Swartz, “but they can turn on a dime.”

Bat makes a sharp turn.

Bat wings are also made out of soft skin – which Swartz calls “compliant.” This gives bats yet another advantage over birds and insects.

“If your wing is made of compliant skin,” she said, “then it billows and that gives you extra lift.”

Not all bat wings are the same, though. Mexican free-tailed bats, which are abundant in California’s Central Valley, have stiffer wings than species like the lesser dog-faced fruit bat found in Southeast Asia.

“As we’ve studied the Mexican free-tailed bats, it turns out that their wing motions look very much like birds’,” said Swartz. “The wing stays pretty rigid, even though they have the same joints than the fruit bats.”

Mexican free-tailed bat. Credit: Nick Hristov and Tatjana Hubel, Brown University

Swartz believes the differences in the wing capabilities of Mexican free-tailed bats and lesser dog-faced fruit bats are related to the differences in their diets. The Mexican free-tailed bats eat mainly insects, while the lesser dog-faced fruit bats eat, well, mainly fruit. Fruit-eating bats need to move through their habitat slower than insect-eating bats, Swartz said. And because they’re moving more slowly, it’s harder for them to maintain lift.

“It might be that the animals that need to fly more slowly need the three-dimensional complexity to make up for that,” she said.

Watch more videos from the Swartz and Breuer labs.

Watch QUEST TV’s story on Northern California’s bats.

Bat Flight a Mechanical Marvel 10 March,2016Gabriela Quirós


Gabriela Quirós

Gabriela Quirós is a video producer for KQED Science and the coordinating producer for Deep Look. She started her journalism career 25 years ago as a newspaper reporter in Costa Rica, where she grew up. She won two national reporting awards there for series on C-sections and organic agriculture, and developed a life-long interest in health reporting. She moved to the Bay Area in 1996 to study documentary filmmaking at the University of California-Berkeley, where she received master’s degrees in journalism and Latin American studies. She joined KQED as a TV producer when its science series QUEST started in 2006 and has covered everything from Alzheimer’s to bee die-offs to dark energy. She has won five regional Emmys and has shared awards from the Jackson Hole Wildlife Film Festival, the Society of Professional Journalists and the Society of Environmental Journalists. Independent from her work in KQED's science unit, she produced and directed the hour-long documentary Beautiful Sin, about the surprising story of how Costa Rica became the only country in the world to outlaw in vitro fertilization. The film aired nationally on public television stations in 2015.

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